NRC Information No. 90-21: Potential failure of motor-operated butterfly valves to operate because valve seat friction was underestimated

International Nuclear Information System (INIS)

Rossi, C.E.

1992-01-01

In October 1988, at Catawba Nuclear Station Unit 1, a motor-operated butterfly valve in the service water system failed to open under high differential pressure conditions. The licensee concluded that the valve manufacturer, BIF/General Signal Corporation, had underestimated the degree to which the material used in the valve seat would harden with age (the responsibility for these valves has been transferred to Paul-Munroe Enertech). This underestimation of the age hardening had led the manufacturer to assume valve seat friction forces that were less than the actual friction forces in the installed valve. To overcome the larger-than-anticipated friction forces, the licensee's engineering staff recommended the open torque switch for 56 butterfly valves be reset to the maximum allowable value. The systems in which these valves are located include the component cooling water system, service water system, and various ventilation systems. By July 26, 1989, the torque switch adjustments were completed at Catawba Units 1 and 2. After reviewing the final settings, the licensee's engineering staff determined that the actuators for three butterfly valves in the component cooling water system might not be able to overcome the friction forces resulting from maximum seat hardening. On December 13, 1989, the licensee determined that the failure of these BIF/General Signal motor-operated valves (MOVs) could cause a loss of cooling water to residual heat removal system heat exchangers. To resolve the concern regarding the operability of these BIF/General Signal valves, a torque switch bypass was installed on two of the actuators to allow full motor capability during opening

Dynamic testing of POSI-SEAL motor-operated butterfly valves using strain gages

International Nuclear Information System (INIS)

Richard, M.C.; Chiou, D.

1994-01-01

Utilities operating nuclear power plants recognize that the correct functioning of all motor-operated valves, and particularly those in safety-related systems, is of paramount importance. The U.S. Nuclear Regulatory Commission has issued Generic Letter 89-10 relative to this concern. Operability must be demonstrated under design-basis conditions. In order to demonstrate operability of motor-operated butterfly valves, the valve stem torque must be determined. The valve stem torque is a function of seat material, stem packing, stem bearing friction, and hydrodynamic lift and drag. The total valve operating hydrodynamic torque can be predicted using the valve manufacturer's data and the differential pressure. In order to validate the valve manufacturer's data, the actual total valve hydrodynamic torque is measured using strain gages mounted directly on the valve stem. This paper presents the results of comparing the predicted total valve operating hydrodynamic torque with the actual total valve operating hydrodynamic torque for six POSI-SEAL Class 150 high performance butterfly valves

Remote operated valves - the Bolivian approach

Energy Technology Data Exchange (ETDEWEB)

Cuellar, O.; Arce, G.; Blanco, E.; Collazos, A.; Chavarria, E. [Transredes S.A., Transporte de Hidrocarburos, La Paz (Bolivia)

2005-07-01

For pipeline operators, the Remote Operated Valves (ROV) are tools to isolate pipe segments and contain any potential spill and they are also useful tools to provide data on operating conditions. Projects and articles about the locations and site layouts were developed to install Remote Operated Valves and the criteria for their use; each location has its own environmental, social and logistical particulars. This article describes the approach used to install ROV in Bolivia and the final design installed discussions and lessons learned about the: criteria to define the location, layout equipment installed and shelter and particulars of the location. (author)

Training aids: the motor operator valve trainer

International Nuclear Information System (INIS)

McCulloch, B.

1987-01-01

The spectrum of training aids used in the nuclear industry runs the gamut from the very basic (i.e., valve training aids - gate, globe, check) to the highly complex (i.e., nuclear full scope simulator). Designing and purchasing the best training aids take much time, detailed investigation, and good understanding of plant operations. The training aid that has given the New York Power Authority the best results has been the motor operator valve (MOV) trainer. Some of the items that make the MOV trainer a good choice are: (1) large number of MOVs in the plant, (2) importance of MOVs to safe plant operation, (3) detailed MOV procedures used by the plant, (4) history of MOV problems, and (5) ability to demonstrate important concepts and operation - hammer blow effect, torque and limit switch adjustment and functions, and actual sequence of operation of the limitorque valve operator

Durability Tests of Ball Valve Prototype with Flowmeter Operation

Science.gov (United States)

Rogula, J.; Romanik, G.

2018-02-01

The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

In-operation inspection technology development-4 ''development of degradation prediction technology for motor-operated valves''

International Nuclear Information System (INIS)

Kikuo, Takeshima; Yuichi, Higashikawa; Masahiro, Koike; Kenji, Matsumoto; Eiji, O'shima

2001-01-01

A method for degradation predicting technology has been proposed for motor operated valves in nuclear power plants which is based on the concept of condition monitoring for maintenance. This method (degradation prediction technology) eliminates the unnecessary overhaul of valves and realizes high reliability and economy. The degradation mechanism was clarified by long time heating experiments of gasket and gland packing and the wear test for them and stem nut to research valve parts degradation by stress (pressure, temperature, etc) during plant operation. Effective electric power measurements for motor operated valves were confirmed to be useful discovering valve part failures. The motor operated valve degradation prediction system was developed on the basis of the experiment results and mechanism. The system is able to predict the degradation of valve parts (gasket/gland packing, stem, stem nut, etc) utilizing plant data (pressure, temperature, etc) and effective power of the motor. The life of valve parts can be estimated from the experimental results. (authors)

Application of artificial intelligence to motor operated valve testing

International Nuclear Information System (INIS)

Bogard, T.; Bednar, F.; Matty, T.; Kent, R.

1989-01-01

Improper valve maintenance can be a significant roadblock to successful power plant operation. There have been events during which motor operated valves failed on demand due to improper switch settings. For nuclear electric generating stations, these events have led to regulatory requirements such as NRC Bulletin 85-03 and NRC Bulletin 89-10 Safety Related Motor Operated Valve Testing and Surveillance which imposes strict testing and programmatic requirements on motor operated valves (MOV). Part of the requirements include performing diagnostic testing to verify stem thrust loads and switch settings. Diagnostic equipment must be non-intrusive, minimize valve disassembly, and reduce plant refueling critical path time for testing. In this paper an on-line diagnostic system using sensors to measure stem forces, motor current, and valve position, and a portable system employing these same sensor inputs in addition to torque, limit and torque bypass switch inputs is described. Sophisticated graphic software is employed to display data or trace information. A rule based artificial intelligence (AI) system is used to analyze sensor outputs. Objectives for valve diagnostics, sample AI rules, results of actual field testing, and system software/hardware architecture are presented

Worchester Solenoid Actuated Gas Operated MCO Isolation Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as integral parts of the actuator that are used in process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) to prevent MCO vent drain to either reduce air in-leakage or loss of He. The valves have couplings for transverse actuator mounting

Worcester Solenoid-Actuated Gas Operated MCO Isolation Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as Integral parts of the actuator that are used in different process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) for MCO isolation to either reduce air in leakage or loss of He. All valves have coupling for transverse actuator mounting

Operational durability of a giant ER valve for Braille display

Science.gov (United States)

Luning, Xu; Han, Li; Yufei, Li; Shen, Rong; Kunquan, Lu

2017-05-01

The compact configuration of giant ER (electrorheological) valves provides the possibility of realizing a full-page Braille display. The operational durability of ER valves is a key issue in fulfilling a Braille display. A giant ER valve was used to investigate the variations in pressure drops and critical pressure drops of the valves over a long period under some typical operational parameters. The results indicate that neither the pressure drops nor critical pressure drops of giant ER valves show apparent deterioration over a long period. Without ER fluid exchange, a blockage appears in the channel of the valve because the ER structures induced by an external electric field cannot be broken by the Brownian motion of hydraulic oil molecules when the external electric field is removed. Forcing ER fluid flow is an effective and necessary method to keep the channel of the valve unblocked. Thus the operational durability of the valve using giant ER fluids is able to meet the demands of Braille display.

Enhancement of pressurizer safety valve operability by seating design improvement

International Nuclear Information System (INIS)

Moisidis, N.T.; Ratiu, M.D.

1994-01-01

Operating conditions specific to Pressurizer Safety Valves (PSVs) have led to numerous problems and have caused industry and NRC concerns regarding the adequacy of spring loaded self-actuated safety valves for Reactor Coolant System (RCS) overpressure protection. Specific concerns are: setpoint drift, spurious actuations and leakage. Based on testing and valve construction analysis of a Crosby model 6M6 PSV, it was established that the primary contributor to the valve problems is a susceptibility to weak seating. To eliminate spring instability, a new spring washer was designed, which guides the spring and precludes its rotation from the reference installed position. Results of tests performed on a prototype PSV equipped with the modified upper spring washer has shown significant improvements in valve operability and a consistent setpoint reproducibility to less than ±1% of the PSV setpoint (testing of baseline, unmodified valve, resulted in a setpoint drift of ±2%). Enhanced valve operability will result in a significant decrease in operating and maintenance costs associated with valve maintenance and testing. In addition, the enhanced setpoint reproducibility will allow the development of a nitrogen to steam correlation for future in-house PSV testing which will result in further reductions in costs associated with valve testing

Operating experience feedback report -- Pressure locking and thermal binding of gate valves

International Nuclear Information System (INIS)

Hsu, C.

1993-03-01

The potential for valve inoperability caused by pressure locking and thermal binding has been known for many years in the nuclear industry. Pressure locking or thermal binding is a common-mode failure mechanism that can prevent a gate valve from opening, and could render redundant trains of safety systems or multiple safety systems inoperable. In spite of numerous generic communications issued in the past by the Nuclear Regulatory Commission (NRC) and industry, pressure locking and thermal binding continues to occur to gate valves installed in safety-related systems of both boding water reactors (BWRs) and pressurized water reactors (PWRs). The generic communications to date have not led to effective industry action to fully identify, evaluate, and correct the problem. This report provides a review of operating events involving these failure mechanisms. As a result of this review this report: (1) identifies conditions when the failure mechanisms have occurred, (2) identifies the spectrum of safety systems that have been subjected to the failure mechanisms, and (3) identifies conditions that may introduce the failure mechanisms under both normal and accident conditions. On the basis of the evaluation of the operating events, the Office for Analysis and Evaluation of Operational Data (AEOD) of the NRC concludes that the binding problems with gate valves are an important safety issue that needs priority NRC and industry attention. This report also provides AEOD's recommendation for actions to effectively prevent the occurrence of valve binding failures

Enhancement of pressurizer safety valve operability by seating design improvement

International Nuclear Information System (INIS)

Moisidis, N.T.; Ratiu, M.D.

1995-01-01

Operating conditions specific to pressurizer safety valves (PSVs) have led to numerous problems and have caused industry and NRC concerns regarding the adequacy of spring-loaded self-actuated safety valves for reactor coolant system (RCS) overpressure protection. Specific concerns are: setpoint drift, spurious actuations, and pressure protection. Specific concerns are: setpoint drift, spurious actuations, and leakage. Based on testing and valve construction analysis of a Crosby model 6M6 PSV (Moisidis and Ratiu, 1992), it was established that the primary contributor to the valve problems is a susceptibility to weak seating. To eliminate spring instability, a new spring washer was designed, which guides the spring and precludes its rotation from the reference installed position. Results of tests performed on a prototype PSV equipped with the modified upper spring washer has shown significant improvements in valve operability and a consistent setpoint reproducibility to less than ±1% of the PSV setpoint (testing of baseline, unmodified valve, resulted in a setpoint drift of ± 2%). Enhanced valve operability will result in a significant decrease in operating and maintenance costs associated with valve maintenance and testing. In addition, the enhanced setpoint reproducibility will allow the development of a nitrogen to steam correlation for future in-house PSV testing which will result in further reductions in costs associated with valve testing

Survey of valve operator-related events occurring during 1978, 1979 and 1980

International Nuclear Information System (INIS)

Brown, E.J.; Ashe, F.S.

1983-01-01

The survey approach was to analyze several events and identify trends or patterns. The primary data source was licensee event reports (LERs) and consisted of 444 total valve operator events with 193 motor operator events which served as the basis for this study. The investigation revealed that motor-operated events could be grouped in three major categories which are torque switches, limit switches, and motors. The major findings are: (1) Torque switches do not appear to be a dominant cause of valve assembly inoperability. The reported information suggests torque switch events are an indication of symptomatic change with time in valve operability characteristics rather than a root cause of valve inoperability. (2) Repetitive problems are occurring with valve operators. It may occur on the same valve, a valve in similar service in a similar system, or a valve in similar service in a redundant train of the same system. (3) The plant operating staff objective appears to be a mode of finding measures to return inoperable equipment to operational status rather than to determine root causes of inoperability. (4) Motor burnout of valve motor operators has occurred quite frequently in High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) systems of BWR units. (orig./GL)

Prediction of a required dynamic torque for motor-operated butterfly valves

International Nuclear Information System (INIS)

Bae, J. H.; Lee, K. N.; Jeong, W. K.

