Dynamical modeling and free vibration analysis of spinning pipes conveying fluid with axial deployment

Science.gov (United States)

Liang, Feng; Yang, Xiao-Dong; Zhang, Wei; Qian, Ying-Jing

2018-03-01

In this paper, a dynamical model of simply-supported spinning pipes conveying fluid with axial deployment is proposed and the transverse free vibration and stability for such a doubly gyroscopic system involving time-dependent parameters are investigated. The partial differential equations of motion are derived by the extended Hamilton principle and then truncated by the Galerkin technique. The time-variant frequencies, mode shapes and responses to initial conditions are comprehensively investigated to reveal the dynamical essence of the system. It is indicated that the qualitative stability evolution of the system mainly depends on the effect of fluid-structure interaction (FSI), while the spinning motion will enhance the pipe rigidity and eliminate the buckling instability. The dynamical evolution of a retracting pipe is almost inverse to that of the deploying one. The pipe possesses different mode configurations of spatial curves as the pipe length increases and some modal and response characteristics of the present system are found rather distinct from those of deploying cantilevered structures.

Inelastic response of piping systems subjected to in-structure seismic excitation

International Nuclear Information System (INIS)

Campbell, R.D.; Kennedy, R.P.; Trasher, R.D.

1983-01-01

A study was undertaken to examine the inelastic response of single-degree-of-freedom systems and a simple piping system to varying levels of earthquake loading with superimposed static loading. The objective was to examine the conservatism inherent in ASME code rules for the design of piping systems by quantifying the ratio of the dynamic margin to the static margin for various degrees of inelastic strain, system frequencies and instructure time histories. Previous studies of elastic, perfectly-plastic and bilinear strain-hardening, single-degree-of-freedom models subjected to earthquake ground motion records have demonstrated the conservatism in current design methodology and design codes for earthquake resistant design of structures. This study compares response of single degree of freedom and simple piping system subjected to typical in-structure earthquake time histories and focuses on the excess margin inherent in current design criteria for piping systems. It is shown that the factor of safety against failure is variable and is dependent upon the frequency content of the loading, the dynamic characteristics of the piping system and the allowable system ductility. A recommendation is made for revision to current criteria on the basis of maintaining a constant factor of safety for dynamic and static loading

Investigation of the conservatism associated with different combinations between primary and secondary piping responses

International Nuclear Information System (INIS)

Wang, Y.K.; Subudhi, M.; Bezler, P.

1983-01-01

This report includes the findings of an investigation of the conservatism associated with different combinations between the primary and secondary stress components for piping systems under dynamic loading, such as in an earthquake event. The primary stresses are induced by piping response to its mass inertia effects. The secondary stresses are induced by relative displacements of piping supports. The study involves an independnent time history analysis of several typical piping models to predict a best estimate of the actual dynamic and pseudo-static pipe responses to an earthquake. These piping systems are also analyzed using the response spectrum method to obtain the maximum primary stress components. Secondary stresses are next calculated by performing a set of static analyses which provide the worst stress condition. The two components are then combined by both SRSS and absolute sum methods as the results are compared with time history solutions. It is found that the SRSS combination of the primary and secondary stress components yield acceptable results provided the secondary stress component is calculated in the most unfavorable phasing relationship among displacements of piping supports

Novel developments in linear modal description of piping system dynamic behavior

International Nuclear Information System (INIS)

Revesz, Z.

1989-01-01

Novel developments in dynamic analysis of piping systems are described. The ASME BPV Codes, 1986 describes methods that are considered as adequate to analyze piping systems under dynamic loading, and also states that the method described in the codes are not the only acceptable ones. With straightforward application of the principles and methods laid down in the code novel numerical techniques can be developed. These techniques allow to obtain correct, conservative estimates of the piping system response and to reduce the computed stresses the same time. Beyond that, the particular algorithm which is presented is also suitable to analyze systems which include non-linear (viscous) damping elements

A new approach to solve elastoplastic dynamic piping problems

International Nuclear Information System (INIS)

Leite de Andrade, J.E.; Guerreiro Ribeiro, S.V.

1981-01-01

A new method to perform the elastoplastic dynamic analysis of pipes is presented here, in which the pipe is analysed as a beam, and a bilinear eleastic-plastic behavior for the material is assumed. Pipe whip restraints are simulated as spring of bilinear elastic-plastic behavior with the provision for considering viscous damping. A numerical method was implemented in which plastic strain is treated as equivalent applied (force or moment) excitations, reducing the elastoplastic analysis of the structure to an elastic analysis of the same structure with a set of additional applied excitations. So the stiffness matrix and the eigenvectors do not vary with time. This procedure allows the response of the system to be computed by using dynamic influence coefficients, which are calculated from the elastic solution. For those structures whose dynamic elastic solutions are known in closed form, the present scheme seems to be very attractive, e.g., simple supported and cantilever beams. For those structures with unknown analytical elastic solutions, the finite element method will provide them. (orig./GL)

Response margins investigation of piping dynamic analyses using the independent support motion method and PVRC [Pressure Vessel Research Committee] damping

International Nuclear Information System (INIS)

Bezler, P.; Wang, Y.K.; Reich, M.

1988-03-01

An evaluation of Independent Support Motion (ISM) response spectrum methods of analysis coupled with the Pressure Vessel Research Committee (PVRC) recommendation for damping, to compute the dynamic component of the seismic response of piping systems, was completed. Response estimates for five piping/structural systems were developed using fourteen variants of the ISM response spectrum method, the Uniform Support Motions response spectrum method and the ISM time history analysis method, all based on the PVRC recommendations for damping. The ISM/PVRC calculational procedures were found to exhibit orderly characteristics with levels of conservatism comparable to those obtained with the ISM/uniform damping procedures. Using the ISM/PVRC response spectrum method with absolute combination between group contributions provided consistently conservative results while using the ISM/PVRC response spectrum method with square root sum of squares combination between group contributions provided estimates of response which were deemed to be acceptable

An experimental study of the response of the multiple support piping systems

International Nuclear Information System (INIS)

Chiba, T.; Koyanagi, R.

1987-01-01

From the test results, following remarks have been obtained. 1. Since the effect of internal pressure was not so small on the stress response, its effect should be considered in the design of piping systems. 2. The effect of the phase of excitations was fairly dominant to the response of piping systems. From this fact, the adopting of the support structures which have different dynamic characteristics may be one of the more realistic approaches to reduce the response of piping systems. 3. The acceleration responses near the support points are always underestimated because the natural modes of the analysis are zero at these support points. 4. If the pseudo-static response is dominant, the stress responses near the support points are always overestimated by the ABS method to support groups. In such case the SRSS method is recommended. 5. The 10% method to the closely spaced modes is conservative for the flexible piping. The closely spaced mode methods to these flexible piping systems should be used carefully. 6. The SRSS combination method is offered the reasonable results to the space, modes and support groups in the multiple response spectra method. (orig.)

A piezoelectric transducer for measurement of dynamic strain in pipes

Energy Technology Data Exchange (ETDEWEB)

Lannes, Daniel P.; Gama, Antonio L. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

2009-07-01

This work presents a new strain transducer developed mainly for the inspection and evaluation of piping systems with excessive vibration. Vibration is one of the most common causes of piping failures. These failures could be avoided if the vibration problems were identified and quickly evaluated. Procedures for evaluation of piping vibration are usually based on pipe velocity or displacement. Although simple and fast, these procedures do not provide precise information on the risk of piping fatigue failure. Through the measurement of pipe dynamic strains the risk of failure due to vibration can be determined more accurately. The measurement of strain is usually performed using the conventional strain gauge method. Although efficient and accurate, the implementation of the conventional strain gauge technique may become a difficult task in certain industrial scenarios. Motivated by the need of a simple and rapid method for pipe dynamic strain measurement, a piezoelectric dynamic strain transducer was developed. This work presents a description of the piezoelectric strain transducer and the preliminary results of pipe strain measurements. The transducer can be applied directly to the pipe through magnetic bases allowing for the quick measurement of the dynamic strains in many points of the pipe. The transducer signal can be read with the same commercial data collectors used for accelerometers. (author)

Dynamics of large-diameter water pipes in hydroelectric power plants

Science.gov (United States)

Pavić, G.; Chevillotte, F.; Heraud, J.

2017-04-01

An outline is made of physical behaviour of water - filled large pipes. The fluid-wall coupling, the key factor governing the pipe dynamics, is discussed in some detail. Different circumferential pipe modes and the associated cut-on frequencies are addressed from a theoretical as well as practical point of view. Major attention is paid to the breathing mode in view of its importance regarding main dynamic phenomena, such as water hammer. Selected measurement results done at EDF are presented to demonstrate how an external, non-intrusive sensor can detect pressure pulsations of the breathing mode in a pressure pipe. Differences in the pressure measurement using intrusive and non-intrusive sensors reveal the full complexity of large-diameter pipe dynamics.

The effect of cyclic and dynamic loads on carbon steel pipe

International Nuclear Information System (INIS)

Rudland, D.L.; Scott, P.M.; Wilkowski, G.M.

1996-02-01

This report presents the results of four 152-mm (6-inch) diameter, unpressurized, circumferential through-wall-cracked, dynamic pipe experiments fabricated from STS410 carbon steel pipe manufactured in Japan. For three of these experiments, the through-wall crack was in the base metal. The displacement histories applied to these experiments were a quasi-static monotonic, dynamic monotonic, and dynamic, cyclic (R = -1) history. The through-wall crack for the third experiment was in a tungsten-inert-gas weld, fabricated in Japan, joining two lengths of STS410 pipe. The displacement history for this experiment was the same history applied to the dynamic, cyclic base metal experiment. The test temperature for each experiment was 300 C (572 F). The objective of these experiments was to compare a Japanese carbon steel pipe material with US pipe material, to ascertain whether this Japanese steel was as sensitive to dynamic and cyclic effects as US carbon steel pipe. In support of these pipe experiments, quasi-static and dynamic, tensile and fracture toughness tests were conducted. An analysis effort was performed that involved comparing experimental crack initiation and maximum moments with predictions based on available fracture prediction models, and calculating J-R curves for the pipe experiments using the η-factor method

Dynamic Load on a Pipe Caused by Acetylene Detonations – Experiments and Theoretical Approaches

Directory of Open Access Journals (Sweden)

Axel Sperber

1999-01-01

Full Text Available The load acting on the wall of a pipe by a detonation, which is travelling through, is not yet well characterized. The main reasons are the limited amount of sufficiently accurate pressure time history data and the requirement of considering the dynamics of the system. Laser vibrometry measurements were performed to determine the dynamic response of the pipe wall on a detonation. Different modelling approaches were used to quantify, theoretically, the radial displacements of the pipe wall. There is good agreement between measured and predicted values of vibration frequencies and the propagation velocities of transverse waves. Discrepancies mainly due to wave propagation effects were found in the amplitudes of the radial velocities. They might be overcome by the use of a dynamic load factor or improved modelling methods.

Pipe rupture and steam/water hammer design loads for dynamic analysis of piping systems

International Nuclear Information System (INIS)

Strong, B.R. Jr.; Baschiere, R.J.

1978-01-01

The design of restraints and protection devices for nuclear Class I and Class II piping systems must consider severe pipe rupture and steam/water hammer loadings. Limited stress margins require that an accurate prediction of these loads be obtained with a minimum of conservatism in the loads. Methods are available currently for such fluid transient load development, but each method is severely restricted as to the complexity and/or the range of fluid state excursions which can be simulated. This paper presents a general technique for generation of pipe rupture and steam/water hammer design loads for dynamic analysis of nuclear piping systems which does not have the limitations of existing methods. Blowdown thrust loadings and unbalanced piping acceleration loads for restraint design of all nuclear piping systems may be found using this method. The technique allows the effects of two-phase distributed friction, liquid flashing and condensation, and the surrounding thermal and mechanical equipment to be modeled. A new form of the fluid momentum equation is presented which incorporates computer generated fluid acceleration histories by inclusion of a geometry integral termed the 'force equivalent area' (FEA). The FEA values permit the coupling of versatile thermal-hydraulic programs to piping dynamics programs. Typical applications of the method to pipe rupture problems are presented and the resultant load histories compared with existing techniques. (Auth.)

Nonlinear dynamic analysis of high energy line pipe whip

International Nuclear Information System (INIS)

Hsu, L.C.; Kuo, A.Y.; Tang, H.T.

1983-01-01

To facilitate potential cost savings in pipe whip protection design, TVA conducted a 1'' high pressure line break test to investigate the pipe whip behavior. The test results are available to EPRI as a data base for a generic study on nonlinear dynamic behavior of piping systems and pipe whip phenomena. This paper describes a nonlinear dynamic analysis of the TVA high energy line tests using ABAQUS-EPGEN code. The analysis considers the effects of large deformation and high strain rate on resisting moment and energy absorption capability of the analyzed piping system. The numerical results of impact forces, impact velocities, and reaction forces at pipe supports are compared to the TVA test data. The pipe whip impact time and forces have also been calculated per the current NRC guidelines and compared. The calculated pipe support reaction forces prior to impact have been found to be in good agreement with the TVA test data except for some peak values at the very beginning of the pipe break. These peaks are believed to be due to stress wave propagation which cannot be addressed by the ABAQUS code. Both the effects of elbow crushing and strain rate have been approximately simulated. The results are found to be important on pipe whip impact evaluation. (orig.)

Response of the primary piping loop to an HCDA

International Nuclear Information System (INIS)

Chang, Y.W.; Moneim, M.T.A.; Wang, C.Y.; Gvildys, J.

1975-01-01

The paper describes a method for analyzing the response of the primary piping loop that consists of straight pipes, elbows, and other components connected in series and subject to hypothetical core disruptive accident (HCDA) loads at both ends of the loop. The complete hydrodynamic equations in two-dimensions, that include both the nonlinear convective and viscous dissipation terms are used for the fluid dynamics together with the implicit ICE technique. The external walls of the pipes and components are treated as thin shells in which the analysis accounts for the membrane and bending strength of the wall, elastic-plastic material behavior, as well as large deformation under the effect of transient loading conditions. In the straight pipes, the flow is assumed to be axisymmetric; in the elbow regions, the two dimensions considered are the r and theta directions. The flow in the other components is also assumed to be axisymmetric; the components are modeled as a circular cylinder, in which the radius of the cylinder can be varied to conform with the outside shape of the component and the flow area inside can be changed independently from the outside shape. However, they must remain axially symmetric. The method is applied to a piping loop which consists of six elastic-plastic pipes and five rigid elbows connected in series and subjected to pressure pulses at both ends of the loop

Elastic-plastic dynamic behavior of guard pipes due to sudden opening of longitudinal cracks in the inner pipe and crash to the guard pipe wall

International Nuclear Information System (INIS)

Theuer, E.; Heller, M.

1979-01-01

Integrity of guard pipes is an important parameter in the design of nuclear steam supply systems. A guard pipe shall withstand all kinds of postulated inner pipe breaks without failure. Sudden opening of a crack in the inner pipe and crash of crack borders to the guard pipe wall represent a shock problem where complex phenomena of dynamic plastification as well as dynamic behavior of the entire system have to be taken in consideration. The problem was analyzed by means of Finite Element computation using the general purpose program MARC. Equation of motion was resolved by direct integration using the Newmark β-operator. Analysis shows that after 1,2 m sec crack borders touch the guard pipe wall for the first time. At this moment a considerable amount of local plastification appears in the inner pipe wall, while the guard pipe is nearly unstressed. After initial touching, the crack borders begin to slip along the guard pipe wall. Subsequently, a short withdrawal of the crack borders and a new crash occur, while the inner pipe rolls along the guard pipe wall. The analysis procedure described is suitable for designing numerous guard pipe geometries as well as U-Bolt restraint systems which have to withstand high-energy pipe rupture impact. (orig.)

Analysis of pressure wave transients and seismic response in LMFBR piping systems using the SHAPS code

International Nuclear Information System (INIS)

Zeuch, W.R.; Wang, C.Y.

1985-01-01

This paper presents some of the current capabilities of the three-dimensional piping code SHAPS and demonstrates their usefulness in handling analyses encountered in typical LMFBR studies. Several examples demonstrate the utility of the SHAPS code for problems involving fluid-structure interactions and seismic-related events occurring in three-dimensional piping networks. Results of two studies of pressure wave propagation demonstrate the dynamic coupling of pipes and elbows producing global motion and rigorous treatment of physical quantities such as changes in density, pressure, and strain energy. Results of the seismic analysis demonstrate the capability of SHAPS to handle dynamic structural response within a piping network over an extended transient period of several seconds. Variation in dominant stress frequencies and global translational frequencies were easily handled with the code. 4 refs., 10 figs

Margins for an in-plant piping system under dynamic loading

International Nuclear Information System (INIS)

Kot, C.A.; Srinivasan, M.G.; Hsieh, B.J.

1991-01-01

The objective of this study is to verify that piping designed according to current practice does indeed have a large margin against failure and to quantify the excess capacity for piping and dynamic pipe supports on the basis of data obtained in a series of high-level seismic experiments (designated SHAM) on an in-plant piping system at the HDR (Heissdampfreaktor) Test Facility in Germany. 4 refs., 6 tabs

Calculation of dynamic hydraulic forces in nuclear plant piping systems

International Nuclear Information System (INIS)

Choi, D.K.

1982-01-01

A computer code was developed as one of the tools needed for analysis of piping dynamic loading on nuclear power plant high energy piping systems, including reactor safety and relief value upstream and discharge piping systems. The code calculates the transient hydraulic data and dynamic forces within the one-dimensional system, caused by a pipe rupture or sudden value motion, using a fixed space and varying time grid-method of characteristics. Subcooled, superheated, homogeneous two-phase and transition flow regimes are considered. A non-equilibrium effect is also considered in computing the fluid specific volume and fluid local sonic velocity in the two-phase mixture. Various hydraulic components such as a spring loaded or power operated value, enlarger, orifice, pressurized tank, multiple pipe junction (tee), etc. are considered as boundary conditions. Comparisons of calculated results with available experimental data shows a good agreement. (Author)

Effects of supporting structures on dynamic response of nuclear power plant equipment and piping systems

International Nuclear Information System (INIS)

Stoykovich, M.

1982-01-01

This paper presents the evaluation of the effects of supporting structures in dynamic analysis of equipment or piping systems, which involves formulations for determining reduced stiffness and mass matrices associated with the number of degrees of freedom corresponding to the support nodal points of a finite element model. Also, evaluation of a composite damping matrix associated with different damping properties of supporting structures, equipment, and piping systems is considered. Determination of spring constants, effective masses and mass moments of inertia, and damping values as fractions of critical damping on the basis of the theory of rigid bases on the surfaces of an elastic halfspace is demonstrated

Vibration response of a pipe subjected to two-phase flow: Analytical formulations and experiments

Energy Technology Data Exchange (ETDEWEB)

Ortiz-Vidal, L. Enrique, E-mail: leortiz@sc.usp.br [Department of Mechanical Engineering, Sao Carlos School of Engineering, University of Sao Paulo (USP), Av., Trabalhador São-carlense, 400, 13566-970 São Carlos, SP (Brazil); Mureithi, Njuki W., E-mail: njuki.mureithi@polymtl.ca [Department of Mechanical Engineering, Polytechnique Montreal, Département de Géniemécanique 2900, H3T 1J7 Montreal, QC (Canada); Rodriguez, Oscar M.H., E-mail: oscarmhr@sc.usp.br [Department of Mechanical Engineering, Sao Carlos School of Engineering, University of Sao Paulo (USP), Av., Trabalhador São-carlense, 400, 13566-970 São Carlos, SP (Brazil)

2017-03-15

Highlights: • Analytical formulations for two-phase flow-induced vibration (2-FIV) are presented. • Standard deviation of acceleration pipe response is a function of the square of shear velocity. • Peak frequency is correlated to hydrodynamic mass and consequently to void fraction. • Dynamic pipe response increases with increasing mixture velocity and void fraction. • Hydrodynamic mass in 2-FIV in horizontal pipe is proportional to mixture density. - Abstract: This paper treats the two-phase flow-induced vibration in pipes. A broad range of two-phase flow conditions, including bubbly, dispersed and slug flow, were tested in a clamped-clamped straight horizontal pipe. The vibration response of both transversal directions for two span lengths was measured. From experimental results, an in-depth discussion on the nature of the flow excitation and flow-parameters influence is presented. The hydrodynamic mass parameter is also studied. Experimental results suggest that it is proportional to mixture density. On the other hand, two analytical formulations were developed and tested against experimental results. One formulation predicts the quadratic trend between standard deviation of acceleration and shear velocity found in experiments. The other formulation indicates that the peak-frequency of vibration response depends strongly on void fraction. It provides accurate predictions of peak-frequency, predicting 97.6% of the data within ±10% error bands.

Calculation of fluid (steam) hammer loading to piping systems by the response spectrum method

International Nuclear Information System (INIS)

Krause, G.; Schrader, W.; Leimbach, K.R.

1983-01-01

Today computations of fluid and steam hammer loading to piping systems are usually performed as a time-history analysis in which the transient pressure forces act as external excitations. For practical purposes it is desirable to be able to treat fluid hammer loading using the response spectrum method similarily as loads from external events. Two advantages arise from the use of spectra in the analysis of piping systems subjected to dynamic force excitations. Firstly, the response spectrum method is much less sensitive to model idealization than the time-history method. Secondly, computational efforts are reduced. In this paper the algorithm for the treatment of force excitations through the modal response spectrum method is briefly presented. The effect of the residuum accounting for higher modes which are not part of the modal decomposition is considered. In particular various methods of superposition of the responses of the dynamic forces and of the modes are investigated. Results and comparisons are presented of several response spectrum analyses and time-history analyses. (orig.)

High-level seismic tests of piping at the HDR [Heissdampfreaktor

International Nuclear Information System (INIS)

Kot, C.A.; Srinivasan, M.G.; Hsieh, B.J.; Costello, J.F.

1989-01-01

As part of the second-phase testing at the Heissdampfreaktor (HDR) Test Facility in Kahl/Main, Federal Republic of Germany (FRG), high-level seismic experiments, designated SHAM, were performed on an in-plant piping system during the period of 19 April to 27 May 1988. The objectives of the SHAM experiments were to (1) study the response of piping subjected to seismic excitation levels that exceed design levels manifold and which may result in failure/plastification of pipe supports and pipe elements; (2) provide data for the validation of linear and nonlinear pipe response analyses; (3) compare and evaluate, under identical loading conditions, the performance of various dynamic support system, ranging from very flexible to very stiff support configurations; (4) establish seismic margins for piping, dynamic pipe supports, and pipe anchorages; and (5) investigate the response, operability, and fragility of dynamic supports and of a typical US gate valve under extreme levels of seismic excitation. A brief description of the SHAM tests is provided, followed by highlights of the test results that are given primarily in the form of maximum response values. Also presented are very limited comparisons of experimental data and pretest analytical predictions. 6 refs., 8 figs

Piping dynamic analysis by the synthesis method

International Nuclear Information System (INIS)

Bezler, P.; Curreri, J.R.

1976-01-01

Since piping systems are a frequent source of noise and vibrations, their efficient dynamic analysis is imperative. As an alternate to more conventional analyses methods, an application of the synthesis method to piping vibrations analyses is demonstrated. Specifically, the technique is illustrated by determining the normal modes and natural frequencies of a composite bend from the normal mode and natural frequency data of two component parts. A comparison of the results to those derived for the composite bend by other techniques is made

Effect of dynamic monotonic and cyclic loading on fracture behavior for Japanese carbon steel pipe STS410

Energy Technology Data Exchange (ETDEWEB)

Kinoshita, Kanji; Murayama, Kouichi; Ogata, Hiroyuki [and others

1997-04-01

The fracture behavior for Japanese carbon steel pipe STS410 was examined under dynamic monotonic and cyclic loading through a research program of International Piping Integrity Research Group (EPIRG-2), in order to evaluate the strength of pipe during the seismic event The tensile test and the fracture toughness test were conducted for base metal and TIG weld metal. Three base metal pipe specimens, 1,500mm in length and 6-inch diameter sch.120, were employed for a quasi-static monotonic, a dynamic monotonic and a dynamic cyclic loading pipe fracture tests. One weld joint pipe specimen was also employed for a dynamic cyclic loading test In the dynamic cyclic loading test, the displacement was controlled as applying the fully reversed load (R=-1). The pipe specimens with a circumferential through-wall crack were subjected four point bending load at 300C in air. Japanese STS410 carbon steel pipe material was found to have high toughness under dynamic loading condition through the CT fracture toughness test. As the results of pipe fracture tests, the maximum moment to pipe fracture under dynamic monotonic and cyclic loading condition, could be estimated by plastic collapse criterion and the effect of dynamic monotonic loading and cyclic loading was a little on the maximum moment to pipe fracture of the STS410 carbon steel pipe. The STS410 carbon steel pipe seemed to be less sensitive to dynamic and cyclic loading effects than the A106Gr.B carbon steel pipe evaluated in IPIRG-1 program.

Effect of dynamic monotonic and cyclic loading on fracture behavior for Japanese carbon steel pipe STS410

International Nuclear Information System (INIS)

Kinoshita, Kanji; Murayama, Kouichi; Ogata, Hiroyuki

1997-01-01

The fracture behavior for Japanese carbon steel pipe STS410 was examined under dynamic monotonic and cyclic loading through a research program of International Piping Integrity Research Group (EPIRG-2), in order to evaluate the strength of pipe during the seismic event The tensile test and the fracture toughness test were conducted for base metal and TIG weld metal. Three base metal pipe specimens, 1,500mm in length and 6-inch diameter sch.120, were employed for a quasi-static monotonic, a dynamic monotonic and a dynamic cyclic loading pipe fracture tests. One weld joint pipe specimen was also employed for a dynamic cyclic loading test In the dynamic cyclic loading test, the displacement was controlled as applying the fully reversed load (R=-1). The pipe specimens with a circumferential through-wall crack were subjected four point bending load at 300C in air. Japanese STS410 carbon steel pipe material was found to have high toughness under dynamic loading condition through the CT fracture toughness test. As the results of pipe fracture tests, the maximum moment to pipe fracture under dynamic monotonic and cyclic loading condition, could be estimated by plastic collapse criterion and the effect of dynamic monotonic loading and cyclic loading was a little on the maximum moment to pipe fracture of the STS410 carbon steel pipe. The STS410 carbon steel pipe seemed to be less sensitive to dynamic and cyclic loading effects than the A106Gr.B carbon steel pipe evaluated in IPIRG-1 program

Considering dynamic friction and proper structural response in hydraulic load cases for realistic piping design

International Nuclear Information System (INIS)

Diesselhorst, T.; Diatschuk, P.; Schnellhammer, W.

2005-01-01

Concerning the design for hydraulic load cases there is always a sequence of fluid- and structural dynamic calculations, where the structural vibrations are induced by the time depending fluid forces. Therefore, in order to prevent excessive structural reactions, it is most important to avoid conservative fluid dynamic results. That refers to the maximum value of the pressure surge as well as to the damping of pressure oscillations. This is especially relevant in case of fluid-structure resonance. To meet these requirements the effect of dynamic wall friction was implemented in our fluid dynamic code. Thus, a more realistic damping behavior of the fluid forces was achieved. In the structural analysis code the damping of the pipe structure could be more accurate adapted to the real conditions. Additionally the local damping by viscous damper was included in the model. At supports now non-linear behavior like clearances can be simulated. The possibility of coupled calculation was installed to consider the effect of fluid structure interaction. The programmed effects are validated against measurement results from power plant systems. The favorable effects of the program improvements are demonstrated by typical examples. These included the realistic damping of pressure oscillations as well as a case of fluid-structure resonance. Additionally the effectiveness of the improved models of piping supports is demonstrated. (authors)

CEASEMT system: the TEDEL code. Pipings - Plasticity - Dynamics - Statics - Buckling - Thermoplasticity - Creep - Large displacements - FLUIDS - SEISMS - ASME

International Nuclear Information System (INIS)

Hoffmann, Alain; Jeanpierre, Francoise; Axisa, Francois; Chevalier, Gerard; Lepareux, Michel.

1977-01-01

The TEDEL code is intended for elastic and plastic computation of three-dimensional pipes and frames with possible junction to shells. The structures are described with using assemblies of beam elements, or piping elements such as, curved pipes, 90 0 elbows, tees, any elements, the stiffness properties of which are given to TEDEL. TEDEL allows the dynamic computation of the structures: search of eigenfrequencies and eigenmodes of vibration, time response to any time-dependent canvassing. This response can be obtained either from recombining a number of eigenmodes, or from a direct numerical integration of the dynamics equation. In these last two cases TEDEL accounts for some possible damping. A TEDEL option allows critical buckling loads to be computed (Euler). The structures can offer any shapes comprising any number of materials. The data are readout without any format, and distributed in optional commands with a precise physical meaning: GEOMETRY, MATERIALS, LOAD, COMPUTATION, END. A dynamical memory control allows the size of the routine to be adapted to the problem to be treated. For pipings, an option is intended for an automatic checking of the stress level with regard to the limiting values of the ASME. Geometrical data, node positions, element numbering are given by COCO which also delivers perspective drawings for the structure to be studied. The results on magnetic tapes can be treated by the subroutines ESPACE-VISU-TEMPS [fr

Numerical evaluation of cracked pipes under dynamic loading

International Nuclear Information System (INIS)

Petit, M.; Jamet, P.

1989-01-01

In order to apply the leak-before-break concept to piping systems, the behavior of cracked pipes under dynamic, and especially seismic, loadings must be studied. A simple finite element model of a cracked pipe has been developed and implemented in the general purpose computer code CASTEM 2000. The model is a generalization of the approach proposed by Paris and Tada (1). Considered loads are bending moment and axial force (representing thermal expansion and internal pressure.) The elastic characteristics of the model are determined using the Zahoor formulae for the geometry-dependent factors. Owing to the material behabior plasticity must be taken into account. To represent the crack growth, the material is defined by two characteristic values: J 1c which is the level of energy corresponding to crack initiation and the tearing modulus, T, which governs the length of propagation of the crack. For dynamic loads, unilateral conditions are imposed to represent crack closure. The model has been used for the design of dynamic tests to be conducted on shaking tables. Test principle is briefly described and numerical results are presented. Finally evaluation of margin, due to plasticity, in comparison with the standard design procedure is made

Free vibration analysis of multi-span pipe conveying fluid with dynamic stiffness method

International Nuclear Information System (INIS)

Li Baohui; Gao Hangshan; Zhai Hongbo; Liu Yongshou; Yue Zhufeng

2011-01-01

Research highlights: → The dynamic stiffness method was proposed to analysis the free vibration of multi-span pipe conveying fluid. → The main advantage of the proposed method is that it can hold a high precision even though the element size is large. → The flowing fluid can weaken the pipe stiffness, when the fluid velocity increases, the natural frequencies of pipe are decreasing. - Abstract: By taking a pipe as Timoshenko beam, in this paper the original 4-equation model of pipe conveying fluid was modified by taking the dynamic effects of fluid into account. The shape function that always used in the finite element method was replaced by the exact wave solution of the modified four equations. And then the dynamic stiffness was deduced for the free vibration of pipe conveying fluid. The proposed method was validated by comparing the results of critical velocity with analytical solution for a simply supported pipe at both ends. In the example, the proposed method was applied to calculate the first three natural frequencies of a three span pipe with twelve meters long in three different cases. The results of natural frequency for the pipe conveying stationary fluid fitted well with that calculated by finite element software Abaqus. It was shown that the dynamic stiffness method can still hold high precision even though the element's size was quite large. And this is the predominant advantage of the proposed method comparing with conventional finite element method.

Development of new damping devices for piping

International Nuclear Information System (INIS)

Kobayashi, Hiroe

1991-01-01

An increase of the damping ratio is known to be very effective for the seismic design of a piping system. Increasing the damping ratio and reducing the seismic response of the piping system, the following three types of damping devices for piping systems are introduced: (1) visco-elastic damper, (2) elasto-plastic damper and (3) compact dynamic damper. The dynamic characteristics of these damping devices were investigated by the component test and the applicability of them to the piping system was confirmed by the vibration test using a three dimensional piping model. These damping devices are more effective than mechanical snubbers to reduce the vibration of the piping system. (author)

Dynamic Stability of Pipe Conveying Fluid with Crack and Attached Masses

International Nuclear Information System (INIS)

Ahn, Tae Soo; Yoon, Han Ik; Son, In Soo; Ahn, Sung Jin

2007-01-01

In this paper, the dynamic stability of a cracked simply supported pipe conveying fluid with an attached mass is investigated. Also, the effect of attached masses on the dynamic stability of a simply supported pipe conveying fluid is presented for the different positions and depth of the crack. Based on the Euler-Bernoulli beam theory, the equation of motion can be constructed by the energy expressions using extended Hamilton's principle. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The crack is assumed to be in the first mode of a fracture and to be always opened during the vibrations. Finally, the critical flow velocities and stability maps of the pipe conveying fluid are obtained by changing the attached masses and crack severity

Development of nonlinear dynamic analysis program for nuclear piping systems

International Nuclear Information System (INIS)

Kamichika, Ryoichi; Izawa, Masahiro; Yamadera, Masao

1980-01-01

In the design for nuclear power piping, pipe-whip protection shall be considered in order to keep the function of safety related system even when postulated piping rupture occurs. This guideline was shown in U.S. Regulatory Guide 1.46 for the first time and has been applied in Japanese nuclear power plants. In order to analyze the dynamic behavior followed by pipe rupture, nonlinear analysis is required for the piping system including restraints which play the role of an energy absorber. REAPPS (Rupture Effective Analysis of Piping Systems) has been developed for this purpose. This program can be applied to general piping systems having branches etc. Pre- and post- processors are prepared in this program in order to easily input the data for the piping engineer and show the results optically by use of a graphic display respectively. The piping designer can easily solve many problems in his daily work by use of this program. This paper describes about the theoretical background and functions of this program and shows some examples. (author)

Crack stability in a representative piping system under combined inertial and seismic/dynamic displacement-controlled stresses. Subtask 1.3 final report

International Nuclear Information System (INIS)

Scott, P.; Olson, R.; Wilkowski, O.G.; Marschall, C.; Schmidt, R.

1997-06-01

This report presents the results from Subtask 1.3 of the International Piping Integrity Research Group (IPIRG) program. The objective of Subtask 1.3 is to develop data to assess analysis methodologies for characterizing the fracture behavior of circumferentially cracked pipe in a representative piping system under combined inertial and displacement-controlled stresses. A unique experimental facility was designed and constructed. The piping system evaluated is an expansion loop with over 30 meters of 16-inch diameter Schedule 100 pipe. The experimental facility is equipped with special hardware to ensure system boundary conditions could be appropriately modeled. The test matrix involved one uncracked and five cracked dynamic pipe-system experiments. The uncracked experiment was conducted to evaluate piping system damping and natural frequency characteristics. The cracked-pipe experiments evaluated the fracture behavior, pipe system response, and stability characteristics of five different materials. All cracked-pipe experiments were conducted at PWR conditions. Material characterization efforts provided tensile and fracture toughness properties of the different pipe materials at various strain rates and temperatures. Results from all pipe-system experiments and material characterization efforts are presented. Results of fracture mechanics analyses, dynamic finite element stress analyses, and stability analyses are presented and compared with experimental results

Crack stability in a representative piping system under combined inertial and seismic/dynamic displacement-controlled stresses. Subtask 1.3 final report

Energy Technology Data Exchange (ETDEWEB)

Scott, P.; Olson, R.; Wilkowski, O.G.; Marschall, C.; Schmidt, R.

1997-06-01

This report presents the results from Subtask 1.3 of the International Piping Integrity Research Group (IPIRG) program. The objective of Subtask 1.3 is to develop data to assess analysis methodologies for characterizing the fracture behavior of circumferentially cracked pipe in a representative piping system under combined inertial and displacement-controlled stresses. A unique experimental facility was designed and constructed. The piping system evaluated is an expansion loop with over 30 meters of 16-inch diameter Schedule 100 pipe. The experimental facility is equipped with special hardware to ensure system boundary conditions could be appropriately modeled. The test matrix involved one uncracked and five cracked dynamic pipe-system experiments. The uncracked experiment was conducted to evaluate piping system damping and natural frequency characteristics. The cracked-pipe experiments evaluated the fracture behavior, pipe system response, and stability characteristics of five different materials. All cracked-pipe experiments were conducted at PWR conditions. Material characterization efforts provided tensile and fracture toughness properties of the different pipe materials at various strain rates and temperatures. Results from all pipe-system experiments and material characterization efforts are presented. Results of fracture mechanics analyses, dynamic finite element stress analyses, and stability analyses are presented and compared with experimental results.

Dynamic pipe control with a multiple digit automatic measuring device

International Nuclear Information System (INIS)

Jenzer, P.

1984-01-01

With the flow rotating method, thin-walled pipes can be produced with very tight tolerances and high mechanical sturdiness. The measuring device permits a dynamic control of these pipes, the outer diameter of which can lie between 70 and 300 mm, the length between 500 and 2000 mm and the wall thickness between 0,5 and 10 mm. Depending on the pipe type, up to 27 measurements in a maximum of 5 measuring levels are to be controlled. (orig.) [de

Optimization of a pump-pipe system by dynamic programming

DEFF Research Database (Denmark)

Vidal, Rene Victor Valqui; Ferreira, Jose S.

1984-01-01

In this paper the problem of minimizing the total cost of a pump-pipe system in series is considered. The route of the pipeline and the number of pumping stations are known. The optimization will then consist in determining the control variables, diameter and thickness of the pipe and the size of...... of the pumps. A general mathematical model is formulated and Dynamic Programming is used to find an optimal solution....

Incremental-hinge piping analysis methods for inelastic seismic response prediction

International Nuclear Information System (INIS)

Jaquay, K.R.; Castle, W.R.; Larson, J.E.

1989-01-01

This paper proposes nonlinear seismic response prediction methods for nuclear piping systems based on simplified plastic hinge analyses. The simplified plastic hinge analyses utilize an incremental series of flat response spectrum loadings and replace yielded components with hinge elements when a predefined hinge moment is reached. These hinge moment values, developed by Rodabaugh, result in inelastic energy dissipation of the same magnitude as observed in seismic tests of piping components. Two definitions of design level equivalent loads are employed: one conservatively based on the peaks of the design acceleration response spectra, the other based on inelastic frequencies determined by the method of Krylov and Bogolyuboff recently extended by Lazzeri to piping. Both definitions account for piping system inelastic energy dissipation using Newmark-Hall inelastic response spectrum reduction factors and the displacement ductility results of the incremental-hinge analysis. Two ratchet-fatigue damage models are used: one developed by Rodabaugh that conservatively correlates Markl static fatigue expressions to seismic tests to failure of piping components; the other developed by Severud that uses the ratchet expression of Bree for elbows and Edmunds and Beer for straights, and defines ratchet-fatigue interaction using Coffin's ductility based fatigue equation. Comparisons of predicted behavior versus experimental results are provided for a high-level seismic test of a segment of a representative nuclear plant piping system. (orig.)

Pressurized water-reactor feedwater piping response to water hammer

International Nuclear Information System (INIS)

Arthur, D.

1978-03-01

The nuclear power industry is interested in steam-generator water hammer because it has damaged the piping and components at pressurized water reactors (PWRs). Water hammer arises when rapid steam condensation in the steam-generator feedwater inlet of a PWR causes depressurization, water-slug acceleration, and slug impact at the nearest pipe elbow. The resulting pressure pulse causes the pipe system to shake, sometimes violently. The objective of this study is to evaluate the potential structural effects of steam-generator water hammer on feedwater piping. This was accomplished by finite-element computation of the response of two sections of a typical feedwater pipe system to four representative water-hammer pulses. All four pulses produced high shear and bending stresses in both sections of pipe. Maximum calculated pipe stresses varied because the sections had different characteristics and were sensitive to boundary-condition modeling

Dynamic J-R Characteristics of RCS Pipe Materials for Ulchin Unit 3/4. (Evaluation of Dynamic Strain Aging Effects)

Energy Technology Data Exchange (ETDEWEB)

Hong, Jun Hwa; Lee, Bong Sang; Yoon, Ji Hyun; Oh, Jong Myung; Kim, Jin Won [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-09-01

5 materials (45 1T-CT specimens) were tested to evaluate dynamic J-R characteristics of RCS Pipe Materials for Ulchin Unit 3/4 (Evaluation of Dynamic Strain Aging Effects). The tests were performed by DCPD method at 316 deg C and 25 deg C. The loading rates were 1000mm/min and 2000mm/min. The objectives of this project were to obtain the dynamic J-R curves data of ferritic steels for application of LBB to the RCS pipes of Ulchin Unit 3/4. The test results showed that all of the tested dynamic J-R curves of 5 materials were above the lower bound curve of static J-R curve of pipe materials for Ulchin Unit 3/4. 10 refs., 4 tabs., 16 figs. (author)

Comparison of a nonlinear dynamic model of a piping system to test data

International Nuclear Information System (INIS)

Blakely, K.D.; Howard, G.E.; Walton, W.B.; Johnson, B.A.; Chitty, D.E.

1983-01-01

Response of a nonlinear finite element model of the Heissdampfreaktor recirculation piping loop (URL) was compared to measured data, representing the physical benchmarking of a nonlinear model. Analysis-test comparisons of piping response are presented for snapback tests that induced extreme nonlinear behavior of the URL system. Nonlinearities in the system are due to twelve swaybraces (pipe supports) that possessed nonlinear force-deflection characteristics. These nonlinearities distorted system damping estimates made by using the half-power bandwidth method on Fourier transforms of measured accelerations, with the severity of distortion increasing with increasing degree of nonlinearity. Time domain methods, which are not so severely affected by the presence of nonlinearities, were used to compute system damping ratios. Nonlinear dynamic analyses were accurately and efficiently performed using the pseudo-force technique and the finite element program MSC/NASTRAN. Measured damping was incorporated into the model for snapback simulations. Acceleration time histories, acceleration Fourier transforms, and swaybrace force time histories of the nonlinear model, plus several linear models, were compared to test measurements. The nonlinear model predicted three-fourths of the measured peak accelerations to within 50%, half of the accelerations to within 25%, and one-fifth of the accelerations to within 10%. This nonlinear model predicted accelerations (in the time and frequency domains) and swaybrace forces much better than did any of the linear models, demonstrating the increased accuracy resulting from properly simulating nonlinear support behavior. In addition, earthquake response comparisons were made between the experimentally validated nonlinear model and a linear model. Significantly lower element stresses were predicted for the nonlinear model, indicating the potential usefulness of nonlinear simulations in piping design assessments. (orig.)

Comparison study of time history and response spectrum responses for multiply supported piping systems

International Nuclear Information System (INIS)

Wang, Y.K.; Subudhi, M.; Bezler, P.

1983-01-01

In the past decade, several investigators have studied the problem of independent support excitation of a multiply supported piping system to identify the real need for such an analysis. This approach offers an increase in accuracy at a small increase in computational costs. To assess the method, studies based on the response spectrum approach using independent support motions for each group of commonly connected supports were performed. The results obtained from this approach were compared with the conventional envelope spectrum and time history solutions. The present study includes a mathematical formulation of the independent support motion analysis method suitable for implementation into an existing all purpose piping code PSAFE2 and a comparison of the solutions for some typical piping system using both Time History and Response Spectrum Methods. The results obtained from the Response Spectrum Methods represent the upper bound solution at most points in the piping system. Similarly, the Seismic Anchor Movement analysis based on the SRP method over predicts the responses near the support points and under predicts at points away from the supports

Nonlinear piping damping and response predictions

International Nuclear Information System (INIS)

Severud, L.K.; Weiner, E.O.; Lindquist, M.R.; Anderson, M.J.; Wagner, S.E.

1986-10-01

The high level dynamic testing of four prototypic piping systems, used to provide benchmarks for analytical prediction comparisons, is overviewed. The size of pipe tested ranged from one-inch to six-inches in diameter and consisted of carbon steel or stainless steel material. Failure of the tested systems included progressive gross deformation or some combination of ratchetting-fatigue. Pretest failure predictions and post test comparisons using simplified elastic and elasto-plastic methods are presented. Detailed non-linear inelastic analyses are also shown, along with a typical ratchet-fatigue failure calculation. A simplified method for calculating modal equivalent viscous damping for snubbers and plastic hinges is also described. Conclusions are made regarding the applicability of the various analytical failure predictive methods and recommendations are made for future analytic and test efforts

Torsional vibration of a pipe pile in transversely isotropic saturated soil

Science.gov (United States)

Zheng, Changjie; Hua, Jianmin; Ding, Xuanming

2016-09-01

This study considers the torsional vibration of a pipe pile in a transversely isotropic saturated soil layer. Based on Biot's poroelastic theory and the constitutive relations of the transversely isotropic medium, the dynamic governing equations of the outer and inner transversely isotropic saturated soil layers are derived. The Laplace transform is used to solve the governing equations of the outer and inner soil layers. The dynamic torsional response of the pipe pile in the frequency domain is derived utilizing 1D elastic theory and the continuous conditions at the interfaces between the pipe pile and the soils. The time domain solution is obtained by Fourier inverse transform. A parametric study is conducted to demonstrate the influence of the anisotropies of the outer and inner soil on the torsional dynamic response of the pipe pile.

Research program plan: piping. Volume 3

International Nuclear Information System (INIS)

Vagins, M.; Strosnider, J.

1985-07-01

Regulatory issues related to piping can be divided into the three areas of pipe cracking, postulated design basis pipe breaks, and design of piping for seismic and other dynamic loads. The first two of these issues are in the domain of the Materials Engineering Branch (MEBR), while the last of the three issues is the responsibility of the Mechanical/Structural Engineering Branch. This volume of the MEBR Research Plan defines the critical aspects of the pipe cracking and postulated design basis pipe break issues and identifies those research efforts and results necessary for their resolution. In general, the objectives of the MERB Piping Research Program are to provide experimentally validated analytic techniques and appropriate material properties characterization methods and data to support regulatory activities related to evaluating and ensuring piping integrity

The response of liquid-filled pipes to vapour collapse

International Nuclear Information System (INIS)

Tijsseling, A.S.; Fan, D.

1991-01-01

The collapse of vapour cavities in liquid is usually accompanied with almost instantaneous pressure rises. These pressure rises impose severe loads on liquid-conveying pipes whenever the cavities become sufficiently large. Due to the impact nature of loadings, movement of the pipe walls can be expected. Tests are performed in a water-filled closed pipe suspended by thin steel wires. Vaporous cavities are induced in the liquid by hitting the pipe axially by a steel rod. The volume of the cavities can be varied by changing the initial pressure of the water. The developing and collapsing of cavities in the liquid is inferred from pressure measurements. Strain gauges and a laser Doppler vibrometer are used to record the response of the pipe to these pressures. The test results are compared with predictions from a numerical model. The model describes 1) axial stress wave propagations in the pipe and 2) water hammer and cavitation phenomena in the liquid. Pipe and liquid interact via 1) the radial expansion and contraction of the pipe wall and 2) the closed ends of the pipe, where large vapour cavities may develop. (author)

Vibration analysis for IHTS piping system of LMR conveying hot liquid sodium

International Nuclear Information System (INIS)

Koo, Gyeong Hoi; Lee, Hyeong Yeon; Lee, Jae Han

2001-01-01

In this paper, the vibration characteristics of IHTS(Intermediate Heat Transfer System) piping system of LMR(Liquid Metal Reactor) conveying hot liquid sodium are investigated to eliminate the pipe supports for economic reasons. To do this, a 3-dimensional straight pipe element and a curved pipe element conveying fluid are formulated using the dynamic stiffness method of the wave approach and coded to be applied to any complex piping system. Using this method, the dynamic characteristics including the natural frequency, the frequency response functions, and the dynamic instability due to the pipe internal flow velocity are analyzed. As one of the design parameters, the vibration energy flow is also analyzed to investigate the disturbance transmission paths for the resonant excitation and the non-resonant excitations

Heat pipe dynamic behavior

Science.gov (United States)

Issacci, F.; Roche, G. L.; Klein, D. B.; Catton, I.

1988-01-01

The vapor flow in a heat pipe was mathematically modeled and the equations governing the transient behavior of the core were solved numerically. The modeled vapor flow is transient, axisymmetric (or two-dimensional) compressible viscous flow in a closed chamber. The two methods of solution are described. The more promising method failed (a mixed Galerkin finite difference method) whereas a more common finite difference method was successful. Preliminary results are presented showing that multi-dimensional flows need to be treated. A model of the liquid phase of a high temperature heat pipe was developed. The model is intended to be coupled to a vapor phase model for the complete solution of the heat pipe problem. The mathematical equations are formulated consistent with physical processes while allowing a computationally efficient solution. The model simulates time dependent characteristics of concern to the liquid phase including input phase change, output heat fluxes, liquid temperatures, container temperatures, liquid velocities, and liquid pressure. Preliminary results were obtained for two heat pipe startup cases. The heat pipe studied used lithium as the working fluid and an annular wick configuration. Recommendations for implementation based on the results obtained are presented. Experimental studies were initiated using a rectangular heat pipe. Both twin beam laser holography and laser Doppler anemometry were investigated. Preliminary experiments were completed and results are reported.

OTEC Cold Water Pipe-Platform Subsystem Dynamic Interaction Validation

Energy Technology Data Exchange (ETDEWEB)

Varley, Robert [Lockheed Martin Corporation, Manassas, VA (United States); Halkyard, John [John Halkyard and Associates, Houston, TX (United States); Johnson, Peter [BMT Scientific Marine Services, Inc., Houston, TX (United States); Shi, Shan [Houston Offshore Engineering, Houston, TX (United States); Marinho, Thiago [Federal Univ. of Rio de Janeiro (Brazil). LabOceano

2014-05-09

A commercial floating 100-megawatt (MW) ocean thermal energy conversion (OTEC) power plant will require a cold water pipe (CWP) with a diameter of 10-meter (m) and length of up to 1,000 m. The mass of the cold water pipe, including entrained water, can exceed the mass of the platform supporting it. The offshore industry uses software-modeling tools to develop platform and riser (pipe) designs to survive the offshore environment. These tools are typically validated by scale model tests in facilities able to replicate real at-sea meteorological and ocean (metocean) conditions to provide the understanding and confidence to proceed to final design and full-scale fabrication. However, today’s offshore platforms (similar to and usually larger than those needed for OTEC applications) incorporate risers (or pipes) with diameters well under one meter. Secondly, the preferred construction method for large diameter OTEC CWPs is the use of composite materials, primarily a form of fiber-reinforced plastic (FRP). The use of these material results in relatively low pipe stiffness and large strains compared to steel construction. These factors suggest the need for further validation of offshore industry software tools. The purpose of this project was to validate the ability to model numerically the dynamic interaction between a large cold water-filled fiberglass pipe and a floating OTEC platform excited by metocean weather conditions using measurements from a scale model tested in an ocean basin test facility.

Analysis of piping system response to seismic excitations

International Nuclear Information System (INIS)

Wang, C.Y.

1987-01-01

This paper describes a numerical algorithm for analyzing piping system response to seismic excitations. The numerical model of the piping considers hoop, flexural, axial, and torsional modes of deformation. Hoop modes generated from internal hydrodynamic loading are superimposed on the bending and twisting modes by two extra degrees of freedom. A time-history analysis technique using the implicit temporal integration scheme is addressed. The time integrator uses a predictor-corrector successive iterative scheme which satisfies the equation of motion. Both geometrical and material nonlinearities are considered. Multiple support excitations, fluid effect, piping insulation, and material dampings can be included in the analysis. Two problems are presented to illustrate the method. The results are discussed in detail

Dynamic Analysis of Offshore Oil Pipe Installation Using the Absolute Nodal Coordinate Formulation

DEFF Research Database (Denmark)

Nielsen, Jimmy D; Madsen, Søren B; Hyldahl, Per Christian

2013-01-01

The Absolute Nodal Coordinate Formulation (ANCF) has shown promising results in dynamic analysis of structures that undergo large deformation. The method relaxes the assumption of infinitesimal rotations. Being based in a fixed inertial reference frame leads to a constant mass matrix and zero......, are included to mimic the external forces acting on the pipe during installation. The scope of this investigation is to demonstrate the ability using the ANCF to analyze the dynamic behavior of an offshore oil pipe during installation...

The IPIRG-1 pipe system fracture tests: Experimental results

International Nuclear Information System (INIS)

Scott, P.; Olson, R.J.; Wilkowski, G.M.

1994-01-01

As part of the First International Piping Integrity Research Group (IPIRG-1) program, six dynamic pipe system experiments were conducted. The objective of these experiments was to generate experimental data to assess analysis methodologies for characterizing the fracture behavior of circumferentially cracked pipe in a representative piping system subjected to combined inertial and displacement-controlled stresses. A unique experimental facility was designed and constructed. The pipe system evaluated was an expansion loop with over 30 m (100 feet) of 16-inch nominal diameter Schedule 100 pipe. The experimental facility was equipped with special hardware to ensure that system boundary conditions could be appropriately modeled. The test matrix involved one uncracked and five cracked dynamic pipe system experiments. The uncracked-pipe experiment was conducted to evaluate the piping system damping and natural frequency characteristics. The cracked-pipe experiments were conducted to evaluate the fracture behavior, piping system response, and fracture stability characteristics of five different materials. All cracked-pipe experiments were conducted at PWR conditions. Material characterization efforts provided the tensile and fracture toughness properties of the different pipe materials at various strain rates and temperatures. Key results from the six pipe system experiments and material characterization efforts are presented. Detailed analyses will be published in a companion paper

Effect of lumped mass and support stiffness on pipe seismic response

International Nuclear Information System (INIS)

Chang, P.S.Y.

1986-01-01

In performing pipe stress analysis, generic support stiffness values are typically used to predict the response of the piping systems. Consistent design of every support to match the generic stiffness value is difficult. The difference between the actual and generic stiffness may affect the results of pipe stresses and support reactions. The objective of this study is to develop an acceptance criteria for the actual support stiffness and to avoid unnecessary reanalysis. The support mass in the restraint direction and mass within the pipe span can also affect the piping system behavior and this study will discuss this mass effect as well. Added mass and change in support stiffness will cause the piping system to shift frequency

Pipe support optimization in nuclear power plants

International Nuclear Information System (INIS)

Cleveland, A.B.; Kalyanam, N.

1984-01-01

A typical 1000 MWe nuclear power plant consists of 80,000 to 100,000 feet of piping which must be designed to withstand earthquake shock. For the required ground motion, seismic response spectra are developed for safety-related structures. These curves are used in the dynamic analysis of piping systems with pipe-stress analysis computer codes. To satisfy applicable Code requirements, the piping systems also require analysis for weight, thermal and possibly other lasting conditions. Bechtel Power Corporation has developed a design program called SLAM (Support Location Algorithm) for optimizing pipe support locations and types (rigid, spring, snubber, axial, lateral, etc.) while satisfying userspecified parameters such as locations, load combinations, stress and load allowables, pipe displacement and cost. This paper describes SLAM, its features, applications and benefits

Experimental study on dynamic pipe fracture in consideration of hydropower plant model

Directory of Open Access Journals (Sweden)

Kazumi Ishikawa

2009-12-01

Full Text Available In the case of sudden valve closure, water hammer creates the most powerful pressure and damage to pipeline systems. The best way to protect the pipeline system is to eliminate water hammer. The main reasons for water hammer occurrence are valve closure, high initial velocity, and static pressure. However, it is difficult to eliminate water hammer. Water hammer tends to occur when the valve is being closed. In this study, the pipe fracture caused by static water pressure, gradually increasing pressure, and suddenly increasing pressure were compared experimentally in a breaking PVC test pipe. The quasi-static zone, the dynamic zone, and the transition zone are defined through the results of those experiments, with consideration of the fracture patterns of test pipes and impulses. The maximum pressure results were used to design the pipeline even though it is in the dynamic zone.

Effects of dynamic coupling between freestanding steel containment and attached piping

International Nuclear Information System (INIS)

Kennedy, R.P.; Kincaid, R.H.; Short, S.A.

1981-01-01

This paper presents an accurate, practical method of converting uncoupled response time history results obtained from an uncoupled structure model into coupled response time histories using a post-processor routine. The method is rigorous and only requires the modal properties of the uncoupled structure model, the modal properties of the uncoupled attached equipment model, and the uncoupled time histories of the attachment points on the structure. Coupled response spectra or time histories for use as input to an uncoupled equipment model are obtained. Comparisons of coupled versus uncoupled analysis results are presented for representative piping systems attached to a typical BWR Mark III steel containment subjected to vibration from safety relief valve discharge with a fundamental frequency of 12 Hz. It is shown that the coupled response spectra at piping attachment points are reduced by a factor between 2 and 5 from the amplified uncoupled spectra at each significant piping modal frequency above 20 Hz for representative major piping systems attached to the unstiffened portion of the steel shell. Responses at lower frequencies are not generally reduced and may increase by coupling effects for the input loading and shell model studied. Peak accerations are generally significantly reduced while peak displacements may be decreased or increased. Rules are presented for estimating the coupling effects between freestanding steel shells and attached equipment. (orig./HP)

Nonlinear dynamic analysis of piping systems using the pseudo force method

International Nuclear Information System (INIS)

Prachuktam, S.; Bezler, P.; Hartzman, M.

1979-01-01

Simple piping systems are composed of linear elastic elements and can be analyzed using conventional linear methods. The introduction of constraint springs separated from the pipe with clearance gaps to such systems to cope with the pipe whip or other extreme excitation conditions introduces nonlinearities to the system, the nonlinearities being associated with the gaps. Since these spring-damper constraints are usually limited in number, descretely located, and produce only weak nonlinearities, the analysis of linear systems including these nonlinearities can be carried out by using modified linear methods. In particular, the application of pseudo force methods wherein the nonlinearities are treated as displacement dependent forcing functions acting on the linear system were investigated. The nonlinearities induced by the constraints are taken into account as generalized pseudo forces on the right-hand side of the governing dynamic equilibrium equations. Then an existing linear elastic finite element piping code, EPIPE, was modified to permit application of the procedure. This option was inserted such that the analyses could be performed using either the direct integration method or via a modal superposition method, the Newmark-Beta integration procedure being employed in both methods. The modified code was proof tested against several problems taken from the literature or developed with the nonlinear dynamics code OSCIL. The problems included a simple pipe loop, cantilever beam, and lumped mass system subjected to pulsed and periodic forcing functions. The problems were selected to gage the overall accuracy of the method and to insure that it properly predicted the jump phenomena associated with nonlinear systems. (orig.)

Dynamics of the nozzle valve with regard to the properties of the piping system

Directory of Open Access Journals (Sweden)

Klas Roman

2018-01-01

Full Text Available It is obvious that the main function of the nozzle valve is to shut off the stream of fluid in the piping system. The response rate of the valve to the decreasing or reversing flow in the system will then depend on the valve properties and equally on the properties of the piping system. The interaction of these two elements is also important for the origin of pressure pulsations in the system. While the pressure pulsations were the cause for design of this particular valve it should be noted that the general design of the valve for any pipeline system is not possible. The valve cannot properly work under all circumstances and operating conditions. With respect to this, the dynamic properties of the valve will be assessed on the basis of the valve equation of motion and the pipeline model. An adequate response of the whole system can be obtained by combining both approaches. The valve equations of motion are also complemented by CFD simulations, which enable to capture the movement of the valve disc with respect to flow rate.

SHAM: High-level seismic tests of piping at the HDR

International Nuclear Information System (INIS)

Kot, C.A.; Srinivasan, M.G.; Hsieh, B.J.; Malcher, L.; Schrammel, D.; Steinhilber, H.; Costello, J.F.

1988-01-01

As part of the second phase of vibrational/earthquake investigations at the HDR (Heissdampfreaktor) Test Facility in Kahl/Main, FRG, high-level simulated seismic tests (SHAM) were performed during April--May 1988 on the VKL (Versuchskreislauf) in-plant piping system with two servohydraulic actuators, each capable of generating 40 tons of force. The purpose of these experiments was to study the behavior of piping subjected to seismic excitation levels that exceed design levels manifold and may result in failure/plastification of pipe supports and pipe elements, and to establish seismic margins for piping and pipe supports. The performance of six different dynamic pipe support systems was compared in these tests and the response, operability, and fragility of dynamic supports and of a typical US gate valve were investigated. Data obtained in the tests are used to validate analysis methods. Very preliminary evaluations lead to the observation that, in general, failures of dynamic supports (in particular snubbers) occur only at load levels that substantially exceed the design capacity. Pipe strains at load levels exceeding the design level threefold are quite small, and even when exceeding the design level eightfold are quite tolerable. Hence, under seismic loading, even at extreme levels and in spite of multiple support failures, pipe failure is unlikely. 5 refs., 16 figs

Development of seismic design method for piping system supported by elastoplastic damper. 3. Vibration test of three-dimensional piping model and its response analysis

International Nuclear Information System (INIS)

Namita, Yoshio; Kawahata, Jun-ichi; Ichihashi, Ichiro; Fukuda, Toshihiko.

1995-01-01

Component and piping systems in current nuclear power plants and chemical plants are designed to employ many supports to maintain safety and reliability against earthquakes. However, these supports are rigid and have a slight energy-dissipating effect. It is well known that applying high-damping supports to the piping system is very effective for reducing the seismic response. In this study, we investigated the design method of the elastoplastic damper [energy absorber (EAB)] and the seismic design method for a piping system supported by the EAB. Our final goal is to develop technology for applying the EAB to the piping system of an actual plant. In this paper, the vibration test results of the three-dimensional piping model are presented. From the test results, it is confirmed that EAB has a large energy-dissipating effect and is effective in reducing the seismic response of the piping system, and that the seismic design method for the piping system, which is the response spectrum mode superposition method using each modal damping and requires iterative calculation of EAB displacement, is applicable for the three-dimensional piping model. (author)

Comparison of elastic and inelastic seismic response of high temperature piping systems

International Nuclear Information System (INIS)

Thomas, F.M.; McCabe, S.L.; Liu, Y.

1994-01-01

A study of high temperature power piping systems is presented. The response of the piping systems is determined when subjected to seismic disturbances. Two piping systems are presented, a main steam line, and a cold reheat line. Each of the piping systems are modeled using the ANSYS computer program and two analyses are performed on each piping system. First, each piping system is subjected to a seismic disturbance and the pipe material is assumed to remain linear and elastic. Next the analysis is repeated for each piping system when the pipe material is modeled as having elastic-plastic behavior. The results of the linear elastic analysis and elastic-plastic analysis are compared for each of the two pipe models. The pipe stresses, strains, and displacements, are compared. These comparisons are made so that the effect of the material yielding can be determined and to access what error is made when a linear analysis is performed on a system that yields

Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

Science.gov (United States)

Liu, Feifei; Lan, Fengchong; Chen, Jiqing

2016-07-01

Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a ;segmented; thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed ;segmented; model shows more precise than the ;non-segmented; model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the ;segmented; model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

Experimental basis for parameters contributing to energy dissipation in piping systems

International Nuclear Information System (INIS)

Ibanez, P.; Ware, A.G.

1985-01-01

The paper reviews several pipe testing programs to suggest the phenomena causing energy dissipation in piping systems. Such phenomena include material damping, plasticity, collision in gaps and between pipes, water dynamics, insulation straining, coupling slippage, restraints (snubbers, struts, etc.), and pipe/structure interaction. These observations are supported by a large experimental data base. Data are available from in-situ and laboratory tests (pipe diameters up to about 20 inches, response levels from milli-g's to responses causing yielding, and from excitation wave forms including sinusoid, snapback, random, and seismic). A variety of pipe configurations have been tested, including simple, bare, straight sections and complex lines with bends, snubbers, struts, and insulation. Tests have been performed with and without water and at zero to operating pressure. Both light water reactor and LMFBR piping have been tested

Main steam system piping response under safety/relief valve opening events

International Nuclear Information System (INIS)

Swain, E.O.; Esswein, G.A.; Hwang, H.L.; Nieh, C.T.

1980-01-01

The stresses in the main steam branch pipe of a Boiling Water Reactor due to safety/relief valve blowdown has been measured from an in situ piping system test. The test results were compared with analytical results. The predicted stresses using the current state of art analytical methods used for BWR SRV discharge transient piping response loads were found to be conservative when compared to the measured stress values. 3 refs

Mathematical modeling of the dynamic stability of fluid conveying pipe based on integral equation formulations

International Nuclear Information System (INIS)

Elfelsoufi, Z.; Azrar, L.

2016-01-01

In this paper, a mathematical modeling of flutter and divergence analyses of fluid conveying pipes based on integral equation formulations is presented. Dynamic stability problems related to fluid pressure, velocity, tension, topography slope and viscoelastic supports and foundations are formulated. A methodological approach is presented and the required matrices, associated to the influencing fluid and pipe parameters, are explicitly given. Internal discretizations are used allowing to investigate the deformation, the bending moment, slope and shear force at internal points. Velocity–frequency, pressure-frequency and tension-frequency curves are analyzed for various fluid parameters and internal elastic supports. Critical values of divergence and flutter behaviors with respect to various fluid parameters are investigated. This model is general and allows the study of dynamic stability of tubes crossed by stationary and instationary fluid on various types of supports. Accurate predictions can be obtained and are of particular interest for a better performance and for an optimal safety of piping system installations. - Highlights: • Modeling the flutter and divergence of fluid conveying pipes based on RBF. • Dynamic analysis of a fluid conveying pipe with generalized boundary conditions. • Considered parameters fluid are the pressure, tension, slopes topography, velocity. • Internal support increase the critical velocity value. • This methodologies determine the fluid parameters effects.

A comparative study on effective dynamic modeling methods for flexible pipe

Energy Technology Data Exchange (ETDEWEB)

Lee, Chang Ho; Hong, Sup; Kim, Hyung Woo [Korea Research Institute of Ships and Ocean Engineering, Daejeon (Korea, Republic of); Kim, Sung Soo [Chungnam National University, Daejeon (Korea, Republic of)

2015-07-15

In this paper, in order to select a suitable method that is applicable to the large deflection with a small strain problem of pipe systems in the deep seabed mining system, the finite difference method with lumped mass from the field of cable dynamics and the substructure method from the field of flexible multibody dynamics were compared. Due to the difficulty of obtaining experimental results from an actual pipe system in the deep seabed mining system, a thin cantilever beam model with experimental results was employed for the comparative study. Accuracy of the methods was investigated by comparing the experimental results and simulation results from the cantilever beam model with different numbers of elements. Efficiency of the methods was also examined by comparing the operational counts required for solving equations of motion. Finally, this cantilever beam model with comparative study results can be promoted to be a benchmark problem for the flexible multibody dynamics.

Finite-element analysis of flawed and unflawed pipe tests

International Nuclear Information System (INIS)

James, R.J.; Nickell, R.E.; Sullaway, M.F.

1989-12-01

Contemporary versions of the general purpose, nonlinear finite element program ABAQUS have been used in structural response verification exercises on flawed and unflawed austenitic stainless steel and ferritic steel piping. Among the topics examined, through comparison between ABAQUS calculations and test results, were: (1) the effect of using variations in the stress-strain relationship from the test article material on the calculated response; (2) the convergence properties of various finite element representations of the pipe geometry, using shell, beam and continuum models; (3) the effect of test system compliance; and (4) the validity of ABAQUS J-integral routines for flawed pipe evaluations. The study was culminated by the development and demonstration of a ''macroelement'' representation for the flawed pipe section. The macroelement can be inserted into an existing piping system model, in order to accurately treat the crack-opening and crack-closing static and dynamic response. 11 refs., 20 figs., 1 tab

Response of piping system with semi-active variable stiffness damper under tri-directional seismic excitation

International Nuclear Information System (INIS)

Praveen Kumar; Jangid, R.S.; Reddy, G.R.

2013-01-01

Highlights: ► Piping system with semi-active variable stiffness damper is investigated under different seismic excitations. ► Switching control law and modified switching control law are adopted. ► There exist an optimum parameters of the SAVSD. ► Substantial reduction of the seismic response of piping system with SAVSD is observed. ► Good amount of energy dissipation is observed. -- Abstract: Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure. In this paper, semi-active variable stiffness dampers (SAVSDs) have been studied to mitigate seismic response and vibration control of piping system used in the process industries, fossil and fissile fuel power plant. The SAVSD changes its stiffness depending upon the piping response and accordingly adds the control forces in the piping system. A study is conducted on the performance of SAVSD due to variation in device stiffness ratios in the switching control law and modified switching control law, which plays an important role in the present control algorithm of the damper. The effectiveness of the SAVSD in terms of reduction in the responses, namely, displacements, accelerations and base shear of the piping system is investigated by comparing uncontrolled responses under four different artificial earthquake motions with increasing amplitudes. The analytical results demonstrate that the SAVSDs under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping systems

Response of piping system with semi-active variable stiffness damper under tri-directional seismic excitation

Energy Technology Data Exchange (ETDEWEB)

Praveen Kumar, E-mail: praveen@barc.gov.in [Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jangid, R.S. [Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Reddy, G.R. [Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2013-05-15

Highlights: ► Piping system with semi-active variable stiffness damper is investigated under different seismic excitations. ► Switching control law and modified switching control law are adopted. ► There exist an optimum parameters of the SAVSD. ► Substantial reduction of the seismic response of piping system with SAVSD is observed. ► Good amount of energy dissipation is observed. -- Abstract: Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure. In this paper, semi-active variable stiffness dampers (SAVSDs) have been studied to mitigate seismic response and vibration control of piping system used in the process industries, fossil and fissile fuel power plant. The SAVSD changes its stiffness depending upon the piping response and accordingly adds the control forces in the piping system. A study is conducted on the performance of SAVSD due to variation in device stiffness ratios in the switching control law and modified switching control law, which plays an important role in the present control algorithm of the damper. The effectiveness of the SAVSD in terms of reduction in the responses, namely, displacements, accelerations and base shear of the piping system is investigated by comparing uncontrolled responses under four different artificial earthquake motions with increasing amplitudes. The analytical results demonstrate that the SAVSDs under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping systems.

Stability of cracked pipe under seismic/dynamic displacement-controlled stresses. Subtask 1.2 final report

International Nuclear Information System (INIS)

Kramer, G.; Veith, P.; Marschall, C.

1997-06-01

Results of displacement-controlled pipe fracture experiments, analyses, and material characterization efforts performed within the International Piping Integrity Research Group, IPIRG, Program Subtask 1.2 are discussed. Effects of dynamic versus quasi-static and monotonic versus cyclic loading were evaluated for ductile tearing of two materials, A106 Grade B ferritic steel and TP304 austenitic steel. Twelve through-wall-cracked pipe experiments were conducted on 6-inch diameter Schedule 120 pipe at 288 C (550 F). The results indicated dynamic loading at seismic strain rates marginally increased the load-carrying capacity of austenitic steel. The ferritic steel tested was sensitive to dynamic strain-aging, and consequently, its load-carrying capacity decreased at dynamic strain rates. Two parameters were found to affect the apparent ductile crack growth resistance during cyclic loading, load ratio (R) and incremental plastic displacement that occurs in a cycle. Cyclic (R = 0) loading had minimal effect on ductile tearing for both materials. However, fully reversed loading decreased the load-carrying capacity and toughness for both materials. The incremental plastic displacement can be as important as the load ratio; however, it is harder to quantify from design stress reports. Large plastic displacements will minimize the effect of negative load ratios

Dynamic stability of a curved pipe bent in the arc of a circle on hinge ...

Indian Academy of Sciences (India)

of numerical solution of the dynamic stability of a pipe in its plane are developed. An example of a ... Most scientific researches in the area of vibrations of pipes conveying liquids are concerned with investigation of ..... is good coincidence. 5.

Design of dynamic loading support on high temperature pipe

International Nuclear Information System (INIS)

Sitandung, Y.B.; Bandriyana, B.

2002-01-01

As a follow up to pipe stress analysis result caused by high temperature operation loading, a design of dynamic loading support was made. The type of variable and constant support as acceptable choosing are applicated for reduce of over stress and over load on piping system. Analysis line schedule of AP600 as an example with apply three dynamic loading support (two type variable and one type constant support). The pre-design of the third support above are based on analysis result with follow the support catalog and field condition wherein its supports are installed. To guarantee the performance and accurate of the support, checking is performed for spring working rate tolerance, support variability and swing angle. The design results of variable spring are loads, size, working rate, type tolerance, spring rate, variability, long and sway angle with each values 5000; 15; 1,25; VM; 0.655; 1080; 0.114; 114,5; 0,48 for S1 and 2045; 12; 0,583; VS; 0,237; 900; 0,132; 130; 0,34 for S3

Role of theoretical dynamics in vibration diagnostics of pipe systems

International Nuclear Information System (INIS)

Rejent, B.

1992-01-01

The importance of vibration diagnostics of pipe systems and the relevance of theoretical dynamics are shown using examples. The problems are discussed of vibration diagnostics of the primary circuit of a nuclear power plant with viscous seismic dampers installed. (M.D.) 7 figs., 5 refs

Development of solutions to benchmark piping problems

Energy Technology Data Exchange (ETDEWEB)

Reich, M; Chang, T Y; Prachuktam, S; Hartzman, M

1977-12-01

Benchmark problems and their solutions are presented. The problems consist in calculating the static and dynamic response of selected piping structures subjected to a variety of loading conditions. The structures range from simple pipe geometries to a representative full scale primary nuclear piping system, which includes the various components and their supports. These structures are assumed to behave in a linear elastic fashion only, i.e., they experience small deformations and small displacements with no existing gaps, and remain elastic through their entire response. The solutions were obtained by using the program EPIPE, which is a modification of the widely available program SAP IV. A brief outline of the theoretical background of this program and its verification is also included.

INEL/USNRC pipe damping experiments and studies

International Nuclear Information System (INIS)

Ware, A.G.

1987-08-01

Since the previous paper on this subject presented at the 8th SMiRT Conference, the Idaho National Engineering Laboratory (INEL) has conducted further research on piping system damping for the United States Nuclear Regulatory Commission (USNRC). These efforts have included vibration tests on two laboratory piping systems at response frequencies up to 100 Hz, and damping data calculations from both of these two systems and from a third laboratory piping system test series. In addition, a statistical analysis was performed on piping system damping data from tests representative of seismic and hydrodynamic events of greater than minimal excitation. The results of this program will be used to assist regulators in establishing suitable damping values for use in dynamic analyses of nuclear piping systems, and in revising USNRC Regulatory Guide (RG) 1.61

A comparison of time-history elastic plastic piping analysis with measurement

International Nuclear Information System (INIS)

Scavuzzo, R.J.; Sansalone, K.H.

1992-01-01

The GE/ETEC Green piping system was subjected to high seismic inputs from hydraulic sleds at each pipe foundation. These inputs were high enough to force bending stresses into the plastic regime. Strain gages recorded the pipe response at various positions within the system. The ABAQUS finite element code was used to model this piping system and the dynamic input. Problems associated with the dynamic input are discussed. Various types of finite elements were evaluated for accurancy. Both an elastic time-history analysis and an elastic-plastic time-history analysis of the system were conducted. Results of these analyses are compared to each other and the experimental data. These comparisons indicated that elastic analysis of dynamic strains are conservative at all points of comparison and that there is good agreement between the nonlinear elastic-plastic analysis and experimental data. (orig.)

Seismic analysis response factors and design margins of piping systems

International Nuclear Information System (INIS)

Shieh, L.C.; Tsai, N.C.; Yang, M.S.; Wong, W.L.

1985-01-01

The objective of the simplified methods project of the Seismic Safety Margins Research Program is to develop a simplified seismic risk methodology for general use. The goal is to reduce seismic PRA costs to roughly 60 man-months over a 6 to 8 month period, without compromising the quality of the product. To achieve the goal, it is necessary to simplify the calculational procedure of the seismic response. The response factor approach serves this purpose. The response factor relates the median level response to the design data. Through a literature survey, we identified the various seismic analysis methods adopted in the U.S. nuclear industry for the piping system. A series of seismic response calculations was performed. The response factors and their variabilities for each method of analysis were computed. A sensitivity study of the effect of piping damping, in-structure response spectra envelop method, and analysis method was conducted. In addition, design margins, which relate the best-estimate response to the design data, are also presented

PWR pressurizer discharge piping system on-site testing

International Nuclear Information System (INIS)

Anglaret, G.; Lasne, M.

1983-08-01

Framatome PWR systems includes the installation of safety valves and relief valves wich permit the discharge of steam from the pressurizer to the pressurizer relief tank through discharge piping system. Water seal expulsion pluration then depends on valve stem lift dynamics which can vary according to water-stem interaction. In order to approaches the different phenomenons, it was decided to perform a test on a 900 MWe French plant, test wich objectives are: characterize the mechanical response of the discharge piping to validate a mechanical model; open one, two or several valves among the following: one safety valve and three pilot operated relief valves, at a time or sequentially and measure the discharge piping transient response, the support loads, the

Seismic response and damping tests of small bore LMFBR piping and supports

International Nuclear Information System (INIS)

Barta, D.A.; Anderson, M.J.; Severud, L.K.; Lindquist, M.R.

1984-01-01

Seismic testing and analysis of a prototypical Liquid Metal Fast Breeder Reactor (LMFBR) small bore piping system is described. Measured responses to simulated seismic excitations are compared with analytical predictions based on NRC Regulatory Guide 1.61 and measured system damping values. The test specimen was representative of a typical LMFBR insulated small bore piping system, and it was supported from a rigid test frame by prototypic dead weight supports, mechanical snubbers and pipe clamps

Modal spectral analysis of piping: Determination of the significant frequency range

International Nuclear Information System (INIS)

Geraets, L.H.

1981-01-01

This paper investigates the influence of the number of modes on the response of a piping system in a dynamic modal spectral analysis. It shows how the analysis can be limited to a specific frequency range of the pipe (independent of the frequency range of the response spectrum), allowing cost reduction without loss in accuracy. The 'missing mass' is taken into account through an original technique. (orig./HP)

The effects of cyclic and dynamic loading on the fracture resistance of nuclear piping steels. Technical report, October 1992--April 1996

Energy Technology Data Exchange (ETDEWEB)

Rudland, D.L.; Brust, F.; Wilkowski, G.M.

1996-12-01

This report presents the results of the material property evaluation efforts performed within Task 3 of the IPIRG-2 Program. Several related investigations were conducted. (1) Quasi-static, cyclic-load compact tension specimen experiments were conducted using parameters similar to those used in IPIRG-1 experiments on 6-inch nominal diameter through-wall-cracked pipes. These experiments were conducted on a TP304 base metal, an A106 Grade B base metal, and their respective submerged-arc welds. The results showed that when using a constant cyclic displacement increment, the compact tension experiments could predict the through-wall-cracked pipe crack initiation toughness, but a different control procedure is needed to reproduce the pipe cyclic crack growth in the compact tension tests. (2) Analyses conducted showed that for 6-inch diameter pipe, the quasi-static, monotonic J-R curve can be used in making cyclic pipe moment predictions; however, sensitivity analyses suggest that the maximum moments decrease slightly from cyclic toughness degradation as the pipe diameter increases. (3) Dynamic stress-strain and compact tension tests were conducted to expand on the existing dynamic database. Results from dynamic moment predictions suggest that the dynamic compact tension J-R and the quasi-static stress-strain curves are the appropriate material properties to use in making dynamic pipe moment predictions.

The effects of cyclic and dynamic loading on the fracture resistance of nuclear piping steels. Technical report, October 1992--April 1996

International Nuclear Information System (INIS)

Rudland, D.L.; Brust, F.; Wilkowski, G.M.

1996-12-01

This report presents the results of the material property evaluation efforts performed within Task 3 of the IPIRG-2 Program. Several related investigations were conducted. (1) Quasi-static, cyclic-load compact tension specimen experiments were conducted using parameters similar to those used in IPIRG-1 experiments on 6-inch nominal diameter through-wall-cracked pipes. These experiments were conducted on a TP304 base metal, an A106 Grade B base metal, and their respective submerged-arc welds. The results showed that when using a constant cyclic displacement increment, the compact tension experiments could predict the through-wall-cracked pipe crack initiation toughness, but a different control procedure is needed to reproduce the pipe cyclic crack growth in the compact tension tests. (2) Analyses conducted showed that for 6-inch diameter pipe, the quasi-static, monotonic J-R curve can be used in making cyclic pipe moment predictions; however, sensitivity analyses suggest that the maximum moments decrease slightly from cyclic toughness degradation as the pipe diameter increases. (3) Dynamic stress-strain and compact tension tests were conducted to expand on the existing dynamic database. Results from dynamic moment predictions suggest that the dynamic compact tension J-R and the quasi-static stress-strain curves are the appropriate material properties to use in making dynamic pipe moment predictions

Coupled dynamic analysis of subsea pipe laying operations

Energy Technology Data Exchange (ETDEWEB)

Silva, Danilo Machado Lawinscky da; Jacob, Breno Pinheiro [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Civil. Lab. of Computational Methods and Offshore Systems

2009-12-19

It is recognized that deep water offshore oil exploitation activities requires the use of sophisticated computational tools to predict the behavior of floating offshore systems under the action of environmental loads. These computational tools should be able to perform coupled dynamic analyses, considering the non-linear interaction of the hydrodynamic behavior of the platform with the structural/hydrodynamic behavior of the mooring lines and risers, represented by Finite Element models. The use of such a sophisticated computational tool becomes mandatory not only for the design of production platforms, but also for the simulation of offshore installation operations. For instance, in the installation of submarine pipelines, the wall thickness design may not be governed by the pressure containment requirements of the pipeline during the operation, but by the installation process, specifically the combined action of bending, tension and hydrostatic pressure acting on the pipeline, that is also submitted to the motions of the lay barge. Therefore, the objective of this work is to present the results of numerical simulations of S-lay installation procedures using a computational tool that performs dynamic analysis coupling the structural behavior of the pipe with the hydrodynamic behavior of the vessel motions under environmental conditions. This tool rigorously considers the contact between the pipeline and its supports (lay barge, stinger, seabed). The results are compared to traditional pipe laying simulations based on RAO motions. (author)

Report of the U.S. Nuclear Regulatory Commission Piping Review Committee. Summary and evaluation of historical strong-motion earthquake seismic response and damage to aboveground industrial piping

International Nuclear Information System (INIS)

1985-04-01

The primary purpose of this report is to collect in one reference document the observation and experience that has been developed with regard to the seismic behavior of aboveground, building-supported, industrial-type process piping (similar to piping used in nuclear power plants) in strong-motion earthquakes. The report will also contain observations regarding the response of piping in strong-motion experimental tests and appropriate conclusions regarding the behavior of such piping in large earthquakes. Recommendations are included covering the future design of such piping to resist earthquake motion damage based on observed behavior in large earthquakes and simulated shake table testing. Since available detailed data on the behavior of aboveground (building-supported) piping are quite limited, this report will draw heavily on the observations and experiences of experts in the field. In Section 2 of this report, observed earthquake damage to aboveground piping in a number of large-motion earthquakes is summarized. In Section 3, the available experience from strong-motion testing of piping in experimental facilities is summarized. In Section 4 are presented some observations that attempt to explain the observed response of piping to strong-motion excitation from actual earthquakes and shake table testing. Section 5 contains the conclusions based on this study and recommendations regarding the future seismic design of piping based on the observed strong-motion behavior and material developed for the NPC Piping Review Committee. Finally, in Section 6 the references used in this study are presented. It should be understood that the use of the term piping in this report, in general, is limited to piping supported by building structures. It does not include behavior of piping buried in soil media. It is believed that the seismic behavior of buried piping is governed primarily by the deformation of the surrounding soil media and is not dependent on the inertial response

Seismic response analysis of a piping system subjected to multiple support excitations in a base isolated NPP building

International Nuclear Information System (INIS)

Surh, Han-Bum; Ryu, Tae-Young; Park, Jin-Sung; Ahn, Eun-Woo; Choi, Chul-Sun; Koo, Ja Choon; Choi, Jae-Boong; Kim, Moon Ki

2015-01-01

Highlights: • Piping system in the APR 1400 NPP with a base isolation design is studied. • Seismic response of piping system in base isolated building are investigated. • Stress classification method is examined for piping subjected to seismic loading. • Primary stress of piping is reduced due to base isolation design. • Substantial secondary stress is observed in the main steam piping. - Abstract: In this study, the stress response of the piping system in the advanced power reactor 1400 (APR 1400) with a base isolation design subjected to seismic loading is addressed. The piping system located between the auxiliary building with base isolation and the turbine building with a fixed base is considered since it can be subjected to substantial relative support movement during seismic events. First, the support responses with respect to the base characteristic are investigated to perform seismic analysis for multiple support excitations. Finite element analyses are performed to predict the piping stress response through various analysis methods such as the response spectrum, seismic support movement and time history method. To separately evaluate the inertial effect and support movement effect on the piping stress, the stress is decomposed into a primary and secondary stress using the proposed method. Finally, influences of the base isolation design on the piping system in the APR 1400 are addressed. The primary stress based on the inertial loading is effectively reduced in a base isolation design, whereas a considerable amount of secondary stress is generated in the piping system connecting a base isolated building with a fixed base building. It is also confirmed that both the response spectrum analysis and seismic support movement analysis provide more conservative estimations of the piping stress compared to the time history analysis

Numerical and experimental analysis of the vibratory behavior of a nuclear power plant piping system excitated by a pump

International Nuclear Information System (INIS)

Vatin, E.; Guillou, J.; Tephany, F.; Trollat, C.

1993-08-01

This paper presents a study on the dynamic response of piping systems installed in the French 1300 MWe Nuclear Power Plants. Variations in pressure are generated by a multi-staged centrifugal pump mounted on the piping system and provide a dynamic excitation of the pipe. This type of dynamic loading has led to nozzle cracks for some of the pipes, whereas, for other installations, it has not be found detrimental. This study presents an explanation of the different dynamic behavior observed at the various plants. To this end, a numerical model, calibrated with on-site measurements, is impleted. (authors). 8 figs., 1 tab., 5 refs

Proceedings of transient thermal-hydraulics and coupled vessel and piping system responses 1991

International Nuclear Information System (INIS)

Wang, G.Y.; Shin, Y.W.; Moody, F.J.

1991-01-01

This book reports on transient thermal-hydraulics and coupled vessel and piping system responses. Topics covered include: nuclear power plant containment designs; analysis of control rods; gate closure of hydraulic turbines; and shock wave solutions for steam water mixtures in piping systems

Seismicity as dynamic load of pipes and fittings

International Nuclear Information System (INIS)

Rejent, B.

1984-01-01

The load is discussed of pipe systems and fittings for nuclear power plants which may result from earthquakes, etc. Modifications of the equation of motion are discussed which may be solved using the response spectrum method or the method of direct numerical integration. A mathematical description of both methods is given. The seismic resistance of fittings, pumps, etc., is experimentally determined by loking for their eigenfrequencies and monitoring the response of equipment to resonance oscillations. The principle is described of uniaxial hydraulic and mechanical shock absorbers and a viscous damper. The presented computation method was used for evaluating the primary circuit (Sigma Modrany) and rods for the remote control of fittings (Sigma Hodonin) supplied for the Mochovce nuclear power plant. Variants were compared of seismic protection of the primary circuit by hydraulic and mechanical shock absorbers with viscous dampers and of circuits without any protection. The unprotected system oscillates in the first harmonic, the system with shock absorbers keeps the deflections within the range of the shock absorber function (to 2 mm), and the system using viscous dampers oscillates approximately according to the first waveform with a deflection of around 11 mm. A diagram and a dynamic model are presented of a rod for the remote control of fittings. Figure shows the computation model and the response of this rod in individual time moments, both affected and not affected by play in the dilatation joint. Table shows the effect of play in the dilatation joint on deformation maxima and on rod bend stress from a symmetric load of 8g. (E.S.)

Piping dynamics in mid-altitude mountains under a temperate climate: the Bieszczady Mts., the Eastern Carpathians

Science.gov (United States)

Bernatek-Jakiel, Anita; Jakiel, Michał; Krzemień, Kazimierz

2017-04-01

Soil erosion is caused not only by overland flow, but also by subsurface flow. Piping which is a process of mechanical removal of soil particles by concentrated subsurface flow is frequently being overlooked and not accounted for in soil erosion studies. However, it seems that it is far more widespread than it has often been supposed. Furthermore, our knowledge about piping dynamics and its quantification currently relies on a limited number of data available for mainly loess-mantled areas and marl badlands. Therefore, this research aims to recognize piping dynamics in mid-altitude mountains under a temperate climate, where piping occurs in Cambisols, not previously considered as piping-prone soils. The survey was carried out in the Bereźnica Wyżna catchment (305 ha), in the Bieszczady Mts. (the Eastern Carpathians, Poland), where 188 collapsed pipes were mapped. The research was based on the monitoring of selected piping systems located within grasslands (1971-1974, 2013-2016). The development of piping systems is mainly induced by the elongation of pipes and creation of new collapses (closed depressions and sinkholes), rather than by the enlargement of existing piping forms, or the deepening of pipes. It draws attention to the role of dense vegetation (grasslands) in the delay of pipe collapses and, also, to the boundary of pipe development (soil-bedrock interface). The obtained results reveal an episodic, and even stochastic nature of piping activity, expressed by varied one-year and short-term (3 years) erosion rates, and pipe elongation. Changes in soil loss vary significantly between different years (up to 27.36 t ha-1 y-1), reaching the rate of 1.34 t ha-1 y-1 for the 45-year study period. The elongation of pipes also differs, from no changes to 36 m during one year. The results indicate that soil loss due to piping can cause high soil loss even in highly vegetated lands (grasslands), which are generally considered as areas without a significant erosion

Pipe rupture test results: 4-inch pipe whip tests under PWR LOCA conditions

International Nuclear Information System (INIS)

Miyazaki, Noriyuki; Ueda, Shuzo; Isozaki, Toshikuni; Kato, Rokuro; Kurihara, Ryoichi; Yano, Toshikazu; Miyazono, Shohachiro

1982-09-01

This report summarizes the results of 4-inch pipe whip tests (RUN No. 5506, 5507, 5508 and 5604) under the PWR LOCA conditions. The dynamic behaviors of the test pipe and restraints were studied in the tests. In the tests, the gap between the test pipe and the restraints was kept at the constant value of 8.85 mm and the overhang length was varied from 250 mm to 650 mm. The dynamic behaviors of the test pipe and the restraint were made clear by the outputs of strain gages and the measurements of residual deformations. The data of water hammer in subcooled water were also obtained by the pressure transducers mounted on the test pipe. The main conclusions obtained from the tests are as follows. (1) The whipping of pipe can be prevented more effectively as the overhang length becomes shorter. (2) The load acting on the restraint-support structure becomes larger as the overhang length becomes shorter. (3) The restraint farther from the break location does not limit the pipe movement except for the first impact when the overhang length is long. (4) The ultimate moment M sub(u) of the pipe at the restraint location can be used to predict the plastic collapse of the whipping pipe. (5) The restraints slide along the pipe axis and are subjected to bending moment, when the overhang length is long. (author)

Investigation of elastic stability of the lower part of drill pipe string (dynamic problems)

Energy Technology Data Exchange (ETDEWEB)

Griguletskii, V.G.

1981-12-01

Based on V.V. Bolotin's results, the problem of dynamic stability of the lower part of a string of drill pipes in a vertical well is formulated (and solved in the first approximation). An investigation of the phenomena during the interaction between lengthwise and transverse oscillations of the bottom part of the drill pipe string is carried out. Excitation conditions are determined and the mechanism of the onset of parametric oscillations is explained. 20 refs.

Alternate procedures for the seismic analysis of multiply supported piping systems

International Nuclear Information System (INIS)

Subudhi, M.; Bezler, P.