2002-01-01

This study describes the methodology for predicting a required dynamic torque in motor-operated butterfly valves. The results of this methodology have been compared with test data for motor-operated butterfly valves in nuclear power plant. With the close review of test data and torque prediction, it is concluded that the prediction methodology is conservative to predict a required dynamic torque of motor-operated butterfly valves. In addition, the information of correct differential pressure is vital to predict a required dynamic torque of motor-operated butterfly valves

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

Continuous-flow cardiac assistance: effects on aortic valve function in a mock loop.

Science.gov (United States)

Tuzun, Egemen; Rutten, Marcel; Dat, Marco; van de Vosse, Frans; Kadipasaoglu, Cihan; de Mol, Bas

2011-12-01

As the use of left ventricular assist devices (LVADs) to treat end-stage heart failure has become more widespread, leaflet fusion--with resul-tant aortic regurgitation--has been observed more frequently. To quantitatively assess the effects of nonpulsatile flow on aortic valve function, we tested a continuous-flow LVAD in a mock circulatory system (MCS) with an interposed valve. To mimic the hemodynamic characteristics of LVAD patients, we utilized an MCS in which a Jarvik 2000 LVAD was positioned at the base of a servomotor-operated piston pump (left ventricular chamber). We operated the LVAD at 8000 to 12,000 rpm, changing the speed in 1000-rpm increments. At each speed, we first varied the outflow resistance at a constant stroke volume, then varied the stroke volume at a constant outflow resistance. We measured the left ventricular pressure, aortic pressure, pump flow, and total flow, and used these values to compute the change, if any, in the aortic duty cycle (aortic valve open time) and transvalvular aortic pressure loads. Validation of the MCS was demonstrated by the simulation of physiologic pressure and flow waveforms. At increasing LVAD speeds, the mean aortic pressure load steadily increased, while the aortic duty cycle steadily decreased. Changes were consistent for each MCS experimental setting, despite variations in stroke volume and outflow resistance. Increased LVAD flow results in an impaired aortic valve-open time due to a pressure overload above the aortic valve. Such an overload may initiate structural changes, causing aortic leaflet fusion and/or regurgitation. Copyright © 2011 Elsevier Inc. All rights reserved.

Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

Directory of Open Access Journals (Sweden)

Harish Ramakrishna

2015-01-01

Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

A quarter of a century of experience with aortic valve-sparing operations.

Science.gov (United States)

David, Tirone E; Feindel, Christopher M; David, Carolyn M; Manlhiot, Cedric

2014-09-01

To examine the late outcomes of aortic valve-sparing operations to treat patients with aortic root aneurysm with and without aortic insufficiency (AI) in a cohort of patients followed up prospectively since 1988. A total of 371 consecutive patients had undergone aortic valve-sparing surgery (mean age, 47 ± 15 years; 78% men) from 1988 through 2010. In addition to the aortic root aneurysm, 47% had moderate or severe AI, 35.5% had Marfan syndrome, 12.1% had type A aortic dissection, 9.2% had bicuspid aortic valve, 8.4% had mitral insufficiency, 16.1% had aortic arch aneurysm, and 10.2% had coronary artery disease. Reimplantation of the aortic valve was used in 296 patients and remodeling of the aortic root in 75. Cusp repair by plication of the free margin along the nodule of Arantius was used in 36.6% of patients, and reinforcement of the free margin with a double layer of fine Gore-Tex suture in 24.2%. The patients were followed up prospectively with images of the aortic root for a median follow-up of 8.9 ± 5.2 years. A total of 4 operative and 39 late deaths occurred. Survival at 18 years was 76.8% ± 4.31%, lower than that for the general population matched for age and gender. Age, type A aortic dissection, impaired ventricular function, and preoperative AI were associated with increased mortality on multivariable analysis. Reoperations on the aortic valve were performed in 8 patients for recurrent AI and in 2 for infective endocarditis. Freedom from reoperation on the aortic valve at 18 years was 94.8% ± 2.0%. No predictors of the need for reoperation were found on multivariable analysis. Eighteen patients developed AI greater than mild. Freedom from AI greater than mild at 18 years was 78.0% ± 4.8%. No predictors of recurrent AI were identified on multivariable analysis. Aortic valve-sparing operations continue to provide excellent clinical outcomes, although a slow but progressive deterioration of aortic valve function seems to occur during the first 2

Development of advanced diagnostic technologies for motor-operated valves

International Nuclear Information System (INIS)

Hegi, Kotaro; Shimizu, Shunichi; Higuma, Koji; Nishino, Koji; Osaki, Kenji; Watanabe, Kazumi; Hamano, Frank

2010-01-01

As use of condition-based maintenance is allowed in the new regulatory inspection system employed in Japan's nuclear power plants in 2009, development of advanced diagnostic technologies for motor-operated valves (MOVs) is now required. This report discusses advanced technologies in valve-setup verification, valve performance evaluation, monitoring of valve/actuator conditions by performance diagnostic system and moreover detection of stem crack by ultrasonic diagnostic system. (author)

Diaphragms in air-operated valves

Energy Technology Data Exchange (ETDEWEB)

Groeger, J.E.

1996-12-01

The author will present current issues related to diaphgrams in air-operated valves. Altran Materials Engineering, Inc., often performs root-cause analyses for nuclear power plant owners. The author will discuss various analyses that have been performed or are currently underway.

Outcomes of Aortic Valve-Sparing Operations in Marfan Syndrome.

Science.gov (United States)

David, Tirone E; David, Carolyn M; Manlhiot, Cedric; Colman, Jack; Crean, Andrew M; Bradley, Timothy

2015-09-29

In many cardiac units, aortic valve-sparing operations have become the preferred surgical procedure to treat aortic root aneurysm in patients with Marfan syndrome, based on relatively short-term outcomes. This study examined the long-term outcomes of aortic valve-sparing operations in patients with Marfan syndrome. All patients with Marfan syndrome operated on for aortic root aneurysm from 1988 through 2012 were followed prospectively for a median of 10 years. Follow-up was 100% complete. Time-to-event analyses were calculated using the Kaplan-Meier method with log-rank test for comparisons. A total of 146 patients with Marfan syndrome had aortic valve-sparing operations. Reimplantation of the aortic valve was performed in 121 and remodeling of the aortic root was performed in 25 patients. Mean age was 35.7 ± 11.4 years and two-thirds were men. Nine patients had acute, 2 had chronic type A, and 3 had chronic type B aortic dissections before surgery. There were 1 operative and 6 late deaths, 5 caused by complications of dissections. Mortality rate at 15 years was 6.8 ± 2.9%, higher than the general population matched for age and sex. Five patients required reoperation on the aortic valve: 2 for endocarditis and 3 for aortic insufficiency. Three patients developed severe, 4 moderate, and 3 mild-to-moderate aortic insufficiency. Rate of aortic insufficiency at 15 years was 7.9 ± 3.3%, lower after reimplantation than remodeling. Nine patients developed new distal aortic dissections during follow-up. Rate of dissection at 15 years was 16.5 ± 3.4%. Aortic valve-sparing operations in patients with Marfan syndrome were associated with low rates of valve-related complications in long-term follow-up. Residual and new aortic dissections were the leading cause of death. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Replacement screws valve operating under Trunnion; Substituicao de parafusos de valvulas Trunnion em regime de operacao

Energy Technology Data Exchange (ETDEWEB)

Souza Netto, Charles de; Santos, Rogerio Andre Zolin dos; Arnhold, Diego [Companhia de Gas do Estado do Rio Grande do Sul (SULGAS), Porto Alegre, RS (Brazil); Jacques, Rodrigo das Neves [Guidotti e Vieira Manutencao Industrial Ltda., Canoas, RS (Brazil)

2012-07-01

The report shows the process created for the substitution and extraction of bearing screws of the Trunnion valves, in operation. The methodology was developed at the 'Companhia de Gas do Estado do Rio Grande do Sul - SULGAS', with the objective of avoiding failure emergency situations, and or sudden breaking of the screws of fixation of the lid of the inferior bearing of the Trunnion valves. it is a preventive process of substitution of these screws, that after a great period of use in atmospheres with high potential of oxidation present structural failure. The breaking of these components creates a leaking process by the inferior lid of the valves, fact that is intended to be avoided with the application of the technical procedure of this report, guaranteeing the integrity of the valves that are vital components for the continuous operation of the gas pipe line. (author)

Operability of the valves in the french pressurized water nuclear plants

International Nuclear Information System (INIS)

Conte, M.; Vrillon, B.

1986-10-01

There are about 10 000 valves in a PWR, which must have a high standard of reliability. This confidence can be obtained by a continuous effort at every important stage, in the maintenance of the product's quality: design, loop qualifying tests, manufacture, plant start-up tests, maintenance and periodic tests during operation, feed-back of experience. This paper describes more particularly the loop qualifying tests

Left atrial isolation associated with mitral valve operations.

Science.gov (United States)

Graffigna, A; Pagani, F; Minzioni, G; Salerno, J; Viganò, M

1992-12-01

Surgical isolation of the left atrium was performed for the treatment of chronic atrial fibrillation secondary to valvular disease in 100 patients who underwent mitral valve operations. From May 1989 to September 1991, 62 patients underwent mitral valve operations (group I); 19, mitral valve operations and DeVega tricuspid annuloplasty (group II); 15, mitral and aortic operations (group III); and 4, mitral and aortic operations and DeVega tricuspid annuloplasty (group IV). Left atrial isolation was performed, prolonging the usual left paraseptal atriotomy toward the left fibrous trigone anteriorly and the posteromedial commissure posteriorly. The incision was conducted a few millimeters apart from the mitral valve annulus, and cryolesions were placed at the edges to ensure complete electrophysiological isolation of the left atrium. Operative mortality accounted for 3 patients (3%). In 79 patients (81.4%) sinus rhythm recovered and persisted until discharge from the hospital. No differences were found between the groups (group I, 80.7%; group II, 68.5%; group III, 86.7%; group IV, 75%; p = not significant). Three late deaths (3.1%) were registered. Long-term results show persistence of sinus rhythm in 71% of group I, 61.2% of group II, 85.8% of group III, and 100% of group IV. The unique risk factor for late recurrence of atrial fibrillation was found to be preoperative atrial fibrillation longer than 6 months. Due to the satisfactory success rate in recovering sinus rhythm, we suggest performing left atrial isolation in patients with chronic atrial fibrillation undergoing valvular operations.

Motor current signature analysis for determining operational readiness of motor-operated valves (MOVs)

International Nuclear Information System (INIS)

Kryter, R.C.; Haynes, H.D.

1987-01-01

Motor current signature analysis (MCSA) is a novel diagnostic process for condition monitoring of electric-motor-driven mechanical equipment (e.g., pumps, motor-operated valves, compressors, and processing machinery). The MCSA process identifies, characterizes, and trends over time the instantaneous load variations of mechanical equipment in order to diagnose changes in the condition of the equipment (e.g., due to degradation or service wear), which, if allowed to continue, may lead to failure. It monitors the instantaneous variations (noise content) in the electric current flowing through the power leads to the electric motor that drives the equipment. The motor itself thereby acts as a transducer, sensing both large and small, long-term and rapid, mechanical load variations and converting them to variations in the induced current generated in the motor windings. This motor current noise signature is detected, amplified, and further processed as needed to examine its time domain and frequency domain (spectral) characteristics. The operational principles of MCSA and the nonintrusive data collection apparatus and procedure used with MOVs will be described. Data collected from MOVs in both laboratory and in-plant environments will also be shown to illustrate the ability of MCSA to ''see'' the detailed inner workings of the valve and operator and thus to detect degraded performance at an incipient stage. (Set of 18 vugraphs)

Regulatory standpoints on the design-basis capability of safety-related motor-operated valves(MOVs) and power-operated gate valves(POGVs)

International Nuclear Information System (INIS)

Kim, W. T.; Kum, O. H.

1999-01-01

The weakness in the design-basis capability of Motor-Operated Valves(MOVs) and the susceptibility to Pressure Locking and Thermal Binding phenomena of Power-Operated Gate Valves(POGVs) have been major concerns to be resolved in the nuclear society in and abroad since Three Mile Island accident occurred in the USA in 1979. Through detailed analysis of operating experience and regulatory activities, some MOVs and POGVs have been found to be unreliable in performing their safety functions when they are required to do so under certain conditions, especially under design-basis accident conditions. Further, it is well understood that these safety problems may not be identified by the typical valve in-service testing(IST). USNRC has published three Generic Letters, GL 89-10, GL 95-07, and GL 96-05, requiring nuclear plant licensees to take appropriate actions to resolve the problems mentioned above. Korean nuclear regulatory body has made public an administration measure called 'Regulatory recommendation to verify safety functions of the safety-related MOVs and POGVs' on June 13, 1997, and in this administration measure Korean utility is asked to submit written documents to show how it assure design-basis capability of these valves. The following are among the major concerns being considered from a regulation standpoint. Program scope and implementation priority, dynamic tests under differential pressure conditions, accuracy of diagnostic equipment, torque switch setting and torque bypass percentage, weak link analysis, motor actuator sizing, corrective actions taken to resolve pressure locking and thermal binding susceptibility, and a periodic verification program for the valves once design-basis capability has been verified

In-operation inspection technology development-4 ''development of degradation prediction technology for motor-operated valves''

Energy Technology Data Exchange (ETDEWEB)

Kikuo, Takeshima; Yuichi, Higashikawa [Hitachi Engineering and Production Div., Nuclear Systems Div., Hitachi, Ltd., Ibaraki (Japan); Masahiro, Koike [Power and Industrial Systems R and D Lab., Hitachi, Ltd., (Japan); Kenji, Matsumoto [Tokyo Research and Development Center, Japan Power Engineering and Inspection Corp. (Japan); Eiji, O' shima [Tokyo Institute of Technology (Japan)

2001-07-01

A method for degradation predicting technology has been proposed for motor operated valves in nuclear power plants which is based on the concept of condition monitoring for maintenance. This method (degradation prediction technology) eliminates the unnecessary overhaul of valves and realizes high reliability and economy. The degradation mechanism was clarified by long time heating experiments of gasket and gland packing and the wear test for them and stem nut to research valve parts degradation by stress (pressure, temperature, etc) during plant operation. Effective electric power measurements for motor operated valves were confirmed to be useful discovering valve part failures. The motor operated valve degradation prediction system was developed on the basis of the experiment results and mechanism. The system is able to predict the degradation of valve parts (gasket/gland packing, stem, stem nut, etc) utilizing plant data (pressure, temperature, etc) and effective power of the motor. The life of valve parts can be estimated from the experimental results. (authors)

Operational Experience and Consolidations for the Current Lead Control Valves of the Large Hadron Collider

CERN Document Server

Perin, A; Pirotte, O; Krieger, B; Widmer, A

2012-01-01

The Large Hadron Collider superconducting magnets are powered by more than 1400 gas cooled current leads ranging from 120 A to 13000 A. The gas flow required by the leads is controlled by solenoid proportional valves with dimensions from DN 1.8 mm to DN 10 mm. During the first months of operation, signs of premature wear were found in the active parts of the valves. This created major problems for the functioning of the current leads threatening the availability of the LHC. Following the detection of the problems, a series of measures were implemented to keep the LHC running, to launch a development program to solve the premature wear problem and to prepare for a global consolidation of the gas flow control system. This article describes first the difficulties encountered and the measures taken to ensure a continuous operation of the LHC during the first year of operation. The development of new friction free valves is then presented along with the consolidation program and the test equipment developed to val...

Detection circuit of solenoid valve operation and control rod drive mechanism utilizing the circuit

International Nuclear Information System (INIS)

Ono, Takehiko.

1976-01-01

Object: To detect the operation of a plunger and detect opening and closing operations of a solenoid valve driving device due to change in impedance of a coil for driving the solenoid valve to judge normality and abnormality of the solenoid valve, thereby increasing reliance and safety of drive and control apparatus of control rods. Structure: An arrangement comprises a drive and operation detector section wherein the operation of a solenoid driving device for controlling power supply to a coil for driving the solenoid valve to control opening and closing of the solenoid valve, and a plunger operation detector section for detecting change in impedance of the drive coil to detect that the plunger of the solenoid valve is either in the opening direction or closing direction, whereby a predetermined low voltage such as not to activate the solenoid valve even when the solenoid valve is open or closed is applied to detect a current flowing into the coil at that time, thus detecting an operating state of the plunger. (Yoshino, Y.)

Non intrusive check valve diagnostics at Bruce A

International Nuclear Information System (INIS)

Marsch, S.P.

1997-01-01

Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

Non intrusive check valve diagnostics at Bruce A

Energy Technology Data Exchange (ETDEWEB)

Marsch, S.P. [Ontario Hydro, Bruce Nuclear Generating Station A, Tiverton, ON (Canada)

1997-07-01

Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

Worcester 1 Inch Solenoid-Actuated Gas-Operated VPS System Ball Valve

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valve incorporates a solenoid and limit switches as integral parts of the actuator. The valve is normally open and fails safe to the closed position. The associated valve position switch is class GS

MOVES: A knowledge-based system for maintenance planning for motor-operated valves

International Nuclear Information System (INIS)

Winter, M.

1987-01-01

Over the past several years, knowledge-based expert systems have emerged as an important part of the general research area known as artificial intelligence. This paper describes a cooperative effort between faculty members at Iowa State University and engineers at the Duane Arnold Energy Center [a 545-MW(electric) boiling water reactor operated by Iowa Electric Light and Power Company] to explore the development of an advisory system for valve maintenance planning. This knowledge-based program, known as Motor-Operated Valves Expert System (MOVES), has a data base that currently includes safety-related motor-operated valves (∼117 valves). Valve maintenance was selected as the subject for the expert system because of the importance of valves in nuclear plant and their impact of plant availability. MOVES is being developed using the microcomputer-(IBM compatible) based expert system tool INSIGHT2+. The authors have found that the project benefits both the university and the utility

Dynamic performance of self-operated three-way valve used in a hybrid air conditioner

International Nuclear Information System (INIS)

Zhang, Penglei; Zhou, Dehai; Shi, Wenxing; Li, Xianting; Wang, Baolong

2014-01-01

A hybrid air conditioner combining a thermosyphon cycle with a vapor compression refrigeration cycle has a large energy saving potential compared with a common air conditioner for spaces requiring year-round cooling. The performance of the switch between the vapor compression mode and the thermosyphon mode largely impacts the safety and reliability of hybrid air conditioners. Therefore, a self-operated three-way valve is proposed. A thermodynamic model and a kinetic model are developed in this paper to evaluate the dynamic performance of the switch valve. The effects of the spring force constant, compressor discharging volume, fit clearance and piston length on the dynamic performance of the switch valve are analyzed. In conclusion, the proposed self-operated three-way valve can realize the switch operation accurately. - Highlights: •A self-operated three-way valve is proposed for hybrid air conditioners. •The thermodynamic model and kinetic model of the self-operated three-way valve are developed. •The validity of models is verified by experiments. •Effects of four main design parameters on the operating performance of the valve are researched

Safety significance of inadvertent operation of motor-operated valves in nuclear power plants

International Nuclear Information System (INIS)

Ruger, C.J.; Higgins, J.C.; Carbonaro, J.F.; Hall, R.E.

1994-01-01

Concerns about the consequences of valve mispositioning were brought to the forefront following an event at Davis Besse in 1985. The concern related to the ability to reposition open-quotes position-changeableclose quotes motor-operated valves (MOVs) from the control room in the event of their inadvertent operation and was documented in U.S. Nuclear Regulatory Commission (USNRC) Bulletin 85-03 and Generic Letter (GL) 89-10. The mispositioned MOVs may not be able to be returned to their required position due to high differential pressure or high flow conditions across the valves. The inability to reposition such valves may have significantly safety consequences, as in the Davis Besse event. However, full consideration of such mispositioning in safety analyses and in MOV test programs can be labor intensive and expensive. Industry raised concerns that consideration of position-changeable valves under GL 89-10 would not decrease the probability of core damage to an extent that would justify licensee costs. As a response, Brookhaven National Laboratory has conducted separate scoping studies for both boiling water reactors (BWRs) and pressurized water reactors (PWRs) using probabilistic risk assessment (PRA) techniques to determine if such valve mispositioning by itself is significant to safety. The approach used internal events PRA models to survey the order of magnitude of the risk-significance of valve mispositioning by considering the failure of selected position-changeable MOVs. The change in core damage frequency was determined for each valve considered, and the results were presented as a risk increase ratio for each of four assumed MOV failure rates. The risk increase ratios resulting from this failure rate sensitivity study can be used as a basis for a determination of the risk-significance of the MOV mispositioning issues for BWRs and PWRs

Independent deterministic analysis of the operational event with turbine valve closure and one atmospheric dump valve stuck open

International Nuclear Information System (INIS)

Rijova, N.

2007-01-01

The paper presents the results of the independent analysis of the operational event which took place on 07.11.2003 at Unit 1 of Rostov NPP. The event started with switching off the electrical generator of the turbine due to a short cut at the local switching substation. The turbine isolating valves closed to prevent damage of the turbine. The condenser dump valves (BRU-K) and the atmospheric dump valves (BRU-A) opened to release the vapour generated in the steam generators. After the pressure decrease in the steam generators BRU-K and BRU-A closed but one valve stuck opened. The emergency core cooling system was activated automatically. The main circulation pump of the loop corresponding to the steam generator with the stuck BRU-A was tripped. The stuck valve was closed by the operational stuff manually. No safety limits were violated. The analysis of the event was carried out using ATHLET code. A reasonable agreement was achieved between the calculated and measured values. (author)

Twenty-five-year experience with the Björk-Shiley convexoconcave heart valve: a continuing clinical concern.

Science.gov (United States)

Blot, William J; Ibrahim, Michel A; Ivey, Tom D; Acheson, Donald E; Brookmeyer, Ron; Weyman, Arthur; Defauw, Joseph; Smith, J Kermit; Harrison, Donald

2005-05-31

The first Björk-Shiley convexoconcave (BSCC) prosthetic heart valves were implanted in 1978. The 25th anniversary provided a stimulus to summarize the research data relevant to BSCC valve fracture, patient management, and current clinical options. Published and unpublished data on the risks of BSCC valve fracture and replacement were compiled, and strategies for identifying candidates for prophylactic valve reoperation were summarized. By December 2003, outlet strut fractures (OSFs), often with fatal outcomes, had been reported in 633 BSCC valves (0.7% of 86,000 valves implanted). Fractures still continue to occur, but average rates of OSFs in 60 degrees valves are now valve characteristics, especially valve angle and size, with weaker effects associated with other manufacturing variables. OSF risks are mildly lower among women than men but decline sharply with advancing age. The risks of valve replacement typically greatly exceed those of OSF. By comparing individualized estimated risks of OSF versus valve replacement, guidelines have been developed to identify the small percentage of BSCC patients (mostly younger men) who would be expected to have a gain in life expectancy should reoperative surgery be performed. Twenty-five years after the initial BSCC valve implants, fractures continue to occur. Continued monitoring of BSCC patients is needed to track and quantify risks and enable periodic updating of guidelines for patients and their physicians.

Long-term performance of motor-operated valves

Energy Technology Data Exchange (ETDEWEB)

Scarbrough, T.G.

1996-12-01

The U.S. Nuclear Regulatory Commission (NRC) requires that motor-operated valves (MOVs) important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed. Despite these requirements, operating experience and research revealed problems with the performance of MOVs in operating nuclear power plants. In response to the concerns about MOV performance, the NRC issued Generic Letter (GL) 89-10, {open_quotes}Safety-Related Motor-Operated Valve Testing and Surveillance,{close_quotes} and its supplements. Most licensees have completed the aspects of their GL 89-10 programs associated with the review of MOV design bases, verification of MOV switch settings initially, testing of MOVs under design-basis conditions where practicable, and improvement of evaluations of MOV failures and necessary corrective action. Licensees are establishing processes to ensure that the long-term aspects of their MOV programs, such as periodic verification of MOV capability and the trending of MOV problems, are maintained. The NRC staff is developing a generic letter to address periodic verification of MOV design-basis capability.

Long-term performance of motor-operated valves

International Nuclear Information System (INIS)

Scarbrough, T.G.