1985-01-01

The seismic design of secondary systems such as piping requires knowledge of the motions at various locations of the primary structures. When the structure or buildings are subjected to earthquake-like excitations at the ground level, the responses at different floor levels may be quite different from each other. This difference depends on the building and soil frequency characteristics, the characteristics of the input signals, the damping levels, and soil-structure interaction effects. When multiple independent excitations are considered in the analysis of piping systems, the responses can be considered to have two distinct components. One is due to the inertia of masses alone (dynamic component) and the other is due to the time varying differential motion of the support points (pseudo-static component). To address this problem, a sample of six piping systems, two of which were subjected to thirty-three earthquakes, were studied to develop a statistical assessment of different methods of predicting the dynamic, pseudo-static and combined response. Both uniform and independent support motion methods were considered. The results are obtained in tabular form. The mean and standard deviation for the two piping systems subjected to thirty-three earthquakes were obtained to allow an assessment of the adequacy and level of conservatism associated with each method. These results are also displayed in graphical form for selected, critical locations in the piping systems. The limitations of each method and recommendations are discussed

Optimum design for pipe-support allocation against seismic loading

International Nuclear Information System (INIS)

Hara, Fumio; Iwasaki, Akira

1996-01-01

This paper deals with the optimum design methodology of a piping system subjected to a seismic design loading to reduce its dynamic response by selecting the location of pipe supports and whereby reducing the number of pipe supports to be used. The author employs the Genetic Algorithm for obtaining a reasonably optimum solution of the pipe support location, support capacity and number of supports. The design condition specified by the support location, support capacity and the number of supports to be used is encored by an integer number string for each of the support allocation candidates and they prepare many strings for expressing various kinds of pipe-support allocation state. Corresponding to each string, the authors evaluate the seismic response of the piping system to the design seismic excitation and apply the Genetic Algorithm to select the next generation candidates of support allocation to improve the seismic design performance specified by a weighted linear combination of seismic response magnitude, support capacity and the number of supports needed. Continuing this selection process, they find a reasonably optimum solution to the seismic design problem. They examine the feasibility of this optimum design method by investigating the optimum solution for 5, 7 and 10 degree-of-freedom models of piping system, and find that this method can offer one a theoretically feasible solution to the problem. They will be, thus, liberated from the severe uncertainty of damping value when the pipe support guaranties the design capacity of damping. Finally, they discuss the usefulness of the Genetic Algorithm for the seismic design problem of piping systems and some sensitive points when it will be applied to actual design problems

Influence of tip mass on dynamic behavior of cracked cantilever pipe conveying fluid with moving mass

International Nuclear Information System (INIS)

Yoon, Han Ik; Son, In Soo

2005-01-01

In this paper, we studied about the effect of the open crack and a tip mass on the dynamic behavior of a cantilever pipe conveying fluid with a moving mass. The equation of motion is derived by using Lagrange's equation and analyzed by numerical method. The cantilever pipe is modelled by the Euler-Bernoulli beam theory. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The influences of the crack, the moving mass, the tip mass and its moment of inertia, the velocity of fluid, and the coupling of these factors on the vibration mode, the frequency, and the tip-displacement of the cantilever pipe are analytically clarified

Performing dynamic time history analyses by extension of the response spectrum method

International Nuclear Information System (INIS)

Hulbert, G.M.

1983-01-01

A method is presented to calculate the dynamic time history response of finite-element models using results from response spectrum analyses. The proposed modified time history method does not represent a new mathamatical approach to dynamic analysis but suggests a more efficient ordering of the analytical equations and procedures. The modified time history method is considerably faster and less expensive to use than normal time hisory methods. This paper presents the theory and implementation of the modified time history approach along with comparisons of the modified and normal time history methods for a prototypic seismic piping design problem

Assessment of the dynamic response of systems and measures to enhance their safety

International Nuclear Information System (INIS)

Serban, Viorel; Androne, Marian; Ciocan, George Alexandru; Zamfir, Madalina; Florea, Ioana; Panait, Adrian; Prisecaru, Ilie

2007-01-01

Buildings, equipment and pipe networks are dynamically, oscillating structures that may build-up energy or not, from the excitation, amplifying or damping their response as a function of the rate between the system vibration Eigen period and the repetition period of the dynamic excitation and the system damping capacity. This paper is an analysis in time and frequency of the dynamic response of an oscillating system subject to a periodic excitation. The results of the conducted analysis show how a system must be sized for the transfer of energy from excitation to the system be minimized, the system builds-up as less kinetic and elastic energy as possible and the system response to accelerations, velocity and distortions be also minimal. (author)

Inertial Effects on Finite Length Pipe Seismic Response

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Virginia Corrado

2012-01-01

Full Text Available A seismic analysis for soil-pipe interaction which accounts for length and constraining conditions at the ends of a continuous pipe is developed. The Winkler model is used to schematize the soil-structure interaction. The approach is focused on axial strains, since bending strains in a buried pipe due to the wave propagation are typically a second-order effect. Unlike many works, the inertial terms are considered in solving equations. Accurate numerical simulations are carried out to show the influence of pipe length and constraint conditions on the pipe seismic strain. The obtained results are compared with results inferred from other models present in the literature. For free-end pipelines, inertial effects have significant influence only for short length. On the contrary, their influence is always important for pinned pipes. Numerical simulations show that a simple rigid model can be used for free-end pipes, whereas pinned pipes need more accurate models.

Analysis of piping response to thermal and operational transients

International Nuclear Information System (INIS)

Wang, C.Y.

1987-01-01

The reactor piping system is an extremely complex three-dimensional structure. Maintaining its structural integrity is essential to the safe operation of the reactor and the steam-supply system. In the safety analysis, various transient loads can be imposed on the piping which may cause plastic deformation and possible damage to the system, including those generated from hydrodynamic wave propagations, thermal and operational transients, as well as the seismic events. At Argonne National Laboratory (ANL), a three-dimensional (3-D) piping code, SHAPS, aimed for short-duration transients due to wave propagation, has been developed. Since 1984, the development work has been shifted to the long-duration accidents originating from the thermal and operational transient. As a result, a new version of the code, SHAPS-2, is being established. This paper describes many features related to this later development. To analyze piping response generated from thermal and operational transients, a 3-D implicit finite element algorithm has been developed for calculating the hoop, flexural, axial, and torsional deformations induced by the thermomechanical loads. The analysis appropriately accounts for stresses arising from the temperature dependence of the elastic material properties, the thermal expansion of the materials, and the changes in the temperature-dependent yield surface. Thermal softening, failure, strain rate, creep, and stress ratching can also be considered

Simplified analytical methods and experimental correlations of damping in piping during dynamic high-level inelastic response

International Nuclear Information System (INIS)

Severud, L.K.

1987-01-01

Simplified methods for predicting equivalent viscous damping are used to assess damping contributions due to piping inelastic plastic hinge action and support snubbers. These increments are compared to experimental findings from shake and snap-back tests of several pipe systems. Good correlations were found confirming the usefulness of the simplified methods

Application of mathematical model for high viscous damper to dynamic analysis of NPP pipings

International Nuclear Information System (INIS)

Kostarev, V.V.; Bercovsky, A.M.; Kireev, O.B.; Vasiliev, P.S.

1993-01-01

The problems of dynamic analysis of Nuclear Power Plants (NPP) piping systems are considered in the paper. The special calculation program for PC has been developed that enables to estimate the seismic margin for any piping system with different antiseismic devices having nonlinear characteristics. The calculated comparison has been done for two antiseismic supports that are widely used now, namely: a High Viscous Damper (HVD) and a Seismic Stop Support (SSS) with the application, as an example, to the well known pipeline BM3 (USNRC). (author)

Application of mathematical model for high viscous damper to dynamic analysis of NPP pipings

Energy Technology Data Exchange (ETDEWEB)

Kostarev, V V; Bercovsky, A M; Kireev, O B; Vasiliev, P S [CKTI VIBROSEISM (CVS), St. Petersburg (Russian Federation)

1993-07-01

The problems of dynamic analysis of Nuclear Power Plants (NPP) piping systems are considered in the paper. The special calculation program for PC has been developed that enables to estimate the seismic margin for any piping system with different antiseismic devices having nonlinear characteristics. The calculated comparison has been done for two antiseismic supports that are widely used now, namely: a High Viscous Damper (HVD) and a Seismic Stop Support (SSS) with the application, as an example, to the well known pipeline BM3 (USNRC). (author)

Experimental study of plastic responses of pipe elbows

International Nuclear Information System (INIS)

Greenstreet, W.L.

1978-01-01

Load-deflection responses were determined experimentally for sixteen 152.4-mm (6-in.) (nominal) commercial carbon steel pipe elbows and four 152.4-mm (6-in.) stainless steel elbows. Each specimen was loaded with an external force of sufficient magnitude to produce predominantly plastic response. The influences of bend radius and wall thickness were studied, as well as the effect of internal prssure on load-deflection behavior. Comparisons of results from stainless steel and from carbon steel elbows indicate differences in responses attributable to material differences. The results were interpreted in terms of limit analysis concepts, and collapse loads were determined. Trends given by the collapse loads are identified and discussed

Effect of PVRC damping with independent support motion response spectrum analysis of piping systems

International Nuclear Information System (INIS)

Wang, Y.K.; Bezler, P.; Shteyngart, S.

1986-01-01

The Technical Committee for Piping Systems of the Pressure Vessel Research Committee (PVRC) has recommended new damping values to be used in the seismic analyses of piping systems in nuclear power plants. To evaluate the effects of coupling these recommendations with the use of independent support motion analyses methods, two sets of seismic analyses have been carried out for several piping systems. One set based on the use of uniform damping as specified in Regulatory Guide 1.61, the other based on the PVRC recommendations. In each set the analyses were performed using independent support motion time history and response spectrum methods as well as the envelope spectrum method. In the independent response spectrum analyses, 14 response estimates were in fact obtained by considering different combination procedures between the support group contributions and all sequences of combinations between support groups, modes and directions. For each analysis set, the response spectrum results were compared with time history estimates of those results. Comparison tables were then prepared depicting the percentage by which the response spectrum estimates exceeded the time history estimates. By comparing the result tables between both analysis sets, the impact of PVRC damping can be observed. Preliminary results show that the degree of exceedance of the response spectrum estimates based on PVRC damping is less than that based on uniform damping for the same piping problem. Expressed differently the results obtained if ISM methods are coupled with PVRC damping are not as conservative as those obtained using uniform damping

Evaluation and summary of seismic response of above ground nuclear power plant piping to strong motion earthquakes

International Nuclear Information System (INIS)

Stevenson, J.D.

1985-01-01

The purpose of this paper is to summarize the observations and experience which has been developed relative to the seismic behavior of above-ground, building-supported, industrial type piping (similar to piping used in nuclear power plants) in strong motion earthquakes. The paper also contains observations regarding the response of piping in experimental tests which attempted to excite the piping to failure. Appropriate conclusions regarding the behavior of such piping in large earthquakes and recommendations as to future design of such piping to resist earthquake motion damage are presented based on observed behavior in large earthquakes and simulated shake table testing

Analysis of the jet pipe electro-hydraulic servo valve with finite element methods

Directory of Open Access Journals (Sweden)

Kaiyu Zhao

2018-01-01

Full Text Available The dynamic characteristics analysis about the jet pipe electro-hydraulic servo valve based on experience and mathematical derivation was difficult and not so precise. So we have analysed the armature feedback components, torque motor and jet pipe receiver in electrohydraulic servo valve by sophisticated finite element analysis tools respectively and have got physical meaning data on these parts. Then the data were fitted by Matlab and the mathematical relationships among them were calculated. We have done the dynamic multi-physical fields’ Simulink co-simulation using above mathematical relationship, and have got the input-output relationship of the overall valve, the frequency response and step response. This work can show the actual working condition accurately. At the same time, we have considered the materials and the impact of the critical design dimensions in the finite element analysis process. It provides some new ideas to the overall design of jet pipe electro-hydraulic servo valve.

Nuclear power plant piping damping parametric effects

International Nuclear Information System (INIS)

Ware, A.G.

1983-01-01

The present NRC guidelines for structural damping to be used in the dynamic stress analyses of nuclear power plant piping systems are generally considered to be overly conservative. As a result, plant designers have in many instances used a considerable number of seismic supports to keep stresses calculated by large scale piping computer codes below the allowable limits. In response to this problem, the NRC and EG and G Idaho are engaged in programs to evaluate piping system damping, in order to provide more realistic and less conservative values to be used in seismic analyses. To generate revised guidelines, solidly based on technical data, new experimental data need to be generated and assessed, and the parameters which influence piping system damping need to be quantitatively identified. This paper presents the current state-of-the-art knowledge in the United States on parameters which influence piping system damping. Examples of inconsistencies in the data and areas of uncertainty are explained. A discussion of programs by EG and G Idaho and other organizations to evaluate various effects is included, and both short and long range goals of the program are outlined

Piping benchmark problems for the ABB/CE System 80+ Standardized Plant

International Nuclear Information System (INIS)

Bezler, P.; DeGrassi, G.; Braverman, J.; Wang, Y.K.

1994-07-01

To satisfy the need for verification of the computer programs and modeling techniques that will be used to perform the final piping analyses for the ABB/Combustion Engineering System 80+ Standardized Plant, three benchmark problems were developed. The problems are representative piping systems subjected to representative dynamic loads with solutions developed using the methods being proposed for analysis for the System 80+ standard design. It will be required that the combined license licensees demonstrate that their solution to these problems are in agreement with the benchmark problem set. The first System 80+ piping benchmark is a uniform support motion response spectrum solution for one section of the feedwater piping subjected to safe shutdown seismic loads. The second System 80+ piping benchmark is a time history solution for the feedwater piping subjected to the transient loading induced by a water hammer. The third System 80+ piping benchmark is a time history solution of the pressurizer surge line subjected to the accelerations induced by a main steam line pipe break. The System 80+ reactor is an advanced PWR type

The application of viscous dampers as pipe restraints

International Nuclear Information System (INIS)

Keowen, R.S.; Hueffmann, G.; Mays, B.; Rencher, D.

1993-01-01

Dynamic loading of power generation piping systems may result in nonpermissable deflections and stresses. Fatigue failure translate to increased maintenance costs and possible lost revenue. Undesirable loading can occur due to external events such as earthquakes and internal events such as water and steam hammer, two-phase flow and cavitation. Sway braces and snubbers have been employed to reduce the negative effects of piping motion in emergency cases, however, repetitive loading due to internal events has caused premature wear and failure. Visco elastic dampers, however, have proven to be piping response due to slugging, steam hammer and other repetitive loads. Functional and modeling aspects of visco elastic dampers are discussed, experimental evidence of their effectiveness in a steam hammer application is presented and examples of primary coolant loop restraint applications are illustrated

Simplified inelastic seismic response analysis of piping system using improved capacity spectrum method

International Nuclear Information System (INIS)

Iijima, Tadashi

2005-01-01

We applied improved capacity spectrum method (ICSM) to a piping system with an asymmetric load-deformation relationship in a piping elbow. The capacity spectrum method can predict an inelastic response by balancing the structural capacity obtained from the load-deformation relationship with the seismic demand defined by an acceleration-displacement response spectrum. The ICSM employs (1) effective damping ratio and period that are based on a statistical methodology, (2) practical procedures necessary to obtain a balance between the structural capacity and the seismic demand. The effective damping ratio and period are defined so as to maximize the probability that predicted response errors lie inside the -10 to 20% range. However, without taking asymmetry into consideration the displacement calculated by using the load-deformation relationship on the stiffer side was 39% larger than that of a time history analysis by a direct integral method. On the other hand, when asymmetry was taken into account, the calculated displacement was only 14% larger than that of a time history analysis. Thus, we verified that the ICSM could predict the inelastic response with errors lying within the -10 to 20% range, by taking into account the asymmetric load-deformation relationship of the piping system. (author)

Uplifting Behavior of Shallow Buried Pipe in Liquefiable Soil by Dynamic Centrifuge Test

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Bo Huang

2014-01-01

Full Text Available Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure.

Uplifting Behavior of Shallow Buried Pipe in Liquefiable Soil by Dynamic Centrifuge Test

Science.gov (United States)

Liu, Jingwen; Ling, Daosheng

2014-01-01

Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure. PMID:25121140

Uplifting behavior of shallow buried pipe in liquefiable soil by dynamic centrifuge test.

Science.gov (United States)

Huang, Bo; Liu, Jingwen; Lin, Peng; Ling, Daosheng

2014-01-01

Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure.

Study of near-source earthquake effects on flexible buried pipes

Science.gov (United States)

Davis, Craig Alan

2000-10-01

An investigation is carried out, using strong ground motion recordings, field measurements, and new analytical models, on large diameter flexible buried pipes shaken in the 1994 Northridge earthquake near field. Case studies are presented for corrugated metal pipes (CMP) in the Van Norman Complex (VNC) vicinity in Los Angeles, California. In 1994 the VNC yielded an unprecedented number of strong motion recordings with high acceleration and velocity. These recordings contain forward directivity pulses and provided the largest velocity ever instrumentally recorded (180 cm/s). The recorded motions were significantly different in the longitudinal and transverse directions and had approximately half the amplitude at the VNC center than on the north and south ends. The seismic performances of 61 underground CMPs are presented, beginning with detailed studies of a 2.4 m diameter pipe that suffered complete lateral buckling collapse at the Lower San Fernando Dam (LSFD). The case histories identify factors controlling large diameter CMP seismic performances that are incorporated into several newly developed models for the analysis and design of buried structures. Each model progressively improves the understanding of buried pipe behavior. Simple acceleration- and strain-based pseudo-static models are initially developed to identify main causes for CMP damage. Elasto-dynamic models for transverse SV waves are later used to understand flexible pipe response in the frequency and time domains and are compared with existing solutions. Finally, pseudo-static models, which analyze pipe responses in terms of free-field strains, are formulated to account for dynamic amplification, non-vertical wave incidence, soil layering, and trench backfill soil stiffness. The elastic models are used to investigate soil-pipe interface shear stress and non-linear soil behavior and show that the maximum pipe hoop force is best characterized by assuming no interface slippage. The models explain the

Application of sensitivity analysis for optimized piping support design

International Nuclear Information System (INIS)

Tai, K.; Nakatogawa, T.; Hisada, T.; Noguchi, H.; Ichihashi, I.; Ogo, H.

1993-01-01

The objective of this study was to see if recent developments in non-linear sensitivity analysis could be applied to the design of nuclear piping systems which use non-linear supports and to develop a practical method of designing such piping systems. In the study presented in this paper, the seismic response of a typical piping system was analyzed using a dynamic non-linear FEM and a sensitivity analysis was carried out. Then optimization for the design of the piping system supports was investigated, selecting the support location and yield load of the non-linear supports (bi-linear model) as main design parameters. It was concluded that the optimized design was a matter of combining overall system reliability with the achievement of an efficient damping effect from the non-linear supports. The analysis also demonstrated sensitivity factors are useful in the planning stage of support design. (author)

Report of the US Nuclear Regulatory Commission Piping Review Committee. Volume 4. Evaluation of other loads and load combinations

International Nuclear Information System (INIS)

1984-12-01

Six topical areas were covered by the Task Group on Other Dynamic Loads and Load Combinations as described below: Event Combinations - dealing with the potential simultaneous occurrence of earthquakes, pipe ruptures, and water hammer events in the piping design basis; Response Combinations - dealing with multiply supported piping with independent inputs, the sequence of combinations between spacial and modal components of response, and the treatment of high frequency modes in combination with low frequency modal responses; Stress Limits/Dynamic Allowables - dealing with inelastic allowables for piping and strain rate effects; Water Hammer Loadings - dealing with code and design specifications for these loadings and procedures for identifying potential water hammer that could affect safety; Relief Valve Opening and Closing Loads - dealing with the adequacy of analytical tools for predicting the effects of these events and, in addition, with estimating effective cycles for fatigue evaluations; and Piping Vibration Loads - dealing with evaluation procedures for estimating other than seismic vibratory loads, the need to consider reciprocating and rotary equipment vibratory loads, and high frequency vibratory loads. NRC staff recommendations or regulatory changes and additional study appear in this report

Flow induced vibrations of piping system (Vibration sources - Mechanical response of the pipes)

International Nuclear Information System (INIS)

Gibert, R.J.; Axisa, F.; Villard, B.

1978-01-01

In order to design the supports of piping system, an estimation of the vibration induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary. To evaluate the power spectra of all the main sources generated by the flow. These sources are located at the singular points of the circuit (enlargements, bends, valves, etc. ...). To calculate the modal parameters of fluid containing pipes. This paper presents: a methodical study of the most current singularities. Inter-correlation spectra of local pressure fluctuation downstream from the singularity and correlation spectra of associated acoustical sources have been measured. A theory of noise generation by unsteady flow in internal acoustics has been developed. All these results are very useful for evaluating the source characteristics in most practical pipes. A comparison between the calculation and the results of an experimental test has shown a good agreement

Evaluation of dynamic loads induced by transient regimes of fluid flows in the pipe systems and devices of reducing the loads and their effects

International Nuclear Information System (INIS)

Serban, Viorel; Chirita, Alexandru Mihai; Androne, Marian; Alexandru, Constantin; Ciuca, Camelia; Badara, Janina; Alexandru, Carmen

1995-01-01

The paper presents the analytic methods for estimating the dynamic effects induced in pipe systems in transient regimes. They are based on computation programs developed in order to check the behaviour of ECCS and EWS under 'water hammer effect' and the behaviour of the primary circuit system under stresses caused by pipe cracks. Computation examples are presented in order to emphasize the capabilities of the programs to model transient phenomena in complex pipe networks. The overpressure induced by the water hammer effect, as revealed by comparing several transient regimes, depends on the fluid viscosity, the initial speed, the duration of starting the transient regime, the system rigidity, etc. Values several ten times higher that the initial one could be thus reached. An overview of new types of devices designed for damping the effect of water hammer phenomenon, as well as of sustaining supports for pipe systems and equipment able to damp the vibrations produced by the transient regimes of fluid flows and seismic movements is presented. These devices have also to cope with the high shocks produced by pipe breakage as well as high static loads. The paper contains the following sections: 1. Introduction; 2. Evaluating dynamic loads associated to the water hammer phenomenon; 3. Determining loads associated to the water hammer phenomenon for the ECC system of the Cernavoda NPP Unit 1; 4. Device for reducing the water hammer effects; 5. Evaluating dynamic loads associated to pipe cracks; 6. Determining loads associated to pipe cracks in the Cernavoda NPP primary circuit; 7. Devices for absorbing and damping the dynamic loads in pipe systems and equipment; 8. Conclusions. (authors)

An experimental study on damping characteristics of mechanical snubber for nuclear power plant piping systems

International Nuclear Information System (INIS)

Chiba, T.; Kobayashi, H.; Kitamura, K.; Ando, K.; Koyanagi, R.

1983-01-01

The objectives of this study are 1) to clarify the damping characteristics and the dynamic stiffness of mechanical snubber, 2) to take the damping characteristics of mechanical snubber into the damping evaluation method obtained in SDREP. Therefore, following vibration tests were conducted. 1) Component test: As a first step, mechanical snubbers were excited with sinusoidal wave, and damping ratio and dynamic stiffness were measured at several loading levels. 2) Piping model test: Second, a 8'' diameter x 16 m length 3-dimensional piping model simulating the supporting conditions of actual piping systems was tested. Damping ratio and made shapes of piping model with mechanical snubbers were measured at several supporting conditions and response levels. From the results of these tests, the damping characteristics and the dynamic stiffness of mechanical snubber can be summarized as follows: 1) The damping effect of mechanical snubber is as strong as that of oil snubber. 2) Mechanical snubber contributes effectively to the damping of piping system, and it is indicated that the damping characteristics of mechanical snubber is applicable to the damping evaluation method obtained in SDREP. (orig./HP)

Shock Wave Speed and Transient Response of PE Pipe with Steel-Mesh Reinforcement

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Wuyi Wan

2016-01-01

Full Text Available A steel mesh can improve the tensile strength and stability of a polyethylene (PE pipe in a water supply pipeline system. However, it can also cause more severe water hammer hazard due to increasing wave speed. In order to analyze the influence of the steel mesh on the shock wave speed and transient response processes, an improved wave speed formula is proposed by incorporating the equivalent elastic modulus. A field measurement validates the wave speed formula. Moreover, the transient wave propagation and extreme pressures are simulated and compared by the method of characteristics (MOC for reinforced PE pipes with various steel-mesh densities. Results show that a steel mesh can significantly increase the shock wave speed in a PE pipe and thus can cause severe peak pressure and hydraulic surges in a water supply pipeline system. The proposed wave speed formula can more reasonably evaluate the wave speed and improve the transient simulation of steel-mesh-reinforced PE pipes.

Fatigue of LMFBR piping due to flow stratification

International Nuclear Information System (INIS)

Woodward, W.S.

1983-01-01

Flow stratification due to reverse flow was simulated in a 1/5-scale water model of a LMFBR primary pipe loop. The stratified flow was observed to have a dynamic interface region which oscillated in a wave pattern. The behavior of the interface was characterized in terms of location, local temperature fluctuation and duration for various reverse flow conditions. A structural assessment was performed to determine the effects of stratified flow on the fatigue life of the pipe. Both the static and dynamic aspects of flow stratification were examined. The dynamic interface produces thermal striping on the inside of the pipe wall which is shown to have the most deleterious effect on the pipe wall and produce significant fatigue damage relative to a static interface

Fatigue of LMFBR piping due to flow stratification

Energy Technology Data Exchange (ETDEWEB)

Woodward, W.S.

1983-01-01

Flow stratification due to reverse flow was simulated in a 1/5-scale water model of a LMFBR primary pipe loop. The stratified flow was observed to have a dynamic interface region which oscillated in a wave pattern. The behavior of the interface was characterized in terms of location, local temperature fluctuation and duration for various reverse flow conditions. A structural assessment was performed to determine the effects of stratified flow on the fatigue life of the pipe. Both the static and dynamic aspects of flow stratification were examined. The dynamic interface produces thermal striping on the inside of the pipe wall which is shown to have the most deleterious effect on the pipe wall and produce significant fatigue damage relative to a static interface.

Instability predictions for circumferentially cracked Type-304 stainless-steel pipes under dynamic loading. Final report

International Nuclear Information System (INIS)

Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

1982-04-01

This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models

Safety design guide for pipe rupture protection for CANDU 9

International Nuclear Information System (INIS)

Lee, Duk Su; Chang, Woo Hyun; Lee, Nam Young; A. C. D. Wright

1996-03-01

This safety design guide for pipe rupture protection identifies high-energy systems in which pipe ruptures must be postulated to occur, as well as systems that must be protected from the dynamic effects of such ruptures. Dynamic effects considered in this SDG consist of pipe whip (including missiles generated by pipe ruptures, if any) and jet impingement, Requirements for protection against the dynamic effects of a postulated pipe rupture and method of protection of essential structures, systems and components are specified for these effects. The change status for the regulatory requirements, code and standards should be traced and this safety design guide shall be updated accordingly. 2 tabs., 5 refs. (Author) .new

BNL NONLINEAR PRE TEST SEISMIC ANALYSIS FOR THE NUPEC ULTIMATE STRENGTH PIPING TEST PROGRAM

International Nuclear Information System (INIS)

DEGRASSI, G.; HOFMAYER, C.; MURPHY, C.; SUZUKI, K.; NAMITA, Y.

2003-01-01

The Nuclear Power Engineering Corporation (NUPEC) of Japan has been conducting a multi-year research program to investigate the behavior of nuclear power plant piping systems under large seismic loads. The objectives of the program are: to develop a better understanding of the elasto-plastic response and ultimate strength of nuclear piping; to ascertain the seismic safety margin of current piping design codes; and to assess new piping code allowable stress rules. Under this program, NUPEC has performed a large-scale seismic proving test of a representative nuclear power plant piping system. In support of the proving test, a series of materials tests, static and dynamic piping component tests, and seismic tests of simplified piping systems have also been performed. As part of collaborative efforts between the United States and Japan on seismic issues, the US Nuclear Regulatory Commission (USNRC) and its contractor, the Brookhaven National Laboratory (BNL), are participating in this research program by performing pre-test and post-test analyses, and by evaluating the significance of the program results with regard to safety margins. This paper describes BNL's pre-test analysis to predict the elasto-plastic response for one of NUPEC's simplified piping system seismic tests. The capability to simulate the anticipated ratcheting response of the system was of particular interest. Analyses were performed using classical bilinear and multilinear kinematic hardening models as well as a nonlinear kinematic hardening model. Comparisons of analysis results for each plasticity model against test results for a static cycling elbow component test and for a simplified piping system seismic test are presented in the paper

Simulation of bending stress variation in long buried thick-walled pipes under the earth’s movement using combined linear dynamics and beam theories

Directory of Open Access Journals (Sweden)

Salau Tajudeen A.O.

2014-01-01

Full Text Available This study reported a simulation approach to the understanding of the interactions between a buried pipe and the soil system by computing the bending stress variation of harmonically-excited buried pipes. The established principles of linear dynamics theory and simple beam theory were utilised in the analysis of the problem of buried pipe bending stress accumulation and its dynamics. With regards to the parameters that influence the bending stress variations, the most important are the isolation factor, uniform external load, and the corresponding limiting conditions. The simulated mathematical expressions, containing static and dynamic parameters of the buried pipe and earth, were coded in Fortran programming language and applied in the simulation experiment. The results obtained showed that harmonically-excited buried thick-walled pipe became stable and effective when the ratio of the natural frequency of vibration to the forced frequency is greater than 2.0, whenever the damped factor is used as the control parameter for the maximum bending stress. The mirror image of the stress variation produces variation in the location of the maximum bending stress in quantitative terms. The acceptable pipe materials for the simulated cases must have yield strength in bending greater than or equal to 13.95 MPa. The results obtained in this work fill a gap in the literature and will be useful to pipeline engineers and designers, as well as to environmental scientists in initialising and controlling environmental issues and policy formulation concerning the influence of buried pipe on the soil and water in the environment.

Multi-mode vibration control of piping system

International Nuclear Information System (INIS)

Minowa, Takeshi; Seto, Kazuto; Iiyama, Fumiya; Sodeyama, Hiroshi

1999-01-01

In this paper, dual dynamic absorbers are applied to the piping system in order to control the multiple vibration modes. ANSYS, which is one of the software based on FEM(finite element method), is used for the design of dual dynamic absorbers as well as for the determination of their optimum installing positions. The dual dynamic absorbers designed optimally for controlling the first three vibration modes perform just like a houde damper in higher frequency and have an effect on controlling higher modes. To use this advantage, three dual dynamic absorbers are installed in positions where they influence higher modes, and not only the first three modes of the piping system but also the extensive modes are controlled. Practical experimental study has also been carried out and it is shown that a dual dynamic absorber is suitable for controlling the vibration of the piping system. (author)

Flight initiation distances of nesting Piping Plovers (Charadrius melodus in response to human disturbance

Directory of Open Access Journals (Sweden)

Joel G. Jorgensen

2016-06-01

Full Text Available Birds frequently interact with people when they occur in coupled human-ecological or anthropogenic environments, which makes the protection of legally protected species a challenge. Flight initiation distances (FIDs are often used to inform development of appropriate buffer distances required for human exclusion zones used to protect birds nesting in anthropogenic landscapes. Piping Plovers (Charadrius melodus are protected by the Endangered Species Act in the United States and often nest in areas used by humans. Studies evaluating Piping Plover FIDs are limited and implementation of exclusion zones has been inconsistent across the species' range. We measured Piping Plover response and FIDs to naturally occurring stimuli on public beaches at Lake McConaughy, Nebraska, USA. Piping Plover FIDs differed most by stimulus class (vehicle, human, dog, human with dog, Julian day, and hour of day. Piping Plover FIDs were greatest for dog and human with dog compared to humans and vehicles. For all types of stimuli, Piping Plover FIDs decreased over time during the nesting season and increased slightly during each day. In the majority of instances in which Piping Plovers left their nests, return times to the nest were relatively short (less than three minutes. These results suggest Piping Plovers become habituated to the presence of human-related stimuli over the course of a nesting season, but other explanations such as parental investment and risk allocation cannot be excluded. Additional research and improved guidance regarding the implementation of exclusion zones is needed so managers can implement effective protection programs in anthropogenic landscapes.

Small-bore-piping seismic-test findings

International Nuclear Information System (INIS)

Severud, L.K.; Barta, D.A.; Anderson, M.J.

1981-12-01

Description is given of a test series in which a 1-inch diameter stainless steel pipe system was subjected to dynamic testing. The test system consisted of approximately 40-feet of schedule 40 pipe, with several bends and risers, supported from a rigid test frame. FFTF prototypic pipe clamps, dead weight supports, mechanical snubbers, and insulation were utilized. Several variations of the pipe support configuration were tested. Measured test results are compared with analytical predictions for each configuration. Plans for future testing are discussed

Structural dynamics and fracture mechanics calculations of the behaviour of a DN 425 test piping system subjected to transient loading by water hammer

International Nuclear Information System (INIS)

Kussmaul, K.; Kobes, E.; Diem, H.; Schrammel, D.; Brosi, S.

1994-01-01

Within the scope of the German HDR safety programme, several tests were carried out to investigate transient pipe loading initiated by a simulated double-ended guillotine break event, and subsequent closure of a feedwater check valve (water hammer, blow-down). Numerical analyses by means of finite element programmes were performed in parallel to the experiments. Using water hammer tests of a DN 425 piping system with predamaged components, the procedure of such analyses will be demonstrated. The results are presented, beginning with structural dynamic calculations of the undamaged piping; followed by coupling of structural dynamics and fracture mechanics computations with simple flaw elements (line spring); and finishing with costly three-dimensional fracture mechanics analyses. A good description of the real piping behaviour can be made by the numerical methods, even in the case of high plastification processes. ((orig.))

Condensation of steam in horizontal pipes: model development and validation

International Nuclear Information System (INIS)

Szijarto, R.

2015-01-01

This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich presents the development and validation of a model for the condensation of steam in horizontal pipes. Condensation models were introduced and developed particularly for the application in the emergency cooling system of a Gen-III+ boiling water reactor. Such an emergency cooling system consists of slightly inclined horizontal pipes, which are immersed in a cold water tank. The pipes are connected to the reactor pressure vessel. They are responsible for a fast depressurization of the reactor core in the case of accident. Condensation in horizontal pipes was investigated with both one-dimensional system codes (RELAP5) and three-dimensional computational fluid dynamics software (ANSYS FLUENT). The performance of the RELAP5 code was not sufficient for transient condensation processes. Therefore, a mechanistic model was developed and implemented. Four models were tested on the LAOKOON facility, which analysed direct contact condensation in a horizontal duct

Instability predictions for circumferentially cracked Type-304 stainless-steel pipes under dynamic loading. Final report. [BWR

Energy Technology Data Exchange (ETDEWEB)

Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

1982-04-01

This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models.

Variation of structural damping with response amplitude in piping systems

International Nuclear Information System (INIS)

Ware, A.G.

1986-01-01

From tests conducted over the last several years, it has become apparent that structural damping is not a single number applicable to all piping systems, but is highly dependent on piping system parameters such as supports, response amplitude, and insulation. As a result, there is considerable scatter in the available data. Furthermore, the relationships between the parameters and damping are often highly complex, interrelated, and difficult to predict. From tests of piping supported by various typical methods, two basic types of energy dissipation in the supports can be observed. The first is friction such as between spring hangers and their housings or in the internal mechanisms of constant force hangers. The second is impacting such as occurs in snubbers, rigid struts, and rod hangers. Overall, these effects lead to a wide variety of possibilities that can occur at low vibration levels and can change with only a slight perturbation of vibration amplitude. This can account for much of the scatter in the data at low strain levels. Thus damping is almost impossible to predict at low amplitudes, and extrapolation of this type data to higher amplitudes is cautioned. However, once strain levels rise above 100 to 200 micro in/in, the damping trend becomes easier to characterize. From the 100 to 200 micro in/in to 800 to 1000 micro in/in range the damping is fairly constant and is induced primarily by the supports. At the upper end of this range a threshold is reached in which damping increases with increasing strain amplitude. Data in the high strain (plastic range) is sparse since the test usually renders the pipe unsuitable for further use. 15 refs

Evaluation of seismic margins for an in-plant piping system

International Nuclear Information System (INIS)

Kot, C.A.; Srinivasan, M.G.; Hsieh, B.J.

1991-01-01

Earthquake experience as well as experiments indicate that, in general, piping systems are quite rugged in resisting seismic loadings. Therefore there is a basis to hold that the seismic margin against pipe failure is very high for systems designed according to current practice. However, there is very little data, either from tests or from earthquake experience, on the actual margin or excess capacity (against failure from seismic loading) of in-plant piping systems. Design of nuclear power plant piping systems in the US is governed by the criteria given in the ASME Boiler and Pressure Vessel (B ampersand PV) Code, which assure that pipe stresses are within specified allowable limits. Generally linear elastic analytical methods are used to determine the stresses in the pipe and forces in pipe supports. The objective of this study is to verify that piping designed according to current practice does indeed have a large margin against failure and to quantify the excess capacity for piping and dynamic pipe supports on the basis of data obtained in a series of high-level seismic experiments (designated SHAM) on an in-plant piping system at the HDR (Heissdampfreaktor) Test Facility in Germany. Note that in the present context, seismic margin refers to the deterministic excess capacities of piping or supports compared to their design capacities. The excess seismic capacities or margins of a prototypical in-plant piping system and its components are evaluated by comparing measured inputs and responses from high-level simulated seismic experiments with design loads and allowables. Large excess capacities are clearly demonstrated against pipe and overall system failure with the lower bound being about four. For snubbers the lower bound margin is estimated at two and for rigid strut supports at five. 4 refs., 2 figs., 2 tabs

Evaluation of the influence of seismic restraint characteristics on breeder reactor piping systems

International Nuclear Information System (INIS)

Mello, R.M.; Pollono, L.P.

1979-01-01

For the Clinch River Breeder Reactor Plant (CRBRP) heat transport system piping within the reactor containment building, dynamic analyses of the piping loops have been performed to study the effect of restraint stiffness on the dynamic behavior of the piping. In addition, analysis and testing of typical CRBRP restraint system components have been performed for the purpose of quantifying and verifying the basic characteristics of the restraints used in the piping system dynamic analysis

Comparison of multiple support excitation solution techniques for piping systems

International Nuclear Information System (INIS)

Sterkel, H.P.; Leimbach, K.R.

1980-01-01

Design and analysis of nuclear power plant piping systems exposed to a variety of dynamic loads often require multiple support excitation analysis by modal or direct time integration methods. Both methods have recently been implemented in the computer program KWUROHR for static and dynamic analysis of piping systems, following the previous implementation of the multiple support excitation response spectrum method (see papers K 6/15 and K 6/15a of the SMiRT-4 Conference). The results of multiple support excitation response spectrum analyses can be examined by carrying out the equivalent time history analyses which do not distort the time phase relationship between the excitations at different support points. A frequent point of discussion is multiple versus single support excitation. A single support excitation analysis is computationally straightforward and tends to be on the conservative side, as the numerical results show. A multiple support excitation analysis, however, does not incur much more additional computer cost than the expenditure for an initial static solution involving three times the number, L, of excitation levels, i.e. 3L static load cases. The results are more realistic than those from a single support excitation analysis. A number of typical nuclear plant piping systems have been analyzed using single and multiple support excitation algorithms for: (1) the response spectrum method, (2) the modal time history method via the Wilson, Newmark and Goldberg integration operators and (3) the direct time history method via the Wilson integration operator. Characteristic results are presented to compare the computational quality of all three methods. (orig.)

Response of HDR-VKL piping system to seismic test excitations: Comparison of analytical predictions and test measurements

International Nuclear Information System (INIS)

Srinivasan, M.G.; Kot, C.A.; Hsieh, B.J.

1989-01-01

As part of the earthquake investigations at the HDR (Heissdampfreaktor) Test Facility in Kahl/Main, FRG, simulated seismic tests (SHAM) were performed during April--May 1988 on the VKL (Versuchskreislauf) piping system. The purpose of these experiments was to study the behavior of piping subjected to a range of seismic excitation levels including those that exceed design levels manifold and that might induce failure of pipe supports or plasticity in the pipe runs, and to establish seismic margins for piping and pipe supports. Data obtained in the tests are also used to validate analysis methods. Detailed reports on the SHAM experiments are given elsewhere. The objective of this document is to evaluate a subsystem analysis module of the SMACS code. This module is a linear finite-element based program capable of calculating the response of nuclear power plant subsystems subjected to independent multiple-acceleration input excitation. The evaluation is based on a comparison of computational results of simulation of SHAM tests with corresponding test measurements

Characterization of Flow Dynamics and Reduced-Order Description of Experimental Two-Phase Pipe Flow

Science.gov (United States)

Viggiano, Bianca; SkjæRaasen, Olaf; Tutkun, Murat; Cal, Raul Bayoan

2017-11-01

Multiphase pipe flow is investigated using proper orthogonal decomposition for tomographic X-ray data, where holdup, cross sectional phase distributions and phase interface characteristics are obtained. Instantaneous phase fractions of dispersed flow and slug flow are analyzed and a reduced order dynamical description is generated. The dispersed flow displays coherent structures in the first few modes near the horizontal center of the pipe, representing the liquid-liquid interface location while the slug flow case shows coherent structures that correspond to the cyclical formation and breakup of the slug in the first 10 modes. The reconstruction of the fields indicate that main features are observed in the low order dynamical descriptions utilizing less than 1 % of the full order model. POD temporal coefficients a1, a2 and a3 show interdependence for the slug flow case. The coefficients also describe the phase fraction holdup as a function of time for both dispersed and slug flow. These flows are highly applicable to petroleum transport pipelines, hydroelectric power and heat exchanger tubes to name a few. The mathematical representations obtained via proper orthogonal decomposition will deepen the understanding of fundamental multiphase flow characteristics.

Real-time numerical evaluation of dynamic tests with sudden closing of valves in piping systems

International Nuclear Information System (INIS)

Geidel, W.; Leimbach, K.R.

1979-01-01

The sudden closing of a valve in a piping system causes a build-up of pressure which, in turn, causes severe vibrations of the structural system. The licensing procedure calls for on-site tests to determine the dynamic effects of such closing of valves, and to check the stresses and displacements against the allowable ones. The measurements include time histories of displacements, accelerations and internal pressure. The computer program KWUROHR for the static and dynamic analysis of piping systems has been used by KWU and several subcontractors during the past four vears. This program has been extended by adding a subroutine package which computes time histories of displacements, accelerations and stresses resulting from the input of measured time histories of internal pressures at selected locations. The computer algorithm establishes the topological connectivity between the internal pressure measuring locations, to set up a logic for linear pressure interpolation between these points and pressure steps at reducers and valves. A minimum number of input points is required to give realistic results. (orig.)

Significance of high level test data in piping design

International Nuclear Information System (INIS)

McLean, J.L.; Bitner, J.L.

1991-01-01

During the 1980's the piping technical community in the U.S. initiated a series of research activities aimed at reducing the conservatism inherent in nuclear piping design. One of these activities was directed at the application of the ASME Code rules to the design of piping subjected to dynamic loads. This paper surveys the test data obtained from three groups in the U.S. and none in the U.K., and correlates the findings as they relate to the failure modes of piping subjected to seismic loads. The failure modes experienced as the result of testing at dynamic loads significantly in excess of anticipated loads specified for any of the ASME Code service levels are discussed. A recommendation is presented for modifying the Code piping rules to reduce the conservatism inherent in seismic design

Current results for the NRC's short cracks in piping and piping welds research program

International Nuclear Information System (INIS)

Wilkowski, G.; Krishnaswamy, P. Brust, F.; Francini, R.; Ghadiali, N.; Kilinski, T.; Marschall, C.; Rahman, S.; Rosenfield, A.; Scott, P.

1994-01-01

The overall objective of the Short Cracks in Piping and Piping Welds Program is to verify and improve engineering analyses to predict the fracture behavior of circumferentially cracked pipe under quasi-static loading with particular attention to crack lengths typically used in LBB or flaw evaluation criteria. The program consists of 8 technical tasks as listed below. Task 1 Short through-wall-cracked (TWC) pipe evaluations. Task 2 Short surface-cracked pipe evaluations. Task 3 Bi-metallic weld crack evaluations. Task 4 Dynamic strain aging and crack instabilities. Task 5 Fracture evaluations of anisotropic pipe. Task 6 Crack-opening-area evaluations. Task 7 NRCPIPE Code improvements. Task 8 Additional efforts. Since the last WRSM meeting several additional tasks have been initiated in this program. These are discussed in Task 8. Based on results to date, the first seven tasks have also been modified as deemed necessary. The most significant accomplishments in each of these tasks since the last WRSIM meeting are discussed below. The details of all the results presented here are published in the semiannual reports from this program

Application of NARX neural networks in thermal dynamics identification of a pulsating heat pipe

International Nuclear Information System (INIS)

Lee Yawei; Chang Tienli

2009-01-01

The pulsating heat pipe (PHP) receiving much attention in industries is a novel type of cooling device. The distinguishing feature of PHPs is the unsteady flow oscillations formed by the passing non-uniform distributions of vapour plugs and liquid slugs. This study introduces a methodology of a non-linear auto-regressive with exogenous (NARX) neural network to analyze the thermal dynamics of a PHP in both the time and frequency domains. Three heating powers: 30, 70, and 110 W are tested, and all the predicted results are presented in quite good agreement with the measured results. Herein, the harmonic analysis of the non-linear structure can be equivalently conducted with generalized frequency response functions (GFRFs). Based on the non-linear coupling between the various input spectral components, the interpretations of the higher order GFRFs have been extensively presented for demonstrating the non-linear effects on the heat transfer of a PHP at different operating conditions

Pipe supports and anchors - LMFBR applications

International Nuclear Information System (INIS)

Anderson, M.J.

1983-06-01

Pipe design and support design can not be treated as separate disciplines. A coordinated design approach is required if LMFBR pipe system adequacy is to be achieved at a reasonable cost. It is particularly important that system designers understand and consider those factors which influence support train flexibility and thus the pipe system dynamic stress levels. The system approach must not stop with the design phase but should continue thru the erection and acceptance test procedures. The factors that should be considered in the design of LMFBR pipe supports and anchors are described. The various pipe support train elements are described together with guidance on analysis, design and application aspects. Post erection acceptance and verification test procedures are then discussed

Evaluation of stress histories of reactor coolant loop piping for pipe rupture prediction

International Nuclear Information System (INIS)

Lu, S.C.; Larder, R.A.; Ma, S.M.