1996-01-01

The U.S. Nuclear Regulatory Commission (NRC) requires that motor-operated valves (MOVs) important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed. Despite these requirements, operating experience and research revealed problems with the performance of MOVs in operating nuclear power plants. In response to the concerns about MOV performance, the NRC issued Generic Letter (GL) 89-10, open-quotes Safety-Related Motor-Operated Valve Testing and Surveillance,close quotes and its supplements. Most licensees have completed the aspects of their GL 89-10 programs associated with the review of MOV design bases, verification of MOV switch settings initially, testing of MOVs under design-basis conditions where practicable, and improvement of evaluations of MOV failures and necessary corrective action. Licensees are establishing processes to ensure that the long-term aspects of their MOV programs, such as periodic verification of MOV capability and the trending of MOV problems, are maintained. The NRC staff is developing a generic letter to address periodic verification of MOV design-basis capability

SEBIM pilot operated valves - CANDU and other applications

International Nuclear Information System (INIS)

Schaumburg, Gerald; Hera, Vlad

1999-01-01

The SEBIM Group, located at Chateauneuf-les-Martigues, near Marseilles, on the Mediterranean coast of France, is a market leader for the pilot operated safety relief valves in the nuclear industry. Its valves, which are subject to rigorous safety and reliability criteria, are intended to satisfy the most exigent requirements of not only the nuclear but also other demanding applications. The group manufacturing units are equipped with the state-of-the-art machinery, technical equipment and computer facilities. All personnel is highly specialized and trained. Among many applications the valves designed and manufactured by SEBIM for the biggest CANDU reactors in Canada were subjected to exceptionally difficult testing conditions, prior of being excepted by Ontario Hydro and passed all tests successfully. As a consequence Darlington N.G.S. was equipped with one of the most advanced SEBIM pressure protection piece of equipment, the Tandem Pilot Operated Pressure Relief Valve. Due to the demonstrated qualities of our product we were able to obtain the necessary registration of our valve original design with the appropriate Canadian authorities, both at the provincial level and at the federal level. One may find SEBIM protection and other type of equipment in civilian nuclear plants all over Europe as well as in military applications, like the French Navy. The SEBIM valves, covering a range between 15 mm and 160 mm diameter and capable of withstanding an inlet pressure from 2 MPa to 20 MPa and the temperature of the fluid up to 450 dec. C, are very strong competitors in the specialized field. Among these valves the tandems have special design and special qualities, for special applications. As mentioned above, two of these tandems are used, in parallel, on the Bleed Condenser vessels of the Darlington units to provide the ultimate protection of the Pressure and Inventory Control System and, through it, to the Main Heat Transfer System which is the primary cooling source

[A clinical experience of continuous warm blood cardioplegia in two cases of repeat aortic valve surgery].

Science.gov (United States)

Nagaoka, H; In-nami, R; Watanabe, M; Funakoshi, N; Hirooka, K; Fujiwara, A

1992-11-01

The continuous warm blood cardioplegia (CWBC) was used for myocardial protection during aortic cross clamping in two cases of repeat aortic valve operations with good results. Case 1: A 46-year-old man, who underwent an aortic valve replacement because of the rheumatic aortic regurgitation (AR) in 1978, have suffered from orthopnea due to para-prosthetic valvular regurgitation since 1983. He was revealed to have bi-ventricular hypertrophy with myocardial damage on ECG, EF 0.27 on UCG, PCWP 20 mmHg and severe AR on cardiac catheterization. Case 2: A 43-year-old man, who had an aortic valvuloplasty for the non-rheumatic incompetency in 1981, have had a recurrent regurgitation, resulting in left ventricular hypertrophy accompanied by chest pain. Both cases were reoperated upon, having aortic valve replacement with mechanical prosthetic valves through the re-median sternotomy, utilizing CWBC with good recovery. CWBC provides an ideal circumstances for myocardial oxygen utilization during aortic cross clamping and moreover a benefit that needs not the wide dissection of the heart in a redo case because it has no need of topical cooling and ventricular defibrillation following aortic declamping. In conclusion, CWBC is very useful in a repeat aortic valve surgery.

Application of signature analysis for determining the operational readiness of motor-operated valves under blowdown test conditions

International Nuclear Information System (INIS)

Haynes, H.D.

1988-01-01

In support of the NRC-funded Nuclear Plant Aging Research (NPAR) program, Oak Ridge National Laboratory (ORNL) has carried out a comprehensive aging assessment of Motor-Operated Valves (MOVs). As part of this work, ORNL participated in the Gate Valve Flow Interruption Blowdown (GVFIB) tests carried out in Huntsville, Alabama. The GVFIB tests were intended primarily to determine the behavior of motor-operated gate valves under the temperature, pressure, and flow conditions expected to be experienced by isolation valves in Boiling Water Reactors (BWRs) during a high energy line break (blowdown) outside of containment. In addition, the tests provided an excellent opportunity to evaluate signature analysis methods for determining the operational readiness of the MOVs under those accident conditions. ORNL acquired motor current and torque switch shaft angular position data on two test MOVs during various times of the GVFIB tests. The reduction in operating ''margin'' of both MOVs due to the presence of additional valve running loads imposed by high flow was clearly observed in motor current and torque switch angular position signatures. In addition, the effects of differential pressure, fluid temperature, and line voltage on MOV operations were observed and more clearly understood as a result of utilizing signature analysis techniques. 1 ref.; 16 figs

The effects of load-sensitive behavior on the operability margins of motor-operated gate valves

International Nuclear Information System (INIS)

Steele, R. Jr.; Russell, M.J.; DeWall, K.G.; Watkins, J.C.

1993-01-01

Testing of motor-operated gate valves at various loads has produced a phenomenon we call load-sensitive behavior. This phenomenon has a significant effect on the accuracy of the methods used (and proposed) in the nuclear industry for determining that these valves can perform their design basis function. A valve subjected to tests with low flow and pressure loadings may achieve a stem thrust (at seating) analytically determined to be adequate for design basis flows and pressures, but this is no guarantee that the valve will achieve the same stem thrust when actually subjected to those design basis loads. This is because the friction at the interface between the stem and the stem nut is higher in tests with higher flow and pressure loadings, and this loss to friction is outside the control of the motor-operator's torque switch. This paper identifies a tentative method for determining, a stable, useful value for the stem/stem-nut coefficient of friction, one that can possibly be extrapolated and used in calculations to accurately estimate the design basis thrust requirements of these valves

Next-generation nozzle check valve significantly reduces operating costs

Energy Technology Data Exchange (ETDEWEB)

Roorda, O. [SMX International, Toronto, ON (Canada)

2009-01-15

Check valves perform an important function in preventing reverse flow and protecting plant and mechanical equipment. However, the variety of different types of valves and extreme differences in performance even within one type can change maintenance requirements and life cycle costs, amounting to millions of dollars over the typical 15-year design life of piping components. A next-generation non-slam nozzle check valve which prevents return flow has greatly reduced operating costs by protecting the mechanical equipment in a piping system. This article described the check valve varieties such as the swing check valve, a dual-plate check valve, and nozzle check valves. Advancements in optimized design of a non-slam nozzle check valve were also discussed, with particular reference to computer flow modelling such as computational fluid dynamics; computer stress modelling such as finite element analysis; and flow testing (using rapid prototype development and flow loop testing), both to improve dynamic performance and reduce hydraulic losses. The benefits of maximized dynamic performance and minimized pressure loss from the new designed valve were also outlined. It was concluded that this latest non-slam nozzle check valve design has potential applications in natural gas, liquefied natural gas, and oil pipelines, including subsea applications, as well as refineries, and petrochemical plants among others, and is suitable for horizontal and vertical installation. The result of this next-generation nozzle check valve design is not only superior performance, and effective protection of mechanical equipment but also minimized life cycle costs. 1 fig.

Design Optimisation and Conrol of a Pilot Operated Seat Valve

DEFF Research Database (Denmark)

Nielsen, Brian; Andersen, Torben Ole; Hansen, Michael Rygaard

2004-01-01

The paper gives an approach for optimisation of the bandwidth of a pilot operated seat valve for mobile applications. Physical dimensions as well as parameters of the implemented control loop are optimised simultaneously. The frequency response of the valve varies as a function of the pressure drop...

Low pacemaker incidence with continuous-sutured valves: a retrospective analysis.

Science.gov (United States)

Niclauss, Lars; Delay, Dominique; Pfister, Raymond; Colombier, Sebastien; Kirsch, Matthias; Prêtre, René

2017-06-01

Background Permanent pacemaker implantation after surgical aortic valve replacement depends on patient selection and risk factors for conduction disorders. We aimed to identify risk criteria and obtain a selected group comparable to patients assigned to transcatheter aortic valve implantation. Methods Isolated sutured aortic valve replacements in 994 patients treated from 2007 to 2015 were reviewed. Demographics, hospital stay, preexisting conduction disorders, surgical technique, and etiology in patients with and without permanent pacemaker implantation were compared. Reported outcomes after transcatheter aortic valve implantation were compared with those of a subgroup including only degenerative valve disease and first redo. Results The incidence of permanent pacemaker implantation was 2.9%. Longer hospital stay ( p = 0.01), preexisting rhythm disorders ( p pacemaker implantation. Although prostheses were sutured with continuous monofilament in the majority of cases (86%), interrupted pledgetted sutures were used more often in the pacemaker group ( p = 0.002). In the subgroup analysis, the incidence of permanent pacemaker implantation was 2%; preexisting rhythm disorders and the suture technique were still major risk factors. Conclusion Permanent pacemaker implantation depends on etiology, preexisting rhythm disorders, and suture technique, and the 2% incidence compares favorably with the reported 5- to 10-fold higher incidence after transcatheter aortic valve implantation. Cost analysis should take this into account. Often dismissed as minor complication, permanent pacemaker implantation increases the risks of endocarditis, impaired myocardial recovery, and higher mortality if associated with prosthesis regurgitation.

Improvement of seawater booster pump outlet check valve

International Nuclear Information System (INIS)

Li Xuning; Du Yansong; Huang Huimin

2010-01-01

Conventional island seawater booster pump set of QNPC 310 MWe unit are very important in the whole circulating cooling system, and the integrate function of seawater booster pump outlet check valve is the foundation of steady operation of the seawater booster pump set. The article mainly introduce that through the analyses to the reason to the problem that the seawater booster pump outlet check valve of QNPC 310 MWe unit appeared in past years by our team, and considering the influence of operation condition and circumstance, the team improve the seawater booster pump outlet check valve from swing check valve to shuttle check valve which operate more appropriately in the system. By the test of continuous practice, we make further modification to the inner structure of shuttle check valve contrapuntally, and therefore we solve the problem in seawater booster pump outlet check valve fundamentally which has troubled the security of system operation in past years, so we realize the aim of technical improvement and ensure that the system operate in safety and stability. (authors)

Operating experience of main steam isolation valves at Fessenheim and Bugey

International Nuclear Information System (INIS)

Dredemis, G.; Fourest, B.; Giroux, C.

1985-07-01

The paper presents the experience of Hopkinson MSIVs over about 40 reactor-years (1977 to 1984) of operation at Fessenheim and Bugey units (900 MWe PWR). The various problems encountered including ageing effects on auxiliary equipments and increases in closure time are discussed. The corrective actions undertaken by the utility and the safety assessment of these events performed by the french safety authorities are also described. This study is the synthesis of an in-depth analysis of Main Steam Isolation Valves (MSIV) and their auxiliary circuits equipping the Bugey and Fessenheim 900 MWe PWR nuclear power plants. These valves are different from those installed in the other French 900 MWe PWR reactors. The evaluation of the operation of these valves was made on the basis of incidents which occured during operation of the units or during the periodic tests, as well as anomalies discovered during maintenance operations. This analysis proved that the anomalies related to the design of the valves, as well as to their manufacture and installation, had been correctly dealt with. Furthermore, it should have also revealed potential anomalies due to ageing of the equipment

EPRI flow-loop/in situ test program for motor-operated valves

International Nuclear Information System (INIS)

Hosler, J.F.; Dorfman, L.S.

1994-01-01

The Electric Power Research Institute is undertaking a comprehensive research program to develop and validate methods for predicting the performance of common motor-operated gate, global, and butterfly valves. To assess motor-operated valve (MOV) performance characteristics and provide a basis for methods validation, full-scale testing was conducted on 62 MOVs. Tests were performed in four flow-loop facilities and in nine nuclear units. Forty-seven gate, five globe, and 10 butterfly valves were tested under a wide range of flow and differential pressure conditions. The paper describes the test program scope, test configurations, instrumentation and data acquisition, testing approach, and data analysis methods. Key results are summarized

Remotely handled and remotely operated valve, particularly for the hot part of radioactive plants

International Nuclear Information System (INIS)

Radovan, G.; Sandling, M.J.; Davidson, J.W.; Blaseck, K.; Hoffmeister, L.; Westendorf, H.

1988-01-01

The valve consists of a valve whose valve housing is built into a pipeline. The wear parts of the valve to be replaced, such as the valve body and valve seat, are combined into a replacement part. The replacement part and a clamp act together so that the replacement part is interlocked with the valve housing in the closed operating position. The exchange can be made by undoing a single central screw. (DG) [de

Worcester 1 Inch Solenoid-Actuated Gas Operated SCHe System Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fail closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated

State of the art in the diagnosis of motor-operated valves

International Nuclear Information System (INIS)

Vallana Poncela, F.

1994-01-01

The requirements of US NRC Generic Letter 89-10 have promoted the use of the different methods of diagnosis available on the market. The capacity of such systems for the measurement of torque and thrust in the valve stem, in practice, the only device used to test the adjustments of the motor-operated valve control switches. Details of the different measurement methods currently used are given, together with the degree of accuracy to be expected, based on the data published and obtained from the validation tests. The principal characteristics of Empresarios Agrupados DIVAL System are described, highlighting the high degree of accuracy and the measurement capacity, in both no-load and operating conditions, with flow and differential pressure through the valve. (Author)

Implementation challenges of a motor operated valve program

International Nuclear Information System (INIS)

Ferguson, T.L.

1995-01-01

Electric motor operated valves (MOVs) have become a global focus of attention for Nuclear Power Plant (NPP) operators due to reported operability problems in the last decade. Many NPPs have or are in the process of setting up maintenance programs to address MOV operability issues. Bruce B is in the initial stages of implementing such a program. This paper outlines some of the challenges that have been encountered and how they are being approached to establish an effective program. (author)

Durability of central aortic valve closure in patients with continuous flow left ventricular assist devices.

Science.gov (United States)

McKellar, Stephen H; Deo, Salil; Daly, Richard C; Durham, Lucian A; Joyce, Lyle D; Stulak, John M; Park, Soon J

2014-01-01

A competent aortic valve is essential to providing effective left ventricular assist device support. We have adopted a practice of central aortic valve closure by placing a simple coaptation stitch at left ventricular assist device implantation in patients with significant aortic insufficiency. We conducted a follow-up study to evaluate the efficacy and durability of this procedure. The study included patients who had undergone continuous flow left ventricular assist device implantation. The patients were divided into 2 groups, those who did not require any aortic procedure because the valve was competent and those who underwent central aortic valve closure for mild or greater aortic regurgitation. The clinical endpoints were mortality, progression or recurrence of aortic insufficiency, and reoperation for aortic valve pathologic features. Aortic insufficiency was measured qualitatively from mild to severe on a scale of 0 to 5. A total of 123 patients received continuous flow left ventricular assist devices from February 2007 to August 2011. Of those, 18 (15%) underwent central aortic valve closure at left ventricular assist device implantation because of significant aortic insufficiency (1.8 ± 1.4) and 105 who did not (competent aortic valve, 0.15 ± 0.43; P assist device-supported patients, with follow-up extending into 2 years. Although aortic insufficiency progressed over time in those with minimal native valve regurgitation initially, no such progression was noted in those with central aortic valve closure. Additional investigation is needed to evaluate whether prophylactic central aortic valve closure should be performed at left ventricular assist device implantation to avoid problematic aortic regurgitation developing over time, in particular in patients undergoing left ventricular assist device implantation for life-long (destination therapy) support. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights

NRC test results and operations experience provide insights for a new gate valve stem force correlation

International Nuclear Information System (INIS)

Watkins, John C.; Steele, Robert Jr.; DeWall, Kevin G.; Weidenhamer, G.H.; Rothberg, O.O.

1994-01-01

This paper presents the results of testing sponsored by the NRC to assess valve and motor operator performance under varying pressure and fluid conditions. This effort included an examination of the methods used by the industry to predict the required stem force of a valve, and research to provide guidelines for the extrapolation of in situ test results to design basis conditions.Years ago, when most of these valves were originally installed, the industry used a set of equations to determine analytically that the valves' motor-operators were large enough and the control switches were set high enough to close the valves at their design basis conditions. Our research has identified several inconsistencies with the industry's existing gate valve stem force equation and has challenged the overly simplistic assumptions inherent in its use. This paper discusses the development of the INEL correlation, which serves as the basis for a method to bound the stem force necessary to close flexwedge gate valves whose operational characteristics have been shown to be predictable. As utilities undertake to provide assurance of their valves' operability, this ability to predict analytically the required stem force is especially important for valves that cannot be tested at design basis conditions. For such valves, the results of tests conducted at less severe conditions can be used with the INEL correlation to make the necessary prediction. ((orig.))

Bentall operation, total aortic replacement and mitral valve replacement for a young adult with Marfan syndrome: a case of three-staged operation.

Science.gov (United States)

Inui, K; Shimazaki, Y; Watanabe, T; Kuraoka, S; Minowa, T; Miura, M; Oshikiri, S; Toyama, H

1998-08-01

In Marfan syndrome, the most common cardiovascular abnormalities are dilatation of the aorta and aortic valve regurgitation in adult patients. Mitral valve dysfunction is the most common cause of morbidity and mortality in infants and children with Marfan syndrome, and is not frequently operated on in adult Marfan patients who undergo surgery for diseases of the aortic root and total aorta. This report describes a successfully three-staged operation for a 24 year-old man with Marfan syndrome who underwent an emergent Bentall operation and aortic arch replacement, total aortic replacement and mitral valve replacement over 2 years. Mitral valve regurgitation was mild but increased after the second operation. The graft was tightly adhesive and invasive to the sternum. Endoscopic view was helpful to avoid graft damage at resternotomy. The postoperative course was uneventful in each operation. Microscopic examination of the mitral valve leaflets showed abnormal increase of mucopolysaccharides, and disruption and fragmentation of elastic fibers.

Application of signature analysis for determining the operational readiness of motor-operated valves under blowdown test conditions

International Nuclear Information System (INIS)

Haynes, H.D.

1990-01-01

In support of the NRC-funded Nuclear Plant Aging Research (NPAR) program, Oak Ridge National Laboratory (ORNL) has carried out a comprehensive aging assessment of motor-operated valves (MOVs). As part of this work, ORNL participated in the gate valve flow interrruption blowdown (GVFIB) tests carried out in Huntsville, Alabama. The tests provided an excellent opportunity to evaluate signature analysis methods for determining the operability of MOVs under accident conditions. ORNL acquired motor current and torque switch shaft angular position signatures on two test MOVs during several GVFIB tests. The reduction in operating ''margin'' of both MOVs due to the presence of additional valve running loads imposed by high flow was clearly observed in motor current and torque switch angular position signatures. In addition, the effects of differential pressure, fluid temperature, and line voltage on MOV operations were observed and more clearly understood as a result of utilizing the signature analysis techniques. (orig.)

Wedge gate valves selecting essentials in pipeline systems designing based on permissible operation parameters

Science.gov (United States)

Zakirnichnaya, M. M.; Kulsharipov, I. M.

2017-10-01

Wedge gate valves are widely used at the fuel and energy complex enterprises. The pipeline valves manufacturers indicate the safe operation resource according to the current regulatory and technical documentation. In this case, the resource value of the valve body strength calculation results is taken into consideration as the main structural part. However, it was determined that the wedge gate valves fail before the assigned resource due to the occurrence of conditions under which the wedge breaks in the hooks and, accordingly, the sealing integrity is not ensured. In this regard, it became necessary to assess the conditions under which the resource should be assigned not only to the valve body, but also to take into account the wedge durability. For this purpose, wedge resource calculations were made using the example of ZKL2 250-25 and ZKL2 300-25 valves using the ABAQUS software package FE-SAFE module under the technological parameters influence on the basis of their stressstrain state calculation results. Operating conditions, under which the wedge resource value is lower than the one set by the manufacturer, were determined. A technique for limiting the operating parameters for ensuring the wedge durability during the wedge gate valve assigned resource is proposed.

Long-term results of aortic valve-sparing operations in patients with Marfan syndrome.

Science.gov (United States)

David, Tirone E; Armstrong, Sue; Maganti, Manjula; Colman, Jack; Bradley, Timothy J

2009-10-01

The appropriateness of aortic valve-sparing operations in patients with Marfan syndrome has been questioned. This study examines the long-term results of these operations in patients with Marfan syndrome. From 1988 to 2006, 103 consecutive patients with Marfan syndrome (mean age, 37 +/- 12 years) and aortic root aneurysm had aortic valve-sparing operations. Emergency surgery was performed in 11 patients: 8 for acute type A aortic dissection and 3 for unexplained persistent chest pain. Fourteen patients also had mitral valve surgery. The technique of aortic valve reimplantation was used in 77 patients, and aortic root remodeling was used in 26 patients. Patients were followed prospectively and underwent annual echocardiographic studies. The mean follow-up was 7.3 +/- 4.2 years and 100% complete. There was 1 operative death and 5 late deaths. Four of the 6 deaths were due to complications of aortic dissections. The patients' survival at 15 years was 87.2% compared with 95.6% for the general population of Ontario matched for age and sex. Seven patients had important aortic insufficiency: 4 mild to moderate, 2 moderate, and 1 moderate to severe. Freedom from greater than mild aortic insufficiency at 15 years was 79.2%. Three patients, all after aortic root remodeling, had aortic valve replacement, 2 for aortic insufficiency and 1 for endocarditis. At the most recent follow-up, 97 patients were alive: 86 were in functional class I, and 11 were in functional class II. Aortic valve-sparing operations provided excellent clinical outcomes in this series of patients with Marfan syndrome. Postoperatively, complications of aortic dissections were the leading cause of death.

Long-term results after aortic valve-sparing operation (David I).

Science.gov (United States)

Shrestha, Malakh; Baraki, Hassina; Maeding, Ilona; Fitzner, Sebastian; Sarikouch, Samir; Khaladj, Nawid; Hagl, Christian; Haverich, Axel

2012-01-01

Aortic valve-sparing David procedure has gained broad acceptance. However, few long-term results have been published. We present our results. More than 450 David procedures have been performed in our institution so far. Of these, 126 patients were operated between July 1993 and December 2000. Median age was 57 (8-83) years and 46 (36.5%) were female. As many as 26 (20.6%) had Marfan syndrome, 21 (16.7%) had acute aortic dissection type A (AADA) and 67 (53.2%) had additional procedures. There were six (4.8%) deaths in 30 post-operative period (POD), four of whom had AADA. In the follow-up, there were 32 (25.4%) late deaths, 11 (34.4%) of these were caused by cardiac or underlying disease or op-related. As many as 15 (11.9%) patients were re-operated; six (40%) were Marfan patients and two (13.3%) had early endocarditis. Follow-up echocardiography of 76 (60.3%) event-free patients showed valve insufficiency (AI)≤AI I° in 68 (89.5%) and grade II in 7 (9.2%) patients. Leaflet degeneration due to proposed leaflet contact with the straight Dacron graft was not observed. A total of 36 (47.4%) patients were in New York Heart Association (NYHA) class I, 33 (43.4%) in NYHA II, and five (6.6%) were in class III. During the entire follow-up of 790 patient-years, there was no stroke or major bleeding. Survival at 1, 5 and 10 years was 93%, 85% and 70%, respectively. Freedom from valve replacement at 1, 5 and 10 years was 96%, 91% and 87%, respectively. Regardless of the underlying pathology, valve-sparing David I procedure has acceptable long-term results. Valve-related complications such as stroke or major bleeding is exceedingly low.

Motor operated valve testing and the 'rate of loading' phenomenon

International Nuclear Information System (INIS)

Black, B.R.

1991-01-01

This paper discusses valve design features which affect the ability to predict motor operated valve (MOV) performance and reviews factors which should be considered when selecting switch settings to limit stem loads. Considerable attention is given to the rate of loading phenomenon which affects the relationship between valve stem thrust and actuator spring pack deflection. Equations are developed, and testing is discussed which permit the construction of an MOV dynamic model. Factors which must be considered when maintaining switch settings correct throughout the life of the plant are discussed. And switch setting acceptance criteria for use with baseline Static and Design Basis testing are suggested

Application of diagnostics to determine motor operated valve operational readiness

International Nuclear Information System (INIS)

Eissenberg, D.M.

1987-01-01

ORNL has been carrying out an aging assessment of motor-operated valves (MOVs) with the primary objective of recommending diagnostic methods for detecting and trending aging. As a result of experimental investigations at ORNL, it was discovered that the motor current during a valve stroke was a very useful diagnostic parameter for detecting and trending many MOV drive train load variations. The motor current signatures were analyzed at four levels: mean value for a stroke, gross trends during a stroke, transients, and noise frequency spectra. Examples illustrating the use of this technique are presented. The use of motor current signature analysis was also shown to apply to other electric motor driven equipment. Future work includes developing a data base of MOV diagnostics, including criteria for determining the extent of degradation and application of the technique to other LWR motor driven safety equipment

Application of diagnostics to determine motor-operated valve operational readiness

International Nuclear Information System (INIS)

Eissenberg, D.M.

1986-01-01

ORNL has been carrying out an aging assessment of motor-operated valves (MOVs) with the primary objective of recommending diagnostic methods for detecting and trending aging. As a result of experimental investigations at ORNL, it was discovered that the motor current during a valve stroke was a very useful diagnostic parameter for detecting and trending many MOV drive train load variations. The motor curent signatures were analyzed at four levels: mean value for a stroke, gross trends during a stroke, transients, and noise frequency spectra. Examples illustrating the use of this technique are presented. The use of motor current signature analysis was also shown to apply to other electric motor driven equipment. Future work includes developing a data base of MOV diagnostics, including criteria for determining the extent of degradation and application of the technique to other LWR motor driven safety equipment

Effects on fatigue life of gate valves due to higher torque switch settings during operability testing

International Nuclear Information System (INIS)

Richins, W.D.; Snow, S.D.; Miller, G.K.; Russell, M.J.; Ware, A.G.