1981-01-01

This paper describes the analyses used to evaluate stress histories in the primary coolant loop piping of a selected four-loop PNR power station. In order to make the simulation as realistic as possible, best estimates rather than conservative assumptions were considered throughout. The best estimate solution, however, was aided by a sensitivity study to assess the possible variation of outcomes resulted from uncertainties associated with these assumptions. Sources of stresses considered in the evaluation were pressure, dead weight, thermal expansion, thermal gradients through the pipe wall, residual welding, pump vibrations, and finally seismic excitations. The best estimates of pressure and thermal transient histories arising from plant operations were based on actual plant operation records supplemented by specified plant design conditions. Seismic motions were generated from response spectrum curves developed specifically for the region surrounding the plant site. Stresses due to dead weight and thermal expansion were computed from a three dimensional finite element model which used a combination of pipe, truss, and beam elements to represent the coolant loop piping, the pressure vessel, coolant pumps, steam generators, and the pressurizer. Stresses due to pressure and thermal gradients were obtained by closed form solutions. Seismic stress calculations considered the soil structure interaction, the coupling effect between the containment structure and the reactor coolant system. A time history method was employed for the seismic analysis. Calculations of residual stresses accounted for the actual heat impact, welding speed, weld preparation geometry, and pre- and post-heat treatments. Vibrational stresses due to pump operation were estimated by a dynamic analysis using existing measurements of pump vibrations. (orig./HP)

Gas lensing in a heated spinning pipe

CSIR Research Space (South Africa)

Mafusire, C

2006-07-01

Full Text Available ; and (II) the aberrations introduced to the laser are a function of the distance from the edge of the pipe, as well as the speed of the pipe spin- ning. This is because of the turbulence near the pipe wall. The speed of the pipe will be used...- merically. This work forms the basis for an extended study of the dynamics of beam propa- gation through turbulent systems, and in particular, the following aspects will be explored in future work: (I) Using the recent advances in lasers beam propagation...

Conceptual design of pipe whip restraints using interactive computer analysis

International Nuclear Information System (INIS)

Rigamonti, G.; Dainora, J.

1975-01-01

Protection against pipe break effects necessitates a complex interaction between failure mode analysis, piping layout, and structural design. Many iterations are required to finalize structural designs and equipment arrangements. The magnitude of the pipe break loads transmitted by the pipe whip restraints to structural embedments precludes the application of conservative design margins. A simplified analytical formulation of the nonlinear dynamic problems associated with pipe whip has been developed and applied using interactive computer analysis techniques. In the dynamic analysis, the restraint and the associated portion of the piping system, are modeled using the finite element lumped mass approach to properly reflect the dynamic characteristics of the piping/restraint system. The analysis is performed as a series of piecewise linear increments. Each of these linear increments is terminated by either formation of plastic conditions or closing/opening of gaps. The stiffness matrix is modified to reflect the changed stiffness characteristics of the system and re-started using the previous boundary conditions. The formation of yield hinges are related to the plastic moment of the section and unloading paths are automatically considered. The conceptual design of the piping/restraint system is performed using interactive computer analysis. The application of the simplified analytical approach with interactive computer analysis results in an order of magnitude reduction in engineering time and computer cost. (Auth.)

Seismic analysis of nuclear piping system

International Nuclear Information System (INIS)

Shrivastava, S.K.; Pillai, K.R.V.; Nandakumar, S.

1975-01-01

To illustrate seismic analysis of nuclear power plant piping, a simple piping system running between two floors of the reactor building is assumed. Reactor building floor response is derived from time-history method. El Centre earthquake (1940) accelerogram is used for time-history analysis. The piping system is analysed as multimass lumped system. Behaviour of the pipe during the said earthquake is discussed. (author)

Analysis of the transient compressible vapor flow in heat pipes

Science.gov (United States)

Jang, J. H.; Faghri, A.; Chang, W. S.

1989-01-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual vapor flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures.

Analysis of the transient compressible vapor flow in heat pipe

International Nuclear Information System (INIS)

Jang, J.H.; Faghri, A.; Chang, W.S.

1989-07-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual vapor flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures

Analysis of the transient compressible vapor flow in heat pipe

Science.gov (United States)

Jang, Jong Hoon; Faghri, Amir; Chang, Won Soon

1989-01-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures.

Correlation of analysis with high level vibration test results for primary coolant piping

International Nuclear Information System (INIS)

Park, Y.J.; Hofmayer, C.H.; Costello, J.F.

1992-01-01

Dynamic tests on a modified 1/2.5-scale model of pressurized water reactor (PWR) primary coolant piping were performed using a large shaking table at Tadotsu, Japan. The High Level Vibration Test (HLVT) program was part of a cooperative study between the United States (Nuclear Regulatory Commission/Brookhaven National Laboratory, NRC/BNL) and Japan (Ministry of International Trade and Industry/Nuclear Power Engineering Center). During the test program, the excitation level of each test run was gradually increased up to the limit of the shaking table and significant plastic strains, as well as cracking, were induced in the piping. To fully utilize the test results, NRC/BNL sponsored a project to develop corresponding analytical predictions for the nonlinear dynamic response of the piping for selected test runs. The analyses were performed using both simplified and detailed approaches. The simplified approaches utilize a linear solution and an approximate formulation for nonlinear dynamic effects such as the use of a deamplification factor. The detailed analyses were performed using available nonlinear finite element computer codes, including the MARC, ABAQUS, ADINA and WECAN codes. A comparison of various analysis techniques with the test results shows a higher prediction error in the detailed strain values in the overall response values. A summary of the correlation analyses was presented before the BNL. This paper presents a detailed description of the various analysis results and additional comparisons with test results

Three-dimensional vortex-induced vibrations of supported pipes conveying fluid based on wake oscillator models

Science.gov (United States)

Wang, L.; Jiang, T. L.; Dai, H. L.; Ni, Q.

2018-05-01

The present study develops a new three-dimensional nonlinear model for investigating vortex-induced vibrations (VIV) of flexible pipes conveying internal fluid flow. The unsteady hydrodynamic forces associated with the wake dynamics are modeled by two distributed van der Pol wake oscillators. In particular, the nonlinear partial differential equations of motion of the pipe and the wake are derived, taking into account the coupling between the structure and the fluid. The nonlinear equations of motion for the coupled system are then discretized by means of the Galerkin technique, resulting in a high-dimensional reduced-order model of the system. It is shown that the natural frequencies for in-plane and out-of-plane motions of the pipe may be different at high internal flow velocities beyond the threshold of buckling instability. The orientation angle of the postbuckling configuration is time-varying due to the disturbance of hydrodynamic forces, thus yielding sometimes unexpected results. For a buckled pipe with relatively low cross-flow velocity, interestingly, examining the nonlinear dynamics of the pipe indicates that the combined effects of the cross-flow-induced resonance of the in-plane first mode and the internal-flow-induced buckling on the IL and CF oscillation amplitudes may be significant. For higher cross-flow velocities, however, the effect of internal fluid flow on the nonlinear VIV responses of the pipe is not pronounced.

Pipe rupture test results; 4 inch pipe whip tests under BWR operational condition-clearance parameter experiments

International Nuclear Information System (INIS)

Ueda, Syuzo; Isozaki, Toshikuni; Miyazaki, Noriyuki; Kurihara, Ryoichi; Kato, Rokuro; Saito, Kazuo; Miyazono, Shohachiro

1981-05-01

The purpose of pipe rupture studies in JAERI is to perform the model tests on pipe whip, restraint behavior, jet impingement and jet thrust force, and to establish the computational method for analyzing these phenomena. This report describes the experimental results of pipe whip on the pipe specimens of 4 inch in diameter under BWR condition on which the pressure is 6.77 MPa and the temperature is 285 0 C. The pipe specimens were 114.3 mm (4 inch) in diameter and 8.6 mm in thickness and 4500 mm in length. Four pipe whip restraints used in the tests were the U-bar type of 8 mm in diameter and fabricated from type 304 stainless steel. The experimental parameter was the clearance (30, 50 and 100 mm). The dynamic strain behavior of the pipe specimen and the restraints was investigated by strain gages and their residual deformation was obtained by measuring marking points provided on their surface. The Pressure-time history in the pipe specimens was also obtained by pressure gages. The maximum pipe strain is caused near the restraints and increases with increase of the clearance. The experimental results of pipe whip tests indicate the effectiveness of pipe whip restraints. The ratio of absorbed strain energy of the pipe specimen to that of the restraints is nearly constant for different clearances at the overhang length of 400 mm. (author)

A study of inter linkage effects on Candu feeder piping

International Nuclear Information System (INIS)

Li, M.; Aggarwal, M.L.; Meysner, A.

2005-01-01

A CANDU (Canadian Deuterium Uranium) reactor core consists of a large number of fuel channels where heat is generated. Two feeder pipes are connected to each fuel channel to transport D 2 O coolant into and out of the reactor core. The feeder piping is designed to the requirements of Class 1 piping of Section III NB of the ASME Boiler and Pressure Vessel and CSA Codes. Feeder piping stress analysis is being performed to demonstrate the code compliance check and the fitness for service of feeders. In the past, stress analyses were conducted for each individual feeder without including interaction effects among connected feeders. Interaction effects occur as a result of linkages that exist between feeders to prevent fretting and impacting damage during normal, abnormal and accident conditions. In this paper, a 'combined' approach is adopted to include all feeders connected by inter linkages into one feeder piping model. MSC/NASTRAN finite element software was used in the stress simulation, which contains up to 127 feeder pipes. The ASME Class 1 piping analysis was conducted to investigate the effects of the linkages between feeders. Both seismic time history and broadened response spectra methods were used in the seismic stress calculation. The results show that the effect of linkages is significant in dynamic stresses for all feeder configurations, as well as in static stresses for certain feeder configurations. The single feeder analysis could either underestimate or overestimate feeder stresses depending on the pipe geometry and bend wall thickness. (authors)

A dynamic model of gas flow in a non-uniform pipe

International Nuclear Information System (INIS)

Mensah, S.; Lepp, R.M.

1979-08-01

A gas-line model, based on the analysis of compressible flow with friction, has been developed to describe the dynamics of gas flow in a non-uniform line, i.e. one comprising segments of different lengths and diameters. Acoustic wave analysis was used in a novel way, by considering the line as a cascaded connection of uniform pipes separated by discontinuities. The transmission matrix representing this non-uniform line is the product of the matrices for each element in the system. To facilitate implementation of the theoretical model on a hybrid computer, modal approximatons to its transfer functions were derived. Both models were validated against experimental data. (author)

Piping reliability improvement through passive seismic supports

International Nuclear Information System (INIS)

Baltus, R.; Rubbers, A.

1999-01-01

The nuclear plants designed in the 1970's were equipped with large quantities of snubbers in auxiliary piping systems. The experience revealed a poor performance of snubbers during periodic inspection, while non-nuclear facility piping survived through strong earthquakes. Consequently, seismic design rules evolved towards more realistic criteria and passive dynamic supports were developed to reduce snubber quantities. These solutions improve the pipe reliability during normal operation while reducing the radiation exposure in a sample line is presented with the impact on pipe stresses compared to the results obtained with passive supports named Limit Stops. (author)

Dynamic Response Testing in an Electrically Heated Reactor Test Facility

Science.gov (United States)

Bragg-Sitton, Shannon M.; Morton, T. J.

2006-01-01

Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics, and assess potential design improvements at a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE-100a heat pipe cooled, electrically heated reactor and heat exchanger hardware, utilizing a one-group solution to the point kinetics equations to simulate the expected neutronic response of the system (Bragg-Sitton, 2005). The current paper applies the same testing methodology to a direct drive gas cooled reactor system, demonstrating the applicability of the testing methodology to any reactor type and demonstrating the variation in system response characteristics in different reactor concepts. In each testing application, core power transients were controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. Although both system designs utilize a fast spectrum reactor, the method of cooling the reactor differs significantly, leading to a variable system response that can be demonstrated and assessed in a non-nuclear test facility.

Stress state in the neighborhood of subways and pipe lines under the action of dynamic loads

International Nuclear Information System (INIS)

Alexeyeva, L.A.; Eskalieva, A.Z.; Shershnev, V.V.

2001-01-01

We consider the long underground constructions of deep and shallow types such as transport subways, mines, underground pipes etc. by the action of dynamic lads. Situated in areas of seismic activity, they are subjected to the influence of seismic waves during earthquakes and can be destroyed. Running loads inside constructions (transport for instance) affect upon toughness and stability of both subways and surrounding medium. If underground construction dispose near a day's surface, it acts also on nearby buildings. Evaluations of behavior of underground and pipes under dynamic influences in real conditions of usage are determined of stress state of constructions in the interaction with environment medium. Here underground constructions are simulated by infinitely long cylindrical cavities in utter ambience. As utter ambience the isotropic elastic medium and two-component medium of Biot are researched. Last one allows simulating saturated water oils. The elastic cylindrical shell simulates supporting of a tunnel (or pipeline). Both a tress state of construction and surrounding medium were investigated for a different contact conditions between support of tunnel and environment (rigid, slippery and viscous contacts). (author)

Instability predictions for circumferentially cracked Type-304 stainless steel pipes under dynamic loading. Volume 2. Appendixes. Final report

International Nuclear Information System (INIS)

Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

1982-04-01

This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models

Comparison of fracture toughness values from large-scale pipe system tests and C(T) specimens

International Nuclear Information System (INIS)

Olson, R.; Scott, P.; Marschall, C.; Wilkowski, G.

1993-01-01

Within the International Piping Integrity Research Group (IPIRG) program, pipe system experiments involving dynamic loading with intentionally circumferentially cracked pipe were conducted. The pipe system was fabricated from 406-mm (16-inch) diameter Schedule 100 pipe and the experiments were conducted at 15.5 MPa (2,250 psi) and 288 C (550 F). The loads consisted of pressure, dead-weight, thermal expansion, inertia, and dynamic anchor motion. Significant instrumentation was used to allow the material fracture resistance to be calculated from these large-scale experiments. A comparison of the toughness values from the stainless steel base metal pipe experiment of standard quasi-static and dynamic C(T) specimen tests showed the pipe toughness value was significantly lower than that obtained from C(T) specimens. It is hypothesized that the cyclic loading from inertial stresses in this pipe system experiment caused local degradation of the material toughness. Such effects are not considered in current LBB or pipe flaw evaluation criteria. 4 refs., 14 figs., 1 tab

Design of a cavity heat pipe receiver experiment

Science.gov (United States)

Schneider, Michael G.; Brege, Mark H.; Greenlee, William J.

1992-01-01

A cavity heat pipe experiment has been designed to test the critical issues involved with incorporating thermal energy storage canisters into a heat pipe. The experiment is a replication of the operation of a heat receiver for a Brayton solar dynamic power cycle. The heat receiver is composed of a cylindrical receptor surface and an annular heat pipe with thermal energy storage canisters and gaseous working fluid heat exchanger tubes surrounding it. Hardware for the cavity heat pipe experiment will consist of a sector of the heat pipe, complete with gas tube and thermal energy storage canisters. Thermal cycling tests will be performed on the heat pipe sector to simulate the normal energy charge/discharge cycle of the receiver in a spacecraft application.

Theoretical Study on the Dynamic Behavior of Pipes Conveying Gas-Liquid Flow

Directory of Open Access Journals (Sweden)

Enrique Ortiz-Vidal L.

2018-01-01

Full Text Available The dynamic behavior of clamped-clamped straight pipes conveying gas-liquid two-phase flow is theoretically investigated, specifically the effect of the flow parameters on the frequency of the system. First, the equation of motion is derived based on the classic Païdoussis formulation. Assuming Euler-Bernoulli beam theory, small-deflection approximation and no-slip homogeneous model, a coupled fluid-structure fourth-order partial differential equation (PDE is obtained. Then, the equation of motion is rendered dimensionless and discretized through Galerkin’s method. That method transforms the PDE into a set of Ordinary Differential Equations (ODEs. The system frequency is obtained by solving the system of ODEs by allowing the determinant to be equal to zero. System frequencies for different geometries, structural properties and flow conditions have been calculated. The results show that the system frequency decreases with increasing two-phase flow velocity. By contrast, the former increases with increasing homogeneous void fraction. These theoretical results are in agreement with experimental findings reported in the literature. Furthermore, even for typical two phase flow conditions, the system can become unstable for inadequate chooses of geometry or material of the pipe.

Analysis of water hammer-structure interaction in piping system for a loss of coolant accident in primary loop of pressurized water reactor

International Nuclear Information System (INIS)

Zhang Xiwen; Yang Jinglong; He Feng; Wang Xuefang

2000-01-01

The conventional analysis of water hammer and dynamics response of structure in piping system is divided into two parts, and the interaction between them is neglected. The mechanism of fluid-structure interaction under the double-end break pipe in piping system is analyzed. Using the characteristics method, the numerical simulation of water hammer-structure interaction in piping system is completed based on 14 parameters and 14 partial differential equations of fluid-piping cell. The calculated results for a loss of coolant accident (LOCA) in primary loop of pressurized water reactor show that the waveform and values of pressure and force with time in piping system are different from that of non-interaction between water hammer and structure in piping system, and the former is less than the later

Relative conservatisms of combination methods used in response spectrum analyses of nuclear piping systems

International Nuclear Information System (INIS)

Gupta, S.; Kustu, O.; Jhaveri, D.P.; Blume, J.A.

1983-01-01

The paper presents the conclusions of a comprehensive study that investigated the relative conservatisms represented by various combination techniques. Two approaches were taken for the study, producing mutually consistent results. In the first, 20 representative nuclear piping systems were systematically analyzed using the response spectrum method. The total response was obtained using nine different combination methods. One procedure, using the SRSS method for combining spatial components of response and the 10% method for combining the responses of different modes (which is currently acceptable to the U.S. NRC), was the standard for comparison. Responses computed by the other methods were normalized to this standard method. These response ratios were then used to develop cumulative frequency-distribution curves, which were used to establish the relative conservatism of the methods in a probabilistic sense. In the second approach, 30 single-degree-of-freedom (SDOF) systems that represent different modes of hypothetical piping systems and have natural frequencies varying from 1 Hz to 30 Hz, were analyzed for 276 sets of three-component recorded ground motion. A set of hypothetical systems assuming a variety of modes and frequency ranges was developed. The responses of these systems were computed from the responses of the SDOF systems by combining the spatial response components by algebraic summation and the individual mode responses by the Navy method, or combining both spatial and modal response components using the SRSS method. Probability density functions and cumulative distribution functions were developed for the ratio of the responses obtained by both methods. (orig./HP)

Fracture assessment of Savannah River Reactor carbon steel piping

International Nuclear Information System (INIS)

Mertz, G.E.; Stoner, K.J.; Caskey, G.R.; Begley, J.A.

1991-01-01

The Savannah River Site (SRS) production reactors have been in operation since the mid-1950's. One postulated failure mechanism for the reactor piping is brittle fracture of the original A285 and A53 carbon steel piping. Material testing of archival piping determined (1) the static and dynamic tensile properties; (2) Charpy impact toughness; and (3) the static and dynamic compact tension fracture toughness properties. The nil-ductility transition temperature (NDTT), determined by Charpy impact test, is above the minimum operating temperature for some of the piping materials. A fracture assessment was performed to demonstrate that potential flaws are stable under upset loading conditions and minimum operating temperatures. A review of potential degradation mechanisms and plant operating history identified weld defects as the most likely crack initiation site for brittle fracture. Piping weld defects, as characterized by radiographic and metallographic examination, and low fracture toughness material properties were postulated at high stress locations in the piping. Normal operating loads, upset loads, and residual stresses were assumed to act on the postulated flaws. Calculated allowable flaw lengths exceed the size of observed weld defects, indicating adequate margins of safety against brittle fracture. Thus, a detailed fracture assessment was able to demonstrate that the piping systems will not fail by brittle fracture, even though the NDTT for some of the piping is above the minimum system operating temperature

A study on the multi-dimensional spectral analysis for response of a piping model with two-seismic inputs

International Nuclear Information System (INIS)

Suzuki, K.; Sato, H.

1975-01-01

The power and the cross power spectrum analysis by which the vibration characteristic of structures, such as natural frequency, mode of vibration and damping ratio, can be identified would be effective for the confirmation of the characteristics after the construction is completed by using the response for small earthquakes or the micro-tremor under the operating condition. This method of analysis previously utilized only from the view point of systems with single input so far, is extensively applied for the analysis of a medium scale model of a piping system subjected to two seismic inputs. The piping system attached to a three storied concrete structure model which is constructed on a shaking table was excited due to earthquake motions. The inputs to the piping system were recorded at the second floor and the ceiling of the third floor where the system was attached to. The output, the response of the piping system, was instrumented at a middle point on the system. As a result, the multi-dimensional power spectrum analysis is effective for a more reliable identification of the vibration characteristics of the multi-input structure system

Heat-pipe Earth.

Science.gov (United States)

Moore, William B; Webb, A Alexander G

2013-09-26

The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

Pipe damping studies

International Nuclear Information System (INIS)

Ware, A.G.

1986-01-01

The Idaho National Engineering Laboratory (INEL) is conducting a research program to assist the United States Nuclear Regulatory Commission (USNRC) in determining best-estimate damping values for use in the dynamic analysis of nuclear power plant piping systems. This paper describes four tasks in the program that were undertaken in FY-86. In the first task, tests were conducted on a 5-in. INEL laboratory piping system and data were analyzed from a 6-in. laboratory system at the ANCO Engineers facility to investigate the parameters influencing damping in the seismic frequency range. Further tests were conducted on 3- and 5-in. INEL laboratory piping systems as the second task to determine damping values representative of vibrations in the 33 to 100 Hz range, typical of hydrodynamic transients. In the third task a statistical evaluation of the available damping data was conduted to determine probability distributions suitable for use in probabilistic risk assessments (PRAs), and the final task evaluated damping data at high strain levels

Calculation of piping loads due to filling procedures

International Nuclear Information System (INIS)

Swidersky, Harald; Thiele, Thomas

2012-01-01

Filling procedures in piping systems are usually not load cases that are studied by fluid dynamic and structure dynamic analyses with respect to the integrity of pipes and supports. Although, their frequency is higher than that of postulated accidental transients, therefore they have to be considered for fatigue analyses. The piping and support loads due to filling procedures are caused by the density differences if the transported fluids, for instance in flows with the transport of gas bubbles. The impact duration of the momentum forces is defined by the flow velocity and the length of discontinuities in the piping segments. Filling procedures end very often with a shock pressure, caused by the impact and decelerating of the fluid front at smaller cross sections. The suitability of the thermally hydraulics program RELAP/MOD3.3 for the calculation of realistic loads from filling procedures was studied, the results compared with experimental data. It is shown that dependent on the discretization level the loads are partial significantly underestimated.

Superconducting pipes and levitating magnets.

Science.gov (United States)

Levin, Yan; Rizzato, Felipe B

2006-12-01

Motivated by a beautiful demonstration of the Faraday and the Lenz laws in which a small neodymium magnet falls slowly through a conducting nonferromagnetic tube, we consider the dynamics of a magnet falling coaxially through a superconducting pipe. Unlike the case of normal conducting pipes, in which the magnet quickly reaches the terminal velocity, inside a superconducting tube the magnet falls freely. On the other hand, to enter the pipe the magnet must overcome a large electromagnetic energy barrier. For sufficiently strong magnets, the barrier is so large that the magnet will not be able to penetrate it and will be levitated over the mouth of the pipe. We calculate the work that must done to force the magnet to enter a superconducting tube. The calculations show that superconducting pipes are very efficient at screening magnetic fields. For example, the magnetic field of a dipole at the center of a short pipe of radius a and length L approximately > a decays, in the axial direction, with a characteristic length xi approximately 0.26a. The efficient screening of the magnetic field might be useful for shielding highly sensitive superconducting quantum interference devices. Finally, the motion of the magnet through a superconducting pipe is compared and contrasted to the flow of ions through a trans-membrane channel.

Instability predictions for circumferentially cracked Type-304 stainless steel pipes under dynamic loading. Volume 2. Appendixes. Final report. [BWR

Energy Technology Data Exchange (ETDEWEB)

Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

1982-04-01

This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models.

Seismic testing and analysis of a prototypic nonlinear piping system

International Nuclear Information System (INIS)

Barta, D.A.; Anderson, M.J.; Severud, L.K.

1982-11-01

A series of seismic tests and analyses of a nonlinear Fast Flux Test Facility (FFTF) prototypic piping system are described, and measured responses are compared with analytical predictions. The test loop was representative of a typical LMFBR insulated small bore piping system and it was supported from a rigid test frame by prototypic dead weight supports, mechanical snubbers and pipe clamps. Various piping support configurations were tested and analyzed to evaluate the effects of free play and other nonlinear stiffness characteristics on the piping system response

Laboratory exercises on oscillation modes of pipes

Science.gov (United States)

Haeberli, Willy

2009-03-01

This paper describes an improved lab setup to study the vibrations of air columns in pipes. Features of the setup include transparent pipes which reveal the position of a movable microphone inside the pipe; excitation of pipe modes with a miniature microphone placed to allow access to the microphone stem for open, closed, or conical pipes; and sound insulation to avoid interference between different setups in a student lab. The suggested experiments on the modes of open, closed, and conical pipes, the transient response of a pipe, and the effect of pipe diameter are suitable for introductory physics laboratories, including laboratories for nonscience majors and music students, and for more advanced undergraduate laboratories. For honors students or for advanced laboratory exercises, the quantitative relation between the resonance width and damping time constant is of interest.

CFD model of a spinning pipe gas lens

CSIR Research Space (South Africa)

Snedden, Glen C

2006-07-01

Full Text Available Slides on: Spinning Pipe Gas Lens; Focal Length; Refractive Index; Gas Dynamics; Guess at the gas dynamics; Density Profile; Flow Profile; Rosby Waves; Rayleigh–Taylor Instabilities...

Report of the US Nuclear Regulatory Commission Piping Review Committee. Volume 5. Summary - Piping Review Committee conclusions and recommendations

International Nuclear Information System (INIS)

1985-04-01

This document summarizes a comprehensive review of NRC requirements for Nuclear Piping by the US NRC Piping Review Committee. Four topical areas, addressed in greater detail in Volumes 1 through 4 of this report, are included: (1) Stress Corrosion Cracking in Piping of Boiling Water Reactor Plants; (2) Evaluation of Seismic Design; (3) Evaluation of Potential for Pipe Breaks; and (4) Evaluation of Other Dynamic Loads and Load Combinations. This volume summarizes the major issues, reviews the interfaces, and presents the Committee's conclusions and recommendations for updating NRC requirements on these issues. This report also suggests research or other work that may be required to respond to issues not amenable to resolution at this time

Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

Science.gov (United States)

McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, WIlliam O.; Chang, Li, C.; Hozman, Aron D.; Henry, Michael W.

2012-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007-2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cu ft in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their "t-junctions" connecting the 12 inch supply line to their respective 4 inch branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed "t-junction" connections through non-destructive evaluation testing . Through structural dynamic modeling of the piping system, the root cause of the "t-junction" connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

An assessment of seismic margins in nuclear plant piping

International Nuclear Information System (INIS)

Chen, W.P.; Jaquay, K.R.; Chokshi, N.C.; Terao, D.

1995-01-01

Interim results of an ongoing program to assist the U.S. Nuclear Regulatory Commission (NRC) in developing regulatory positions on the seismic analyses of piping and overall safety margins of piping systems are reported. Results of reviews of previous seismic testing, primarily the Electric Power Research Institute (EPRI)/NRC Piping and Fitting Dynamic Reliability Program, and assessments of the ASME Code, Section III, piping seismic design criteria as revised by the 1994 Addenda are reported. Major issues are identified herein only. Technical details are to be provided elsewhere. (author). 4 refs., 2 figs

Hydrodynamic and Sediment Responses of Open Channels to Exposed Pipe Encasements.

Directory of Open Access Journals (Sweden)

J Q Mao

Full Text Available The effects of exposed pipe encasements on the local variation of hydrodynamic and sediment conditions in a river channel are examined. Laboratory experiments are performed to assess the response of water level, flow regime and bed deformation to several representative types of concrete encasements. The experimental conditions considered are: three types of exposed pipe encasements exposed on the bed, including trapezoidal shape, circular-arc shape and polygonal shape, and three sets of discharges, including annual discharge, once-in-3-year flood, and once-in-50-year flood. Our experiments show that: (1 the amount of backwater definitely depends on the encasement geometric shape and the background discharge; (2 smaller discharges generally tend to induce local scour of river bed downstream of the encasement, and the order of sensitivity of bed deformation to the encasement geometric shape is trapezoidal > circular-arc > polygonal; (3 comparatively speaking, the polygonal encasement may be considered as a suitable protective structure for pipelines across alluvial rivers, with relatively modest effects on the local hydrodynamic conditions and bed stabilization.

Hydrodynamic and Sediment Responses of Open Channels to Exposed Pipe Encasements.

Science.gov (United States)

Mao, J Q; Zhang, H Q; Dai, H C; Yuan, B H; Hu, T F

2015-01-01

The effects of exposed pipe encasements on the local variation of hydrodynamic and sediment conditions in a river channel are examined. Laboratory experiments are performed to assess the response of water level, flow regime and bed deformation to several representative types of concrete encasements. The experimental conditions considered are: three types of exposed pipe encasements exposed on the bed, including trapezoidal shape, circular-arc shape and polygonal shape, and three sets of discharges, including annual discharge, once-in-3-year flood, and once-in-50-year flood. Our experiments show that: (1) the amount of backwater definitely depends on the encasement geometric shape and the background discharge; (2) smaller discharges generally tend to induce local scour of river bed downstream of the encasement, and the order of sensitivity of bed deformation to the encasement geometric shape is trapezoidal > circular-arc > polygonal; (3) comparatively speaking, the polygonal encasement may be considered as a suitable protective structure for pipelines across alluvial rivers, with relatively modest effects on the local hydrodynamic conditions and bed stabilization.

Structural and stress analysis of nuclear piping systems

International Nuclear Information System (INIS)

Hata, Hiromichi

1982-01-01

The design of the strength of piping system is important in plant design, and its outline on the example of PWRs is reported. The standards and guides concerning the design of the strength of piping system are shown. The design condition for the strength of piping system is determined by considering the requirements in the normal operation of plants and for the safety design of plants, and the loads in normal operation, testing, credible accident and natural environment are explained. The methods of analysis for piping system are related to the transient phenomena of fluid, piping structure and local heat conduction, and linear static analysis, linear time response analysis, nonlinear time response analysis, thermal stress analysis and fluid transient phenomenon analysis are carried out. In the aseismatic design of piping system, it is desirable to avoid the vibration together with a building supporting it, and as a rule, to make it into rigid structure. The piping system is classified into high temperature and low temperature pipings. The formulas for calculating stress and the allowable condition, the points to which attention must be paid in the design of piping strength and the matters to be investigated hereafter are described. (Kako, I.)

Vibration analysis of pipes conveying fluid by transfer matrix method

International Nuclear Information System (INIS)

Li, Shuai-jun; Liu, Gong-min; Kong, Wei-tao

2014-01-01

Highlights: • A theoretical study on vibration analysis of pipes with FSI is presented. • Pipelines with high fluid pressure and velocity can be solved by developed method. • Several pipeline schemes are discussed to illustrate the application of the method. • The proposed method is easier to apply compared to most existing procedures. • Influence laws of structural and fluid parameters on FSI of pipe are analyzed. -- Abstract: Considering the effects of pipe wall thickness, fluid pressure and velocity, a developed 14-equation model is presented, which describes the fluid–structure interaction behavior of pipelines. The transfer matrix method has been used for numerical modeling of both hydraulic and structural equations. Based on these models and algorithms, several pipeline schemes are presented to illustrate the application of the proposed method. Furthermore, the influence laws of supports, structural properties and fluid parameters on the dynamic response and natural frequencies of pipeline are analyzed, which shows using the optimal supports and structural properties is beneficial to reduce vibration of pipelines

Structural integrity evaluation of FTL in-pool piping

Energy Technology Data Exchange (ETDEWEB)

Kim, J. Y

1998-05-01

HANARO fuel test loop will be equipped in HANARO to obtain the development betterment of advanced fuel and materials through the irradiation test. The object of this study is to evaluate the structural integrity of FTL in-pool piping by investigating a dynamic analysis of the loop containing a postulated rupture section. The method to perform the dynamic analysis and structural integrity evaluation caused by the pipe whip in water environment can be a reference for a similar structural integrity evaluation. (author). 7 refs., 39 tabs., 34 figs.

Pipe whip analysis using the TEDEL code

International Nuclear Information System (INIS)

Millard, D.; Hoffmann, A.

1985-02-01

In view of their abundance, piping systems are one of the main components in power industries and in particular in nuclear power plants. They must be designed for normal as well as faulted conditions, for safety requirements. The prediction of the dynamic behaviour of the free pipe requires accounting for several nonlinearities. For this purpose, a beam type finite element program (TEDEL) has been used. The aim of this paper is to enlight the main features of this program, when applied to pipe whip analysis. An example of application to a real case will also be presented

Pre-study of dynamic loads on the internals caused by a large pipe break in a BWR; Foerstudie av stroemningsinducerade laster paa interndelar vid brott i huvudcirkulationskretsarna i BWR

Energy Technology Data Exchange (ETDEWEB)

Marcinkiewicz, Jerzy; Lindgren, Anders [Det Norske Veritas Nuclear Technology AB, Stockholm (Sweden)

2002-12-01

Det Norske Veritas Nuclear Technology has performed a literature study of dynamic load on a BWR (Boiling Water Reactor) internals caused by a large pipe break. The goal of the study was to improve the knowledge about the physics of phenomena occurring in the RPV (Reactor Pressure Vessel) after pipe break in the main circulation system and also to make a review of calculation methods, models and computer programs including their capabilities when calculating the dynamic loads. The report presents description of relevant parts of a BWR, initial and boundary conditions, and phenomena determining the loads - rapid depressurization and propagation of pressure wave (including none-equilibrium). Furthermore, the report generally describes possible methodologies for calculating the dynamic loads on internals after the pipe break and the experiences from calculations the dynamic loads with different methods (computer programs) including comparisons with experimental data. Fluid-Structure Interaction methodology and its importance for calculation of dynamic loads on reactor internals is discussed based on experimental data. A very intensive research program for studying and calculating the dynamic loads on internals after pipe breaks has been performed in USA and Germany during the seventies and the eighties. Several computer programs have been developed and a number of large-scale experiments have been performed to calibrate the calculation methods. In spite of the fact that all experiments were performed for PWR several experiences should be valid also for BWR. These experiences, connected mainly to capabilities of computer programs calculating dynamic loads, are discussed in the report.

Experimental studies of PWR primary piping under loca

International Nuclear Information System (INIS)

Caumette, Pierre; Garcia, J.L.

1980-07-01

The experimental program performed on AQUITAINE II facility is directed to study the mechanical behavior of primary PWR pipes and the forces exerted on the neighbouring structures as a consequence of a breach opening. It has been developed in the form of a quadripartite agreement between the Commissariat a l'Energie Atomique, Framatome, Electricite de France and Westinghouse. Some forty tests have been carried out with different pipe configurations (straight tube, elbow, S- or U-shaped tube) and different break types (single or double guillotine). The following aspects are investigated: - the dynamic behavior of the pipe and in particular the formation of a plastic hinge at the restraint; - the impact function of a pipe or an energy-absorbing bumper; - the lateral stability of both ends of a pipe, after a double-guillotine break [fr

Review of nuclear piping seismic design requirements

International Nuclear Information System (INIS)

Slagis, G.C.; Moore, S.E.

1994-01-01

Modern-day nuclear plant piping systems are designed with a large number of seismic supports and snubbers that may be detrimental to plant reliability. Experimental tests have demonstrated the inherent ruggedness of ductile steel piping for seismic loading. Present methods to predict seismic loads on piping are based on linear-elastic analysis methods with low damping. These methods overpredict the seismic response of ductile steel pipe. Section III of the ASME Boiler and Pressure Vessel Code stresses limits for piping systems that are based on considerations of static loads and hence are overly conservative. Appropriate stress limits for seismic loads on piping should be incorporated into the code to allow more flexible piping designs. The existing requirements and methods for seismic design of piping systems, including inherent conservations, are explained to provide a technical foundation for modifications to those requirements. 30 refs., 5 figs., 3 tabs

Piping system damping data at higher frequencies

International Nuclear Information System (INIS)

Ware, A.G.

1987-01-01

Research has been performed at the Idaho National Engineering Laboratory (INEL) for the United States Nuclear Regulatory Commission (USNRC) to determine best-estimate damping values for dynamic analyses of nuclear piping systems excited in the 20 to 100 Hz frequency range. Vibrations in this frequency range are typical of fluid-induced transients, for which no formal pipe damping guidelines exist. The available data found in the open literature and the USNRC/INEL nuclear piping damping data bank were reviewed, and a series of tests on a straight 3-in. (76-mm) piping system and a 5-in. (127-mm) system with several bends and elbows were conducted as part of this research program. These two systems were supported with typical nuclear piping supports that could be changed from test to test during the series. The resulting damping values were ≥ those of the Pressure Vessel Research Committee (PVRC) proposal for unisulated piping. Extending the PVRC damping curve from 20 to 100 Hz at 3% of critical damping would give a satisfactory representation of the test data. This position has been endorsed by the PVRC Technical Committee on Piping Systems. 14 refs

Refined pipe theory for mechanistic modeling of wood development.

Science.gov (United States)

Deckmyn, Gaby; Evans, Sam P; Randle, Tim J

2006-06-01

We present a mechanistic model of wood tissue development in response to changes in competition, management and climate. The model is based on a refinement of the pipe theory, where the constant ratio between sapwood and leaf area (pipe theory) is replaced by a ratio between pipe conductivity and leaf area. Simulated pipe conductivity changes with age, stand density and climate in response to changes in allocation or pipe radius, or both. The central equation of the model, which calculates the ratio of carbon (C) allocated to leaves and pipes, can be parameterized to describe the contrasting stem conductivity behavior of different tree species: from constant stem conductivity (functional homeostasis hypothesis) to height-related reduction in stem conductivity with age (hydraulic limitation hypothesis). The model simulates the daily growth of pipes (vessels or tracheids), fibers and parenchyma as well as vessel size and simulates the wood density profile and the earlywood to latewood ratio from these data. Initial runs indicate the model yields realistic seasonal changes in pipe radius (decreasing pipe radius from spring to autumn) and wood density, as well as realistic differences associated with the competitive status of trees (denser wood in suppressed trees).

Pipe Decontamination Involving String-Foam Circulation

International Nuclear Information System (INIS)

Turchet, J.P.; Estienne, G.; Fournel, B.

2002-01-01

Foam applications number for nuclear decontamination purposes has recently increased. The major advantage of foam decontamination is the reduction of secondary liquid wastes volumes. Among foam applications, we focus on foam circulation in contaminated equipment. Dynamic properties of the system ensures an homogeneous and rapid effect of the foam bed-drifted chemical reagents present in the liquid phase. This paper describes a new approach of foam decontamination for pipes. It is based on an alternated air and foam injections. We called it 'string-foam circulation'. A further reduction of liquid wastes is achieved compared to continuous foam. Secondly, total pressure loss along the pipe is controlled by the total foam length in the pipe. It is thus possible to clean longer pipes keeping the pressure under atmospheric pressure value. This ensures the non dispersion of contamination. This study describes experimental results obtained with a neutral foam as well with an acid foam on a 130 m long loop. Finally, the decontamination of a 44 meters pipe is presented. (authors)

Reliability analysis of stiff versus flexible piping

International Nuclear Information System (INIS)

Lu, S.C.

1985-01-01

The overall objective of this research project is to develop a technical basis for flexible piping designs which will improve piping reliability and minimize the use of pipe supports, snubbers, and pipe whip restraints. The current study was conducted to establish the necessary groundwork based on the piping reliability analysis. A confirmatory piping reliability assessment indicated that removing rigid supports and snubbers tends to either improve or affect very little the piping reliability. The authors then investigated a couple of changes to be implemented in Regulatory Guide (RG) 1.61 and RG 1.122 aimed at more flexible piping design. They concluded that these changes substantially reduce calculated piping responses and allow piping redesigns with significant reduction in number of supports and snubbers without violating ASME code requirements. Furthermore, the more flexible piping redesigns are capable of exhibiting reliability levels equal to or higher than the original stiffer design. An investigation of the malfunction of pipe whip restraints confirmed that the malfunction introduced higher thermal stresses and tended to reduce the overall piping reliability. Finally, support and component reliabilities were evaluated based on available fragility data. Results indicated that the support reliability usually exhibits a moderate decrease as the piping flexibility increases. Most on-line pumps and valves showed an insignificant reduction in reliability for a more flexible piping design

Seismic fragility test of a 6-inch diameter pipe system

International Nuclear Information System (INIS)

Chen, W.P.; Onesto, A.T.; DeVita, V.

1987-02-01

This report contains the test results and assessments of seismic fragility tests performed on a 6-inch diameter piping system. The test was funded by the US Nuclear Regulatory Commission (NRC) and conducted by ETEC. The objective of the test was to investigate the ability of a representative nuclear piping system to withstand high level dynamic seismic and other loadings. Levels of loadings achieved during seismic testing were 20 to 30 times larger than normal elastic design evaluations to ASME Level D limits would permit. Based on failure data obtained during seismic and other dynamic testing, it was concluded that nuclear piping systems are inherently able to withstand much larger dynamic seismic loadings than permitted by current design practice criteria or predicted by the probabilistic risk assessment (PRA) methods and several proposed nonlinear methods of failure analysis

Comparison of ICEPEL predictions with single elbow flexible piping system experiment

International Nuclear Information System (INIS)

A-Moneim, M.T.; Chang, Y.W.

1978-01-01

The ICEPEL Code for coupled hydrodynamic-structural response analysis of piping systems is used to analyze an experiment on the response of flexible piping systems to internal pressure pulses. The piping system consisted of two flexible Nickel-200 pipes connected in series through a 90 0 thick-walled stainless steel elbow. A tailored pressure pulse generated by a calibrated pulse gun is stabilized in a long thick-walled stainless steel pipe leading to the flexible piping system which ended with a heavy blind flange. The analytical results of pressure and circumferential strain histories are discussed and compared against the experimental data obtained by Stanford Research Institute

Damping considerations in CANDU feeder pipe design and analysis

International Nuclear Information System (INIS)

Usmani, S.A.; Saleem, M.A.; So, G.

1990-01-01

Recent developments in pipe damping indicate a trend towards more realistic and less conservative values, which result in less rigid and safer pipe designs. The CANDU-PHW (Canada deuterium uranium, pressurized heavy water) reactor feeder pipe designs have applied similar approaches which permit seismic qualifications without overly restraining these compact arrays of pipes to cater for the large creep and thermal anchor movement. This paper reviews the feeder design aspects, especially pertaining to the design provisions, experimental verification and analytical modelling for seismic qualification in the light of recent pipe dynamic developments. Using illustrative examples, comparison of seismic analysis results is provided for the ASME Code Case N-411 dampings, and those traditionally used in the feeder seismic qualification. The results confirm acceptability of the traditional approach which permit simplified analysis to demonstrate seismic qualificationqualification of CANDU feeder pipes

Offshore pipelaying dynamics

Energy Technology Data Exchange (ETDEWEB)

Jensen, Gullik Anthon

2010-02-15

This thesis considers three issues regarding modeling of of offshore pipe laying dynamics. These are: (i) the formulation of an offshore pipeline installation operation as a control problem, (ii) the development and passivity analysis of a robotic pipe model for a submerged pipe string, suitable for real-time applications in closed- loop control systems, and (iii) the development and validation of a nonlinear FEM model for simulation and control of the elastic pipeline dynamics, including FEM dynamics of a pipeline combined with vessel dynamics, for simulation and control of pipe lay operations under dynamic positioning Pipeline installation is defined as the operation of positioning a pipeline along a reference path on the seabed from a surface vessel. In control terms, this can be stated as a path-following control problem, where the pipe touchdown point tracks the reference path. However, the only controllers for the touchdown point are the pay-out of pipe into the water, and the motion of the surface vessel. Considering that the pipe is an elastic body, and that both the pipe and the vessel are subject to environmental loads, the control problem that must be considered is a dynamic target-tracking problem, where the surface vessel must track a moving target position on the surface in order to control the position of the touchdown point. A target-tracking controller may be implemented as a guidance system, by extending the dynamic positioning system that is common for pipe lay vessels. An important component in the guidance system is the dynamic pipe model mapping touchdown and surface vessel position. Motivated by robotics, a compact system formulation is derived for the suspended pipeline by considering it as a hyper-redundant manipulator with an arbitrary number of links. This model captures the main dynamics of the pipe, including its geometric configuration and top tension. The model is in the state- space, and on a vectorial form using minimal coordinates

International piping integrity research group (IPIRG) program final report

International Nuclear Information System (INIS)

Schmidt, R.; Wilkowski, G.; Scott, P.; Olsen, R.; Marschall, C.; Vieth, P.; Paul, D.