1995-12-01

Some motor operated valves now have higher torque switch settings due to regulatory requirements to ensure valve operability with appropriate margins at design basis conditions. Verifying operability with these settings imposes higher stem loads during periodic inservice testing. These higher test loads increase stresses in the various valve internal parts which may in turn increase the fatigue usage factors. This increased fatigue is judged to be a concern primarily in the valve disks, seats, yokes, stems, and stem nuts. Although the motor operators may also have significantly increased loading, they are being evaluated by the manufacturers and are beyond the scope of this study. Two gate valves representative of both relatively weak and strong valves commonly used in commercial nuclear applications were selected for fatigue analyses. Detailed dimensional and test data were available for both valves from previous studies at the Idaho National Engineering Laboratory. Finite element models were developed to estimate maximum stresses in the internal parts of the valves and to identity the critical areas within the valves where fatigue may be a concern. Loads were estimated using industry standard equations for calculating torque switch settings prior and subsequent to the testing requirements of USNRC Generic Letter 89--10. Test data were used to determine both; (1) the overshoot load between torque switch trip and final seating of the disk during valve closing and (2) the stem thrust required to open the valves. The ranges of peak stresses thus determined were then used to estimate the increase in the fatigue usage factors due to the higher stem thrust loads. The usages that would be accumulated by 100 base cycles plus one or eight test cycles per year over 40 and 60 years of operation were calculated

Results of the motor-operated valve engineering and testing program

International Nuclear Information System (INIS)

Black, B.R.

1994-01-01

The Texas Utilities Electric Company (TU Electric) motor-operated valve (MOV) program for implementing the recommendations of Generic Letter 89-10 has typically included the following: refurbishing each actuator, verifying each actuator's as-built configuration, testing each actuator's motor on a dynamometer, testing each actuator's torque spring pack (which is used to control the torque developed), testing each fully refurbished and reassembled actuator on a torque test stand, and testing as many MOVs as practicable both without fluid flow through the valve and with the maximum test conditions reasonably achievable (static and differential pressures (DP) conditions, respectively). Test data are acquired at 1,000 samples per second for stem thrust, stem torque, stem position, actuator compensator spring pack deflection, actuator torque spring pack deflection, motor current, motor voltage, motor three-phase power, valve upstream pressure, and valve downstream pressure, wherever practicable

Early and late outcomes of 1000 minimally invasive aortic valve operations.

Science.gov (United States)

Tabata, Minoru; Umakanthan, Ramanan; Cohn, Lawrence H; Bolman, Ralph Morton; Shekar, Prem S; Chen, Frederick Y; Couper, Gregory S; Aranki, Sary F

2008-04-01

Minimal access cardiac valve surgery is increasingly utilized. We report our 11-year experience with minimally invasive aortic valve surgery. From 07/96 to 12/06, 1005 patients underwent minimally invasive aortic valve surgery. Early and late outcomes were analyzed. Median patient age was 68 years (range: 24-95), 179 patients (18%) were 80 years or older, 130 patients (13%) had reoperative aortic valve surgery, 86 (8.4%) had aortic root replacement, 62 (6.1%) had concomitant ascending aortic replacement, and 26 (2.6%) had percutaneous coronary intervention on the day of surgery (hybrid procedure). Operative mortality was 1.9% (19/1005). The incidences of deep sternal wound infection, pneumonia and reoperation for bleeding were 0.5% (5/1005), 1.3% (13/1005) and 2.4% (25/1005), respectively. Median length of stay was 6 days and 733 patients (72%) were discharged home. Actuarial survival was 91% at 5 years and 88% at 10 years. In the subgroup of the elderly (> or =80 years), operative mortality was 1.7% (3/179), median length of stay was 8 days and 66 patients (37%) were discharged home. Actuarial survival at 5 years was 84%. There was a significant decreasing trend in cardiopulmonary bypass time, the incidence of bleeding, and operative mortality over time. Minimal access approaches in aortic valve surgery are safe and feasible with excellent outcomes. Aortic root replacement, ascending aortic replacement, and reoperative surgery can be performed with these approaches. These procedures are particularly well-tolerated in the elderly.

Effects of dynamic loading of motor-operated valve actuators

International Nuclear Information System (INIS)

Damerell, P.S.; Daubresse, S.; Wolfe, K.J.; Dogan, T.; Gleeson, J.

1994-01-01

Experience has shown that valves with rising, nonrotating stems that are operated using electro-motor driven actuators can be susceptible to changes in output thrust at a constant torque switch setting as a result of changes in stem load time history. This effect is a concern because tests on these types of valves to verify thrust achieved at torque switch trip are often performed in situ under load conditions different from the required performance conditions. As part of a motor-operated valve research program being carried out by the Electric Power Research Institute, tests of typical electric motor actuators used with nuclear services valves have been performed. The test results show that changes in output thrust with load time history occur o varying degrees on different stem and stem nut combinations. When the effect exists, there is generally an increase in thrust at torque switch trip when load is developed rapidly from low initial loads, compared to when load is developed slowly. The effect is mainly a result of changes in the coefficient of friction at the stem-stem nut interface. The coefficient of friction is temporarily reduced under rapid loading conditions from low initial load, leading to increased thrust. The root cause is hypothesized to be a open-quotes squeeze-filmclose quotes effect, whereby mixed-mode lubrication (hydrodynamic plus boundary) temporarily replaces boundary lubrication. This paper describes the results of tests performed to better understand the phenomenon

Inducement of Design Parameters for Reliability Improvement of Servo Actuator for Hydraulic Valve Operation

Energy Technology Data Exchange (ETDEWEB)

Sung, Baek Ju; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2014-05-15

The precision hydraulic valve is widely used in various industrial field like aircraft, automobile, and general machinery. Servo actuator is the most important device for driving the precise hydraulic valve. The reliable operation of servo actuator effects on the overall hydraulic system. The performance of servo actuator relies on frequency response and step response according to arbitrary input signal. In this paper, we performed the analysis for the components of servo actuator to satisfy the reliable operation and response characteristics through the reliability analysis, and also induced the design parameters to realize the reliable operation and fast response characteristics of servo actuator for hydraulic valve operation through the empirical knowledge of experts and electromagnetic theories. We suggested the design equations to determine the values of design parameters of servo actuator as like bobbin size, length of yoke and plunger and turn number of coil, and verified the achieved design values through FEM analysis and performance tests using some prototypes of servo actuators adapted in hydraulic valve.

Immediate post-operative responses to transcatheter aortic valve implantation

DEFF Research Database (Denmark)

Egerod, Ingrid; Nielsen, Susanne; Lisby, Karen H.

2015-01-01

Background:Conventional treatment for patients with severe symptomatic aortic stenosis is surgical aortic valve replacement (SAVR), but transcatheter aortic valve implantation (TAVI) has become a reliable alternative in high-risk patients.Aims:The aim of our study was to describe the post......-operative patient response to TAVI on the evening of the procedure and the following day before discharge from the coronary care unit. A secondary aim was to compare responses of patients younger and older than 80 years of age.Methods:A prospective, comparative observational study triangulating nurse assessment...

Inservice diagnostic methods for solenoid-operated valves

International Nuclear Information System (INIS)

Kryter, R.C.

1993-01-01

Solenoid-operated valves (SOVs) were studied at Oak Ridge National Laboratory as part of the USNRC Nuclear Plant Aging Research (NPAR) Program. The primary objective of the study was to identify, evaluate, and recommend methods for inspection, surveillance, monitoring, and maintenance of SOVs that can help ensure their operational readiness-that is, their ability to perform required safety functions under all anticipated operating conditions, since failure of one of these small and relatively inexpensive devices could have serious consequences under certain circumstances. An earlier (Phase 1) NPAR program study described SOV failure modes and causes and had identified measurable parameters thought to be linked to the progression of everpresent degradation mechanisms that may ultimately result in functional failure of the valve. Using this earlier work as a guide, the present (Phase 11) study focused on devising and then demonstrating the effectiveness of techniques and equipment with which to measure performance parameters that show promise for detecting the presence and trending the progress of such degradations before they reach a critical stage. Intrusive techniques requiring the addition of magnetic or acoustic sensors or the application of special test signals were investigated briefly, but major emphasis was placed on the examination of condition-indicating techniques that can be applied with minimal cost and impact on plant operation. Experimental results are presented that demonstrate the technical feasibility and practicality of the monitoring techniques assessed in the study, and recommendations for further work are provided

Multifunctional four-port directional control valve constructed from logic valves

International Nuclear Information System (INIS)

Lisowski, E.; Czyżycki, W.; Rajda, J.

2014-01-01

Highlights: • Directional valve with standard ISO 440-08 has been constructed from logic valves. • Only one innovative valve may replace whole family of the standard valves. • CFD analysis and bench tests of the innovative valve has been carried. • Parameters of the innovative valve are equaling or surpassing the standard ones. • The innovative valve has additional possibilities of pressure and flow control. - Abstract: The paper refers to four-port solenoid pilot operated valves, which are subplate mounted in a hydraulic system in accordance with the ISO 4401 standard. Their widespread use in many machines and devices causes a continuing interest in the development of their design by both the scientific centers and the industry. This paper presents an innovative directional control valve based on the use of logic valves and a methodology followed for the design of it by using Solid Edge CAD and ANSYS/Fluent CFD software. The valve design methodology takes into account the need to seek solutions that minimize flow resistance through the valve. For this purpose, the flow paths are prepared by means of CAD software and pressure-flow curves are determined as a result of CFD analysis. The obtained curves are compared with the curves available in the catalogs of spool type directional control valves. The new solution allows to replace the whole family of spool type four-port directional control valves by one valve built of logic valves. In addition, the innovative directional control valve provides leak-proof shutting the flow paths off and also it can control flow rate and even pressure of working liquid. A prototype of the valve designed by the presented method has been made and tested on the test bench. The results quoted in the paper confirm that the developed logic type directional control valve is able to meet all designed connection configurations, and the obtained pressure-flow curves show very good conformity with the results of CFD analysis

Motor-operated valve (MOV) actuator motor and gearbox testing

International Nuclear Information System (INIS)

DeWall, K.; Watkins, J.C.; Bramwell, D.

1997-07-01

Researchers at the Idaho National Engineering and Environmental Laboratory tested the performance of electric motors and actuator gearboxes typical of the equipment installed on motor-operated valves used in nuclear power plants. Using a test stand that simulates valve closure loads against flow and pressure, the authors tested five electric motors (four ac and one dc) and three gearboxes at conditions a motor might experience in a power plant, including such off-normal conditions as operation at high temperature and reduced voltage. They also monitored the efficiency of the actuator gearbox. All five motors operated at or above their rated starting torque during tests at normal voltages and temperatures. For all five motors, actual torque losses due to voltage degradation were greater than the losses calculated by methods typically used for predicting motor torque at degraded voltage conditions. For the dc motor the actual torque losses due to elevated operating temperatures were greater than the losses calculated by the typical predictive method. The actual efficiencies of the actuator gearboxes were generally lower than the running efficiencies published by the manufacturer and were generally nearer the published pull-out efficiencies. Operation of the gearbox at elevated temperature did not affect the operating efficiency

241-AN-A valve pit manifold valves and position indication acceptance test procedure

Energy Technology Data Exchange (ETDEWEB)

VANDYKE, D.W.

1999-08-25

This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

NRC Information No. 88-72: Inadequacies in the design of dc motor-operated valves

International Nuclear Information System (INIS)

Rossi, C.E.

1992-01-01

On July 1, 1988, a high pressure coolant injection (HPCI) steam admission valve failed to open during a post-maintenance test at the Brunswick nuclear power plant, Unit 1. The same valve had failed in December 1987 and on May 28, 1988. The licensee, Carolina Power and Light Company, established a team to investigate the cause of failure, and the team identified the most probable cause as a dc motor failure due to a shunt-winding to series-winding short circuit. The team believed that this condition was precipitated by thermal binding of the valve internals. The previous failure in May was also diagnosed as having been caused by thermal binding. As a result of these failures, the licensee reviewed the design of the dc motor-operated valves for both the HPCI and the reactor core isolation cooling (RCIC) systems. This review identified a number of significant design deficiencies going well beyond the problems with thermal binding. The deficiencies constitute a potential common cause failure mechanism for safety system valves. Unit 1 was shut down on July 14, 1988 to replace the failed HPCI valve motor and to implement design modifications to other motor-operated valves

Development of a smart type motor operated valve for nuclear power plants

Science.gov (United States)

Kim, Chang-Hwoi; Park, Joo-Hyun; Lee, Dong-young; Koo, In-Soo

2005-12-01

In this paper, the design concept of the smart type motor operator valve for nuclear power plant was described. The development objective of the smart valve is to achieve superior accuracy, long-term reliability, and ease of use. In this reasons, developed smart valve has fieldbus communication such as deviceNet and Profibus-DP, auto-tuning PID controller, self-diagnostics, and on-line calibration capabilities. And also, to achieve pressure, temperature, and flow control with internal PID controller, the pressure sensor and transmitter were included in this valve. And, temperature and flow signal acquisition port was prepared. The developed smart valve will be performed equipment qualification test such as environment, EMI/EMC, and vibration in Korea Test Lab. And, the valve performance is tested in a test loop which is located in Seoul National University Lab. To apply nuclear power plant, the software is being developed according to software life cycle. The developed software is verified by independent software V and V team. It is expected that the smart valve can be applied to an existing NPPs for replacing or to a new nuclear power plants. The design and fabrication of smart valve is now being processed.

Prediction of critical flow rates through power-operated relief valves

International Nuclear Information System (INIS)

Abdollahian, D.; Singh, A.

1983-01-01

Existing single-phase and two-phase critical flow models are used to predict the flow rates through the power-operated relief valves tested in the EPRI Safety and Relief Valve test program. For liquid upstream conditions, Homogeneous Equilibrium Model, Moody, Henry-Fauske and Burnell two-phase critical flow models are used for comparison with data. Under steam upstream conditions, the flow rates are predicted either by the single-phase isentropic equations or the Homogeneous Equilibrium Model, depending on the thermodynamic condition of the fluid at the choking plane. The results of the comparisons are used to specify discharge coefficients for different valves under steam and liquid upstream conditions and evaluate the existing approximate critical flow relations for a wide range of subcooled water and steam conditions

NRC inspections of licensee activities to improve the performance of motor-operated valves

International Nuclear Information System (INIS)

Scarbrough, T.G.

1992-01-01

The NRC regulations require that components important to the safe operation of a nuclear power plant be treated in a manner that provides assurance of their proper performance. Despite these regulatory requirements, operating experience and research programs have raised concerns regarding the performance of motor-operated valves (MOVs) in nuclear power plants. In June 1990, the staff issued NUREG-1352, Action Plans for Motor-Operated Valves and Check Valves, which contains planned actions to organize the activities aimed at resolving the concerns about MOV performance. A significant task of the MOV action plan is the staff's review of the implementation of Generic Letter (GL) 89-10 (June 28, 1989), 'Safety-Related Motor-Operated Valve Testing and Surveillance,' and its supplements, by nuclear power plant licensees. The NRC staff has issued several supplements to GL 89-10 to provide additional guidance for use by licensees in responding to the generic letter. The NRC staff has conducted initial inspections of the GL 89-10 programs at most licensee facilities. This paper outlines some of the more significant findings of those inspections. For example, licensees who have begun differential pressure and flow testing have found some MOVs to require more thrust to operate than predicted by the standard industry equation with typical valve factors assumed in the past. The NRC staff has found weaknesses in licensee procedures for conducting the differential pressure and flow tests, the acceptance criteria for the tests in evaluating the capability of the MOV to perform its safety function under design basis conditions, and feedback of the test results into the methodology used by the licensee in predicting the thrust requirements for other MOVs. Some licensees have not made adequate progress toward resolving the MOV issue for their facilities within the recommended schedule of GL 89-10

Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

Science.gov (United States)

Sanders, J. C.; Wilsted, H. D.; Mulcahy, B. A.

1943-01-01

A thermocouple was installed in the crown of a sodium-cooled exhaust valve. The valve was then tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 F was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 rpm. Fuel-air ratio was found to have a large influence on valve temperature, but cooling-air pressure and variation in spark advance had little effect. An increase in engine power by change of speed or mean effective pressure increased the valve temperature. It was found that the temperature of the rear spark-plug bushing was not a satisfactory indication of the temperature of the exhaust valve.

Bentall Operation with Valved Homograft Conduit

Science.gov (United States)

Choudhary, Shiv K.; Talwar, Sachin; Kumar, A. Sampath

2000-01-01

Lesions of the ascending aorta associated with aortic valve disease are usually treated by implanting a prosthetic valved conduit (Bentall procedure). In this report, we present our experience in which a valved homograft conduit was used for the procedure. Six patients underwent a Bentall procedure with the use of a cryopreserved valved homograft conduit. Two of the patients had annuloaortic ectasia, 2 had Marfan syndrome, and 1 had an atherosclerotic aneurysm of the aorta. One patient had severe aortic stenosis due to a bicuspid aortic valve, along with an aneurysm and localized dissection of the ascending aorta. In all of the patients, the aortic annulus was substantially dilated, with accompanying moderate-to-severe aortic regurgitation. A standard procedure was performed with moderate hypothermia, cardiopulmonary bypass, and aortic and bicaval cannulation. The ascending aorta and the aortic valve were replaced with a cryopreserved valved homograft conduit (aortic in 5 patients and pulmonary in 1). The native coronary ostia were anastomosed directly to the homograft. Echocardiography, which was performed intraoperatively, before discharge from the hospital, and at follow-up visits (1 to 36 months), revealed good valve function without dilatation of the homograft conduits. There was 1 late death due to Aspergillus fumigatus endocarditis, 6 months postoperatively. In 1 patient, magnetic resonance imaging performed at 24 months revealed normal caliber of the homograft conduit. We conclude that the Bentall procedure can be performed, safely and with excellent results, using cryopreserved homograft conduits. PMID:11198310

Long-term results after aortic valve-sparing operation (David I)†

Science.gov (United States)

Shrestha, Malakh; Baraki, Hassina; Maeding, Ilona; Fitzner, Sebastian; Sarikouch, Samir; Khaladj, Nawid; Hagl, Christian; Haverich, Axel

2012-01-01

OBJECTIVE Aortic valve-sparing David procedure has gained broad acceptance. However, few long-term results have been published. We present our results. METHODS More than 450 David procedures have been performed in our institution so far. Of these, 126 patients were operated between July 1993 and December 2000. Median age was 57 (8–83) years and 46 (36.5%) were female. As many as 26 (20.6%) had Marfan syndrome, 21 (16.7%) had acute aortic dissection type A (AADA) and 67 (53.2%) had additional procedures. RESULTS There were six (4.8%) deaths in 30 post-operative period (POD), four of whom had AADA. In the follow-up, there were 32 (25.4%) late deaths, 11 (34.4%) of these were caused by cardiac or underlying disease or op-related. As many as 15 (11.9%) patients were re-operated; six (40%) were Marfan patients and two (13.3%) had early endocarditis. Follow-up echocardiography of 76 (60.3%) event-free patients showed valve insufficiency (AI) ≤ AI I° in 68 (89.5%) and grade II in 7 (9.2%) patients. Leaflet degeneration due to proposed leaflet contact with the straight Dacron graft was not observed. A total of 36 (47.4%) patients were in New York Heart Association (NYHA) class I, 33 (43.4%) in NYHA II, and five (6.6%) were in class III. During the entire follow-up of 790 patient-years, there was no stroke or major bleeding. Survival at 1, 5 and 10 years was 93%, 85% and 70%, respectively. Freedom from valve replacement at 1, 5 and 10 years was 96%, 91% and 87%, respectively. CONCLUSIONS: Regardless of the underlying pathology, valve-sparing David I procedure has acceptable long-term results. Valve-related complications such as stroke or major bleeding is exceedingly low. PMID:21632258

Variable valve trains for internal combustion engines to control the valve height and the opening time; Variable Ventiltriebe fuer Verbrennungsmotoren zur Veraenderung von Ventilhub und Oeffnungsdauer

Energy Technology Data Exchange (ETDEWEB)

Martin, Gunther [ThyssenKrupp Presta TecCenter AG, Eschen (Liechtenstein). R and D Projects

2009-11-15

The PDVC (Presta Delta Valve Control) continuously variable valve lift system is a mechanical system of valve control for achieving optimum performance and resulting in improved fuel consumption and reduced emissions across the entire operating range of the combustion engine. The continuous variability allows for engine load control by adjusting the valve height and therefore can also be used to replace the traditional throttle. The advantages are lower fuel consumption, reduction in emissions, quicker engine response, higher torque during the low speed range as well as more stable idling. The PSVC (Presta Shiftable Valve Control) is a 3 step shiftable valve lift system that offers the possibility to achieve a major part of these performance and associated consumption benefits with a simpler and therefore more cost-effective system. (orig.)

Operating reliability of valves in French pressurized water nuclear power plants

International Nuclear Information System (INIS)

Conte

1986-10-01

Taking into account the large numbers of valves (about 10000) of a PWR nuclear power plant, the importance of some valves in the safety functions and the cost resulting from their unavailability, the individual operability of these equipments has to be ensured at a high reliability level. This assurance can be obtained by means of an effort at all the stages which contribute to the quality of the product: design, qualification tests, fabrication, tests at the start-up stage, maintenance and tests during the power plant operation, experience feedback. This paper emphasizes more particularly on the tests carried out on loops of qualification [fr

Device for the simultaneous operation of the closing valve of a vessel and the closing valve of a transport container

International Nuclear Information System (INIS)

Tellier, Claude; Surriray, Michel.

1982-01-01

This device includes mechanisms for unlatching the closing valve of the vessel and securing it to the closing valve of the transport container and other mechanisms for vertically raising the assembly of valves, pivoting it and bringing it into a vertical position in a bulge provided in the bottom of the transport container. For example the first containment is a nuclear reactor vessel and the transport container is used for carrying an item from the vessel to an external area (for instance, a defective pump to the repair area) and for the return transport operation [fr

Numerical and experimental investigation on the performance of safety valves operating with different gases

International Nuclear Information System (INIS)

Dossena, V.; Marinoni, F.; Bassi, F.; Franchina, N.; Savini, M.

2013-01-01

A detailed analysis of the effect related to the expansion of different gases throughout safety relief valves is carried out both numerically and experimentally. The considered gases are air, argon and ethylene, representative of a wide range of specific heat ratios. A first experimental campaign performed in air and argon on a safety relief valve characterized by connection 1/2″ × 1″ and orifice designation D (diameter 10 mm) according to API 526 showed significant reduction both in disc lift and in exhausted mass flow rate, at the nominal overpressure, when operating with argon. In order to gain a deeper insight into the physics involved and to evaluate the valve behavior with other gases, an extensive numerical testing has been performed by means of an accurate CFD code based on discontinuous Galerkin formulation. Numerical results are at first validated against measurements obtained in air on a 2″ J 3″ safety relief valve proving a remarkable accuracy of the computational method. Then the validated solver is applied on the same computational grid using argon and ethylene as working fluids. The three gases are considered as thermally perfect gases. A critical discussion based on the numerical results allows to clarify the fluid dynamic and physical reasons causing the observed trends both in the opening force and in the discharge coefficient. The main conclusion is that particular care must be taken when a safety valve operates with a fluid characterized by a specific heat ratio greater than the one of the gas used during type testing. -- Highlights: ► Effects of different gases on the discharge capacity and operational characteristics on safety relief valves. ► Influence of different specific heat ratio on safety relief valves discharge coefficient. ► Skilful application of Discontinuous Galerkin CFD solver to safety valves performances prediction

Evaluation Of Factors Influencing On Causes Of Prosthetic Valve Re-operation And Early Postoperative Survival Tehran Emam hospital (1991-2001

Directory of Open Access Journals (Sweden)

Rahmani Reaza

2003-06-01

Full Text Available Prosthetic valve re-operation has greater mortality and morbidity than primary valve replacement. By recognition of factors influencing on causes of redo operation and preoperative survival, one can select appropriate prosthesis at primary valve replacement and when operation performed at appropriate time, surgical risk can be reduced."nMethods and Materials: Two hundred patients that underwent prosthetic valve re-operation from October 1991 through November 2001 were included in this study. There were 68 men and 132 women with the mean age of 42:tl 1.8 years. Structural failure was the commonest cause of bio-prosthesis replacement (93%. Valve thrombosis was the common cause of mechanical valve replacement (32%. Age younger Than 50 (P= 0.01 and interval after the first implantation more than 10 years (P= 0.01 affected bio-prosthesis degeneration."nResults: Atrial fibrillation (P<0.01, Older age especially more than 40 (P<0.05 and mitral position (P<0.01 affected mechanical valve thrombosis. Cross clamp time (P= 0.005, Tricuspid insufficiency (P = 0.001, NYHA IV (P = 0.005 and emergent operation (P= 0.001 were independent determinants of hospital mortality."nConclusion: In conclusion, in patients with more than 10-years life expectancy and age younger than 50, mechanical valve can be selected for primary valve replacement. If operation performed before patients reach deteriorated condition, preoperative survival would be excellent.