1992-04-01

This is the final report of the International Piping Integrity Research Group (IPIRG) Programme. The IPIRG Programme was an international group programme managed by the U.S. Nuclear Regulatory Commission and funded by a consortium of organizations from nine nations: Canada, France, Italy, Japan, Sweden, Switzerland, Taiwan, the United Kingdom, and the United states. The objective of the programme was to develop data needed to verify engineering methods for assessing the integrity of nuclear power plant piping that contains circumferential defects. The primary focus was an experimental task that investigated the behaviour of circumferentially flawed piping and piping systems to high-rate loading typical of seismic events. To accomplish these objectives a unique pipe loop test facility was designed and constructed. The pipe system was an expansion loop with over 30 m of 406-mm diameter pipe and five long radius elbows. Five experiments on flawed piping were conducted to failure in this facility with dynamic excitation. The report: provides background information on leak-before-break and flaw evaluation procedures in piping; summarizes the technical results of the programme; gives a relatively detailed assessment of the results from the various pipe fracture experiments and complementary analyses; and, summarizes the advances in the state-of-the-art of pipe fracture technology resulting from the IPIRG Program

Study on unstable fracture characteristics of light water reactor piping

International Nuclear Information System (INIS)

Kurihara, Ryoichi

1998-08-01

Many testing studies have been conducted to validate the applicability of the leak before break (LBB) concept for the light water reactor piping in the world. It is especially important among them to clarify the condition that an inside surface crack of the piping wall does not cause an unstable fracture but ends in a stable fracture propagating only in the pipe thickness direction, even if the excessive loading works to the pipe. Pipe unstable fracture tests performed in Japan Atomic Energy Research Institute had been planned under such background, and clarified the condition for the cracked pipe to cause the unstable fracture under monotonous increase loading or cyclic loading by using test pipes with the inside circumferential surface crack. This paper examines the pipe unstable fracture by dividing it into two parts. One is the static unstable fracture that breaks the pipe with the inside circumferential surface crack by increasing load monotonously. Another is the dynamic unstable fracture that breaks the pipe by the cyclic loading. (author). 79 refs

Application of cyclic J-integral to low cycle fatigue crack growth of Japanese carbon steel pipe

Energy Technology Data Exchange (ETDEWEB)

Miura, N.; Fujioka, T.; Kashima, K. [and others

1997-04-01

Piping for LWR power plants is required to satisfy the LBB concept for postulated (not actual) defects. With this in mind, research has so far been conducted on the fatigue crack growth under cyclic loading, and on the ductile crack growth under excessive loading. It is important, however, for the evaluation of the piping structural integrity under seismic loading condition, to understand the fracture behavior under dynamic and cyclic loading conditions, that accompanies large-scale yielding. CRIEPI together with Hitachi have started a collaborative research program on dynamic and/or cyclic fracture of Japanese carbon steel (STS410) pipes in 1991. Fundamental tensile property tests were conducted to examine the effect of strain rate on tensile properties. Cracked pipe fracture tests under some loading conditions were also performed to investigate the effect of dynamic and/or cyclic loading on fracture behavior. Based on the analytical considerations for the above tests, the method to evaluate the failure life for a cracked pipe under cyclic loading was developed and verified. Cyclic J-integral was introduced to predict cyclic crack growth up to failure. This report presents the results of tensile property tests, cracked pipe fracture tests, and failure life analysis. The proposed method was applied to the cracked pipe fracture tests. The effect of dynamic and/or cyclic loading on pipe fracture was also investigated.

Heat Pipe Reactor Dynamic Response Tests: SAFE-100 Reactor Core Prototype

Science.gov (United States)

Bragg-Sitton, Shannon M.

2005-01-01

The SAFE-I00a test article at the NASA Marshall Space Flight Center was used to simulate a variety of potential reactor transients; the SAFEl00a is a resistively heated, stainless-steel heat-pipe (HP)-reactor core segment, coupled to a gas-flow heat exchanger (HX). For these transients the core power was controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. This type of non-nuclear test is expected to provide reasonable approximation of reactor transient behavior because reactivity feedback is very simple in a compact fast reactor (simple, negative, and relatively monotonic temperature feedback, caused mostly by thermal expansion) and calculations show there are no significant reactivity effects associated with fluid in the HP (the worth of the entire inventory of Na in the core is .tests, the point kinetics model was based on core thermal expansion via deflection measurements. It was found that core deflection was a strung function of how the SAFE-100 modules were fabricated and assembled (in terms of straightness, gaps, and other tolerances). To remove the added variable of how this particular core expands as compared to a different concept, it was decided to use a temperature based feedback model (based on several thermocouples placed throughout the core).

Numerical simulation of temperature and thermal stress for nuclear piping by using computational fluid dynamics analysis and Green’s function

Energy Technology Data Exchange (ETDEWEB)

Boo, Myung-Hwan [Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of); Oh, Chang-Kyun; Kim, Hyun-Su [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of); Choi, Choeng-Ryul [ELSOLTEC, Inc., Yongin (Korea, Republic of)

2017-05-15

Owing to the fact that thermal fatigue is a well-known damage mechanism in nuclear power plants, accurate stress and fatigue evaluation are highly important. Operating experience shows that the design condition is conservative compared to the actual one. Therefore, various fatigue monitoring methods have been extensively utilized to consider the actual operating data. However, defining the local temperature in the piping is difficult because temperature-measuring instruments are limited. The purpose of this paper is to define accurate local temperature in the piping and evaluate thermal stress using Green’s function (GF) by performing a series of computational fluid dynamics analyses considering the complex fluid conditions. Also, the thermal stress is determined by adopting GF and comparing it with that of the design condition. The fluid dynamics analysis result indicates that the fluid temperature slowly varies compared to the designed one even when the flow rate changes abruptly. In addition, the resulting thermal stress can significantly decrease when reflecting the actual temperature.

Experimental Study on Pipe Sections against Impact Loading

Directory of Open Access Journals (Sweden)

Engin GÜCÜYEN

2018-02-01

Full Text Available Pipelines are significant structural systems that transfer necessary materials from one place to another. They are under the effect of static and dynamic loads during their service lives. Investigations have become important to determine the effects of sudden dynamic loads with technological developments. Researchers study the mechanical properties of different materials and structural members under dynamic effects such as earthquake, wind, blast, rock falling and vehicle crushing. For this purpose, different test setups have been developed to investigate the behaviour of test members. In this study, galvanized and water filled galvanized pipe sections having three different diameter values are produced in a laboratory to perform tests under impact loading. The behaviour of the pipes is determined by free falling test apparatus. In addition, measurement devices as accelerometer, dynamic force sensor, lvdt, and data logger are used in the experimental program. So, acceleration, impact force, and displacement values are obtained during the tests. Besides, damage developments of the pipes are also observed to determine the impact resistances of test members. The results are compared to each other and it is stated that while acceleration and impact force values decrease, displacement values increase as the test members approach to collapse damage situation.

Modelling of Aquitaine II pipe whipping test with EUROPLEXUS fast dynamics code

International Nuclear Information System (INIS)

Potapov, S.

2003-01-01

To validate the modelling of multi-physics phenomena with EUROPLEXUS code we considered a pipe whipping problem occurring in thermal hydraulic conditions of a Loss of Coolant Accident in PWR primary circuit. Two numerical fluid-structure interaction (FSI) models, a simplified 'pipe-like' model and a mixed 1D/3D model, were used to simulate both the conditioning phase and a phase of whipping. The results of calculations were compared with existing experimental data. Analysis of numerical results shows that both models give a good prediction of global behaviour of the coupled fluid-structure system, namely for pipe displacements and stresses in the pipe walls, as well as for pressure and velocity in the fluid. By comparison with experimental data, we show that only the mixed EUROPLEXUS model, where the pipe elbow is discretized with shells, allows us to estimate correctly the time history and maximum value of the contact force between the pipe and the obstacle. The 1D model with reduced kinematics (rigid cross section hypothesis) does not allow the correct detection of contact phenomenon. This study shows that the use of mixed numerical models containing simplified and totally 3D parts duly interconnected allows a very efficient and CPU inexpensive numerical analysis which is able to take into account different global and local physical phenomena. (author)

Piping Plover response to coastal storms occurring during the nonbreeding season

Directory of Open Access Journals (Sweden)

Nadine R. Bourque

2015-06-01

Full Text Available The increase in coastal storm frequency and intensity expected under most climate change scenarios is likely to substantially modify beach configuration and associated habitats. This study aimed to analyze the impact of coastal storms on a nesting population of the endangered Piping Plover (Charadrius melodus melodus in southeastern New Brunswick, Canada. Previous studies have shown that numbers of nesting Piping Plovers may increase following storms that create new nesting habitat at individual beaches. However, to our knowledge, no test of this pattern has been conducted over a regional scale. We hypothesized that Piping Plover abundance would increase after large coastal storms occurring during the nonbreeding season. However, we expected a delay in the colonization of newly created habitat owing to low-density populations, combined with high site fidelity of adults and high variability in survival rate of subadults. We tested this hypothesis using a 27-year (1986-2012 data set of Piping Plover abundance and productivity (nesting pairs and fledged young collected at five sites in eastern New Brunswick. We identified 11 major storms that could potentially have modified Piping Plover habitat over the study period. The number of fledged young increased three years after a major storm, but the relationship was much weaker for the number of nesting pairs. These findings are consistent with the hypothesized increase in suitable habitat after coastal storms. Including storm occurrence with other factors influencing habitat quality will enhance Piping Plover conservation strategies.

Acoustic Signal Processing for Pipe Condition Assessment (WaterRF Report 4360)

Science.gov (United States)

Unique to prestressed concrete cylinder pipe (PCCP), individual wire breaks create an excitation in the pipe wall that may vary in response to the remaining compression of the pipe core. This project was designed to improve acoustic signal processing for pipe condition assessment...

Design and analysis for piping systems

International Nuclear Information System (INIS)

Sterkel, H.-P.; Cutrim, J.H.C.

1981-01-01

The procedure and the typical techniques that are used in NUCLEN for the design and the calculation of the piping of Nuclear Plants. The classification system are generically described and the analysis techniques which are used for the design and verification of the piping systems, i.e. pressure design for the dimensioning of the wallthicknesses, temperature and dead weight analysis together with determination of support points, are shown. The techniques of dynamic design and analyses are described for earthquake and pressure impulse loadings. (Author) [pt

Structural consideration for hot and cold pipe clamps in LMFBR applications

International Nuclear Information System (INIS)

Anderson, M.J.; Huang, S.N.; Kappauf, H.; Wagner, S.E.; Wirtz, K.H.

1983-01-01

A series of analytical studies are described which evaluate stress levels induced in a 600 mm high temperature, thin-wall sodium pipeline by two alternate clamp designs. The first design consists of a band mounted directly on the pipe and is called the hot clamp. The second design consists of a band mounted using insulation standoffs and is called the cold clamp. Pipe stress levels induced by transient thermal dead weight and seismic loads are discussed. Pipe stress levels and system dynamic spring rates are presented. Procedures utilized to combine clamp induced pipe stress with other short and long term pipe system stresses are detailed. Recommendations for practical application in LMFBR pipe systems are made

Structural considerations for hot and cold pipe clamps in LMFBR applications

International Nuclear Information System (INIS)

Anderson, M.J.; Huang, S.N.; Wagner, S.E.; Kappauf, H.; Wirtz, K.H.

1983-01-01

A series of analytical studies are described which evaluate stress levels induced in a 600 mm high temperature, thin-wall sodium pipeline by two alternate clamp designs. The first design consists of a band mounted directly on the pipe and is called the hot clamp. The second design consists of a band mounted using insulation standoffs and is called the cold clamp. Pipe stress levels induced by transient thermal dead weight and seismic loads are discussed. Pipe stress levels and system dynamic spring rates are presented. Procedures utilized to combine clamp induced pipe stress with other short and long term pipe system stresses are detailed. Recommendations for practical application in LMFBR pipe systems are made

Soil-pipe interaction modeling for pipe behavior prediction with super learning based methods

Science.gov (United States)

Shi, Fang; Peng, Xiang; Liu, Huan; Hu, Yafei; Liu, Zheng; Li, Eric

2018-03-01

Underground pipelines are subject to severe distress from the surrounding expansive soil. To investigate the structural response of water mains to varying soil movements, field data, including pipe wall strains in situ soil water content, soil pressure and temperature, was collected. The research on monitoring data analysis has been reported, but the relationship between soil properties and pipe deformation has not been well-interpreted. To characterize the relationship between soil property and pipe deformation, this paper presents a super learning based approach combining feature selection algorithms to predict the water mains structural behavior in different soil environments. Furthermore, automatic variable selection method, e.i. recursive feature elimination algorithm, were used to identify the critical predictors contributing to the pipe deformations. To investigate the adaptability of super learning to different predictive models, this research employed super learning based methods to three different datasets. The predictive performance was evaluated by R-squared, root-mean-square error and mean absolute error. Based on the prediction performance evaluation, the superiority of super learning was validated and demonstrated by predicting three types of pipe deformations accurately. In addition, a comprehensive understand of the water mains working environments becomes possible.

Pipe-to-pipe impact program

International Nuclear Information System (INIS)

Alzheimer, J.M.; Bampton, M.C.C.; Friley, J.R.; Simonen, F.A.

1984-06-01

This report documents the tests and analyses performed as part of the Pipe-to-Pipe Impact (PTPI) Program at the Pacific Northwest Laboratory. This work was performed to assist the NRC in making licensing decisions regarding pipe-to-pipe impact events following postulated breaks in high energy fluid system piping. The report scope encompasses work conducted from the program's start through the completion of the initial hot oil tests. The test equipment, procedures, and results are described, as are analytic studies of failure potential and data correlation. Because the PTPI Program is only partially completed, the total significance of the current test results cannot yet be accurately assessed. Therefore, although trends in the data are discussed, final conclusions and recommendations will be possible only after the completion of the program, which is scheduled to end in FY 1984

Technical considerations for flexible piping design in nuclear power plants

International Nuclear Information System (INIS)

Lu, S.C.; Chou, C.K.

1985-01-01

The overall objective of this research project is to develop a technical basis for flexible piping designs which will improve piping reliability and minimize the use of pipe supports, snubbers, and pipe whip restraints. The current study was conducted to establish the necessary groundwork based on the piping reliability analysis. A confirmatory piping reliability assessment indicated that removing rigid supports and snubbers tends to either improve or affect very little the piping reliability. A couple of changes to be implemented in Regulatory Guide (RG) 1.61 and RG 1.122 aimed at more flexible piping design were investigated. It was concluded that these changes substantially reduce calculated piping responses and allows piping redesigns with significant reduction in number of supports and snubbers without violating ASME code requirements

Sensitivity Analysis on Elbow Piping Components in Seismically Isolated NPP under Seismic Loading

Energy Technology Data Exchange (ETDEWEB)

Ju, Hee Kun; Hahm, Dae Gi; Kim, Min Kyu [KAERI, Daejeon (Korea, Republic of); Jeon, Bub Gyu; Kim, Nam Sik [Pusan National University, Busan (Korea, Republic of)

2016-05-15

In this study, the FE model is verified using specimen test results and simulation with parameter variations are conducted. Effective parameters will randomly sampled and used as input values for simulations to be applied to the fragility analysis. pipelines are representative of them because they could undergo larger displacements when they are supported on both isolated and non-isolated structures simultaneously. Especially elbows are critical components of pipes under severed loading conditions such as earthquake action because strain is accumulated on them during the repeated bending of the pipe. Therefore, seismic performance of pipe elbow components should be examined thoroughly based on the fragility analysis. Fragility assessment of interface pipe should take different sources of uncertainty into account. However, selection of important sources and repeated tests with many random input values are very time consuming and expensive, so numerical analysis is commonly used. In the present study, finite element (FE) model of elbow component will be validated using the dynamic test results of elbow components. Using the verified model, sensitivity analysis will be implemented as a preliminary process of seismic fragility of piping system. Several important input parameters are selected and how the uncertainty of them are apportioned to the uncertainty of the elbow response is to be studied. Piping elbows are critical components under cyclic loading conditions as they are subjected large displacement. In a seismically isolated NPP, seismic capacity of piping system should be evaluated with caution. Seismic fragility assessment preliminarily needs parameter sensitivity analysis about the output of interest with different input parameter values.

Applications of equivalent linearization approaches to nonlinear piping systems

International Nuclear Information System (INIS)

Park, Y.; Hofmayer, C.; Chokshi, N.

1997-01-01

The piping systems in nuclear power plants, even with conventional snubber supports, are highly complex nonlinear structures under severe earthquake loadings mainly due to various mechanical gaps in support structures. Some type of nonlinear analysis is necessary to accurately predict the piping responses under earthquake loadings. The application of equivalent linearization approaches (ELA) to seismic analyses of nonlinear piping systems is presented. Two types of ELA's are studied; i.e., one based on the response spectrum method and the other based on the linear random vibration theory. The test results of main steam and feedwater piping systems supported by snubbers and energy absorbers are used to evaluate the numerical accuracy and limitations

Mechanical Interaction in Pressurized Pipe Systems: Experiments and Numerical Models

Directory of Open Access Journals (Sweden)

Mariana Simão

2015-11-01

Full Text Available The dynamic interaction between the unsteady flow occurrence and the resulting vibration of the pipe are analyzed based on experiments and numerical models. Waterhammer, structural dynamic and fluid–structure interaction (FSI are the main subjects dealt with in this study. Firstly, a 1D model is developed based on the method of characteristics (MOC using specific damping coefficients for initial components associated with rheological pipe material behavior, structural and fluid deformation, and type of anchored structural supports. Secondly a 3D coupled complex model based on Computational Fluid Dynamics (CFD, using a Finite Element Method (FEM, is also applied to predict and distinguish the FSI events. Herein, a specific hydrodynamic model of viscosity to replicate the operation of a valve was also developed to minimize the number of mesh elements and the complexity of the system. The importance of integrated analysis of fluid–structure interaction, especially in non-rigidity anchored pipe systems, is equally emphasized. The developed models are validated through experimental tests.

Correlation of energy balance method to dynamic pipe rupture analysis

International Nuclear Information System (INIS)

Kuo, H.H.; Durkee, M.

1983-01-01

When using an energy balance approach in the design of pipe rupture restraints for nuclear power plants, the NRC specifies in its Standard Review Plan 3.6.2 that the input energy to the system must be multiplied by a factor of 1.1 unless a lower value can be justified. Since the energy balance method is already quite conservative, an across-the-board use of 1.1 to amplify the energy input appears unneccessary. The paper's purpose is to show that this 'correlation factor' could be substantially less than unity if certain design parameters are met. In this paper, result of nonlinear dynamic analyses were compared to the results of the corresponding analyses based on the energy balance method which assumes constant blowdown forces and rigid plastic material properties. The appropriate correlation factors required to match the energy balance results with the dynamic analyses results were correlated to design parameters such as restraint location from the break, yield strength of the energy absorbing component, and the restraint gap. It is shown that the correlation factor is related to a single nondimensional design parameter and can be limited to a value below unity if appropriate design parameters are chosen. It is also shown that the deformation of the restraints can be related to dimensionless system parameters. This, therefore, allows the maximum restraint deformation to be evaluated directly for design purposes. (orig.)

Application of LBB to high energy piping systems in operating PWR

Energy Technology Data Exchange (ETDEWEB)

Swamy, S.A.; Bhowmick, D.C. [Westinghouse Nuclear Technology Division, Pittsburgh, PA (United States)

1997-04-01

The amendment to General Design Criterion 4 allows exclusion, from the design basis, of dynamic effects associated with high energy pipe rupture by application of leak-before-break (LBB) technology. This new approach has resulted in substantial financial savings to utilities when applied to the Pressurized Water Reactor (PWR) primary loop piping and auxiliary piping systems made of stainless steel material. To date majority of applications pertain to piping systems in operating plants. Various steps of evaluation associated with the LBB application to an operating plant are described in this paper.

Recommendations for analysis of stress corrosion in pipe systems exposed to thermohydraulic transients

International Nuclear Information System (INIS)

Bjoerndahl, Olof; Letzter, Adam; Marcinkiewicz, Jerzy; Segle, Peter

2007-03-01

structural analysis are determined. The criteria given for these two essential parameters and criteria for data reduction of loading signals are shown to be reasonable. The present study shows that the expected error in calculated stress response is an order of magnitude larger than that of that of the error in the generated loading signals given a certain ε PN . Investigations with the aim to determine appropriate requirements on the thermohydraulic model in generating the loading, i.e. the largest applicable value of ε PN , has not been part of this project. While waiting for this investigation to be done, the recommendation in determining f Pipe is that a value of ε PN < 0.005 is used. Recommendations for analysis of the stress response in piping systems subjected to thermohydraulic loads are given in the report. Two new projects are also suggested. The first one includes a limited study with the aim to verify suggested requirements on the thermohydraulic model in generating the thermohydraulic loading. The second project concerns elastic-plastic analysis of piping systems subjected to dynamic loading and how to perform these analyses and evaluate the results according to ASME

Seismic Capacity Estimation of Steel Piping Elbow under Low-cycle Fatigue Loading

Energy Technology Data Exchange (ETDEWEB)

Jeon, Bub Gyu; Kim, Sung Wan; Choi, Hyoung Suk; Kim, Nam Sik [Pusan National University, Busan (Korea, Republic of); Hahm, Dae Gi [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In some cases, this large relative displacement can increase seismic risk of the isolated facility. Especially, a inelastic behavior of crossover piping system to connect base isolated building and fixed base building can caused by a large relative displacement. Therefore, seismic capacity estimation for isolated piping system is needed to increase safety of nuclear power plant under seismic condition. Dynamic behavior analysis of piping system under seismic condition using shake table tests was performed by Touboul et al in 1995. In accordance with their study, plastic behavior could be occurred at pipe elbow under seismic condition. Experimental researches for dynamic behavior of typical piping system in nuclear power plant have been performed for several years by JNES(Japan Nuclear Energy Safety Organization) and NUPEC(Nuclear Power Engineering Corporation). A low cycle ratcheting fatigue test was performed with scaled model of elbow which is a weakest component in piping system by Mizuno et al. In-plane cyclic loading tests under internal pressure condition were performed to evaluate the seismic capacity of the steel piping elbow. Leakage phenomenon occurred on and near the crown in piping elbow. Those cracks grew up in axial direction. The fatigue curve was estimated from test results. In the fatigue curve, loading amplitude exponentially decreased as the number of cycles increased. A FEM model of piping elbow was modified with test results. The relationships between displacement and force from tests and numerical analysis was well matched.

Uncertainty analysis for probabilistic pipe fracture evaluations in LBB applications

International Nuclear Information System (INIS)

Rahman, S.; Ghadiali, N.; Wilkowski, G.

1997-01-01

During the NRC's Short Cracks in Piping and Piping Welds Program at Battelle, a probabilistic methodology was developed to conduct fracture evaluations of circumferentially cracked pipes for application to leak-rate detection. Later, in the IPIRG-2 program, several parameters that may affect leak-before-break and other pipe flaw evaluations were identified. This paper presents new results from several uncertainty analyses to evaluate the effects of normal operating stresses, normal plus safe-shutdown earthquake stresses, off-centered cracks, restraint of pressure-induced bending, and dynamic and cyclic loading rates on the conditional failure probability of pipes. systems in BWR and PWR. For each parameter, the sensitivity to conditional probability of failure and hence, its importance on probabilistic leak-before-break evaluations were determined

Uncertainty analysis for probabilistic pipe fracture evaluations in LBB applications

Energy Technology Data Exchange (ETDEWEB)

Rahman, S.; Ghadiali, N.; Wilkowski, G.

1997-04-01

During the NRC`s Short Cracks in Piping and Piping Welds Program at Battelle, a probabilistic methodology was developed to conduct fracture evaluations of circumferentially cracked pipes for application to leak-rate detection. Later, in the IPIRG-2 program, several parameters that may affect leak-before-break and other pipe flaw evaluations were identified. This paper presents new results from several uncertainty analyses to evaluate the effects of normal operating stresses, normal plus safe-shutdown earthquake stresses, off-centered cracks, restraint of pressure-induced bending, and dynamic and cyclic loading rates on the conditional failure probability of pipes. systems in BWR and PWR. For each parameter, the sensitivity to conditional probability of failure and hence, its importance on probabilistic leak-before-break evaluations were determined.

International Piping Integrity Research Group (IPIRG) Program. Final report

International Nuclear Information System (INIS)

Wilkowski, G.; Schmidt, R.; Scott, P.

1997-06-01

This is the final report of the International Piping Integrity Research Group (IPIRG) Program. The IPIRG Program was an international group program managed by the U.S. Nuclear Regulatory Commission and funded by a consortium of organizations from nine nations: Canada, France, Italy, Japan, Sweden, Switzerland, Taiwan, the United Kingdom, and the United States. The program objective was to develop data needed to verify engineering methods for assessing the integrity of circumferentially-cracked nuclear power plant piping. The primary focus was an experimental task that investigated the behavior of circumferentially flawed piping systems subjected to high-rate loadings typical of seismic events. To accomplish these objectives a pipe system fabricated as an expansion loop with over 30 meters of 16-inch diameter pipe and five long radius elbows was constructed. Five dynamic, cyclic, flawed piping experiments were conducted using this facility. This report: (1) provides background information on leak-before-break and flaw evaluation procedures for piping, (2) summarizes technical results of the program, (3) gives a relatively detailed assessment of the results from the pipe fracture experiments and complementary analyses, and (4) summarizes advances in the state-of-the-art of pipe fracture technology resulting from the IPIRG program

International Piping Integrity Research Group (IPIRG) Program. Final report

Energy Technology Data Exchange (ETDEWEB)

Wilkowski, G.; Schmidt, R.; Scott, P. [and others

1997-06-01

This is the final report of the International Piping Integrity Research Group (IPIRG) Program. The IPIRG Program was an international group program managed by the U.S. Nuclear Regulatory Commission and funded by a consortium of organizations from nine nations: Canada, France, Italy, Japan, Sweden, Switzerland, Taiwan, the United Kingdom, and the United States. The program objective was to develop data needed to verify engineering methods for assessing the integrity of circumferentially-cracked nuclear power plant piping. The primary focus was an experimental task that investigated the behavior of circumferentially flawed piping systems subjected to high-rate loadings typical of seismic events. To accomplish these objectives a pipe system fabricated as an expansion loop with over 30 meters of 16-inch diameter pipe and five long radius elbows was constructed. Five dynamic, cyclic, flawed piping experiments were conducted using this facility. This report: (1) provides background information on leak-before-break and flaw evaluation procedures for piping, (2) summarizes technical results of the program, (3) gives a relatively detailed assessment of the results from the pipe fracture experiments and complementary analyses, and (4) summarizes advances in the state-of-the-art of pipe fracture technology resulting from the IPIRG program.

Investigation of transient cavitating flow in viscoelastic pipes

International Nuclear Information System (INIS)

Keramat, A; Tijsseling, A S; Ahmadi, A

2010-01-01

A study on water hammer in viscoelastic pipes when the fluid pressure drops to liquid vapour pressure is performed. Two important concepts including column separation and the effects of retarded strains in the pipe wall on the fluid response have been investigated separately in recent works, but there is some curiosity as to how the results for pressure and discharge are when column separation occurs in a viscoelastic pipe. For pipes made of plastic such as polyethylene (PE) and polyvinyl chloride (PVC), viscoelasticity is a crucial mechanical property which changes the hydraulic and structural transient responses. Based on previous developments in the analysis of water hammer, a model which is capable of analysing column separation in viscoelastic pipes is presented and used for solving the selected case studies. For the column-separation modelling the Discrete Vapour Cavity Model (DVCM) is utilised and the viscoelasticity property of the pipe wall is modelled by Kelvin-Voigt elements. The effects of viscoelasticity play an important role in the column separation phenomenon because it changes the water hammer fundamental frequency and so affects the time of opening or collapse of the cavities. Verification of the implemented computer code is performed for the effects of viscoelasticity and column separation - separately and simultaneously - using experimental results from the literature. In the provided examples the focus is placed on the simultaneous effect of viscoelasticity and column separation on the hydraulic transient response. The final conclusions drawn are that if rectangular grids are utilised the DVCM gives acceptable predictions of the phenomenon and that the pipe wall material's retarded behaviour strongly dampens the pressure spikes caused by column separation.

Investigation of transient cavitating flow in viscoelastic pipes

Science.gov (United States)

Keramat, A.; Tijsseling, A. S.; Ahmadi, A.

2010-08-01

A study on water hammer in viscoelastic pipes when the fluid pressure drops to liquid vapour pressure is performed. Two important concepts including column separation and the effects of retarded strains in the pipe wall on the fluid response have been investigated separately in recent works, but there is some curiosity as to how the results for pressure and discharge are when column separation occurs in a viscoelastic pipe. For pipes made of plastic such as polyethylene (PE) and polyvinyl chloride (PVC), viscoelasticity is a crucial mechanical property which changes the hydraulic and structural transient responses. Based on previous developments in the analysis of water hammer, a model which is capable of analysing column separation in viscoelastic pipes is presented and used for solving the selected case studies. For the column-separation modelling the Discrete Vapour Cavity Model (DVCM) is utilised and the viscoelasticity property of the pipe wall is modelled by Kelvin-Voigt elements. The effects of viscoelasticity play an important role in the column separation phenomenon because it changes the water hammer fundamental frequency and so affects the time of opening or collapse of the cavities. Verification of the implemented computer code is performed for the effects of viscoelasticity and column separation - separately and simultaneously - using experimental results from the literature. In the provided examples the focus is placed on the simultaneous effect of viscoelasticity and column separation on the hydraulic transient response. The final conclusions drawn are that if rectangular grids are utilised the DVCM gives acceptable predictions of the phenomenon and that the pipe wall material's retarded behaviour strongly dampens the pressure spikes caused by column separation.

Pulse mitigation and heat transfer enhancement techniques. Volume 3: Liquid sodium heat transfer facility and transient response of sodium heat pipe to pulse forward and reverse heat load

Science.gov (United States)

Chow, L. C.; Hahn, O. J.; Nguyen, H. X.

1992-08-01

This report presents the description of a liquid sodium heat transfer facility (sodium loop) constructed to support the study of transient response of heat pipes. The facility, consisting of the loop itself, a safety system, and a data acquisition system, can be safely operated over a wide range of temperature and sodium flow rate. The transient response of a heat pipe to pulse heat load at the condenser section was experimentally investigated. A 0.457 m screen wick, sodium heat pipe with an outer diameter of 0.127 m was tested under different heat loading conditions. A major finding was that the heat pipe reversed under a pulse heat load applied at the condenser. The time of reversal was approximately 15 to 25 seconds. The startup of the heat pipe from frozen state was also studied. It was found that during the startup process, at least part of the heat pipe was active. The active region extended gradually down to the end of the condenser until all of the working fluid in the heat pipe was molten.

Pressure Response of Various Gases in a Pneumatic Resistance Capacitance System and Pipe

Science.gov (United States)

Peng, J.; Youn, C.; Tadano, K.; Kagawa, T.

2017-10-01

City gas, such as propane and methane, is widely used as a fuel in households and factories. Recently, hydrogen as a clean and efficient fuel has been proposed for fuel cell vehicles. However, few studies have investigated pressure control and response of gases considering their properties. This study investigated the static flow rate characteristics in an orifice with four gases—air, propane, methane, and hydrogen. Then, a pressure response experiment was performed using a pneumatic resistance capacitance system comprising an isothermal chamber and a nozzle flapper, and the time constant of the pressure response with various gases was analysed with a mathematical model. The simulation results agreed with the experimental data. Finally, the differences in pressure propagation in a pipe with various gases were explicated by a pressure response experiment. The results showed that the pressure response speed of hydrogen is faster than that of the other three gases because of its small molecular weight. Therefore, the pressure control equipment of hydrogen needs a high response speed.

Dynamic load effects on gate valve operability

International Nuclear Information System (INIS)

Steele, R. Jr.; MacDonald, P.E.; Arendts, J.G.

1986-01-01

The Idaho National Engineering Laboratory (INEL) participated in an internationally sponsored seismic research program conducted at the decommissioned Heissdampfreaktor (HDR) located in the Federal Republic of Germany. An existing piping system was modified by installation of an 8-in., naturally aged, motor-operated gate valve from a US nuclear power plant and a piping support system of US design. Six other piping support systems of varying flexibility from stiff to flexible were also installed at various times during the tests. Additional valve loadings included internal hydraulic loads and, during one block of tests, elevated temperature. The operability and integrity of the aged gate valve and the dynamic response of the various piping support system were measured during 25 representative seismic events

Parametric Study on Ultimate Failure Criteria of Elbow Piping Components in Seismically Isolated NPP

Energy Technology Data Exchange (ETDEWEB)

Hahm, Dae Gi; Ki, Min Kyu [KAERI, Daejeon (Korea, Republic of); Jeon, Bub Gyu; Kim, Nam Sik [Pusan National University, Busan (Korea, Republic of)

2016-05-15

It is well known that the interface pipes between isolated and non-isolated structures will become the most critical in the seismically isolated NPPs. Therefore, seismic performance of such interface pipes should be evaluated comprehensively especially in terms of the seismic fragility capacity. To evaluate the seismic capacity of interface pipes in the isolated NPP, firstly, we should define the failure mode and failure criteria of critical pipe components. Hence, in this study, we performed the dynamic tests of elbow components which were installed in a seismically isolated NPP, and evaluated the ultimate failure mode and failure criteria by using the test results. To do this, we manufactured 25 critical elbow component specimens and performed cyclic loading tests under the internal pressure condition. The failure mode and failure criteria of a pipe component will be varied by the design parameters such as the internal pressure, pipe diameter, loading type, and loading amplitude. From the tests, we assessed the effects of the variation parameters onto the failure criteria. For the tests, we generated the seismic input protocol of relative displacement between the ends of elbow component. In this paper, elbow in piping system was defined as a fragile element and numerical model was updated by component test. Failure mode of piping component under seismic load was defined by the dynamic tests of ultimate pipe capacity. For the interface piping system, the seismic capacity should be carefully estimated since that the required displacement absorption capacity will be increased significantly by the adoption of the seismic isolation system. In this study, the dynamic tests were performed for the elbow components which were installed in an actual NPPs, and the ultimate failure mode and failure criteria were also evaluated by using the test results.

Pipe whip: a summary of the damage observed in BNL pipe-on-pipe impact tests

International Nuclear Information System (INIS)

Baum, M.R.

1987-01-01

This paper describes examples of the damage resulting from the impact of a whipping pipe on a nearby pressurised pipe. The work is a by-product of a study of the motion of a whipping pipe. The tests were conducted with small-diameter pipes mounted in rigid supports and hence the results are not directly applicable to large-scale plant applications where flexible support mountings are employed. The results illustrate the influence of whipping pipe energy, impact position and support type on the damage sustained by the target pipe. (author)

Effects of valve characteristics and pipe diameter on water hammer phenomena

International Nuclear Information System (INIS)

Hur, J.; Kim, T. H.; Mun, B. H.; Choi, H. Y.; Lee, K. W.; Noh, T. S.

2001-01-01

The water hammer phenomena mean that the dynamic loads are induced on the pipe, the pipe support and the equipments in the system due to the sudden change of the flow velocity inside the pipe. The sudden changes are mainly caused by the valve sudden on/off and pump sudden start/trip. To develop a selection criterion of the parts to be analyzed for the water hammer, the effects of the valve characteristics and pipe diameter on the water hammer are analyzed. The analyses using Method of Characteristics (MOC) show that the effects of the valve pressure difference and the valve opening time are very significant, but the effects of the pipe diameter are not dominant

Dynamic circumferential ductile crack motion in finite length pipes with various end loadings

International Nuclear Information System (INIS)

Emery, A.F.; Kobayashi, A.S.; Love, W.J.; Perl, M.; Kistler, B.

1981-01-01

The computed time history, crack opening shape and tip velocity are presented for the ductile crack extension of circumferential cracks in finite length pipes. The pipes are loaded by: a) constant axial tension, b) constant axial displacement, c) constant end moment, and d) constant end rotation to study the effects of these significantly different types of loads. The crack extension is based upon a critical crack opening angle criterion. The results indicate that the extent of the crack movement and the extension velocity is primarily dependent upon the inertia of the moving pipe segments. With sufficient linear momentum, complete severance is obtained, while if the movement is more rotation than translation the cracks either do not extend or do so only slightly. Thus in tougher material, once it begins to extend, the crack may easily encircle the pipe while in more brittle materials it may not, since the moving segments of the pipe have not had time to develop sufficient momentum to force the continued extension of the crack into regions which are initially in compression. (orig.)

Design considerations for the protection from the effects of pipe rupture

International Nuclear Information System (INIS)

1975-11-01

The methods which are employed by Ebasco Services, Inc. to satisfy the requirement of 10 CFR 50, Appendix A, General Design Criterion (GDC) 4 are discussed. This criterion provides the design basis for protection against the dynamic effects of postulated piping failures (ruptures and cracks) in Nuclear Power Plants. The criteria for postulating pipe failure locations, determining the dynamic effects associated with the postulated failure and designing the plant to satisfactorily withstand postulated pipe failures have been the subject of a great deal of recent work by the nuclear power industry and the Nuclear Regulatory Commission (NRC). This topical report is largely based upon that work as well as upon Ebasco's independent development of analytical tools to aid in the plant design process

Seismic analysis of piping with nonlinear supports

International Nuclear Information System (INIS)

Barta, D.A.; Huang, S.N.; Severud, L.K.

1980-01-01

The modeling and results of nonlinear time-history seismic analyses for three sizes of pipelines restrained by mechanical snubbes are presented. Numerous parametric analyses were conducted to obtain sensitivity information which identifies relative importance of the model and analysis ingredients. Special considerations for modeling the pipe clamps and the mechanical snubbers based on experimental characterization data are discussed. Comparisions are also given of seismic responses, loads and pipe stresses predicted by standard response spectra methods and the nonlinear time-history methods

Pipe support

International Nuclear Information System (INIS)

Pollono, L.P.

1979-01-01

A pipe support for high temperature, thin-walled piping runs such as those used in nuclear systems is described. A section of the pipe to be suppported is encircled by a tubular inner member comprised of two walls with an annular space therebetween. Compacted load-bearing thermal insulation is encapsulated within the annular space, and the inner member is clamped to the pipe by a constant clamping force split-ring clamp. The clamp may be connected to pipe hangers which provide desired support for the pipe

IPIRG programs - advances in pipe fracture technology

International Nuclear Information System (INIS)

Wilkowski, G.; Olson, R.; Scott, P.

1997-01-01

This paper presents an overview of the advances made in fracture control technology as a result of the research performed in the International Piping Integrity Research Group (IPIRG) program. The findings from numerous experiments and supporting analyses conducted to investigate the behavior of circumferentially flawed piping and pipe systems subjected to high-rate loading typical of seismic events are summarized. Topics to be discussed include; (1) Seismic loading effects on material properties, (2) Piping system behavior under seismic loads, (3) Advances in elbow fracture evaluations, and (4) open-quotes Realclose quotes piping system response. The presentation for each topic will be illustrated with data and analytical results. In each case, the state-of-the-art in fracture mechanics prior to the first IPIRG program will be contrasted with the state-of-the-art at the completion of the IPIRG-2 program

IPIRG programs - advances in pipe fracture technology

Energy Technology Data Exchange (ETDEWEB)

Wilkowski, G.; Olson, R.; Scott, P. [Batelle, Columbus, OH (United States)

1997-04-01

This paper presents an overview of the advances made in fracture control technology as a result of the research performed in the International Piping Integrity Research Group (IPIRG) program. The findings from numerous experiments and supporting analyses conducted to investigate the behavior of circumferentially flawed piping and pipe systems subjected to high-rate loading typical of seismic events are summarized. Topics to be discussed include; (1) Seismic loading effects on material properties, (2) Piping system behavior under seismic loads, (3) Advances in elbow fracture evaluations, and (4) {open_quotes}Real{close_quotes} piping system response. The presentation for each topic will be illustrated with data and analytical results. In each case, the state-of-the-art in fracture mechanics prior to the first IPIRG program will be contrasted with the state-of-the-art at the completion of the IPIRG-2 program.

Pipe clamp effects on thin-walled pipe design

International Nuclear Information System (INIS)

Lindquist, M.R.

1980-01-01

Clamp induced stresses in FFTF piping are sufficiently large to require structural assessment. The basic principles and procedures used in analyzing FFTF piping at clamp support locations for compliance with ASME Code rules are given. Typical results from a three-dimensional shell finite element pipe model with clamp loads applied over the clamp/pipe contact area are shown. Analyses performed to categorize clamp induced piping loads as primary or secondary in nature are described. The ELCLAMP Computer Code, which performs analyses at clamp locations combining clamp induced stresses with stresses from overall piping system loads, is discussed. Grouping and enveloping methods to reduce the number of individual clamp locations requiring analysis are described

Flow induced vibrations of piping

International Nuclear Information System (INIS)

Gibert, R.J.; Axisa, F.

1977-01-01

In order to design the supports of piping systems, estimations of the vibrations induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary to calculate the model parameters of liquid containing pipes. In most computer codes, fluid effects are accounted for just by adding the fluid mass to the structure. This may lead to serious errors. This paper presents a method to take into account these effects, by solving a coupled mechanical-acoustical problem: the computer code TEDEL of the C.E.A /D.E.M.T. System, based on the finite-elements method, has been extended to calculate simultaneously the pressure fluctuations in the fluid and the vibrations of the pipe. By this way the mechanical-acoustical coupled eigenmodes of any piping system can be obtained. These eigenmodes are used to determine the response of the system to various sources. Equations have been written in the hypohesis that acoustical wave lengths remain large compared to the diameter of the pipe. The method has been checked by an experiment performed on the GASCOGNE loop at D.E.M.T. The piping system under test consists of a tube with four elbows. The circuit is ended at each extremity by a large vessel which performs acoustical isolation by generating modes for the pressure. Excitation of the circuit is caused by a valve located near the downstream vessel. This provides an efficient localised broad band acoustical source. The comparison between the test results and the calculations has shown that the low frequency resonant characteristics of the pipe and the vibrational amplitude at various flow-rates can be correctly predicted

Characterization of radioactive contamination inside pipes with the Pipe Explorer{trademark} system. Final report

Energy Technology Data Exchange (ETDEWEB)

Cremer, C.D.; Kendrick, D.T.; Lowry, W.; Cramer, E.

1997-09-30

The Department of Energy (DOE) is currently in the process of decommissioning and dismantling many of its nuclear materials processing facilities that have been in use for several decades. Site managers throughout the DOE complex must employ the safest and most cost effective means to characterize, remediate and recycle or dispose of hundreds of miles of potentially contaminated piping and duct work. The DOE discovered that standard characterization methods were inadequate for its pipes, drains, and ducts because many of the systems are buried or encased. In response to the DOE`s need for a more specialized characterization technique, Science and Engineering Associates, Inc. (SEA) developed the Pipe Explorer{trademark} system through a DOE Office of Science and Technology (OST) contract administered through the Federal Energy Technology Center (FETC). The purpose of this report is to serve as a comprehensive overview of all phases of the Pipe Explorer{trademark} development project. The report is divided into 6 sections. Section 2 of the report provides an overview of the Pipe Explorer{trademark} system, including the operating principles of using an inverting membrane to tow sensors into pipes. The basic components of the characterization system are also described. Descriptions of the various deployment systems are given in Section 3 along with descriptions of the capabilities of the deployment systems. During the course of the development project 7 types of survey instruments were demonstrated with the Pipe Explorer{trademark} and are a part of the basic toolbox of instruments available for use with the system. These survey tools are described in Section 4 along with their typical performance specifications. The 4 demonstrations of the system are described chronologically in Section 5. The report concludes with a summary of the history, status, and future of the Pipe Explorer{trademark} system in Section 6.

Characterization of radioactive contamination inside pipes with the Pipe Explorer trademark system. Final report

International Nuclear Information System (INIS)

Cremer, C.D.; Kendrick, D.T.; Lowry, W.; Cramer, E.

1997-01-01

The Department of Energy (DOE) is currently in the process of decommissioning and dismantling many of its nuclear materials processing facilities that have been in use for several decades. Site managers throughout the DOE complex must employ the safest and most cost effective means to characterize, remediate and recycle or dispose of hundreds of miles of potentially contaminated piping and duct work. The DOE discovered that standard characterization methods were inadequate for its pipes, drains, and ducts because many of the systems are buried or encased. In response to the DOE's need for a more specialized characterization technique, Science and Engineering Associates, Inc. (SEA) developed the Pipe Explorer trademark system through a DOE Office of Science and Technology (OST) contract administered through the Federal Energy Technology Center (FETC). The purpose of this report is to serve as a comprehensive overview of all phases of the Pipe Explorer trademark development project. The report is divided into 6 sections. Section 2 of the report provides an overview of the Pipe Explorer trademark system, including the operating principles of using an inverting membrane to tow sensors into pipes. The basic components of the characterization system are also described. Descriptions of the various deployment systems are given in Section 3 along with descriptions of the capabilities of the deployment systems. During the course of the development project 7 types of survey instruments were demonstrated with the Pipe Explorer trademark and are a part of the basic toolbox of instruments available for use with the system. These survey tools are described in Section 4 along with their typical performance specifications. The 4 demonstrations of the system are described chronologically in Section 5. The report concludes with a summary of the history, status, and future of the Pipe Explorer trademark system in Section 6

Investigation method of torsional properties and damages of glass/epoxy composite pipes

Directory of Open Access Journals (Sweden)

Putić Slaviša S.

2006-01-01

Full Text Available Pipes made of composites glass fiber/epoxy resin are predominantly used in the chemical industry, construction, infrastructure and war technique. The pipes made for this purpose are in their use exposed to static and dynamic loading. Depending on the purpose, the pipes, especially those in complex structures, can be loaded by torsion. In that case, exceeding allowed tensions can cause damages such as cracking the fibers and matrix delamination. These damages can lead to the appearance of cracks on the pipes and in many cases to complete breakage of the pipe. Because of this, it is very important to evaluate composite pipes exposed to torsion and find out in which way the construction is weakened, what actually is the main goal of this paper.

Experimental and computational analysis of pressure response in a multiphase flow loop

Science.gov (United States)

Morshed, Munzarin; Amin, Al; Rahman, Mohammad Azizur; Imtiaz, Syed

2016-07-01

The characteristics of multiphase fluid flow in pipes are useful to understand fluid mechanics encountered in the oil and gas industries. In the present day oil and gas exploration is successively inducing subsea operation in the deep sea and arctic condition. During the transport of petroleum products, understanding the fluid dynamics inside the pipe network is important for flow assurance. In this case the information regarding static and dynamic pressure response, pressure loss, optimum flow rate, pipe diameter etc. are the important parameter for flow assurance. The principal aim of this research is to represents computational analysis and experimental analysis of multi-phase (L/G) in a pipe network. This computational study considers a two-phase fluid flow through a horizontal flow loop with at different Reynolds number in order to determine the pressure distribution, frictional pressure loss profiles by volume of fluid (VOF) method. However, numerical simulations are validated with the experimental data. The experiment is conducted in 76.20 mm ID transparent circular pipe using water and air in the flow loop. Static pressure transducers are used to measure local pressure response in multiphase pipeline.

Seismic analysis of liquid metal reactor piping systems

International Nuclear Information System (INIS)

Wang, C.Y.

1987-01-01

To safely assess the adequacy of the LMR piping, a three-dimensional piping code, SHAPS, has been developed at Argonne National Laboratory. This code was initially intended for calculating hydrodynamic-wave propagation in a complex piping network. It has salient features for treating fluid transients of fluid-structure interactions for piping with in-line components. The code also provides excellent structural capabilities of computing stresses arising from internal pressurization and 3-D flexural motion of the piping system. As part of the development effort, the SHAPS code has been further augmented recently by introducing the capabilities of calculating piping response subjected to seismic excitations. This paper describes the finite-element numerical algorithm and its applications to LMR piping under seismic excitations. A time-history analysis technique using the implicit temporal integration scheme is addressed. A 3-D pipe element is formulated which has eight degrees of freedom per node (three displacements, three rotations, one membrane displacement, and one bending rotation) to account for the hoop, flexural, rotational, and torsional modes of the piping system. Both geometric and material nonlinearities are considered. This algorithm is unconditionally stable and is particularly suited for the seismic analysis

Transient dynamic crack propagation in gas pressurised pipelines

International Nuclear Information System (INIS)

Caldis, E.S.; Owen, D.R.J.; Taylor, C.

1983-01-01

The prime limitation of dynamic fracture analysis is the lack of a fundamental crack advance theory which can be easily and economically adopted for use with numerical models. The necessity for the inclusion of inertia effects in the solution of certain problem classes is now evident, but most transient dynamic fracture models considered to date include (of necessity) some intuitive/empirical parameters with a frequent need of a priori knowledge of experimental solutions. The particular problem considered in this study is Mode I transient dynamic crack propagation in gas pressurised pipelines. The steel pipe is modelled using thin shell Semiloof finite elements and its transient response is coupled to a one-dimensional finite element model of the compressible gas equations, incorporating a lateral gas flow parameter. The pipe is governed by the usual dynamic equilibrium equation which is discretised in the time domain by a central difference explicit algorithm. The compressible gas response is modelled by the Continuity and Momentum equations and time discretisation is performed by means of a fully backward difference scheme in time. (orig./GL)

Seismic design evaluation guidelines for buried piping for the DOE HLW Facilities

International Nuclear Information System (INIS)

Lin, Chi-Wen; Antaki, G.; Bandyopadhyay, K.; Bush, S.H.; Costantino, C.; Kennedy, R.

1995-01-01

This paper presents the seismic design and evaluation guidelines for underground piping for the Department of Energy (DOE) High-Level-Waste (HLW) Facilities. The underground piping includes both single and double containment steel pipes and concrete pipes with steel lining, with particular emphasis on the double containment piping. The design and evaluation guidelines presented in this paper follow the generally accepted beam-on-elastic-foundation analysis principle and the inertial response calculation method, respectively, for piping directly in contact with the soil or contained in a jacket. A standard analysis procedure is described along with the discussion of factors deemed to be significant for the design of the underground piping. The following key considerations are addressed: the design feature and safety requirements for the inner (core) pipe and the outer pipe; the effect of soil strain and wave passage; assimilation of the necessary seismic and soil data; inertial response calculation for the inner pipe; determination of support anchor movement loads; combination of design loads; and code comparison. Specifications and justifications of the key parameters used, stress components to be calculated and the allowable stress and strain limits for code evaluation are presented

Stopped-pipe wind instruments: Acoustics of the panpipes

Science.gov (United States)

Fletcher, N. H.

2005-01-01

Stopped-pipe jet-excited musical instruments are known in many cultures, those best-known today being the panpipes or syrinx of Eastern Europe and of the Peruvian Andes. Although the playing style differs, in each case the instrument consists of a set of graduated bamboo pipes excited by blowing across the open tops. Details of the excitation aerodynamics warrant examination, particularly as the higher notes contain amplitudes of the even harmonics approaching those of the odd harmonics expected from a stopped pipe. Analysis shows that the jet offset is controlled by the fluid dynamics of the jet, and is such that appreciable even-harmonic excitation is generated. The theory is largely confirmed by measurements on a player. .

Study on structural integrity of thinned wall piping against seismic loading-overview and future program

International Nuclear Information System (INIS)

Nakamura, Izumi; Otani, Akihito; Shiratori, Masaki

2005-01-01

In order to clarify the behavior of thinned wall pipes under seismic events, cyclic in-plane and/or out-of-plane bending tests on thinned straight pipe and elbow and also shaking table tests using degraded piping system models were conducted. Relation between the failure mode and thinned condition and the influence of the final failure mode of degraded piping systems were investigated. In addition to these experiments, elastic-plastic FEM analysis using ABAQUS were conducted on thinned piping elements. It has been found that the strain concentrated point could be predicted and the cause of its generation could be explained by the simulated deformation behavior of the pipe. In order to predict the piping system's maximum response under elastic-plastic response, a simple response prediction method was proposed. Further tests and safety margin analyses of thinned pipes against seismic loading will be performed. (T. Tanaka)

A elastic-plastic model for pipe whip

International Nuclear Information System (INIS)

Maneschy, J.E.A.

1980-04-01

The dynamic behavior of a cantilever beam simulating a pipe after full rupture at a given cross-section is investigated. This problem, known as pipe whip, has to be analysed within the frame of plastic deformations. The physical model is represented by a cantilever, subjected to a step-load at the free end, and a support designed to absorb the maximum possible kinetic energy of the tube generated by suddenly applied force. The analysis is performed using the Bernoulli theory for straight beams, assuming for the moment-curvature relation a bi-linear law. (author)

Heat losses through pipe connections in hot water stores

DEFF Research Database (Denmark)

Andersen, Elsa; Fan, Jianhua; Furbo, Simon

2007-01-01

The heat loss from pipe connections at the top of hot water storage tanks with and without a heat trap is investigated theoretically and compared to similar experimental investigations. Computational Fluid Dynamics (CFD) is used for the theoretical analysis. The investigations show that the heat...... loss from an ideally insulated pipe connected to the top of a hot water tank is mainly due to a natural convection flow in the pipe, that the heat loss coefficient of pipes connected to the top of a hot water tank is high, and that a heat trap can reduce the heat loss coefficient significantly. Further......, calculations show that the yearly thermal performance of solar domestic hot water systems is strongly reduced if the hot water tank has a thermal bridge located at the top of the tank....

Laboratory piping system vibration tests to determine parametric effects on damping in the seismic frequency range

International Nuclear Information System (INIS)

Ware, A.G.

1987-01-01

A pipe damping research program is being conducted for the United States Nuclear Regulatory Commission at the Idaho National Engineering Laboratory to establish more realistic, best-estimate damping values for use in dynamic structural analyses of piping systems. As part of this program, tests were conducted on a 5-in. (128 mm ID) laboratory piping system to determine the effects of pressure, support configuration, insulation and response amplitude on damping. The tests were designed to produce a wide range of damping values, from very low damping in lightly excited uninsulated systems with few supports, to higher damping under conditions of either/or insulation, high level excitation, and various support arrangements. The effect of pressure at representative seismic levels was considered to be minimal. The supports influence damping at all excitation levels; damping was highest when a mechanical snubber was present in the system. The addition of insulation produced a large increase in damping for the hydraulic shaker excitation tests, but there was no comparable increase for the snapback excitation tests. Once a response amplitude of approximately one-half yield stress was reached, overall damping increased to relatively high levels (>10% of critical)

Visual observation of a heat pipe working characteristics

International Nuclear Information System (INIS)

Tsuyuzaki, Noriyoshi; Saito, Takashi; Ishigami, Shinya; Kawada, Michitaka; Konno, Masanobu; Kaminaga, Fumito; Okamoto, Yoshizo.

1988-10-01

When the heat pipe is used in a nuclear engineering field, it is indispensable to understand transient characteristics of an accident condition as well as in a steady state at a normal operation. However there have been few informations about the transient characteristics of a heat pipe in case of rapid temperature or heat load change in an evaporator section. The purpose of this study is to examine transient and steady state characteristics of a gravity assisted heat pipe and variable conductance heat pipe(VCHP) which will be used in a neutron irradiation capsule. This report presents results of visual observation of boiling and condensation patterns on steady state or transient condition in a visible heat pipe made of a glass. The response time of the heat pipe is on the order of a few seconds when the temperature of the evaporator part is kept above the operating temperature. (author)

Comparative study of computational model for pipe whip analysis

International Nuclear Information System (INIS)

Koh, Sugoong; Lee, Young-Shin

1993-01-01

Many types of pipe whip restraints are installed to protect the structural components from the anticipated pipe whip phenomena of high energy lines in nuclear power plants. It is necessary to investigate these phenomena accurately in order to evaluate the acceptability of the pipe whip restraint design. Various research programs have been conducted in many countries to develop analytical methods and to verify the validity of the methods. In this study, various calculational models in ANSYS code and in ADLPIPE code, the general purpose finite element computer programs, were used to simulate the postulated pipe whips to obtain impact loads and the calculated results were compared with the specific experimental results from the sample pipe whip test for the U-shaped pipe whip restraints. Some calculational models, having the spring element between the pipe whip restraint and the pipe line, give reasonably good transient responses of the restraint forces compared with the experimental results, and could be useful in evaluating the acceptability of the pipe whip restraint design. (author)

Comparative performance of passive devices for piping system under seismic excitation

Energy Technology Data Exchange (ETDEWEB)

Kumar, Praveen, E-mail: pra_veen74@rediffmail.com [Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India); Jangid, R.S. [Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076 (India); Reddy, G.R. [Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India)

2016-03-15

Highlights: • Correlated the analytical results obtained from the proposed analytical procedures with experimental results in the case of XPD. • Substantial reduction of the seismic response of piping system with passive devices is observed. • Significant increase in the modal damping of the piping system is noted. • There exist an optimum parameters of the passive devices. • Good amount of energy dissipation is observed by using passive devices. - Abstract: Among several passive control devices, X-plate damper, viscous damper, visco-elastic damper, tuned mass damper and multiple tuned mass dampers are popular and used to mitigate the seismic response in the 3-D piping system. In the present paper detailed studies are made to see the effectiveness of the dampers when used in 3-D piping system subjected to artificial earthquake with increasing amplitudes. The analytical results obtained using Wen's model are compared with the corresponding experimental results available which indicated a good match with the proposed analytical procedure for the X-plate dampers. It is observed that there is significant reduction in the seismic response of interest like relative displacement, acceleration and the support reaction of the piping system with passive devices. In general, the passive devices under particular optimum parameters such as stiffness and damping are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping system.

Transient thermal performance analysis of micro heat pipes

International Nuclear Information System (INIS)

Liu, Xiangdong; Chen, Yongping

2013-01-01

A theoretical analysis of transient fluid flow and heat transfer in a triangular micro heat pipes (MHP) has been conducted to study the thermal response characteristics. By introducing the system identification theory, the quantitative evaluation of the MHP's transient thermal performance is realized. The results indicate that the evaporation and condensation processes are both extended into the adiabatic section. During the start-up process, the capillary radius along axial direction of MHP decreases drastically while the liquid velocity increases quickly at the early transient stage and an approximately linear decrease in wall temperature arises along the axial direction. The MHP behaves as a first-order LTI control system with the constant input power as the 'step input' and the evaporator wall temperature as the 'output'. Two corresponding evaluation criteria derived from the control theory, time constant and temperature constant, are able to quantitatively evaluate the thermal response speed and temperature level of MHP under start-up, which show that a larger triangular groove's hydraulic diameter within 0.18–0.42 mm is able to accelerate the start-up and decrease the start-up temperature level of MHP. Additionally, the MHP starts up fastest using the fluid of ethanol and most slowly using the working fluid of methanol, and the start-up temperature reaches maximum level for acetone and minimum level for the methanol. -- Highlights: • Transient thermal response of micro heat pipe is simulated by an improved model. • Control theory is introduced to quantify the thermal response of micro heat pipe. • Evaluation criteria are proposed to represent thermal response of micro heat pipe. • Effects of groove dimensions and working fluids on start-up of micro heat pipe are evaluated

Recent evaluations of crack-opening-area in circumferentially cracked pipes

Energy Technology Data Exchange (ETDEWEB)

Rahman, S.; Brust, F.; Ghadiali, N.; Wilkowski, G.; Miura, N.

1997-04-01

Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. The leak rates depend on the crack-opening area of the through-wall crack in the pipe. In addition to LBB analyses which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessing temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section XI. The objectives of this study were to review, evaluate, and refine current predictive models for performing crack-opening-area analyses of circumferentially cracked pipes. The results from twenty-five full-scale pipe fracture experiments, conducted in the Degraded Piping Program, the International Piping Integrity Research Group Program, and the Short Cracks in Piping and Piping Welds Program, were used to verify the analytical models. Standard statistical analyses were performed to assess used to verify the analytical models. Standard statistical analyses were performed to assess quantitatively the accuracy of the predictive models. The evaluation also involved finite element analyses for determining the crack-opening profile often needed to perform leak-rate calculations.

An integrated heat pipe-thermal storage design for a solar receiver

Science.gov (United States)

Keddy, E.; Sena, J. T.; Woloshun, K.; Merrigan, M. A.; Heidenreich, G.

Light-weight heat pipe wall elements that incorporate a thermal storage subassembly within the vapor space are being developed as part of the Organic Rankine Cycle Solar Dynamic Power System (ORC-SDPS) receiver for the Space Station application. The operating temperature of the heat pipe elements is in the 770 to 810 K range with a design power throughput of 4.8 kW per pipe. The total heat pipe length is 1.9 M. The Rankine cycle boiler heat transfer surfaces are positioned within the heat pipe vapor space, providing a relatively constant temperature input to the vaporizer. The heat pipe design employs axial arteries and distribution wicked thermal storage units with potassium as the working fluid. Performance predictions for this configuration have been conducted and the design characterized as a function of artery geometry, distribution wick thickness, porosity, pore size, and permeability.

Subsystem response analysis for the Seismic Safety Margins Research Program

International Nuclear Information System (INIS)

Chuang, T.Y.

1981-01-01

A review of the state-of-the-art of seismic qualification methods of subsystem has been completed. This task assesses the accuracy of seismic analysis techniques to predict dynamic response, and also identifies and quantifies sources of random and modeling undertainty in subsystem response determination. The subsystem has been classified as two categories according to the nature of support: multiply supported subsystems (e.g., piping systems) and singly supported subsystems (e.g., pumps, turbines, electrical control panels, etc.). The mutliply supported piping systems are analyzed by multisupport input time history method. The input motions are the responses of major structures. The dynamic models of the subsystems identified by the event/fault tree are created. The responses calculated by multisupport input time history method are consistent with the fragility parameters. These responses are also coordinated with the event/fault tree description. The subsystem responses are then evaluated against the fragility curves of components and systems and incorporated in the event/fault tree analysis. (orig./HP)

IPIRG-2 task 1 - pipe system experiments with circumferential cracks in straight-pipe locations. Final report, September 1991--November 1995

Energy Technology Data Exchange (ETDEWEB)

Scott, P.; Olson, R.; Marschall, C.; Rudland, D. [and others

1997-02-01

This report presents the results from Task 1 of the Second International Piping Integrity Research Group (IPIRG-2) program. The IPIRG-2 program is an international group program managed by the US Nuclear Regulatory Commission (US NRC) and funded by a consortium of organizations from 15 nations including: Bulgaria, Canada, Czech Republic, France, Hungary, Italy, Japan, Republic of Korea, Lithuania, Republic of China, Slovak Republic, Sweden, Switzerland, the United Kingdom, and the United States. The objective of the program was to build on the results of the IPIRG-1 and other related programs by extending the state-of-the-art in pipe fracture technology through the development of data needed to verify engineering methods for assessing the integrity of nuclear power plant piping systems that contain defects. The IPIRG-2 program included five main tasks: Task 1 - Pipe System Experiments with Flaws in Straight Pipe and Welds Task 2 - Fracture of Flawed Fittings Task 3 - Cyclic and Dynamic Load Effects on Fracture Toughness Task 4 - Resolution of Issues From IPIRG-1 and Related Programs Task 5 - Information Exchange Seminars and Workshops, and Program Management. The scope of this report is to present the results from the experiments and analyses associated with Task 1 (Pipe System Experiments with Flaws in Straight Pipe and Welds). The rationale and objectives of this task are discussed after a brief review of experimental data which existed after the IPIRG-1 program.

IPIRG-2 task 1 - pipe system experiments with circumferential cracks in straight-pipe locations. Final report, September 1991--November 1995

International Nuclear Information System (INIS)

Scott, P.; Olson, R.; Marschall, C.; Rudland, D.

1997-02-01

This report presents the results from Task 1 of the Second International Piping Integrity Research Group (IPIRG-2) program. The IPIRG-2 program is an international group program managed by the US Nuclear Regulatory Commission (US NRC) and funded by a consortium of organizations from 15 nations including: Bulgaria, Canada, Czech Republic, France, Hungary, Italy, Japan, Republic of Korea, Lithuania, Republic of China, Slovak Republic, Sweden, Switzerland, the United Kingdom, and the United States. The objective of the program was to build on the results of the IPIRG-1 and other related programs by extending the state-of-the-art in pipe fracture technology through the development of data needed to verify engineering methods for assessing the integrity of nuclear power plant piping systems that contain defects. The IPIRG-2 program included five main tasks: Task 1 - Pipe System Experiments with Flaws in Straight Pipe and Welds Task 2 - Fracture of Flawed Fittings Task 3 - Cyclic and Dynamic Load Effects on Fracture Toughness Task 4 - Resolution of Issues From IPIRG-1 and Related Programs Task 5 - Information Exchange Seminars and Workshops, and Program Management. The scope of this report is to present the results from the experiments and analyses associated with Task 1 (Pipe System Experiments with Flaws in Straight Pipe and Welds). The rationale and objectives of this task are discussed after a brief review of experimental data which existed after the IPIRG-1 program

Seismic test of high temperature piping for HTGR

International Nuclear Information System (INIS)

Kobatake, Kiyokazu; Midoriyama, Shigeru; Ooka, Yuzi; Suzuki, Michiaki; Katsuki, Taketsugu

1983-01-01

Since the high temperature pipings for the high temperature gas-cooled reactor contain helium gas at 1000 deg C and 40 kgf/cm 2 , the double-walled pipe type consisting of the external pipe serving as the pressure boundary and the internal pipe with heat insulating structure was adopted. Accordingly, their aseismatic design is one of the important subjects. Recently, for the purpose of grasping the vibration characteristics of these high temperature pipings and obtaining the data required for the aseismatic design, two specimens, that is, a double-walled pipe model and a heat-insulating structure, were made, and the vibration test was carried out on them, using a 30 ton vibration table of Kawasaki Heavy Industries Ltd. In the high temperature pipings of the primary cooling system for the multi-purpose, high temperature gas-cooled experimental reactor, the external pipes of 32 B bore as the pressure boundary and the internal pipes of 26 B bore with internal heat insulation consisting of double layers of fiber and laminated metal insulators as the temperature boundary were adopted. The testing method and the results are reported. As the spring constant of spacers is larger and clearance is smaller, the earthquake wave response of double-walled pipes is smaller, and it is more advantageous. The aseismatic property of the heat insulation structure is sufficient. (Kako, I.)

IEA-R1 renewed primary coolant piping system stress analysis

International Nuclear Information System (INIS)

Fainer, Gerson; Faloppa, Altair A.; Oliveira, Carlos A. de; Mattar Neto, Miguel

2015-01-01

A partial replacement of the IEA-R1 piping system was conducted in 2014. The aim of this work is to perform the stress analysis of the renewed primary piping system of the IEA-R1, taking into account the as built conditions and the pipe modifications. The nuclear research reactor IEA-R1 is a pool type reactor designed by Babcox-Willcox, which is operated by IPEN since 1957. The primary coolant system is responsible for removing the residual heat of the Reactor core. As a part of the life management, a regular inspection detected some degradation in the primary piping system. In consequence, part of the piping system was replaced. The partial renewing of the primary piping system did not imply in major piping layout modifications. However, the stress condition of the piping systems had to be reanalyzed. The structural stress analysis of the primary piping systems is now presented and the final results are discussed. (author)

Dynamic response of IPEN experimental water loop

International Nuclear Information System (INIS)

Faya, A.J.G.; Bassel, W.S.

1982-10-01

A mathematical model has been developed to analyze the transient thermal response of the I.P.E.N. water loop during change of power operations. The model is capable of estimating the necessary test section power and heat exchanger mass flow rate for a given operating temperature. It can also determine the maximum heating or cooling rate to avoid thermal shocks in pipes and components. (Author) [pt

Nuclear piping and pipe support design and operability relating to loadings and small bore piping

International Nuclear Information System (INIS)

Stout, D.H.; Tubbs, J.M.; Callaway, W.O.; Tang, H.T.; Van Duyne, D.A.

1994-01-01

The present nuclear piping system design practices for loadings, multiple support design and small bore piping evaluation are overly conservative. The paper discusses the results developed for realistic definitions of loadings and loading combinations with methodology for combining loads under various conditions for supports and multiple support design. The paper also discusses a simplified method developed for performing deadweight and thermal evaluations of small bore piping systems. Although the simplified method is oriented towards the qualification of piping in older plants, this approach is applicable to plants designed to any edition of the ASME Section III or B31.1 piping codes

Application of new developments in coupled seismic analysis of piping systems

International Nuclear Information System (INIS)

Gupta, A.; Gupta, A.K.

1995-01-01

The current practice of calculating the seismic response is to perform the analysis of the primary structure (buildings) and the secondary systems (piping) separately. Earthquake input to the primary system in terms of a design response spectrum. An acceleration time history compatible with the design response spectrum is developed (a non-unique process) and primary system is analyzed to obtain the acceleration histories at the desired floors. Floor time histories are used for generating the corresponding instructure response spectrum (IRIS). The instructure response spectra are used as input at the supports of secondary systems. Further, in case of multiple supports, an envelope spectrum (introducing conservatism) is obtained from the individual support IRS. The effect of relative support motion is incorporated by a worst-case separate static analysis (adding to the conservatism). In the above method, mass interaction between the secondary and primary system is ignored, which may have significant effect at resonant frequencies (further adding to the conservatism). The calculated response may be an order of magnitude higher than they should be. Two computer programs, CREST and CREST-IRIS, were developed at Center for NUclear Power Plant Structures, Equipment and Piping. Any one of the two computer programs together with a piping analysis program can be used to perform an accurate coupled seismic analysis of piping systems. The two computer programs have been validated against the time history analysis for simple problems. In the present study, we have applied CREST to analyze two real-life piping systems. The piping analysis program used in this research is the commercial software PIPESTRESS, developed by DST Computer Services of Geneva, Switzerland. (author). 4 refs., 3 figs., 2 tabs

Analysis of the FFTF primary pipe rupture transients

International Nuclear Information System (INIS)

Perkins, K.R.; Bari, R.A.; Chen, L.C.; Albright, D.C.

1979-01-01

The response of the Fast Flux Test Facility (FFTF) to hypothetical ruptures of the high pressure primary piping has been analyzed using two LMFBR plant systems codes, namely IANUS and DEMO. Comparisons of the average channel temperatures predicted by the two codes show good agreement for identical transients. However, the hot channel temperatures predicted by DEMO are about 60K higher than the corresponding IANUS predictions for severe transients. This difference is attributed to the dynamic hot channel factors employed in DEMO which discount the thermal inertia of the duct walls for rapid transients. DEMO also predicts more severe transients for hot-leg ruptures in FFTF than previously reported analyses for the CRBR

Damping values for nuclear power plant piping during seismic events and fluid-induced transients

International Nuclear Information System (INIS)

Ware, A.G.

1986-01-01

For several years the Idaho National Engineering Laboratory (INEL) has been assisting the United States Nuclear Regulatory Commission (USNRC) in efforts to establish best-estimate damping values for use in the dynamic analysis of nuclear power plant piping systems. Data from a number of piping vibration tests conducted at facilities worldwide (including the INEL) have been collected, evaluated, reported, and placed in a nuclear piping data bank at the INEL. These data are being used to justify changes in allowable damping values for use in nuclear piping design, thus making piping systems safer, less costly, and easier to inspect and maintain

The Second International Piping Integrity Research Group (IPIRG-2) program. Final report, October 1991--April 1996

International Nuclear Information System (INIS)

Hopper, A.; Wilowski, G.; Scott, P.; Olson, R.

1997-03-01

The IPIRG-2 program was an international group program managed by the US NRC and funded by organizations from 15 nations. The emphasis of the IPIRG-2 program was the development of data to verify fracture analyses for cracked pipes and fittings subjected to dynamic/cyclic load histories typical of seismic events. The scope included: (1) the study of more complex dynamic/cyclic load histories, i.e., multi-frequency, variable amplitude, simulated seismic excitations, than those considered in the IPIRG-1 program, (2) crack sizes more typical of those considered in Leak-Before-Break (LBB) and in-service flaw evaluations, (3) through-wall-cracked pipe experiments which can be used to validate LBB-type fracture analyses, (4) cracks in and around pipe fittings, such as elbows, and (5) laboratory specimen and separate effect pipe experiments to provide better insight into the effects of dynamic and cyclic load histories. Also undertaken were an uncertainty analysis to identify the issues most important for LBB or in-service flaw evaluations, updating computer codes and databases, the development and conduct of a series of round-robin analyses, and analyst's group meetings to provide a forum for nuclear piping experts from around the world to exchange information on the subject of pipe fracture technology. 17 refs., 104 figs., 41 tabs

Load-deflection characteristics of small bore insulated pipe clamps

International Nuclear Information System (INIS)

Severud, L.K.; Clark, G.L.

1982-01-01

High temperature LMFBR piping is subject to rapid temperature changes during transient events. Typically, this pipe is supported by specially designed insulated pipe clamps to prevent excessive thermal stress from developing during these transients. The special insulated clamps used on both FFTF and CRBR piping utilize a Belleville spring arrangement to compensate for pipe thermal expansion. Analysis indicates that this produces a non-linear, directionally sensitive clamp spring rate. Since these spring rates influence the seismic response of a supported piping system, it was deemed necessary to evaluate them further by test. This has been accomplished for the FFTF clamps. A more standard insulated pipe clamp, which does not incorporate Belleville springs to accommodate thermal expansion, was also tested. This type clamp is simple in design, and economically attractive. It may have wide application prospects for use in LMFBR small bore auxiliary piping operating at temperatures below 427 0 C. Load deflection tests were conducted on 2.54 CM and 7.62 CM diameter samples of these commercial clamps

Assessment of value-impact associated with the elimination of postulated pipe ruptures from the design basis for nuclear power plants

International Nuclear Information System (INIS)

Holman, G.S.; Chou, C.K.

1985-01-01

The US Nuclear Regulatory Commission is proposing to amend the regulations that currently require that the design basis for nuclear power plants include the postulation of dynamic effects from loss of coolant accidents up to and including the double-ended rupture of the largest pipe in the reactor coolant system. Proposed modifications would allow analyses to serve as a sufficient basis for excluding dynamic effects, including but not necessarily limited to pipe whip and jet impingement, associated with specific pipe ruptures. Only dynamic effects would be impacted; current design requirements for containment sizing and discharge capacity of emergency core cooling systems would remain unchanged. This report presents a detailed analysis of value-impact associated with the proposed amendment for PWR reactor coolant loop piping and for BWR recirculation loop piping. The effect of extending application of the proposed rule change to other piping systems is also assessed in a less quantitative manner

Reconfigurable manufacturing execution system for pipe cutting

Science.gov (United States)

Yin, Y. H.; Xie, J. Y.

2011-08-01

This article presents a reconfigurable manufacturing execution system (RMES) filling the gap between enterprise resource planning and resource layer for pipe-cutting production with mass customisation and rapid adaptation to dynamic market, which consists of planning and scheduling layer and executive control layer. Starting from customer's task and process requirements, the cutting trajectories are planned under generalised mathematical model able to reconfigure in accordance with various intersecting types' joint, and all tasks are scheduled by nesting algorithm to maximise the utilisation rate of rough material. This RMES for pipe cutting has been effectively implemented in more than 100 companies.

Comparison of fracture toughness values from an IPIRG-1 large-scale pipe system test and C(T) specimens on wrought TP304 stainless steel

International Nuclear Information System (INIS)

Olson, R.J.; Scott, P.; Marschall, C.W.; Wilkowski, G.M.

1994-01-01

Within the First International Piping Integrity Research Group (IPIRG-1) program, pipe system experiments involving dynamic loading with intentionally circumferentially cracked pipe were conducted. The pipe system was fabricated from 406-mm (16-inch) diameter Schedule 100 pipe, and the experiments were conducted at a pressure of 15.5 MPa (2,250 psi) and 288 C (550 F). The loads consisted of pressure, dead-weight, thermal expansion, inertia, and dynamic anchor motion. Significant instrumentation was used to allow the material fracture resistance to be calculated from these large-scale experiments. Three independent analyses were used to calculate the toughness directly from one of these pipe experiments. A comparison of the toughness values from the stainless steel base metal pipe experiment to standard quasi-static and dynamic C(T) specimen tests showed the pipe toughness value was significantly lower than that obtained from C(T) specimens. It is hypothesized that the cyclic loading from inertial stresses in this pipe system experiment caused local degradation of the material toughness. Such effects are not considered in current LBB or pipe flaw evaluation criteria

Gas dynamic design of the pipe line compressor with 90% efficiency. Model test approval

Science.gov (United States)

Galerkin, Y.; Rekstin, A.; Soldatova, K.

2015-08-01

Gas dynamic design of the pipe line compressor 32 MW was made for PAO SMPO (Sumy, Ukraine). The technical specification requires compressor efficiency of 90%. The customer offered favorable scheme - single-stage design with console impeller and axial inlet. The authors used the standard optimization methodology of 2D impellers. The original methodology of internal scroll profiling was used to minimize efficiency losses. Radically improved 5th version of the Universal modeling method computer programs was used for precise calculation of expected performances. The customer fulfilled model tests in a 1:2 scale. Tests confirmed the calculated parameters at the design point (maximum efficiency of 90%) and in the whole range of flow rates. As far as the authors know none of compressors have achieved such efficiency. The principles and methods of gas-dynamic design are presented below. The data of the 32 MW compressor presented by the customer in their report at the 16th International Compressor conference (September 2014, Saint- Petersburg) and later transferred to the authors.

Analysis of the one-dimensional transient compressible vapor flow in heat pipes

Science.gov (United States)

Jang, Jong H.; Faghri, Amir; Chang, Won S.

1991-01-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual vapor flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds as well as high mass flow rates are successfully predicted.

Characterisation of a spinning pipe gas lens using a Shack–Hartmann wavefront sensor

CSIR Research Space (South Africa)

Mafusire, C

2007-01-01

Full Text Available A heated horizontal spinning pipe causes gases inside it to assume dynamics resulting in a graded index lens – a spinning pipe gas lens (SPGL). A CFD model is presented which shows that gas exchanges of the SPGL with the surroundings resulting in a...

Seismic proving test of ultimate piping strength (current status of preliminary tests)

International Nuclear Information System (INIS)

Suzuki, K.; Namita, Y.; Abe, H.; Ichihashi, I.; Suzuki, K.; Ishiwata, M.; Fujiwaka, T.; Yokota, H.

2001-01-01

In 1998 Fiscal Year, the 6 year program of piping tests was initiated with the following objectives: i) to clarify the elasto-plastic response and ultimate strength of nuclear piping, ii) to ascertain the seismic safety margin of the current seismic design code for piping, and iii) to assess new allowable stress rules. In order to resolve extensive technical issues before proceeding on to the seismic proving test of a large-scale piping system, a series of preliminary tests of materials, piping components and simplified piping systems is intended. In this paper, the current status of the material tests and the piping component tests is reported. (author)

Calculation of piping loads due to filling procedures; Berechnung von Rohrleitungsbelastungen durch Fuellvorgaenge

Energy Technology Data Exchange (ETDEWEB)

Swidersky, Harald; Thiele, Thomas [TUeV Sued Industrie Service GmbH, Muenchen (Germany)

2012-11-01

Filling procedures in piping systems are usually not load cases that are studied by fluid dynamic and structure dynamic analyses with respect to the integrity of pipes and supports. Although, their frequency is higher than that of postulated accidental transients, therefore they have to be considered for fatigue analyses. The piping and support loads due to filling procedures are caused by the density differences if the transported fluids, for instance in flows with the transport of gas bubbles. The impact duration of the momentum forces is defined by the flow velocity and the length of discontinuities in the piping segments. Filling procedures end very often with a shock pressure, caused by the impact and decelerating of the fluid front at smaller cross sections. The suitability of the thermally hydraulics program RELAP/MOD3.3 for the calculation of realistic loads from filling procedures was studied, the results compared with experimental data. It is shown that dependent on the discretization level the loads are partial significantly underestimated.

Evaluation of vibration and vibration fatigue life for small bore pipe in nuclear power plants

International Nuclear Information System (INIS)

Wang Zhaoxi; Xue Fei; Gong Mingxiang; Ti Wenxin; Lin Lei; Liu Peng

2011-01-01

The assessment method of the steady state vibration and vibration fatigue life of the small bore pipe in the supporting system of the nuclear power plants is proposed according to the ASME-OM3 and EDF evaluation methods. The GGR supporting pipe system vibration is evaluated with this method. The evaluation process includes the filtration of inborn sensitivity, visual inspection, vibration tests, allowable vibration effective velocity calculation and vibration stress calculation. With the allowable vibration effective velocity calculated and the vibration velocity calculated according to the acceleration data tested, the filtrations are performed. The vibration stress at the welding coat is calculated with the spectrum method and compared with the allowable value. The response of the stress is calculated with the transient dynamic method, with which the fatigue life is evaluated with the Miners linear accumulation model. The vibration stress calculated with the spectrum method exceeds the allowable value, while the fatigue life calculated from the transient dynamic method is larger than the designed life with a big safety margin. (authors)

Assessment of LWR piping design loading based on plant operating experience

International Nuclear Information System (INIS)

Svensson, P.O.

1980-08-01

The objective of this study has been to: (1) identify current Light Water Reactor (LWR) piping design load parameters, (2) identify significant actual LWR piping loads from plant operating experience, (3) perform a comparison of these two sets of data and determine the significance of any differences, and (4) make an evaluation of the load representation in current LWR piping design practice, in view of plant operating experience with respect to piping behavior and response to loading

Articulated pipes conveying fluid pulsating with high frequency

DEFF Research Database (Denmark)

Jensen, Jakob Søndergaard

1999-01-01

Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hanging...... pipe position will lose stability if the mean flow speed exceeds a certain critical value. Adding a pulsating component to the fluid flow is shown to stabilize the hanging position for high values of the ratio between fluid and pipe-mass, and to marginally destabilize this position for low ratios....... An approximate nonlinear solution for small-amplitude flutter oscillations is obtained using a fifth-order multiple scales perturbation method, and large-amplitude oscillations are examined by numerical integration of the autonomous model equations, using a path-following algorithm. The pulsating fluid component...

HPFRCC - Extruded Pipes

DEFF Research Database (Denmark)

Stang, Henrik; Pedersen, Carsten

1996-01-01

The present paper gives an overview of the research onHigh Performance Fiber Reinforced Cementitious Composite -- HPFRCC --pipes recently carried out at Department of Structural Engineering, Technical University of Denmark. The project combines material development, processing technique development......-w$ relationship is presented. Structural development involved definition of a new type of semi-flexiblecement based pipe, i.e. a cement based pipe characterized by the fact that the soil-pipe interaction related to pipe deformation is an importantcontribution to the in-situ load carrying capacity of the pipe...

Pipe damping

International Nuclear Information System (INIS)

Ware, A.G.

1985-01-01

Studies are being conducted at the Idaho National Engineering Laboratory to determine whether an increase in the damping values used in seismic structural analyses of nuclear piping systems is justified. Increasing the allowable damping would allow fewer piping supports which could lead to safer, more reliable, and less costly piping systems. Test data from availble literature were examined to determine the important parameters contributing to piping system damping, and each was investigated in separate-effects tests. From the combined results a world pipe damping data bank was established and multiple regression analyses performed to assess the relative contributions of the various parameters. The program is being extended to determine damping applicable to higher frequency (33 to 100 Hz) fluid-induced loadings. The goals of the program are to establish a methodology for predicting piping system damping and to recommend revised guidelines for the damping values to be included in analyses

Seismic behaviour of un-cracked and cracked thin pipes

International Nuclear Information System (INIS)

Blay, N.; Brunet, G.; Gantenbein, F.; Aguilar, J.

1995-01-01

In order to evaluate the seismic behaviour of un-cracked and cracked thin pipes, subjected to high acceleration levels, seismic tests and calculations have been performed on straight thin pipes made of 316L stainless steel, loaded in pure bending by a permanent static and dynamic loading. The seismic tests were carried out on the AZALEE shaking table of the CEA laboratory TAMARIS. The influence of the elasto-plastic model with isotropic or kinematic hardening are studied. 5 refs., 7 figs., 2 tabs

Load-deflection characteristics of small-bore insulated-pipe clamps

International Nuclear Information System (INIS)

Severud, L.K.; Clark, G.L.

1981-12-01

The special insulated clamps used on both FFTF and CRBR piping utilize a Belleville spring arrangement to compensate for pipe thermal expansion. Analysis indicates that this produces a non-linear, directionally sensitive clamp spring rate. Since these spring rates influence the seismic response of a supported piping system, it was deemed necessary to evaluate them further by test. This has been accomplished for the FFTF clamps. A more standard insulated pipe clamp, which does not incorporate Belleville springs to accommodate thermal expansion, was also tested. This type clamp is simple in design, and economically attractive. It may have wide application prospects for use in LMFBR small bore auxiliary piping operating at temperatures below 427 0 C. Load deflection tests were conducted on 2.54 CM and 7.62 CM diameter samples of these commercial clamps

Pipe inspection using the pipe crawler. Innovative technology summary report

International Nuclear Information System (INIS)

1999-05-01

The US Department of Energy (DOE) continually seeks safer and more cost-effective remediation technologies for use in the decontamination and decommissioning (D and D) of nuclear facilities. In several of the buildings at the Fernald Site, there is piping that was used to transport process materials. As the demolition of these buildings occur, disposal of this piping has become a costly issue. Currently, all process piping is cut into ten-foot or less sections, the ends of the piping are wrapped and taped to prevent the release of any potential contaminants into the air, and the piping is placed in roll off boxes for eventual repackaging and shipment to the Nevada Test Site (NTS) for disposal. Alternatives that allow for the onsite disposal of process piping are greatly desired due to the potential for dramatic savings in current offsite disposal costs. No means is currently employed to allow for the adequate inspection of the interior of piping, and consequently, process piping has been assumed to be internally contaminated and thus routinely disposed of at NTS. The BTX-II system incorporates a high-resolution micro color camera with lightheads, cabling, a monitor, and a video recorder. The complete probe is capable of inspecting pipes with an internal diameter (ID) as small as 1.4 inches. By using readily interchangeable lightheads, the same system is capable of inspecting piping up to 24 inches in ID. The original development of the BTX system was for inspection of boiler tubes and small diameter pipes for build-up, pitting, and corrosion. However, the system is well suited for inspecting the interior of most types of piping and other small, confined areas. The report describes the technology, its performance, uses, cost, regulatory and policy issues, and lessons learned

Pipe inspection using the pipe crawler. Innovative technology summary report

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-05-01

The US Department of Energy (DOE) continually seeks safer and more cost-effective remediation technologies for use in the decontamination and decommissioning (D and D) of nuclear facilities. In several of the buildings at the Fernald Site, there is piping that was used to transport process materials. As the demolition of these buildings occur, disposal of this piping has become a costly issue. Currently, all process piping is cut into ten-foot or less sections, the ends of the piping are wrapped and taped to prevent the release of any potential contaminants into the air, and the piping is placed in roll off boxes for eventual repackaging and shipment to the Nevada Test Site (NTS) for disposal. Alternatives that allow for the onsite disposal of process piping are greatly desired due to the potential for dramatic savings in current offsite disposal costs. No means is currently employed to allow for the adequate inspection of the interior of piping, and consequently, process piping has been assumed to be internally contaminated and thus routinely disposed of at NTS. The BTX-II system incorporates a high-resolution micro color camera with lightheads, cabling, a monitor, and a video recorder. The complete probe is capable of inspecting pipes with an internal diameter (ID) as small as 1.4 inches. By using readily interchangeable lightheads, the same system is capable of inspecting piping up to 24 inches in ID. The original development of the BTX system was for inspection of boiler tubes and small diameter pipes for build-up, pitting, and corrosion. However, the system is well suited for inspecting the interior of most types of piping and other small, confined areas. The report describes the technology, its performance, uses, cost, regulatory and policy issues, and lessons learned.

Study on Monitoring Rock Burst through Drill Pipe Torque

OpenAIRE

Zhonghua Li; Liyuan Zhu; Wanlei Yin; Yanfang Song

2015-01-01

This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the a...

Experimental modal analysis of the steam inlet pipe to the Chooz B1 high pressure turbine

International Nuclear Information System (INIS)

Guihot, O.; Anne, J.P.; Chartain, G.; Le Pironnec, D.

1993-05-01

This report presents the results of the modal analysis carried out on one of the steam inlet pipe of the high pressure turbine of the Chooz B1 power plant. This experimental analysis is made within the frame of the research and development project ''dynamical, acoustical and aerodynamical behaviour of the turbogenerator N4''. This research program provides amongst others, numerical studies with the software CIRCUS and ASTER, in order to verify the dynamical behaviour of the designed inlet pipe. The numerical models will be updated from results of the experimental modal analysis to improve the numerical representation of this pipe. All the identified modes in the frequency band [5.2000] Hz are presented in the report. The modal characteristics of the main modes are detailed. Further analysis have been made, in order ease the updating of the numerical models. They consisted in an analysis of the evolution of the dynamical behaviour due to a change of the boundary conditions of the inlet valve frame on one hand and resulting from the presence of an additional mass on the pipe, at the level of the middle flange, on the other hand. The analysis made in low frequency range shows that the pipe is thoroughly embedded in the frame of the high pressure turbine. On the other hand, the boundary conditions on the inlet valve frame are more difficult to determine, because the dynamical behaviour of the valve frame and the upper pipe can not be uncoupled from the considered pipe. The main shell modes of ranks 2, 3 and 4 have been very accurately identified. The most relevant modes to update the numerical models are given. (authors). 48 figs., 18 tabs., 4 refs

Study on Monitoring Rock Burst through Drill Pipe Torque

Directory of Open Access Journals (Sweden)

Zhonghua Li

2015-01-01

Full Text Available This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the analysis, a new device for testing drill pipe torque is developed and a series of experiments is performed under different conditions; the results show that drill pipe torque linearly increases with the increase of coal stress and coal strength; the faster the drilling speed, the larger the drill pipe torque, and vice versa. When monitoring rock burst by drill pipe torque method, the index of rock burst is regarded as a function in which coal stress index and coal strength index are principal variables. The results are important for the forecast of rock burst in coal mine.

Identification of significant problems related to light water reactor piping systems

International Nuclear Information System (INIS)

1980-07-01

Work on the project was divided into three tasks. In Task 1, past surveys of LWR piping system problems and recent Licensee Event Report summaries are studied to identify the significant problems of LWR piping systems and the primary causes of these problems. Pipe cracking is identified as the most recurring problem and is mainly due to the vibration of pipes due to operating pump-pipe resonance, fluid-flow fluctuations, and vibration of pipe supports. Research relevant to the identified piping system problems is evaluated. Task 2 studies identify typical LWR piping systems and the current loads and load combinations used in the design of these systems. Definitions of loads are reviewed. In Task 3, a comparative study is carried out on the use of nonlinear analysis methods in the design of LWR piping systems. The study concludes that the current linear-elastic methods of analysis may not predict accurately the behavior of piping systems under seismic loads and may, under certain circumstances, result in nonconservative designs. Gaps at piping supports are found to have a significant effect on the response of the piping systems

Environmental Assisted Fatigue Evaluation of Direct Vessel Injection Piping Considering Thermal Stratification

International Nuclear Information System (INIS)

Kim, Taesoon; Lee, Dohwan

2016-01-01

As the environmentally assisted fatigue (EAF) due to the primary water conditions is to be a critical issue, the fatigue evaluation for the components and pipes exposed to light water reactor coolant conditions has become increasingly important. Therefore, many studies to evaluate the fatigue life of the components and pipes in LWR coolant environments on fatigue life of materials have been conducted. Among many components and pipes of nuclear power plants, the direct vessel injection piping is known to one of the most vulnerable pipe systems because of thermal stratification occurred in that systems. Thermal stratification occurs because the density of water changes significantly with temperature. In this study, fatigue analysis for DVI piping using finite element analysis has been conducted and those results showed that the results met design conditions related with the environmental fatigue evaluation of safety class 1 pipes in nuclear power plants. Structural and fatigue integrity for the DVI piping system that thermal stratification occurred during the plant operation has conducted. First of all, thermal distribution of the piping system is calculated by computational fluid dynamic analysis to analyze the structural integrity of that piping system. And the fatigue life evaluation considering environmental effects was carried out. Our results showed that the DVI piping system had enough structural integrity and fatigue life during the design lifetime of 60 years

Pipe connector

International Nuclear Information System (INIS)

Sullivan, T.E.; Pardini, J.A.

1978-01-01

A safety test facility for testing sodium-cooled nuclear reactor components includes a reactor vessel and a heat exchanger submerged in sodium in the tank. The reactor vessel and heat exchanger are connected by an expansion/deflection pipe coupling comprising a pair of coaxially and slidably engaged tubular elements having radially enlarged opposed end portions of which at least a part is of spherical contour adapted to engage conical sockets in the ends of pipes leading out of the reactor vessel and in to the heat exchanger. A spring surrounding the pipe coupling urges the end portions apart and into engagement with the spherical sockets. Since the pipe coupling is submerged in liquid a limited amount of leakage of sodium from the pipe can be tolerated

Refined analysis of piping systens according to nuclear standard regulations

International Nuclear Information System (INIS)

Bisconti, N.; Lazzeri, L.; Strona, P.P.

1975-01-01

A number of programs have been selected to perform particular analyses partly coming from available libraries such as SAP 4 for static and dynamic analysis, partly directly written such as TRATE (for thermal analysis), VASTA, VASTB (to perform the analysis required by ASME 3 for pipings of class A and class B), CFRS (for the calculation of floor response spectra etc.). All the programs are automatically linked and directed by a general program (SCATCA for class A and SCATCB for class B pipings). The starting point is a list of the fabrication, thermal, geometrical and seismic data. The geometrical data are plotted (to check for possible errors) and fed to SAP for static and dynamic analysis together with seismic data and thermal data (average temperatures) reelaborated by TRATE 2 code. The raw data from SAP (weight, thermal, fixed points displacements, seismic, other dynamic) are concerned and reordered and fed to COMBIN 2 program together with the other data from thermal analysis (from TRATE 2). From Combin 2 program all the data are listed; each load set to be considered is provided, for each point, with the necessary data (thermal moments, pressure, average temperatures, thermal gradients), all the data from seismic, weight, and other dynamic analysis are also provided. All this amount of data is stored on a file and examined by VASTA code (for class A) or VASTB (for classes B,C) in order to make a decision about the acceptability of the design. Each subprogram may have an independent output in order to check partial results. Details about each program are provided and an exemple is given, together with a discussion of some-particular problems (thermohydraulic set definition, fatigue analysis, etc.)

Fatigue evaluation of piping systems with limited vibration test data

International Nuclear Information System (INIS)

Huang, S.N.

1990-11-01

The safety-related piping in a nuclear power plant may be subjected to pump- or fluid-induced vibrations that, in general, affect only local areas of the piping systems. Pump- or fluid-induced vibrations typically are characterized by low levels of amplitudes and a high number of cycles over the lifetime of plant operation. Thus, the resulting fatigue damage to the piping systems could be an important safety concern. In general, tests and/or analyses are used to evaluate and qualify the piping systems. Test data, however, may be limited because of lack of instrumentation in critical piping locations and/or because of difficulty in obtaining data in inaccessible areas. This paper describes and summarizes a method to use limited pipe vibration test data, along with analytical harmonic response results from finite-element analyses, to assess the fatigue damage of nuclear power plant safety-related piping systems. 5 refs., 2 figs., 11 tabs

A modeling approach for district heating systems with focus on transient heat transfer in pipe networks

DEFF Research Database (Denmark)

Mohammadi, Soma; Bojesen, Carsten

2015-01-01

the temperature in DH systems. The main focus is on modeling transient heat transfer in pipe networks regarding the time delays between the heat supply unit and the consumers, the heat loss in the pipe networks and the consumers’ dynamic heat loads. A pseudo-dynamic approach is adopted and also the implicit...... district heating networks [DHN] characteristics. This paper is presenting a new developed model, which reflects the thermo-dynamic behavior of DHN. It is designed for tree network topologies. The purpose of the model is to serve as a basis for applying a variety of scenarios towards lowering...... finite element method is applied to simulate transient temperature changes in pipe networks. The model is calculating time series data related to supply temperature to the DHN from heat production units, heat loads and return temperature related to each consumer to calculate dynamic temperature changes...

Dynamic analysis of piping with multiple damping mechanisms; Analisis dinamico de tuberias con multiples mecanismos de amortiguamiento

Energy Technology Data Exchange (ETDEWEB)

Ruiz Lopez, Pablo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1990-12-31

This paper describes a damping criterion that allows realizing in a more convenient form the dynamic analysis of piping and structures in general, subjected to independent stimulations, fabricated in different materials and/or damping devices. This criterion, named composed damping, is applicable to the method of modal superimposition. [Espanol] En este trabajo se describe un criterio de amortiguamiento que permite realizar en una forma mas conveniente el analisis dinamico de tuberias y estructuras en general, sujetas a excitaciones independientes, compuestas de diferentes materiales y/o mecanismos de amortiguamiento. Este criterio, denominado amortiguamiento compuesto, es aplicable en el metodo de superposicion modal.

Dynamic analysis of piping with multiple damping mechanisms; Analisis dinamico de tuberias con multiples mecanismos de amortiguamiento

Energy Technology Data Exchange (ETDEWEB)

Ruiz Lopez, Pablo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1989-12-31

This paper describes a damping criterion that allows realizing in a more convenient form the dynamic analysis of piping and structures in general, subjected to independent stimulations, fabricated in different materials and/or damping devices. This criterion, named composed damping, is applicable to the method of modal superimposition. [Espanol] En este trabajo se describe un criterio de amortiguamiento que permite realizar en una forma mas conveniente el analisis dinamico de tuberias y estructuras en general, sujetas a excitaciones independientes, compuestas de diferentes materiales y/o mecanismos de amortiguamiento. Este criterio, denominado amortiguamiento compuesto, es aplicable en el metodo de superposicion modal.

Study on Change of Pipes Formed in the Upper Part of a Collapse in a Crystalline Schist Area and Response of Pipe Flow to Rain

OpenAIRE

平松, 晋也; 前川, 美紀子; 小山内, 信智; Shinya, HIRAMATSU; Mikiko, MAEKAWA; Nobutomo, OSANAI; 高知大学農学部; 高知大学農学部; 国土交通名四国山地砂防工事事務所; Faculty of Agriculture, Kochi University; Faculty of Agriculture, Kochi University; Shikoku Mountainous Region Sabo Work Office, Ministry of Land, Infrastructure and Transport

2002-01-01

Pipes formed by a small animal-activity, root decay and underground erosion exist frequently in the upper part of rain-induced collapse sites. These pipes affect significantly on water discharge and occurrences of hillside landslides in a watershed. Many hillside landslides occurred at Nishiiyayama village in Tokushima Prefecture, on June 29 th, 1999, due to heavy rainfall. In the upper part of C torrent of Tobinosu-valley, hillside landslides occurred, and several pipes appeared. Investigati...

Vibration analysis of the piping system using the modal analysis method, 1

International Nuclear Information System (INIS)

Fujikawa, Takeshi; Kurohashi, Michiya; Inoue, Yoshio

1975-01-01

Modal analysis method was developed for the vibration analysis of piping system in nuclear or chemical plants, with finite element theory, and verified by sinusoidal vibration method. The natural vibration equation for pipings was derived with stiffness, attenuation and mass matrices, and eigenvalues are obtained with usual method, then the forced vibration equation for pipings was derived with the same manner, and the special solutions are given by modal method from the eigenvalues of the natural vibration equation. Three simple piping models (one, two and three dimensional) were made, and the natural vibration frequency was measured with forced input from an electrical dynamic shaker and a sound speaker. The experimental values of natural vibration frequency showed good agreement with the results by the analytical method. Therefore the theoretical approach for piping system vibration was proved to be valid. (Iwase, T.)

Impacting effects of seismic loading in feeder pipes of PHWR power plants

International Nuclear Information System (INIS)

Kumar, R.

1996-01-01

The core of a pressurized heavy water reactor (PHWR) consists of a large number of fuel channels. These fuel channels are connected to the feeder pipes through which the heavy water flows and transports heat from the reactor core to the steam generators. The feeder pipes are several hundreds in number. They run close to each other with small gaps and have several bends. Thus they represent a complex piping system. Under seismic loading, the adjacent feeder pipes may impact each other. In this paper a simplified procedure has been established to assess such impacting effects. The results of the proposed analysis include bending moment and impact force, which provide the stresses due to impacting effects. These results are plotted in nondimensional form so that they could be utilized for any set of feeder pipes. The procedure used for studying the impacting effects includes seismic analysis of individual feeder pipes without impacting effects, selection of pipes for impact analysis, and estimating their maximum impact velocity. Based on the static and dynamic characteristics of the selected feeder pipes, the maximum bending moment, impact force, and stresses are obtained. The results of this study are useful for quick evaluation of the impacting effects in feeder pipes

Secondary pipe rupture at Mihama unit 3

International Nuclear Information System (INIS)

Hajime Ito; Takehiko Sera

2005-01-01

The secondary system pipe rupture occurred on August 9, 2004, while Mihama unit 3 was operating at the rated thermal power. The rupture took place on the condensate line-A piping between the No.4 LP heater and the deaerator, downstream of an orifice used for measuring the condensate flux. The pipe is made of carbon steel, and normally has 558.8 mm diameter and 10 mm thickness. The pipe wall had thinned to 0.4 mm at the point of minimum thickness. It is estimated that the disturbed flow of water downstream of the orifice caused erosion/corrosion and developed wall thinning, leading to a rupture at the thinnest section under internal pressure, about 1MPa. Observation of the pipe internal surface revealed a scale-like pattern typical in this kind of phenomenon. Eleven workers who were preparing for an annual outage that was to start from August 14 suffered burn injuries, of who five died. Since around 1975, we, Kansai Electric, have been checking pipe wall thickness while focusing on the thinning of carbon steel piping in the secondary system. Summarizing the results from such investigation and reviewing the latest technical knowledge including operating experience from overseas utilities, we compiled the pipe thickness management guideline for PWR secondary pipes, 1990. The pipe section that ruptured at the Mihama unit 3 should have been included within the inspection scopes according to the guideline but was not registered on the inspection list. It had not been corrected for almost thirty years. As the result, this pipe section had not been inspected even once since the beginning of the plant operation, 1976. It seems that the quality assurance and maintenance management had not functioned well regarding the secondary system piping management, although we were responsible for the safety of nuclear power plants as licensee. We will review the secondary system inspection procedure and also improve the pipe thickness management guideline. And also, we would replace

Development and application of proposed ASME Section XI Code changes for risk-based inspection of piping

International Nuclear Information System (INIS)

West, R.A.

1996-01-01

This synopsis has been written to describe a perspective on the development and application of ASME Section XI Code changes for risk-based inspection of piping. The content is specifically related to the use of risk-based technology for Inservice Inspection (ISI) of piping and efforts made to support the ASME Research/Westinghouse Owners Group/Millstone Unit 3 approach for use of this technology. The opinions contained herein may or may not reflect those of the ASME Codes and Standards Committees responsible for these activities. In order to take such a detailed technical subject and put it into an understandable format, the author has chosen to provide an analogy to simplify what is actually taking place. Risk-based technology in the ISI of piping can be likened to the process of making and using specifically ground prescription glasses to allow for better vision. It provides a process to develop and use these uniquely ground glasses that will dynamically focus on all the locations and obstacles within a plant's piping systems that could cause that plant to trip and fall; more importantly it identifies the locations where the fall could possibly hurt someone else. In this way, Nuclear Safety is being addressed

Pipe damping

International Nuclear Information System (INIS)

Ware, A.G.; Arendts, J.G.

1984-01-01

A program has been developed to assess the available piping damping data, to generate additional data and conduct seperate effects tests, and to establish a plan for reporting and storing future test results into a data bank. This effort is providing some of the basis for developing higher allowable damping values for piping seismic analyses, which will potentially permit removal of a considerable number of piping supports, particularly snubbers. This in turn will lead to more flexible piping systems which will be less susceptible to thermal cracking, will be easier to maintain and inspect, as well as less costly

Coarse particles-water mixtures flow in pipes

Czech Academy of Sciences Publication Activity Database

Vlasák, Pavel

2017-01-01

Roč. 225, č. 2017 (2017), s. 338-341 ISSN 2411-3336 R&D Projects: GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : hydrotransport * coarse particles pipeline installation * pressure drop * pipe inclination Subject RIV: BK - Fluid Dynamics OBOR OECD: Fluids and plasma physics (including surface physics)

Insulated pipe clamp design

International Nuclear Information System (INIS)

Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

1980-01-01

Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. The design considerations and methods along with the development tests are presented. Special considerations to guard against adverse cracking of the insulation material, to maintain the clamp-pipe stiffness desired during a seismic event, to minimize clamp restraint on the pipe during normal pipe heatup, and to resist clamp rotation or spinning on the pipe are emphasized

Metallurgical failure investigation of a pipe connector fracture of an expansion vessel

International Nuclear Information System (INIS)

Neidel, Andreas

2016-01-01

A pipe connector of an expansion vessel of a safety heat exchanger was torn off in a test facility's natural gas compressor. From a material point of view, the cause of the damage is a fatigue fracture induced by pulsating bending stress. The fatigue fracture originated from both, the pipe's outer surface as well as from its inner surface, which is consistent with the given stress situation (pulsating bending stress). Material defects or welding-induced flaws were not observed. Corrosion, wear, or thermal overload which may have promoted the damage, were not observed either. The primary cause was a major design error. Cases of dynamic load were obviously not duly taken into account during designing, so that the free-swinging mass of the expansion vessel which was mounted to a pipe of a diameter of only half an inch and, furthermore, installed in an angle of 45 (additional static preload.), could cause the fatigue failure induced by pulsating bending stress in the zone of highest stresses at the transition of the expansion vessel and the the pipe connector due to dynamic operating loads which always occur in plants like these.

Report of the US Nuclear Regulatory Commission Piping Review Committee. Volume 2. Evaluation of seismic designs: a review of seismic design requirements for Nuclear Power Plant Piping

Energy Technology Data Exchange (ETDEWEB)

1985-04-01

This document reports the position and recommendations of the NRC Piping Review Committee, Task Group on Seismic Design. The Task Group considered overlapping conservation in the various steps of seismic design, the effects of using two levels of earthquake as a design criterion, and current industry practices. Issues such as damping values, spectra modification, multiple response spectra methods, nozzle and support design, design margins, inelastic piping response, and the use of snubbers are addressed. Effects of current regulatory requirements for piping design are evaluated, and recommendations for immediate licensing action, changes in existing requirements, and research programs are presented. Additional background information and suggestions given by consultants are also presented.

Flow induced vibrations in a PWR piping system

International Nuclear Information System (INIS)

Seligmann, D.C.; Guillou, J.P.

1995-01-01

In this paper, we present and industrial study of the dynamic behaviour of the piping system of a French 1300 M We nuclear power plant. High-amplitude vibrations had been noticed on a safeguard system during the periodical operation startup tests. These vibrations, due to acoustical pump sources, cause fatigue-damage and it is therefore necessary to propose an estimation of the service-life of the piping and to propose modification of piping system to reduce vibrations. First, we define a mechanical model readjusted according to gauged vibratory speeds and construct a vibro-acoustic coupled model and a pump-behaviour model as a source of excitation. Second, we simulate a modification of the supports. The influence of this modification is analysed by comparison of the root mean square values of vibratory speeds and the stresses between the initial system and the modified system. 3 refs., 7 figs

Experiments about the integrity of BWR relief pipes in postulated radiolysis gas combustion. Scenario No.2. Minor steam leakages without any lowering of the water level

International Nuclear Information System (INIS)

Friedrich, A.; Grune, J.; Sempert, K.; Stern, G.; Kuznetsov, M.; Redlinger, R.; Breitung, W.; Franke, T.

2008-01-01

The experiments described in this article were performed to study this comprehensive radiolysis gas scenario: - The relief pipe is filled completely with radiolysis gas (2H 2 +O 2 ). - After opening of the S and R valve, the radiolysis gas is compressed adiabatically by the incoming steam without mixing. - Roughly at the point of peak pressure in the relief pipe (20 bar) the radiolysis gas ignites. This dynamic scenario was studied in steady-state model experiments with a test pipe which corresponds to the relief pipes installed in KKP-1 in terms of materials, dimensions, and manufacturing control. The initial conditions and boundary conditions of the experiments were conservative. In the course of the tests, the maximum dynamic strain and the residual plastic deformation of the test pipe were measured via the transient detonation load. The maximum dynamic strain measured was 0.75%, the maximum residual plastic strain reached 0.15%. The pipe suffered no other deformation above and beyond this slight plastic strain. The radiolysis gas detonation was simulated very well numerically. Using the calculated pressure loads in a structural dynamics model also showed good agreement with the measured maximum dynamic pipe strains. In this way, the experimental findings were confirmed theoretically. The experiments and the calculations showed that postulated radiolysis gas reactions during pressure relief cannot jeopardize the integrity of the relief pipe. (orig.)

A BENCHMARK PROGRAM FOR EVALUATION OF METHODS FOR COMPUTING SEISMIC RESPONSE OF COUPLED BUILDING-PIPING/EQUIPMENT WITH NON-CLASSICAL DAMPING

International Nuclear Information System (INIS)

Xu, J.; Degrassi, G.; Chokshi, N.

2001-01-01

Under the auspices of the US Nuclear Regulatory Commission (NRC), Brookhaven National Laboratory (BNL) developed a comprehensive program to evaluate state-of-the-art methods and computer programs for seismic analysis of typical coupled nuclear power plant (NPP) systems with nonclassical damping. In this program, four benchmark models of coupled building-piping/equipment systems with different damping characteristics were analyzed for a suite of earthquakes by program participants applying their uniquely developed methods and computer programs. This paper presents the results of their analyses, and their comparison to the benchmark solutions generated by BNL using time domain direct integration methods. The participant's analysis results established using complex modal time history methods showed good comparison with the BNL solutions, while the analyses produced with either complex-mode response spectrum methods or classical normal-mode response spectrum method, in general, produced more conservative results, when averaged over a suite of earthquakes. However, when coupling due to damping is significant, complex-mode response spectrum methods performed better than the classical normal-mode response spectrum method. Furthermore, as part of the program objectives, a parametric assessment is also presented in this paper, aimed at evaluation of the applicability of various analysis methods to problems with different dynamic characteristics unique to coupled NPP systems. It is believed that the findings and insights learned from this program will be useful in developing new acceptance criteria and providing guidance for future regulatory activities involving licensing applications of these alternate methods to coupled systems

Fundamentals of piping design

CERN Document Server

Smith, Peter

2013-01-01

Written for the piping engineer and designer in the field, this two-part series helps to fill a void in piping literature,since the Rip Weaver books of the '90s were taken out of print at the advent of the Computer Aid Design(CAD) era. Technology may have changed, however the fundamentals of piping rules still apply in the digitalrepresentation of process piping systems. The Fundamentals of Piping Design is an introduction to the designof piping systems, various processes and the layout of pipe work connecting the major items of equipment forthe new hire, the engineering student and the vetera

Heat pipe

International Nuclear Information System (INIS)

Triggs, G.W.; Lightowlers, R.J.; Robinson, D.; Rice, G.

1986-01-01

A heat pipe for use in stabilising a specimen container for irradiation of specimens at substantially constant temperature within a liquid metal cooled fast reactor, comprises an evaporator section, a condenser section, an adiabatic section therebetween, and a gas reservoir, and contains a vapourisable substance such as sodium. The heat pipe further includes a three layer wick structure comprising an outer relatively fine mesh layer, a coarse intermediate layer and a fine mesh inner layer for promoting unimpeded return of condensate to the evaporation section of the heat pipe while enhancing heat transfer with the heat pipe wall and reducing entrainment of the condensate by the upwardly rising vapour. (author)

Procedure for seismic evaluation and design of small bore piping

International Nuclear Information System (INIS)

Bilanin, W.; Sills, S.

1991-01-01

Simplified methods for the seismic design of small bore piping in nuclear power plants have teen used for many years. Various number of designers have developed unique methods to treat the large number of class 2 and 3 small bore piping systems. This practice has led to a proliferation of methods which are not standardized in the industry. These methods are generally based on enveloping the results of rigorous dynamic or conservative static analysis and result in an excessive number of supports and unrealistically high support loadings. Experience and test data have become available which warranted taking another look at the present methods for analysis of small bore piping. A recently completed Electric Power Research Institute and NCIG (a utility group) activity developed a new procedure for the seismic design and evaluation of small bore piping which provides significant safety and cost benefits. The procedure streamlines the approach to inertial stresses, which is the main feature that achieves the new benefits. Criteria in the procedure for seismic anchor movement and support design are based analysis and focus the designer on credible failure mechanisms. A walkdown of the as-constructed piping system to identify and eliminate undesirable piping features such as adverse spatial interaction is required

Simplified piping analysis methods with inelastic supports

International Nuclear Information System (INIS)

Lin, C.W.; Romanko, A.D.

1986-01-01

Energy absorbing supports (EAS) which contain x-shaped plates or dampers with heavy viscous fluid can absorb a large amount of energy during vibratory motions. The response of piping systems supported by these types of energy absorbing devices can be markedly reduced as compared with ordinary supports using rigid rods, hangers or snubbers. In this paper, a simple multiple support response spectrum technique is presented, which would allow the energy dissipation nature of the EAS be factored in the piping response calculation. In the meantime, the effect of lower system frequencies due to the reduced support stiffness from local yielding is also included in the analysis. Numerical results obtained show that this technique is more conservative than the time history solution by an acceptable and realistic margin; and it has less than 10 percent of the computation cost

Modelling and performance of heat pipes with long evaporator sections

Science.gov (United States)

Wits, Wessel W.; te Riele, Gert Jan

2017-11-01

This paper presents a planar cooling strategy for advanced electronic applications using heat pipe technology. The principle idea is to use an array of relatively long heat pipes, whereby heat is disposed to a long section of the pipes. The proposed design uses 1 m long heat pipes and top cooling through a fan-based heat sink. Successful heat pipe operation and experimental performances are determined for seven heating configurations, considering active bottom, middle and top sections, and four orientation angles (0°, 30°, 60° and 90°). For all heating sections active, the heat pipe oriented vertically in an evaporator-down mode and a power input of 150 W, the overall thermal resistance was 0.014 K/W at a thermal gradient of 2.1 K and an average operating temperature of 50.7 °C. Vertical operation showed best results, as can be expected; horizontally the heat pipe could not be tested up to the power limit and dry-out occurred between 20 and 80 W depending on the heating configuration. Heating configurations without the bottom section active demonstrated a dynamic start-up effect, caused by heat conduction towards the liquid pool and thereafter batch-wise introducing the working fluid into the two-phase cycle. By analysing the heat pipe limitations for the intended operating conditions, a suitable heat pipe geometry was chosen. To predict the thermal performance a thermal model using a resistance network was created. The model compares well with the measurement data, especially for higher input powers. Finally, the thermal model is used for the design of a 1 kW planar system-level electronics cooling infrastructure featuring six 1 m heat pipes in parallel having a long ( 75%) evaporator section.

Basic concepts about application of dual vibration absorbers to seismic design of nuclear piping systems

International Nuclear Information System (INIS)

Hara, F.; Seto, K.

1987-01-01

The design value of damping for nuclear piping systems is a vital parameter in ensuring safety in nuclear plants during large earthquakes. Many experiments and on-site tests have been undertaken in nuclear-industry developed countries to determine rational design values. However damping value in nuclear piping systems is so strongly influenced by many piping parameters that it shows a tremendous dispersion in its experimental values. A new trend has recently appeared in designing nuclear pipings, where they attempt to use a device to absorb vibration energy induced by seismic excitation. A typical device is an energy absorbing device, made of a special material having a high capacity of plasticity, which is installed between the piping and the support. This paper deals with the basic study of application of dual vibration absorbers to nuclear piping systems to accomplish high damping value and reduce consequently seismic response at resonance frequencies of a piping system, showing their effectiveness from not only numerical calculation but also experimental evaluation of the vibration responses in a 3D model piping system equipped with dual two vibration absorbers

Heat exchanger nozzle stresses due to pipe vibration

International Nuclear Information System (INIS)

Wolgemuth, G.A.

1983-01-01

A large diameter pipe in a heavy water production plant was excited into a low frequency vibration due to void collapse of the pipe contents at a sharp vertical drop in the pipe run. Fears that this vibration would fatigue the inlet nozzle to the heat exchanger prompted the introduction of a flow of cold water into the pipe to prevent the two-phase flow from developing but at the cost of reduced heat exchanger efficiency. An investigation was carried out to determine the stress levels in the nozzle with the quenching flow off and suggest means of reducing them if excessive. A finite element dynamic simulation of the pipe run was performed to determine the likely mode shapes. This information was used to optimize the placement of velocity probes on the pipe. Field measurements of vibration were taken for several operating conditions. This data was analyzed and the results used to refine the support stiffness used in the finite element simulation. The finite element model was then used to predict the nozzle forces and moments. In turn this data was used to determine the local stresses in the nozzle. The ASME Section III code was used to determine the allowable fully reversing stresses for the unit in question. It was found that the endurance limit of 83 MPa was exceeded in the analysis only when using the most conservative estimates for each uncertainty. It was recommended that if the safety factor was not deemed high enough, the nozzle should be built up with a reinforcing pad no thicker than 12 mm

Splitting of turbulent spot in transitional pipe flow

Science.gov (United States)

Wu, Xiaohua; Moin, Parviz; Adrian, Ronald J.

2017-11-01

Recent study (Wu et al., PNAS, 1509451112, 2015) demonstrated the feasibility and accuracy of direct computation of the Osborne Reynolds' pipe transition problem without the unphysical, axially periodic boundary condition. Here we use this approach to study the splitting of turbulent spot in transitional pipe flow, a feature first discovered by E.R. Lindgren (Arkiv Fysik 15, 1959). It has been widely believed that spot splitting is a mysterious stochastic process that has general implications on the lifetime and sustainability of wall turbulence. We address the following two questions: (1) What is the dynamics of turbulent spot splitting in pipe transition? Specifically, we look into any possible connection between the instantaneous strain rate field and the spot splitting. (2) How does the passive scalar field behave during the process of pipe spot splitting. In this study, the turbulent spot is introduced at the inlet plane through a sixty degree wide numerical wedge within which fully-developed turbulent profiles are assigned over a short time interval; and the simulation Reynolds numbers are 2400 for a 500 radii long pipe, and 2300 for a 1000 radii long pipe, respectively. Numerical dye is tagged on the imposed turbulent spot at the inlet. Splitting of the imposed turbulent spot is detected very easily. Preliminary analysis of the DNS results seems to suggest that turbulent spot slitting can be easily understood based on instantaneous strain rate field, and such spot splitting may not be relevant in external flows such as the flat-plate boundary layer.

Flow induced vibrations in a PWR piping system

International Nuclear Information System (INIS)

Seligmann, D.; Guillou, J.

1995-11-01

During a recurring bench test of an operating system, high amplitude vibrations have been observed on a safety piping system of a nuclear power plant. Due to the source of the pumps, these vibrations lead to wear damage and it is therefore necessary to estimate the life time of the piping system. This paper describes the methodology used to study the dynamic behaviour and to analyze the damage of a piping system submitted to internal flow. Starting from an experimental modal analysis of the piping system when not i service, we analyse the main parameters of the mechanical behaviour. Following this analysis, we obtain a mechanical model fitting the first experimental modes. On this basis, we build a vibro-acoustical model. This model takes into account the influence of the acoustical pipe length, both above and below the mechanical part, the modelling of acoustical components, the speed of sound. We did not experimentally characterize the pumps. Therefore, we use a numerical model in order to simulate the behaviour of the pumps. This model is based on the theory of the transfer matrix and takes into account the geometric and the hydraulic characteristics of the pump.The modelling of both sources (suction and discharge) connected to the pump is formed by contributions from a source corresponding to the turbulent noise at low frequency, a source at blade passage frequency. This model has been experimentally validated in a laboratory. The final results of the modelling of the complete piping system are in a complete accord with experimental measurements. (author). 3 refs., 7 figs

Fatigue check of nuclear safety class 1 reactor coolant pipe

International Nuclear Information System (INIS)

Wang Qing; Fang Yonggang; Chu Qibao; Xu Yu; Li Hailong

2015-01-01

Fatigue and thermal ratcheting analyses of nuclear safety Class 1 reactor coolant pipe in a nuclear power plant were independently carried out in this paper. The software used for calculation is ROCOCO, which is based on RCC-M code. The difference of nuclear safety Class 1 pipe fatigue evaluation between RCC-M code and ASME code was compared. The main aspects of comparison include the calculation scoping of fatigue design, the calculation method of primary plus secondary stress intensity, the elastic-plastic correction coefficient calculation, and the dynamic load combination method etc. By correcting inconsistent algorithm of ASME code within ROCOCO, the fatigue usage factor and thermal ratcheting design margin of 65 mm and 55 mm wall thickness of the pipe were obtained. The results show that the minimum wall thickness of the pipe must exceed 55 mm and the design value of the thermal ratcheting of 55 mm wall thickness reaches 95% of the allowable value. (authors)

Heat pipe and method of production of a heat pipe

International Nuclear Information System (INIS)

Kemp, R.S.

1975-01-01

The heat pipe consists of a copper pipe in which a capillary network or wick of heat-conducting material is arranged in direct contact with the pipe along its whole length. Furthermore, the interior space of the tube contains an evaporable liquid for pipe transfer. If water is used, the capillary network consists of, e.g., a phosphorus band network. To avoid contamination of the interior of the heat pipe during sealing, its ends are closed by mechanical deformation so that an arched or plane surface is obtained which is in direct contact with the network. After evacuation of the interior space, the remaining opening is closed with a tapered pin. The ratio wall thickness/tube diameter is between 0.01 and 0.6. (TK/AK) [de

Pipe drafting and design

CERN Document Server

Parisher, Roy A; Parisher

2000-01-01

Pipe designers and drafters provide thousands of piping drawings used in the layout of industrial and other facilities. The layouts must comply with safety codes, government standards, client specifications, budget, and start-up date. Pipe Drafting and Design, Second Edition provides step-by-step instructions to walk pipe designers and drafters and students in Engineering Design Graphics and Engineering Technology through the creation of piping arrangement and isometric drawings using symbols for fittings, flanges, valves, and mechanical equipment. The book is appropriate primarily for pipe

Piping benchmark problems for the Westinghouse AP600 Standardized Plant

International Nuclear Information System (INIS)

Bezler, P.; DeGrassi, G.; Braverman, J.; Wang, Y.K.

1997-01-01

To satisfy the need for verification of the computer programs and modeling techniques that will be used to perform the final piping analyses for the Westinghouse AP600 Standardized Plant, three benchmark problems were developed. The problems are representative piping systems subjected to representative dynamic loads with solutions developed using the methods being proposed for analysis for the AP600 standard design. It will be required that the combined license licensees demonstrate that their solutions to these problems are in agreement with the benchmark problem set

Analysis of a piping system under seismic load using incremental hinge technique

International Nuclear Information System (INIS)

Ravi Kiran, A.; Agrawal, M.K.; Reddy, G.R.; Singh, R.K.; Vaze, K.K.; Ghosh, A.K.; Kushwaha, H.S.; Ramesh Babu, R.

2008-01-01

ASME Boiler and Pressure Vessel Code treats piping system as a series of components but not as an overall structural system. Limit analyses and collapse tests at component level are used to establish stress allowables on seismic stresses. The code does not consider the load redistributions and structural redundancy existing in piping systems that prevent system collapse even when one or more individual components loaded beyond their collapse levels. This necessitates a simple analytical method for evaluation of inelastic seismic response at system level. The present paper presents a simplified analytical procedure for predicting inelastic response of a typical piping system subjected to seismic load. The analytical method known as incremental hinge technique is based on plastic system behavior in which the yielded components are replaced with hinge models when a critical hinge moment is reached. It also takes into account the inelastic response spectrum reduction factors and displacement ductility. The analytical method is used to obtain the inelastic response, location of hinge formation and level of base excitation needed for hinge formation. The predicted hinge locations and hinge ordering is compared with the results of a shake table test conducted on the piping system. (author)

Vibrational fatigue failures in short cantilevered piping with socket-welding fittings

International Nuclear Information System (INIS)

Smith, J.K.

1996-01-01

Approximately 80% of the vibrational fatigue failures in nuclear power plants have been caused by high cycle vibrational fatigue. Many of these failures have occurred in short, small bore (2 in. nominal diameter and smaller), unbraced, cantilevered piping with socket-welding fittings. The fatigue failures initiated in the socket welds. These failures have been unexpected, and have caused costly, unscheduled outages in some cases. In order to reduce the number of vibrational fatigue failures in these short cantilevered pipes, an acceleration based vibrational fatigue screening criteria was developed under Electric Power Research Institute (EPRI) sponsorship. In this paper, the acceleration based criteria will be compared to the results obtained from detailed dynamic modeling of a short, cantilevered pipe

Influence of gravity on flutter of cantilevered pipes conveying fluid

Science.gov (United States)

Rivero, Javier; Perez-Saborid, Miguel

2012-11-01

We have considered the dynamics of the nonlinear interaction between a flexible pipe and the conveyed fluid in the presence of gravity. The stability of the system (fllutter and buckling) depends on parameters such as the dimensionless fluid flow rate, the gravity to bending stiffness ratio and the fluid to pipe mass ratio and it has been studied in detail both numerically and experimentally. It has also been found that the stabilizing or destabilizing effects of fluid flow depends crucially on the direction of gravity respect to the undeformed midline of the pipe. We have also computed the post-critical behavior of the system by solving the full nonlinear equations of the problem and analyzed the transfer of energy within the system in the nonlinear regime. We have formulated the problem in terms of the angles of the midline of the pipe instead of its transverse displacements, so that we can deal with large deflections without recurring to the quasi-linear approximations concerning the pipe curvature usually made in the literature. Supported by the Ministerio de Educación, Cultura y Deportes of Spain under grant DPI 2010-20450 C03-02.

Evaluation of piping heat transfer, piping flow regimes, and steam generator heat transfer for the Semiscale Mod-1 isothermal tests

International Nuclear Information System (INIS)

French, R.T.

1975-08-01

Selected experimental data pertinent to piping heat transfer, transient fluid flow regimes, and steam generator heat transfer obtained during the Semiscale Mod-1 isothermal blowdown test series (Test Series 1) are analyzed. The tests in this first test series were designed to provide counterparts to the LOFT nonnuclear experiments. The data from the Semiscale Mod-1 intact and broken loop piping are evaluated to determine the surface heat flux and average heat transfer coefficients effective during the blowdown transient and compared with well known heat transfer correlations used in the RELAP4 computer program. Flow regimes in horizontal pipe sections are calculated and compared with data obtained from horizontal and vertical densitometers and with an existing steady state flow map. Effects of steam generator heat transfer are evaluated quantitatively and qualitatively. The Semiscale Mod-1 data and the analysis presented in this report are valuable for evaluating the adequacy and improving the predictive capability of analytical models developed to predict system response to piping heat transfer, piping flow regimes, and steam generator heat transfer during a postulated loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR). 16 references. (auth)

Drop Weight Impact Behavior of Al-Si-Cu Alloy Foam-Filled Thin-Walled Steel Pipe Fabricated by Friction Stir Back Extrusion

Science.gov (United States)

Hangai, Yoshihiko; Nakano, Yukiko; Utsunomiya, Takao; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

2017-02-01

In this study, Al-Si-Cu alloy ADC12 foam-filled thin-walled stainless steel pipes, which exhibit metal bonding between the ADC12 foam and steel pipe, were fabricated by friction stir back extrusion. Drop weight impact tests were conducted to investigate the deformation behavior and mechanical properties of the foam-filled pipes during dynamic compression tests, which were compared with the results of static compression tests. From x-ray computed tomography observation, it was confirmed that the fabricated foam-filled pipes had almost uniform porosity and pore size distributions. It was found that no scattering of the fragments of collapsed ADC12 foam occurred for the foam-filled pipes owing to the existence of the pipe surrounding the ADC12 foam. Preventing the scattering of the ADC12 foam decreases the drop in stress during dynamic compression tests and therefore improves the energy absorption properties of the foam.

Heat pipes and use of heat pipes in furnace exhaust

Science.gov (United States)

Polcyn, Adam D.

2010-12-28

An array of a plurality of heat pipe are mounted in spaced relationship to one another with the hot end of the heat pipes in a heated environment, e.g. the exhaust flue of a furnace, and the cold end outside the furnace. Heat conversion equipment is connected to the cold end of the heat pipes.

Drill pipe bridge plug

International Nuclear Information System (INIS)

Winslow, D.W.; Brisco, D.P.

1991-01-01

This patent describes a method of stopping flow of fluid up through a pipe bore of a pipe string in a well. It comprises: lowering a bridge plug apparatus on a work string into the pipe string to a position where the pipe bore is to be closed; communicating the pipe bore below a packer of the bridge plug apparatus through the bridge plug apparatus with a low pressure zone above the packer to permit the fluid to flow up through the bridge plug apparatus; engaging the bridge plug apparatus with an internal upset of the pipe string; while the fluid is flowing up through the bridge plug apparatus, pulling upward on the work string and the bridge plug apparatus and thereby sealing the packer against the pipe bore; isolating the pipe bore below the packer from the low pressure zone above the packer and thereby stopping flow of the fluid up through the pipe bore; disconnecting the work string from the bridge plug apparatus; and maintaining the bridge plug apparatus in engagement with the internal upset and sealed against the pipe bore due to an upward pressure differential applied to the bridge plug apparatus by the fluid contained therebelow

Structural and piping issues in the design certification of advanced reactors

International Nuclear Information System (INIS)

Ali, S.A.; Terao, D.; Bagchi, G.

1996-01-01

The purpose of this paper is to discuss the design certification of structures and piping for evolutionary and passive advanced light water reactors. Advanced reactor designs are based on a set of assumed site-related parameters that are selected to envelop a majority of potential nuclear power plant sites. Multiple time histories are used as the seismic design basis in order to cover the majority of potential sites in the US. Additionally, design are established to ensure that surface motions at a particular site will not exceed the enveloped standard design surface motions. State-of-the-art soil-structure interaction (SSI) analyses have been performed for the advanced reactors, which include structure-to-structure interaction for all seismic Category 1 structures. Advanced technology has been utilized to exclude the dynamic effects of pipe rupture from structural design by demonstrating that the probability of pipe rupture is extremely low. For piping design, the advanced reactor vendors have developed design acceptance criteria (DAC) which provides the piping design analysis methods, design procedures, and acceptance criteria. In SECY-93-087 the NRC staff recommended that the Commission approve the approach to eliminate the OBE from the design of structures and piping in advanced reactors and provided guidance which identifies the necessary changes to existing seismic design criteria. The supplemental criteria address fatigue, seismic anchor motion, and piping stress limits when the OBE is eliminated

Rupture disc opening property for using pipe rupture test in JAERI

International Nuclear Information System (INIS)

Kato, Rokuro

1983-03-01

In the Mechanical Strength and Structure Lab of JAERI there are being performed pipe break tests which are a postulated instantaneous guillotine break of the primary coolant piping in nuclear power plants. The test being performed are pipe whip tests and jet discharging tests. The bursting of the rupture disc is initiated by an electrical arc and is concluded by the internal pressure. Because the time characteristics during the opening of the rupture disc affects the dynamic thrust force of the pipe, it is necessary to measure these time characteristics. However, it is difficult to measure the conditions during this continuous opening because at the same time of the opening the high temperature and high pressure water is flashing. Therefore, the rupture disc opening was postulated on the measuring of the effective opening characteristics with electric contraction terminals which were attached to the inner surface of the test pipe downstream of the rupture disc and were extended toward the pipe centerline in a ring whose area is about 60 % of the area of the pipe flow sectional area. The measurement voltage was recorded when the data recorder was started in sequence with the electrical arc release from a trigger signal. As a result, it is evident that under high temperature and high pressure water the effective opening time is delayed by a few milliseconds. (author)

Insulated pipe clamp design

International Nuclear Information System (INIS)

Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

1980-01-01

Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. 5 refs

Refurbishment of the IEAR1 primary coolant system piping supports

International Nuclear Information System (INIS)

Fainer, Gerson; Faloppa, Altair A.; Oliveira, Carlos A. de; Mattar Neto, Miguel

2015-01-01

A partial replacement of the IEA-R1 piping system was concluded in 2014. This paper presents the study and the structural analysis of the IEA-R1 primary circuit piping supports, considering all the changes involved in the replacement. The IEA-R1 is a nuclear reactor for research purposes designed by Babcox-Willcox that is operated by IPEN since 1957. The reactor life management and modernization program is being conducted for the last two decades and already resulted in a series of changes, especially on the reactor coolant system. This set of components, divided in primary and secondary circuit, is responsible for the circulation of water into the core to remove heat. In the ageing management program that includes regular inspection, some degradation was observed in the primary piping system. As result, the renewing of the piping system was conducted in 2014. Moreover the poor condition of some original piping supports gave rise to the refurbishment of all piping supports. The aim of the present work is to review the design of the primary system piping supports taking into account the current conditions after the changes and refurbishment. (author)

Miniature Heat Pipes

Science.gov (United States)

1997-01-01

Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged "heat pipes" for space application. To control the extreme temperature ranges in space, heat pipes are important to spacecraft. The problem was to maintain an 8-watt central processing unit (CPU) at less than 90 C in a notebook computer using no power, with very little space available and without using forced convection. Thermacore's answer was in the design of a powder metal wick that transfers CPU heat from a tightly confined spot to an area near available air flow. The heat pipe technology permits a notebook computer to be operated in any position without loss of performance. Miniature heat pipe technology has successfully been applied, such as in Pentium Processor notebook computers. The company expects its heat pipes to accommodate desktop computers as well. Cellular phones, camcorders, and other hand-held electronics are forsible applications for heat pipes.

Practical application of equivalent linearization approaches to nonlinear piping systems

International Nuclear Information System (INIS)

Park, Y.J.; Hofmayer, C.H.

1995-01-01

The use of mechanical energy absorbers as an alternative to conventional hydraulic and mechanical snubbers for piping supports has attracted a wide interest among researchers and practitioners in the nuclear industry. The basic design concept of energy absorbers (EA) is to dissipate the vibration energy of piping systems through nonlinear hysteretic actions of EA exclamation point s under design seismic loads. Therefore, some type of nonlinear analysis needs to be performed in the seismic design of piping systems with EA supports. The equivalent linearization approach (ELA) can be a practical analysis tool for this purpose, particularly when the response approach (RSA) is also incorporated in the analysis formulations. In this paper, the following ELA/RSA methods are presented and compared to each other regarding their practice and numerical accuracy: Response approach using the square root of sum of squares (SRSS) approximation (denoted RS in this paper). Classical ELA based on modal combinations and linear random vibration theory (denoted CELA in this paper). Stochastic ELA based on direct solution of response covariance matrix (denoted SELA in this paper). New algorithms to convert response spectra to the equivalent power spectral density (PSD) functions are presented for both the above CELA and SELA methods. The numerical accuracy of the three EL are studied through a parametric error analysis. Finally, the practicality of the presented analysis is demonstrated in two application examples for piping systems with EA supports

Use of the modal superposition technique for piping system blowdown analyses

International Nuclear Information System (INIS)

Ware, A.G.; Macek, R.W.

1983-01-01

A standard method of solving for the seismic response of piping systems is the modal superposition technique. Only a limited number of structural modes are considered (typically those up to 33 Hz in the U.S.), since the effect on the calculated response due to higher modes is generally small, and the method can result in considerable computer cost savings over the direct integration method. The modal superposition technique has also been applied to piping response problems in which the forcing functions are due to fluid excitation. Application of the technique to this case is somewhat more difficult, because a well defined cutoff frequency for determining structural modes to be included has not been established. This paper outlines a method for higher mode corrections, and suggests methods to determine suitable cutoff frequencies for piping system blowdown analyses. A numerical example illustrates how uncorrected modal superposition results can produce erroneous stress results

Efficient methods of piping cleaning

Directory of Open Access Journals (Sweden)

Orlov Vladimir Aleksandrovich

2014-01-01

Full Text Available The article contains the analysis of the efficient methods of piping cleaning of water supply and sanitation systems. Special attention is paid to the ice cleaning method, in course of which biological foil and various mineral and organic deposits are removed due to the ice crust buildup on the inner surface of water supply and drainage pipes. These impurities are responsible for the deterioration of the organoleptic properties of the transported drinking water or narrowing cross-section of drainage pipes. The co-authors emphasize that the use of ice compared to other methods of pipe cleaning has a number of advantages due to the relative simplicity and cheapness of the process, economical efficiency and lack of environmental risk. The equipment for performing ice cleaning is presented, its technological options, terms of cleansing operations, as well as the volumes of disposed pollution per unit length of the water supply and drainage pipelines. It is noted that ice cleaning requires careful planning in the process of cooking ice and in the process of its supply in the pipe. There are specific requirements to its quality. In particular, when you clean drinking water system the ice applied should be hygienically clean and meet sanitary requirements.In pilot projects, in particular, quantitative and qualitative analysis of sediments adsorbed by ice is conducted, as well as temperature and the duration of the process. The degree of pollution of the pipeline was estimated by the volume of the remote sediment on 1 km of pipeline. Cleaning pipelines using ice can be considered one of the methods of trenchless technologies, being a significant alternative to traditional methods of cleaning the pipes. The method can be applied in urban pipeline systems of drinking water supply for the diameters of 100—600 mm, and also to diversion collectors. In the world today 450 km of pipelines are subject to ice cleaning method.Ice cleaning method is simple

Application of the cracked pipe element to creep crack growth prediction

Energy Technology Data Exchange (ETDEWEB)

Brochard, J.; Charras, T.

1997-04-01

The modification of a computer code for leak before break analysis is very briefly described. The CASTEM2000 code was developed for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading. The modification extends the capabilities of the cracked pipe element to the determination of fracture parameters under creep conditions (C*, {phi}c and {Delta}c). The model has the advantage of evaluating significant secondary effects, such as those from thermal loading.

Riser pipe elevator

Energy Technology Data Exchange (ETDEWEB)

Bennett, W.; Jimenez, A.F.

1987-09-08

This patent describes a method for storing and retrieving a riser pipe, comprising the steps of: providing an upright annular magazine comprised of an inside annular wall and an outside annular wall, the magazine having an open top; storing the riser pipe in a substantially vertically oriented position within the annular magazine; and moving the riser pipe upwardly through the open top of the annular magazine at an angle to the vertical along at least a portion of the length of the riser pipe.

Dynamic performance of a novel solar photovoltaic/loop-heat-pipe heat pump system

International Nuclear Information System (INIS)

Zhang, Xingxing; Zhao, Xudong; Shen, Jingchun; Xu, Jihuan; Yu, Xiaotong

2014-01-01

Highlights: • A transient model was developed to predict dynamic performance of new PV/LHP system. • The model accuracy was validated by experiment giving less than 9% in error. • The new system had basic and advanced performance coefficients of 5.51 and 8.71. • The new system had a COP 1.5–4 times that for conventional heat pump systems. • The new system had higher exergetic efficiency than PV and solar collector systems. - Abstract: Objective of the paper is to present an investigation into the dynamic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for potential use in space heating or hot water generation. The methods used include theoretical computer simulation, experimental verification, analysis and comparison. The fundamental equations governing the transient processes of solar transmission, heat transfer, fluid flow and photovoltaic (PV) power generation were appropriately integrated to address the energy balances occurring in different parts of the system, e.g., glazing cover, PV cells, fin sheet, loop heat pipe, heat pump cycle and water tank. A dedicated computer model was developed to resolve the above grouping equations and consequently predict the system’s dynamic performance. An experimental rig was constructed and operated under the real weather conditions for over one week in Shanghai to evaluate the system living performance, which was undertaken by measurement of various operational parameters, e.g., solar radiation, photovoltaic power generation, temperatures and heat pump compressor consumption. On the basis of the first- (energetic) and second- (exergetic) thermodynamic laws, an overall evaluation approach was proposed and applied to conduct both quantitative and qualitative analysis of the PV/LHP module’s efficiency, which involved use of the basic thermal performance coefficient (COP th ) and the advanced performance coefficient (COP PV/T ) of such a system. Moreover, a simple comparison

A simplified LBB evaluation procedure for austenitic and ferritic steel piping

International Nuclear Information System (INIS)

Gamble, R.M.; Wichman, K.R.

1997-01-01

The NRC previously has approved application of LBB analysis as a means to demonstrate that the probability of pipe rupture was extremely low so that dynamic loads associated with postulated pipe break could be excluded from the design basis (1). The purpose of this work was to: (1) define simplified procedures that can be used by the NRC to compute allowable lengths for circumferential throughwall cracks and assess margin against pipe fracture, and (2) verify the accuracy of the simplified procedures by comparison with available experimental data for piping having circumferential throughwall flaws. The development of the procedures was performed using techniques similar to those employed to develop ASME Code flaw evaluation procedures. The procedures described in this report are applicable to pipe and pipe fittings with: (1) wrought austenitic steel (Ni-Cr-Fe alloy) having a specified minimum yield strength less than 45 ksi, and gas metal-arc, submerged arc and shielded metal-arc austentic welds, and (2) seamless or welded wrought carbon steel having a minimum yield strength not greater than 40 ksi, and associated weld materials. The procedures can be used for cast austenitic steel when adequate information is available to place the cast material toughness into one of the categories identified later in this report for austenitic wrought and weld materials

A simplified LBB evaluation procedure for austenitic and ferritic steel piping

Energy Technology Data Exchange (ETDEWEB)

Gamble, R.M.; Wichman, K.R.

1997-04-01

The NRC previously has approved application of LBB analysis as a means to demonstrate that the probability of pipe rupture was extremely low so that dynamic loads associated with postulated pipe break could be excluded from the design basis (1). The purpose of this work was to: (1) define simplified procedures that can be used by the NRC to compute allowable lengths for circumferential throughwall cracks and assess margin against pipe fracture, and (2) verify the accuracy of the simplified procedures by comparison with available experimental data for piping having circumferential throughwall flaws. The development of the procedures was performed using techniques similar to those employed to develop ASME Code flaw evaluation procedures. The procedures described in this report are applicable to pipe and pipe fittings with: (1) wrought austenitic steel (Ni-Cr-Fe alloy) having a specified minimum yield strength less than 45 ksi, and gas metal-arc, submerged arc and shielded metal-arc austentic welds, and (2) seamless or welded wrought carbon steel having a minimum yield strength not greater than 40 ksi, and associated weld materials. The procedures can be used for cast austenitic steel when adequate information is available to place the cast material toughness into one of the categories identified later in this report for austenitic wrought and weld materials.

Strain measurements at the HDR-pipe-system under LOCA-load: Effects on elbows and displaced weldings

International Nuclear Information System (INIS)

Hunger, H.

1985-01-01

This paper characterizes some effects which have been detected during strain gauge measurements on a test piping with feed water check valve oscillating under blowdown-load. The ovalization of a pipe elbow subjected to in-plane-bending affects the connected straight pipe; this is shown by means of circumferential stresses. Very high LOCA-load produces plastic strain and changes the pipe dynamics. Artificial displaced welds increase the local strain but no defects have occurred. One example compares stresses from measurement and post-calculation. Moreover there are given some remarks on the optimization of the comparison of measurement and calculation. (orig.)

Control of pipe vibrations; Schwingungsminderung bei Rohrleitungen

Energy Technology Data Exchange (ETDEWEB)

Sinambari, G.R. [FH Bingen, Fachrichtung Umweltschutz, und IBS Ingenieurbuero fuer Schall- und Schwingungstechnik GmbH, Frankenthal (Germany); Thorn, U. [IBS Ingenieurbuero fuer Schall- und Schwingungstechnik GmbH, Frankenthal (Germany)

2005-06-01

Following commissioning of a new vacuum system for the refinery of MiRO Mineraloelraffinerie Oberrhein GmbH and Co. KG, vibrations occurred in the furnace exhaust pipes. As these had to be regarded as critical for the fatigue strength of the pipes, the pipes' vibration response in the critical frequency range was investigated immediately by means of a vibration analysis, and appropriate measures for vibration control were elaborated. All investigations, and the installation of the hydraulic vibration dampers, took place with the system operating. The effectiveness of the measures taken was checked by means of measurements following installation. The measures succeeded in attenuating the vibrations to a level at which, empirically, damage need no longer be expected. This paper illustrates the procedure for developing the vibration control measures and the essential results of the investigations. (orig.)

Ratcheting of pressurized piping subjected to seismic loading

International Nuclear Information System (INIS)

Scavuzzo, R.J.; Lam, P.C.; Gau, J.S.

1992-01-01

The ABAQUS finite element code was used to model a pressurized pipe and subjected to cyclic bending loads to investigate ratcheting. A 1-in. schedule 40 pipe was loaded with a slow (static) cyclic load. The pipe internal pressure was varied from 0 to 6000 psi. In this paper, two types of materials were considered: an elastic perfectly plastic and a bilinear elastic-plastic material. Two types of finite elements of the ABAQUS program were compared to analytical solutions to evaluate the element accuracy in the plastic regime. Depending upon loading conditions and specified material properties, three different responses were observed from the finite element analyses: cyclic plasticity, ratcheting of the hoop strain, or shakedown. These analytical results are compared to some experimental measurements

Comparison and evaluation of flexible and stiff piping systems

International Nuclear Information System (INIS)

Hahn, W.; Tang, H.T.; Tang, Y.K.

1983-01-01

An experimental and numerical study was performed on a piping system, with various support configurations, to assess the difference in piping response for flexible and stiff piping systems. Questions have arisen concerning a basic design philosophy employed in present day piping designs. One basic question is, the reliability of a flexible piping system greater than that of a stiff piping system by virtue of the fact that a flexible system has fewer snubber supports. With fewer snubbers, the pipe is less susceptible to inadvertent thermal stresses introduced by snubber malfunction during normal operation. In addition to the technical issue, the matter of cost savings in flexible piping system design is a significant one. The costs associated with construction, in-service inspection and maintenance are all significantly reduced by reducing the number of snubber supports. The evaluation study, sponsored by the Electric Power Research Institute, was performed on a boiler feedwater line at Consolidated Edison's Indian Point Unit 1. In this study, the boiler feedwater line was tested and analyzed with two fundamentally different support systems. The first system was very flexible, employing rod and spring hangers, and represented the 'old' design philosophy. The pipe system was very flexible with this support system, due to the long pipe span lengths between supports and the fact that there was only one lateral support. This support did not provide much restraint since it was near an anchor. The second system employed strut and snubber supports and represented the 'modern' design philosophy. The pipe system was relatively stiff with this support system, primarily due to the increased number of supports, including lateral supports, thereby reducing the pipe span lengths between supports. The second support system was designed with removable supports to facilitate interchange of the supports with different support types (i.e., struts, mechanical snubbers and hydraulic

Experimental study on fluid mixing phenomena in T-pipe junction with upstream elbow

International Nuclear Information System (INIS)

Hiroshi Ogawa; Minoru Igarashi; Nobuyuki Kimura; Hideki Kamide

2005-01-01

Full text of publication follows: Temperature fluctuation in fluid causes high cycle thermal fatigue in shroud structure according to its amplitude and frequency. There are still some incidents of thermal fatigue and leakage in light water reactors (Japanese PWR Tomari-2 in 2003, French PWR CIVAUX in 1998), and also in sodium cooled reactors (French FBR Phenix in 1992). Mixing tee is a typical component where temperature fluctuation occurs. Water experiment has been carried out to investigate temperature fluctuation characteristics and flow velocity field in a simple T-pipe junction with straight inlet pipings for main and branch lines; test facility is named as WATLON (Water Experiment on Fluid Mixing in T-pipe with Long Cycle Fluctuation). Here, influence of upstream elbow in the main pipe was studied in the WATLON facility. Elbow can be set near the mixing tee in a real plant. Outlet of the elbow has biased velocity distribution and also the secondary flow, which decays unsteadily. Temperature distribution in the mixing tee was measured by a movable tree with 17 thermocouples and velocity field was measured by Dynamic PIV (high speed particle image velocimetry) with sampling frequency of 200 Hz. Measured temperature showed that fluctuation intensity near the wall was larger in the elbow geometry than in the straight inlet pipes in a case of wall jet (branch flow velocity is smaller than main pipe flow velocity); high intensity region in the elbow case was enlarged around the jet exiting from the branch pipe. The result of flow velocity measurement showed that secondary flow and biased flow velocity distributions due to the elbow influenced bending of the jet exiting from the branch pipe and the temperature fluctuation intensity around the jet. The detailed flow velocity distributions and the secondary flow of upstream elbow can be measured by Dynamic PIV. Influence of such elbow was discussed based on detailed temperature data together with fluctuated velocity

Development of LBB Piping Evaluation Diagram for APR 1000 Main Steam Line Piping

International Nuclear Information System (INIS)

Yang, J. S.; Jeong, I. L.; Park, C. Y.; Bai, S. Y.

2010-01-01

This paper presents the piping evaluation diagram (PED) to assess the applicability of Leak-Before- Break(LBB) for APR 1000 main steam line piping. LBB-PED of APR 1000 main steam line piping is independent of its piping geometry and has a function of the loads applied in piping system. Also, in order to evaluate LBB applicability during construction process with only the comparative evaluation of material properties between actually used and expected, the expected changes of material properties are considered in the LBB-PED. The LBB-PED, therefore, can be used for quick LBB evaluation of APR 1000 main steam line piping of both design and construction

PIPE STRESS and VERPIP codes for stress analysis and verifications of PEC reactor piping

International Nuclear Information System (INIS)

Cesari, F.; Ferranti, P.; Gasparrini, M.; Labanti, L.

1975-01-01

To design LMFBR piping systems following ASME Sct. III requirements unusual flexibility computer codes are to be adopted to consider piping and its guard-tube. For this purpose PIPE STRESS code previously prepared by Southern-Service, has been modified. Some subroutine for detailed stress analysis and principal stress calculations on all the sections of piping have been written and fitted in the code. Plotter can also be used. VERPIP code for automatic verifications of piping as class 1 Sct. III prescriptions has been also prepared. The results of PIPE STRESS and VERPIP codes application to PEC piping are in section III of this report

Piping research program plan

International Nuclear Information System (INIS)

1988-09-01

This document presents the piping research program plan for the Structural and Seismic Engineering Branch and the Materials Engineering Branch of the Division of Engineering, Office of Nuclear Regulatory Research. The plan describes the research to be performed in the areas of piping design criteria, environmentally assisted cracking, pipe fracture, and leak detection and leak rate estimation. The piping research program addresses the regulatory issues regarding piping design and piping integrity facing the NRC today and in the foreseeable future. The plan discusses the regulatory issues and needs for the research, the objectives, key aspects, and schedule for each research project, or group of projects focussing of a specific topic, and, finally, the integration of the research areas into the regulatory process is described. The plan presents a snap-shot of the piping research program as it exists today. However, the program plan will change as the regulatory issues and needs change. Consequently, this document will be revised on a bi-annual basis to reflect the changes in the piping research program. (author)

Temperature control with high performance gravity-assist heat pipes

International Nuclear Information System (INIS)

Kemme, J.E.; Deverall, J.E.; Keddy, E.S.; Phillips, J.R.; Ranken, W.A.

1975-01-01

The development of high performance heat pipes for controlling the temperature of irradiation experiments in the Experimental Breeder Reactor (EBR-II) is described. Because this application involves vertical operation in a gravity-assist mode with the evaporator down, several tests were made with sodium and potassium heat pipes in this position to establish their performance limits as a function of operating temperature. Best performance was achieved with a new wick structure consisting of a fine porous liner next to the heat-pipe wall and four helical channels next to the vapor passage. Also, a new modification of heat-pipe theory was discovered for determining performance limits for this type of wick. In its most rudimentary form, this modification says that the dynamic pressure gradient in the vapor stream cannot exceed the gravity gradient causing return of liquid. Once this modification was expressed in the form of a limiting equation, and a term was added to account for the slight capillary force developed in the channels, good agreement was obtained between calculated limits and those measured in several tests with both sodium and potassium. These tests showed rather conclusively that only half of the liquid head in the evaporator section was causing return of condensate, whereas existing theory predicts that the full head of liquid in the heat pipe is available for condensate return. (U.S.)

Fracture toughness evaluations of TP304 stainless steel pipes

International Nuclear Information System (INIS)

Rudland, D.L.; Brust, F.W.; Wilkowski, G.M.

1997-02-01

In the IPIRG-1 program, the J-R curve calculated for a 16-inch nominal diameter, Schedule 100 TP304 stainless steel (DP2-A8) surface-cracked pipe experiment (Experiment 1.3-3) was considerably lower than the quasi-static, monotonic J-R curve calculated from a C(T) specimen (A8-12a). The results from several related investigations conducted to determine the cause of the observed toughness difference are: (1) chemical analyses on sections of Pipe DP2-A8 from several surface-cracked pipe and material property specimen fracture surfaces indicate that there are two distinct heats of material within Pipe DP2-A8 that differ in chemical composition; (2) SEN(T) specimen experimental results indicate that the toughness of a surface-cracked specimen is highly dependent on the depth of the initial crack, in addition, the J-R curves from the SEN(T) specimens closely match the J-R curve from the surface-cracked pipe experiment; (3) C(T) experimental results suggest that there is a large difference in the quasi-static, monotonic toughness between the two heats of DP2-A8, as well as a toughness degradation in the lower toughness heat of material (DP2-A8II) when loaded with a dynamic, cyclic (R = -0.3) loading history

The effects of resonances on time delay estimation for water leak detection in plastic pipes

Science.gov (United States)

Almeida, Fabrício C. L.; Brennan, Michael J.; Joseph, Phillip F.; Gao, Yan; Paschoalini, Amarildo T.

2018-04-01

In the use of acoustic correlation methods for water leak detection, sensors are placed at pipe access points either side of a suspected leak, and the peak in the cross-correlation function of the measured signals gives the time difference (delay) between the arrival times of the leak noise at the sensors. Combining this information with the speed at which the leak noise propagates along the pipe, gives an estimate for the location of the leak with respect to one of the measurement positions. It is possible for the structural dynamics of the pipe system to corrupt the time delay estimate, which results in the leak being incorrectly located. In this paper, data from test-rigs in the United Kingdom and Canada are used to demonstrate this phenomenon, and analytical models of resonators are coupled with a pipe model to replicate the experimental results. The model is then used to investigate which of the two commonly used correlation algorithms, the Basic Cross-Correlation (BCC) function or the Phase Transform (PHAT), is more robust to the undesirable structural dynamics of the pipe system. It is found that time delay estimation is highly sensitive to the frequency bandwidth over which the analysis is conducted. Moreover, it is found that the PHAT is particularly sensitive to the presence of resonances and can give an incorrect time delay estimate, whereas the BCC function is found to be much more robust, giving a consistently accurate time delay estimate for a range of dynamic conditions.

75 FR 4529 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty New...

Science.gov (United States)

2010-01-28

... Compliance Analyst, Office 6, Verification of the Sales Response of Pacific Pipe Public Company, Limited in... Pipe Public Company, Limited, dated August 24, 2009 (Bona Fides Preliminary Memorandum). The Department... Circular Welded Carbon Steel Pipes and Tubes from Thailand: Pacific Pipe Public Company, Limited, dated...

Characterization of radioactive contamination inside pipes with the Pipe Explorer trademark system

International Nuclear Information System (INIS)

Kendrick, D.T.; Cremer, C.D.; Lowry, W.; Cramer, E.

1995-01-01

The U.S. Department of Energy's nuclear facility decommissioning program needs to characterize radiological contamination inside piping systems before the pipe can be recycled, remediated, or disposed. Science and Engineering associates, Inc. under contract with the DOE Morgantown Energy Technology Center has developed and demonstrated the Pipe Explorer trademark system, which uses an inverting membrane to transport various characterization sensors into pipes. The basic process involves inverting (turning inside out) a tubular impermeable membrane under air pressure. A characterization sensor is towed down the interior of the pipe by the membrane. Advantages of this approach include the capability of deploying through constrictions in the pipe, around 90 degrees bends, vertically up and down, and in slippery conditions. Because the detector is transported inside the membrane (which is inexpensive and disposable), it is protected from contamination, which eliminates cross-contamination. Characterization sensors that have been demonstrated with the system thus far include: gamma detectors, beta detectors, video cameras, and pipe locators. Alpha measurement capability is currently under development. A remotely operable Pipe Explorer trademark system has been developed and demonstrated for use in DOE facilities in the decommissioning stage. The system is capable of deployment in pipes as small as 2-inch-diameter and up to 250 feet long. This paper describes the technology and presents measurement results of a field demonstration conducted with the Pipe Explorer trademark system at a DOE site. These measurements identify surface activity levels of U-238 contamination as a function of location in drain lines. Cost savings to the DOE of approximately $1.5 million dollars were realized from this one demonstration

Piping benchmark problems for the General Electric Advanced Boiling Water Reactor

International Nuclear Information System (INIS)

Bezler, P.; DeGrassi, G.; Braverman, J.; Wang, Y.K.

1993-08-01

To satisfy the need for verification of the computer programs and modeling techniques that will be used to perform the final piping analyses for an advanced boiling water reactor standard design, three benchmark problems were developed. The problems are representative piping systems subjected to representative dynamic loads with solutions developed using the methods being proposed for analysis for the advanced reactor standard design. It will be required that the combined license holders demonstrate that their solutions to these problems are in agreement with the benchmark problem set

Solar heating pipe

Energy Technology Data Exchange (ETDEWEB)

Hinson-Rider, G.

1977-10-04

A fluid carrying pipe is described having an integral transparent portion formed into a longitudinally extending cylindrical lens that focuses solar heat rays to a focal axis within the volume of the pipe. The pipe on the side opposite the lens has a heat ray absorbent coating for absorbing heat from light rays that pass through the focal axis.

Reliability of piping system components. Volume 4: The pipe failure event database

Energy Technology Data Exchange (ETDEWEB)

Nyman, R; Erixon, S [Swedish Nuclear Power Inspectorate, Stockholm (Sweden); Tomic, B [ENCONET Consulting GmbH, Vienna (Austria); Lydell, B [RSA Technologies, Visat, CA (United States)

1996-07-01

Available public and proprietary databases on piping system failures were searched for relevant information. Using a relational database to identify groupings of piping failure modes and failure mechanisms, together with insights from published PSAs, the project team determined why, how and where piping systems fail. This report represents a compendium of technical issues important to the analysis of pipe failure events, and statistical estimation of failure rates. Inadequacies of traditional PSA methodology are addressed, with directions for PSA methodology enhancements. A `data driven and systems oriented` analysis approach is proposed to enable assignment of unique identities to risk-significant piping system component failure. Sufficient operating experience does exist to generate quality data on piping failures. Passive component failures should be addressed by today`s PSAs to allow for aging analysis and effective, on-line risk management. 42 refs, 25 figs.

Reliability of piping system components. Volume 4: The pipe failure event database

International Nuclear Information System (INIS)

Nyman, R.; Erixon, S.; Tomic, B.; Lydell, B.

1996-07-01

Available public and proprietary databases on piping system failures were searched for relevant information. Using a relational database to identify groupings of piping failure modes and failure mechanisms, together with insights from published PSAs, the project team determined why, how and where piping systems fail. This report represents a compendium of technical issues important to the analysis of pipe failure events, and statistical estimation of failure rates. Inadequacies of traditional PSA methodology are addressed, with directions for PSA methodology enhancements. A 'data driven and systems oriented' analysis approach is proposed to enable assignment of unique identities to risk-significant piping system component failure. Sufficient operating experience does exist to generate quality data on piping failures. Passive component failures should be addressed by today's PSAs to allow for aging analysis and effective, on-line risk management. 42 refs, 25 figs

Modal analysis of main steam line piping under high energy line break condition

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae-Jin; Kim, Seung Hyun; Je, Sang-Yun; Chang, Yoon-Suk [Kyung Hee University, Yongin (Korea, Republic of)

2016-10-15

If HELB (High Energy Line Break) occurs in NPPs (Nuclear Power Plants), not only environmental effect like release of radioactive material but also secondary structural defects should be considered. Jet impingement phenomenon caused by sudden pipe rupture may lead to severe damage on neighboring safe-related components and other structure. Lots of studies have been conducted to assess dynamic behaviors of the SG and MSL piping while pipe whip restraints and jet impingement shields are taken into account during design stage. Arroyo et al. performed modal analyses of a simple square component to examine the jet impingement phenomenon. Also, structural characteristics were predicted to assure structural integrity against the HELB. In this study, we examined dynamic characteristics of SG and MSL piping in a typical 1000MWe NPP. Simulation was performed by using two commercial computational softwares. In particular, modal analyses were conducted to determine mode shapes and natural frequencies of the structure and maximum displacements. The data obtain from each software were compared and observation was discussed in relation to the jet impingement phenomenon. In this research, modal analyses on the SG and MSL piping were carried out to get natural frequencies, vibration mode shapes and maximum displacements. Thereby, the following key finding was observed. (1) Maximum displacement was calculated at the top of SG outlet nozzle with y-directional bending at the third mode. (2) The differences between two models were respectively 7% in natural frequencies and less than 1% in maximum displacements.

Large-bore pipe decontamination

International Nuclear Information System (INIS)

Ebadian, M.A.

1998-01-01

The decontamination and decommissioning (D and D) of 1200 buildings within the US Department of Energy-Office of Environmental Management (DOE-EM) Complex will require the disposition of miles of pipe. The disposition of large-bore pipe, in particular, presents difficulties in the area of decontamination and characterization. The pipe is potentially contaminated internally as well as externally. This situation requires a system capable of decontaminating and characterizing both the inside and outside of the pipe. Current decontamination and characterization systems are not designed for application to this geometry, making the direct disposal of piping systems necessary in many cases. The pipe often creates voids in the disposal cell, which requires the pipe to be cut in half or filled with a grout material. These methods are labor intensive and costly to perform on large volumes of pipe. Direct disposal does not take advantage of recycling, which could provide monetary dividends. To facilitate the decontamination and characterization of large-bore piping and thereby reduce the volume of piping required for disposal, a detailed analysis will be conducted to document the pipe remediation problem set; determine potential technologies to solve this remediation problem set; design and laboratory test potential decontamination and characterization technologies; fabricate a prototype system; provide a cost-benefit analysis of the proposed system; and transfer the technology to industry. This report summarizes the activities performed during fiscal year 1997 and describes the planned activities for fiscal year 1998. Accomplishments for FY97 include the development of the applicable and relevant and appropriate regulations, the screening of decontamination and characterization technologies, and the selection and initial design of the decontamination system

ASME code and ratcheting in piping components. Final technical report

International Nuclear Information System (INIS)

Hassan, T.; Matzen, V.C.

1999-01-01

The main objective of this research is to develop an analysis program which can accurately simulate ratcheting in piping components subjected to seismic or other cyclic loads. Ratcheting is defined as the accumulation of deformation in structures and materials with cycles. This phenomenon has been demonstrated to cause failure to piping components (known as ratcheting-fatigue failure) and is yet to be understood clearly. The design and analysis methods in the ASME Boiler and Pressure Vessel Code for ratcheting of piping components are not well accepted by the practicing engineering community. This research project attempts to understand the ratcheting-fatigue failure mechanisms and improve analysis methods for ratcheting predictions. In the first step a state-of-the-art testing facility is developed for quasi-static cyclic and seismic testing of straight and elbow piping components. A systematic testing program to study ratcheting is developed. Some tests have already been performed and the rest will be completed by summer'99. Significant progress has been made in the area of constitutive modeling. A number of sophisticated constitutive models have been evaluated in terms of their simulations for a broad class of ratcheting responses. From the knowledge gained from this evaluation study two improved models are developed. These models are demonstrated to have promise in simulating ratcheting responses in piping components. Hence, implementation of these improved models in widely used finite element programs, ANSYS and/or ABAQUS, is in progress. Upon achieving improved finite element programs for simulation of ratcheting, the ASME Code provisions for ratcheting of piping components will be reviewed and more rational methods will be suggested. Also, simplified analysis methods will be developed for operability studies of piping components and systems. Some of the future works will be performed under the auspices of the Center for Nuclear Power Plant Structures

Ratcheting study in pressurized piping components under cyclic loading at room temperature

International Nuclear Information System (INIS)

Ravi Kiran, A.; Agrawal, M.K.; Reddy, G.R.; Vaze, K.K.; Ghosh, A.K.; Kushwaha, H.S.

2006-07-01

The nuclear power plant piping components and systems are often subjected to reversing cyclic loading conditions due to various process transients, seismic and other events. Earlier the design of piping subjected to seismic excitation was based on the principle of plastic collapse. It is believed that during such events, fatigue-ratcheting is likely mode of failure of piping components. The 1995 ASME Boiler and Pressure Vessel code, Section-III, has incorporated the reverse dynamic loading and ratcheting into the code. Experimental and analytical studies are carried out to understand this failure mechanism. The biaxial ratcheting characteristics of SA 333, Gr. 6 steel and SS 304 stainless steel at room temperature are investigated in the present work. Experiments are carried out on straight pipes subjected to internal pressure and cyclic bending load applied in a three point and four point bend test configurations. A shake table test is also carried out on a pressurized elbow by applying sinusoidal base excitation. Analytical simulation of ratcheting in the piping elements is carried out. Chaboche nonlinear kinematic hardening model is used for ratcheting simulation. (author)

Development of Pipe Holding Mechanism for Pipe Inspection Robot Using Flexible Pneumatic Cylinder

Directory of Open Access Journals (Sweden)

Choi Kyujun

2016-01-01

Full Text Available A pipe inspection robot is useful to reduce the inspection cost. In the previous study, a novel pipe inspection robot using a flexible pneumatic cylinder that can move forward along to the pipe by changing the robot’s body naturally was proposed and tested. In this paper, to improve its mobility for a corner of a pipe, the thin pipe holding mechanism using pneumatic bellows was proposed and tested. As a result of its driving test, the holding performance of the mechanism was confirmed.

Piping reliability model development, validation and its applications to light water reactor piping

International Nuclear Information System (INIS)

Woo, H.H.

1983-01-01

A brief description is provided of a three-year effort undertaken by the Lawrence Livermore National Laboratory for the piping reliability project. The ultimate goal of this project is to provide guidance for nuclear piping design so that high-reliability piping systems can be built. Based on the results studied so far, it is concluded that the reliability approach can undoubtedly help in understanding not only how to assess and improve the safety of the piping systems but also how to design more reliable piping systems

Field measurement of the piping system vibration of Ko-Ri unit 4 during the load-following operation

International Nuclear Information System (INIS)

Chung, Tae-Young; Hong, Sung-Yull; Kim, Bum-Nyun.

1989-01-01

During the load-following operation of nuclear power plants, flow rate, temperature, and pressure in the piping system can be varied by changing the electric power output level, and these variations can cause different vibration phenomena in the piping system. The piping system vibration is important because it is directly related to the dynamic stress of the piping system and can affect the life of the piping system through structural fatigue. An assessment of vibration levels for the classes II and III piping systems of the Ko-Ri Unit 4950-MW nuclear power plant was performed according to the given pattern of the load-following operation to study its feasibility from the viewpoint of piping system vibration. The classes II and III piping system vibration of the Ko-Ri Unit 4 may not cause any potential problem under the given pattern of the load-following operation; however, it is recommended that long-term operation in the 85 to 95% power range be avoided as much as possible

Analysis of the thermal performance of heat pipe radiators

Science.gov (United States)

Boo, J. H.; Hartley, J. G.

1990-01-01

A comprehensive mathematical model and computational methodology are presented to obtain numerical solutions for the transient behavior of a heat pipe radiator in a space environment. The modeling is focused on a typical radiator panel having a long heat pipe at the center and two extended surfaces attached to opposing sides of the heat pipe shell in the condenser section. In the set of governing equations developed for the model, each region of the heat pipe - shell, liquid, and vapor - is thermally lumped to the extent possible, while the fin is lumped only in the direction normal to its surface. Convection is considered to be the only significant heat transfer mode in the vapor, and the evaporation and condensation velocity at the liquid-vapor interface is calculated from kinetic theory. A finite-difference numerical technique is used to predict the transient behavior of the entire radiator in response to changing loads.

Evaluation of stormwater micropollutant source control and end-of-pipe control strategies using an uncertainty-calibrated integrated dynamic simulation model

DEFF Research Database (Denmark)

Vezzaro, Luca; Sharma, Anitha Kumari; Ledin, Anna

2015-01-01

(copper, zinc) and organic compounds (fluoranthene). MP fluxes were estimated by using an integrated dynamic model, in combination with stormwater quality measurements. MP sources were identified by using GIS land usage data, runoff quality was simulated by using a conceptual accumulation/washoff model......The estimation of micropollutant (MP) fluxes in stormwater systems is a fundamental prerequisite when preparing strategies to reduce stormwater MP discharges to natural waters. Dynamic integrated models can be important tools in this step, as they can be used to integrate the limited data provided...... by monitoring campaigns and to evaluate the performance of different strategies based on model simulation results. This study presents an example where six different control strategies, including both source-control and end-of-pipe treatment, were compared. The comparison focused on fluxes of heavy metals...

Lateral impact on pressurized glass/epoxy pipes

Energy Technology Data Exchange (ETDEWEB)

Santiago, Rafael C.; Alves, Marcilio [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica], e-mail: rafael.santiago@poli.usp.br, e-mail: maralves@usp.br

2009-07-01

This work studies the impact of a drop mass against glass/epoxy composite pipes. The experimental tests comprises an impact hammer and the set-up is such that a drop mass falls transversally to the main length of the tube. The impact response is measured with a non-contact laser system and reveals some issues explored here in a numerical model. Inner pressure was applied to the tube in order to access its influence on failure. It has been found that the numerical model represents well the structural collapse of a pressurized pipe under a lateral impact. (author)

Heat transfer characteristics and limitations analysis of heat-pipe-cooled thermal protection structure

International Nuclear Information System (INIS)

Guangming, Xiao; Yanxia, Du; Yewei, Gui; Lei, Liu; Xiaofeng, Yang; Dong, Wei

2014-01-01

The theories of heat transfer, thermodynamics and fluid dynamics are employed to develop the coupled heat transfer analytical methods for the heat-pipe-cooled thermal protection structure (HPC TPS), and a three-dimensional numerical method considering the sonic limit of heat pipe is proposed. To verify the calculation correctness, computations are carried out for a typical heat pipe and the results agree well with experimental data. Then, the heat transfer characteristics and limitations of HPC TPS are mainly studied. The studies indicate that the use of heat pipe can reduce the temperature at high heat flux region of structure efficiently. However, there is a frozen startup period before the heat pipe reaching a steady operating state, and the sonic limit will be a restriction on the heat transfer capability. Thus, the effects of frozen startup must be considered for the design of HPC TPS. The simulation model and numerical method proposed in this paper can predict the heat transfer characteristics of HPC TPS quickly and exactly, and the results will provide important references for the design or performance evaluation of HPC TPS. - Highlights: • Numerical methods for the heat-pipe-cooled thermal protection structure are studied. • Three-dimensional simulation model considering sonic limit of heat pipe is proposed. • The frozen startup process of the embedded heat pipe can be predicted exactly. • Heat transfer characteristics of TPS and limitations of heat pipe are discussed

Analytical and numerical modeling for flexible pipes

Science.gov (United States)

Wang, Wei; Chen, Geng

2011-12-01

The unbonded flexible pipe of eight layers, in which all the layers except the carcass layer are assumed to have isotropic properties, has been analyzed. Specifically, the carcass layer shows the orthotropic characteristics. The effective elastic moduli of the carcass layer have been developed in terms of the influence of deformation to stiffness. With consideration of the effective elastic moduli, the structure can be properly analyzed. Also the relative movements of tendons and relative displacements of wires in helical armour layer have been investigated. A three-dimensional nonlinear finite element model has been presented to predict the response of flexible pipes under axial force and torque. Further, the friction and contact of interlayer have been considered. Comparison between the finite element model and experimental results obtained in literature has been given and discussed, which might provide practical and technical support for the application of unbonded flexible pipes.

Background noise of acoustic emission signals in sodium piping loop

International Nuclear Information System (INIS)

Mori, Y.; Aoki, K.; Kuribayashi, K.; Kishi, T.; Sakakibara, Y.

1985-01-01

Background noise measurement in the frequency range of acoustic emission (AE) signals was made on the sodium piping loops of a 50 MW steam generator test facility in the Power Reactor and Nuclear Fuel Development Corporation (PNC). During the dynamic characteristics test of the steam generator over a wide range of operating conditions, the background noise generated on the pipe surface was measured using wideband AE sensor externally mounted with waveguide. Data were obtained for the effect of power loads of steam generator on both amplitude and frequency spectra of background noise signals. Source and nature of background noise were established

Abrasion behavior of graphite pebble in lifting pipe of pebble-bed HTR

Energy Technology Data Exchange (ETDEWEB)

Shen, Ke; Su, Jiageng [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Zhou, Hongbo [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Chinergy Co., LTD., Beijing 100193 (China); Peng, Wei; Liu, Bing [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Yu, Suyun, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, The Key Laboratory for Thermal Science and Power Engineering, Ministry of Educations, Tsinghua University, Beijing 10084 (China)

2015-11-15

Highlights: • Quantitative determination of abrasion rate of graphite pebbles in different lifting velocities. • Abrasion behavior of graphite pebble in helium, air and nitrogen. • In helium, intensive collisions caused by oscillatory motion result in more graphite dust production. - Abstract: A pebble-bed high-temperature gas-cooled reactor (pebble-bed HTR) uses a helium coolant, graphite core structure, and spherical fuel elements. The pebble-bed design enables on-line refueling, avoiding refueling shutdowns. During circulation process, the pebbles are lifted pneumatically via a stainless steel lifting pipe and reinserted into the reactor. Inevitably, the movement of the fuel elements as they recirculate in the reactor produces graphite dust. Mechanical wear is the primary source of graphite dust production. Specifically, the sources are mechanisms of pebble–pebble contact, pebble–wall (structural graphite) contact, and fuel handling (pebble–metal abrasion). The key contribution to graphite dust production is from the fuel handling system, particularly from the lifting pipe. During pneumatic lift, graphite pebbles undergo multiple collisions with the stainless steel lifting pipe, thereby causing abrasion of the graphite pebbles and producing graphite dust. The present work explored the abrasion behavior of graphite pebble in the lifting pipe by measuring the abrasion rate at different lifting velocities. The abrasion rate of the graphite pebble in helium was found much higher than those in air and nitrogen. This gas environment effect could be explained by either tribology behavior or dynamic behavior. Friction testing excluded the possibility of tribology reason. The dynamic behavior of the graphite pebble was captured by analysis of the audio waveforms during pneumatic lift. The analysis results revealed unique dynamic behavior of the graphite pebble in helium. Oscillation and consequently intensive collisions occur during pneumatic lift, causing

Oscillating heat pipes

CERN Document Server

Ma, Hongbin

2015-01-01

This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation,  theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary  factors affecting oscillating motions and heat transfer,  neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes.  The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...

Damping in LMFBR pipe systems

International Nuclear Information System (INIS)

Anderson, M.J.; Barta, D.A.; Lindquist, M.R.; Renkey, E.J.; Ryan, J.A.

1983-06-01

LMFBR pipe systems typically utilize a thicker insulation package than that used on water plant pipe systems. They are supported with special insulated pipe clamps. Mechanical snubbers are employed to resist seismic loads. Recent laboratory testing has indicated that these features provide significantly more damping than presently allowed by Regulatory Guide 1.61 for water plant pipe systems. This paper presents results of additional in-situ vibration tests conducted on FFTF pipe systems. Pipe damping values obtained at various excitation levels are presented. Effects of filtering data to provide damping values at discrete frequencies and the alternate use of a single equivalent modal damping value are discussed. These tests further confirm that damping in typical LMFBR pipe systems is larger than presently used in pipe design. Although some increase in damping occurred with increased excitation amplitude, the effect was not significant. Recommendations are made to use an increased damping value for both the OBE and DBE seismic events in design of LMFBR pipe systems

Heat pipes

CERN Document Server

Dunn, Peter D

1994-01-01

It is approximately 10 years since the Third Edition of Heat Pipes was published and the text is now established as the standard work on the subject. This new edition has been extensively updated, with revisions to most chapters. The introduction of new working fluids and extended life test data have been taken into account in chapter 3. A number of new types of heat pipes have become popular, and others have proved less effective. This is reflected in the contents of chapter 5. Heat pipes are employed in a wide range of applications, including electronics cooling, diecasting and injection mo

An in-pipe mobile micromachine using fluid power. A mechanism adaptable to pipe diameters

International Nuclear Information System (INIS)

Yoshida, Kazuhiro; Yokota, Shinichi; Takahashi, Ken

2000-01-01

To realize micro maintenance robots for small diameter pipes of nuclear reactors and so on, high power in-pipe mobile micromachines have been required. The authors have proposed the bellows microactuator using fluid power and have tried to apply the actuators to in-pipe mobile micromachines. In the previous papers, some inchworm mobile machine prototypes with 25 mm in diameter are fabricated and the traveling performances are experimentally investigated. In this paper, to miniaturize the in-pipe mobile machine and to make it adaptable to pipe diameters, firstly, a simple rubber-tube actuator constrained with a coil-spring is proposed and the static characteristics are investigated. Secondly, a supporting mechanism which utilizes a toggle mechanism and is adaptable to pipe diameters is proposed and the supporting forces are investigated. Finally, an in-pipe mobile micromachine for pipe with 4 - 5 mm in diameter is fabricated and the maximum traveling velocity of 7 mm/s in both ahead and astern movements is experimentally verified. (author)

Application of the cracked pipe element to creep crack growth prediction

Energy Technology Data Exchange (ETDEWEB)

Brochard, J.; Charras, T. [C.E.A.-C.E.-Saclay DRN/DMT, Gif Sur Yvette (France); Ghoudi, M. [C.E.A.-C.E.-Saclay, Gif Sur Yvette (France)

1997-04-01

Modifications to a computer code for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading are very briefly described. The modifications extend the capabilities of the CASTEM2000 code to the determination of fracture parameters under creep conditions. The main advantage of the approach is that thermal loads can be evaluated as secondary stresses. The code is applicable to piping systems for which crack propagation predictions differ significantly depending on whether thermal stresses are considered as primary or secondary stresses.

Russian regulatory approaches to seismic design and seismic analysis of NPP piping

International Nuclear Information System (INIS)

Kaliberda, Y.V.

2003-01-01

The paper presents an overview of Russian regulatory approaches to seismic design and seismic analysis of NPP piping. The paper is focused on categorization and seismic analysis of nuclear power plant items (piping, equipment, supports, valves, but not building structures). The paper outlines the current seismic recommendations, corresponding methods with the examples of calculation models. The paper considers calculation results of the mechanisms of dynamic behavior and the problems of developing a rational and economical approaches to seismic design and seismic protection. (author)

Heat pipes and heat pipe exchangers for heat recovery systems

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, L L; Grakovich, L P; Kiselev, V G; Kurustalev, D K; Matveev, Yu

1984-01-01

Heat pipes and heat pipe exchangers are of great importance in power engineering as a means of recovering waste heat of industrial enterprises, solar energy, geothermal waters and deep soil. Heat pipes are highly effective heat transfer units for transferring thermal energy over large distance (tens of meters) with low temperature drops. Their heat transfer characteristics and reliable working for more than 10-15 yr permit the design of new systems with higher heat engineering parameters.

Pipe restraints for nuclear power plants

International Nuclear Information System (INIS)

Keever, R.E.; Broman, R.; Shevekov, S.

1976-01-01

A pipe restraint for nuclear power plants in which a support member is anchored on supporting surface is described. Formed in the support member is a semicylindrical wall. Seated on the semicylindrical wall is a ring-shaped pipe restrainer that has an inner cylindrical wall. The inner cylindrical wall of the pipe restrainer encircles the pressurized pipe. In a modification of the pipe restraint, an arched-shaped pipe restrainer is disposed to overlie a pressurized pipe. The ends of the arch-shaped pipe restrainer are fixed to support members, which are anchored in concrete or to a supporting surface. A strap depends from the arch-shaped pipe restrainer. The pressurized pipe is supported by the depending strap

An Investigation of Aging Behaviour in Microalloyed Steel (X70) UOE Pipe

Science.gov (United States)

Wiskel, J. B.; Ma, J.; Ivey, D. G.; Henein, H.

Aging of microalloyed steel pipe can occur at relatively low temperatures associated with the pipe coating process and/or during long term storage or use. The aging phenomenon is primarily attributed to C diffusion to dislocations and subsequent pinning of these dislocations. Important factors in the aging process include time, temperature, chemical composition and plastic deformation (arising from the pipe forming process). The work presented in this paper uses a Box-Behnken experimental design to determine the effect of time, temperature, location in the UOE pipe (90° or 180° to the weld), position through the pipe wall thickness (ID, CL or OD) and the steel's C/Nb ratio (0.60, 1.25 and 1.80) on the change in yield strength of three (uncoated) X70 UOE pipes. Quantitative microstructure analysis is undertaken to determine the grain size and microconstituent fractions of the as-received pipe material. Quadratic equations and response surface(s) correlating the significant aging variables with changes in the longitudinal yield stress of the pipe are developed. Both through thickness position and the C/Nb ratio, followed by aging temperature, had the largest effect on the change in longitudinal yield strength.

Torsion instability of Flexible Pipes at the TDP - Torsjonsinstabilitet av fleksible rør med sjøbunnskontakt

OpenAIRE

Hansson, Linn Storesund

2017-01-01

Dynamic flexible risers are a common term for cables, umbilicals and flexible pipes,that are freely or semi-freely suspended between two points (offshore). Flexible pipes are mostly used to transport fluids between platforms/ships etc. to a flow-line/sea floor installation or similar. The safe operating window for the installation is limited by whether induced motion of the installation vessel giving rise to dynamic tension and curvature at the touch-down-zone (TDZ). By investigation and ...

Loading rate effects on strength and fracture toughness of pipe steels used in Task 1 of the IPIRG program

International Nuclear Information System (INIS)

Marschall, C.W.; Landow, M.P.; Wilkowski, G.M.

1993-10-01

Material characterization tests were conducted on laboratory specimens machined from pipes to determine the effect of dynamic loading (i.e., rates comparable to those for high amplitude seismic events) on tensile properties and fracture resistance at 288 C (550 F). Specimens were fabricated from seven different pipes, including carbon steels and stainless steels (both base metal and weld metal), which were to be subjected to full-scale pipe tests in IPIRG Task 1.0. For the stainless steels tested at 288 C (550 F), tensile strength was unchanged, while yield strength and fracture resistance were increased. The increase in fracture resistance was modest for the wrought base metals and substantial for the weld metal and the cast base metal. The carbon steels tested were sensitive to dynamic strain aging, and hence the strength and toughness was affected by both temperature and strain rate effects. The carbon steel base metal and welds exhibited ultimate tensile strength values at 288 C (550 F) that were greater than at room temperature. Furthermore, the ultimate tensile strength at 288 C (550 F) was lowered significantly by increased strain rate and, in the carbon steel base metals, increased strain rate also lowered the fracture resistance, substantially in the base metal of one pipe. In comparing these results to the IPIRG pipe test results to date, it was found that the trends of these tests agree well with the Subtask 1.2 quasi-static and dynamic pipe fracture experiments. Loads measured in the Subtask 1.1 pipe experiments were, however, somewhat higher than would have been expected by the trends observed in the laboratory tests

Characterization of radioactive contamination inside pipes with the Pipe Explorer{sup trademark} system

Energy Technology Data Exchange (ETDEWEB)

Cremer, C.D.; Lowry, W.; Cramer, E. [Science and Engineering Associates, Inc., Albuquerque, NM (United States)] [and others

1995-10-01

The U.S. Department of Energy`s nuclear facility decommissioning program needs to characterize radiological contamination inside piping systems before the pipe can be recycled, remediated, or disposed. Historically, this has been attempted using hand held survey instrumentation, surveying only the accessible exterior portions of pipe systems. Difficulty, or inability of measuring threshold surface contamination values, worker exposure, and physical access constraints have limited the effectiveness of this approach. Science and Engineering associates, Inc. under contract with the DOE Morgantown Energy Technology Center has developed and demonstrated the Pipe Explorer{trademark} system, which uses an inverting membrane to transport various characterization sensors into pipes. The basic process involves inverting (turning inside out) a tubular impermeable membrane under air pressure. A characterization sensor is towed down the interior of the pipe by the membrane.