THE RESULTS OF SURGICAL TREATMENT OF TRICUSPID VALVE INFECTIVE ENDOCARDITIS USING VALVE REPAIR AND VALVE REPLACEMENT OPERATIONS

Directory of Open Access Journals (Sweden)

S. A. Kovalev

2015-01-01

Full Text Available Aim. To evaluate in-hospital and long-term results of surgical treatment of patients with infective endocarditis of the tricuspid valve, to compare the effectiveness of valve repair and valve replacement techniques, and to identify risk factors of mortality and reoperations. Materials and methods. 31 surgical patients with tricuspid valve infective endocarditis were evaluated. Patients were divided into 2 groups. In Group 1 (n = 14 repairs of the tricuspid valve were performed, in Group 2 (n = 17 patients had undergone tricuspid valve replacements. Epidemiological, clinical, microbiological and echocardiographic data were studied. Methods of comparative analysis, the Kaplan–Meier method, and Cox risk models were applied. Results. The most common complication of in-hospital stay was atrioventricular block (17.7% of cases in Group 2. In Group 1, this type of complication was not found. Hospital mortality was 7.14% in Group 1, and 0% in Group 2. Long-term results have shown the significant reduction of heart failure in general cohort and in both groups. In Group 1 the severity of heart failure in the long term was less than in Group 2. No significant differences in the severity of tricuspid regurgitation were found between the groups. In 7-year follow up no cases of death were registered in Group 1. Cumulative survival rate in Group 2 within 60 months was 67.3 ± 16.2%. No reoperations were performed in patients from Group 1. In Group 2, the freedom from reoperation within 60 months was 70.9 ± 15.3%. Combined intervention was found as predictor of postoperative mortality. Prosthetic valve endocarditis was identified as risk factor for reoperation. Conclusion. Valve repair and valve replacement techniques of surgical treatment of tricuspid valve endocarditis can provide satisfactory hospital and long-term results. Tricuspid valve repair techniques allowed reducing the incidence of postoperative atrioventricular block. In the long-term, patients

The wireless diagnostic system for motor operated valves

International Nuclear Information System (INIS)

Ito, Haruo; Akiyama, Michiaki; Suzuki, Syunichi

2010-01-01

To aim at maintenance optimization, a motor operated valve (MOV) diagnostic system called 'MOVDAS' has been developed by using new sensor technologies incorporating torque sensor into the MOV. It has been introduced into nuclear power plants operated by Japan Atomic Power Company (JAPC) for the support of Condition Based Maintenance (CBM). This system, directly checking the torque behavior of the MOV, accurately diagnoses the condition of the MOV during plant operation. Further for the ease of data collection and manpower saving, the wireless diagnostic system based on MOVDAS utilizing Personal Handyphone System (PHS) has been recently introduced into nuclear power plants in JAPC. (author)

Pressure locking and thermal binding of gate valves

Energy Technology Data Exchange (ETDEWEB)

Kelly, E.M.

1996-12-01

Pressure locking and thermal binding represent potential common mode failure mechanisms that can cause safety-related power-operated gate valves to fail in the closed position, thus rendering redundant safety-related systems incapable of performing their safety functions. Supplement 6 to Generic Letter 89-10, {open_quotes}Safety-Related Motor-Operated Gate Valve Testing and Surveillance,{close_quotes} provided an acceptable approach to addressing pressure locking and thermal binding of gate valves. More recently, the NRC has issued Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,{close_quotes} to request that licensees take certain actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the current licensing bases. Over the past two years, several plants in Region I determined that valves in certain systems were potentially susceptible to pressure locking and thermal binding, and have taken various corrective actions. The NRC Region I Systems Engineering Branch has been actively involved in the inspection of licensee actions in response to the pressure locking and thermal binding issue. Region I continues to maintain an active involvement in this area, including participation with the Office of Nuclear Reactor Regulation in reviewing licensee responses to Generic Letter 95-07.

Steady flow torques in a servo motor operated rotary directional control valve

International Nuclear Information System (INIS)

Wang, He; Gong, Guofang; Zhou, Hongbin; Wang, Wei

2016-01-01

Highlights: • A novel servo motor operated rotary directional control valve is proposed. • Steady flow torque is a crucial issue that affects rotary valve performance. • Steady flow torque is analyzed on the aspects of theory, simulation and experiment. • Change law of the steady flow torque with spool rotation angle is explored. • Effect of pressure drop and flow rate on the steady flow torque is studied. - Abstract: In this paper, a servo motor operated rotary directional control valve is proposed, and a systematic analysis of steady flow torques in this valve is provided by theoretical calculation, CFD simulation and experimental test. In the analysis, spool rotation angle corresponding to the maximum orifice opening is tagged as 0°. Over a complete change cycle of the orifice, the range of spool rotation angle is symmetric about 0°. The results show that the direction of steady flow torques in this valve is always the direction of orifice closing. The steady flow torques serve as resistances to the spool rotation when the orifice opening increases, while impetuses to the spool rotation when the orifice opening decreases. At a certain pressure drop or flow rate, steady flow torques are approximately equal and opposite when at spool rotation angles which are symmetric about 0°. When the spool rotates from 0°, at a certain pressure drop, their values increase first then decrease with the spool rotation and reach their maximum values at an angle corresponding to about 1/2 of the maximum orifice opening, and at a certain flow rate, their values increase with the spool rotation. The steady flow torques in this valve are the sums of those in the meter-in and meter-out valve chambers. At a certain spool rotation angle, steady flow torques in the meter-in and meter-out valve chambers are approximately proportional to the pressure drop and the second power of the flow rate through the orifice. Theoretical calculation and CFD simulation can be validated by

Orthogonal optimization of a water hydraulic pilot-operated pressure-reducing valve

Science.gov (United States)

Mao, Xuyao; Wu, Chao; Li, Bin; Wu, Di

2017-12-01

In order to optimize the comprehensive characteristics of a water hydraulic pilot-operated pressure-reducing valve, numerical orthogonal experimental design was adopted. Six parameters of the valve, containing diameters of damping plugs, volume of spring chamber, half cone angle of main spool, half cone angle of pilot spool, mass of main spool and diameter of main spool, were selected as the orthogonal factors, and each factor has five different levels. An index of flowrate stability, pressure stability and pressure overstrike stability (iFPOS) was used to judge the merit of each orthogonal attempt. Embedded orthogonal process turned up and a final optimal combination of these parameters was obtained after totally 50 numerical orthogonal experiments. iFPOS could be low to a fairly low value which meant that the valve could have much better stabilities. During the optimization, it was also found the diameters of damping plugs and main spool played important roles in stability characteristics of the valve.

Application of hydraulic network analysis to motor operated butterfly valves in nuclear power plants

International Nuclear Information System (INIS)

Eldiwany, B.H.; Kalsi, M.S.

1992-01-01

This paper presents the application of hydraulic network analysis to evaluate the performance of butterfly valves in nuclear power plant applications. Required actuation torque for butterfly valves in high-flow applications is often dictated by peak dynamic torque. The peak dynamic torque, which occurs at some intermediate disc position, requires accurate evaluation of valve flow rate and pressure drop throughout the valve stroke. Valve flow rate and pressure drop are significantly affected by the valve flow characteristics and the hydraulic system characteristics, such as pumping capability, piping resistances, single and parallel flow paths, system hydrostatic pressure, and the location of the motor-operated valve (MOV) within the system. A hydraulic network analysis methodology that addresses the effect of these parameters on the MOV performance is presented. The methodology is based on well-established engineering principles. The application of this methodology requires detailed characteristics of both the MOV and the hydraulic system in which it is installed. The valve characteristics for this analysis can be obtained by flow testing or from the valve manufacturer. Even though many valve users, valve manufacturers, and engineering standards have recognized the importance of performing these analyses, none has provided a detailed procedure for doing so

Replacement of five main block valves without interruption of normal operation in a remote NGL station placed at 13400 FT AMSL, challenge and strategies

Energy Technology Data Exchange (ETDEWEB)

Quinto, Yamil; Morales, Raul; Elorreaga, Gerson [Compania Operadora del Gas del Amazonas, Lima (Peru)

2012-07-01

The present paper is aimed to share experience of the replacement of five block valves carried on in a pressure reduction station remotely operated and located in a remote area in The Andes of Peru at 13400 ft AMSL. To accomplish the job, it was necessary the construction of a temporary bypass made of carbon steel pipeline with its own regulating, instrumentation and automation facilities, hence capable of reduce the NGL pressure, controlled and remotely operated by a SCADA system. The temporary bypass connection and disconnection to put on service was carried out using Hot Tap and Line Stop equipment. The replacement of the five block valves was met without interruption of the hydrocarbons flow, and resetting the pressure reduction station to steady operating conditions. Besides the operating works these activities involve safety considerations for personal working in high altitudes. The outputs were the successful replacements of the block valves, and most important was that the NGL continuous flow was met, so both the production and processing plants were supplied with the daily transportation rates in standard conditions, and in accordance with the requirements of the plant operation. (author)

Heavy gas valves

Energy Technology Data Exchange (ETDEWEB)

Steier, L [Vereinigte Armaturen Gesellschaft m.b.H., Mannheim (Germany, F.R.)

1979-01-01

Heavy gas valves must comply with special requirements. Apart from absolute safety in operation there are stringent requirements for material, sealing and ease of operation even in the most difficult conditions. Ball valves and single plate pipe gate valves lateral sealing rings have a dual, double sided sealing effect according to the GROVE sealing system. Single plate gate valves with lateral protective plates are suitable preferably for highly contaminated media. Soft sealing gate valves made of cast iron are used for low pressure applications.

How to insure quality valve remanufacture

International Nuclear Information System (INIS)

Scott, C.F.

1991-01-01

The importance of quality valve repair for the power generation industry is an obvious need for both the owner as well as the consumer. Whether valves are repaired in-line, on-site, or at a valve remanufacturing facility, the selection of a vendor is vital to meeting not only stringent quality requirements, but also to meet start-up schedules and budgets. In the past, the rule of thumb was that repair of a valve could cost approximately 50% of the cost of a new valve and still represent a significant savings to the end user. For power generation facilities, the fact that many valves are welded in not only makes repair more economical, but even vital to continuing normal operations. For those items not welded in, long lead times and higher prices for these normally exotic alloys make remanufactured valves even more attractive. However, even as these advantages of remanufacturing are obvious, some repair organizations continue to cut corners to meet profit demands. The result is suspect quality in some valves. This can lead to premature failures, possible reduced generating capacity, unscheduled outages, and even catastrophic results. Therefore, the choice of a repair organization must be made with care. As the author has said, repair is an obvious option, but the procurement should definitely involve more than just price comparisons. Evaluation must place the emphasis on quality and reliability. Several aspects should be thoroughly investigated and documented in the selection process. These include: personnel; equipment/facilities; procedures; and credentials

Control of spool position of on/off solenoid operated hydraulic valve by sliding-mode controller

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Hak; Hong, Hyun Wook; Park, Myeong Kwan [Pusan National University, Busan (Korea, Republic of); Yun, Young Won [KHPS, Busan (Korea, Republic of)

2015-11-15

The use of on/off solenoid operated hydraulic valves instead of proportional valves has been attracting the interest of many researchers and engineers. However, there exist difficulties in controlling the on/off valve because of highly nonlinear characteristics including hysteresis and saturation. This paper considers the application of on/off solenoid operated hydraulic valves to control position of a hydraulic cylinder with the aim of evaluating, feasibility and practicability of their implementation and understanding the potential benefits when they are used in existing hydraulic systems. Assuming that only the current is measured, a sliding mode observer is designed to estimate the spool position and velocity. To alleviate the aforementioned difficulties in controlling the spool position, a nonlinear observer-based controller of an on/off solenoid valve is designed, taking into account the estimated values, based on a nonlinear model including hysteresis and saturation. The control objective is to track a desired spool trajectory. Simulation and experimental results illustrate the efficiency of the designed controller. The proposed controller is validated again in a single-rod hydraulic actuator. Experimental results show that the fluid flow through the valve orifice by controlling the spool position was successfully controlled.

Enhancements to the Idaho National Engineering Laboratory motor-operated valve assessment software

International Nuclear Information System (INIS)

Holbrook, M.R.; Watkins, J.C.

1994-01-01

In January 1991, the U.S. Nuclear Regulatory Commission (USNRC) commenced Part 1 inspections to review licensee's motor-operated valve (MOV) programs that were developed to address Generic Letter 89-10, open-quotes Safety-Related Motor-Operated Valve Testing and Surveillanceclose quotes. In support, of this effort, the Isolation Valve Assessment (IVA) software, Version 3.10, was developed by the Idaho National Engineering Laboratory (INEL) to enable rapid in-depth review of MOV sizing and torque switch setting calculations. In 1994, the USNRC commenced Part 2 inspections, which involve a more in-depth review of MOV in situ testing relative to design-basis assumptions. The purpose of this paper is to describe the latest INEL and industry research that has been incorporated into Version 4.00 of the IVA software to support the latest round of inspections. Major improvements include (a) using dynamic and static test results to determine MOV performance parameters and validate design-basis engineering assumptions, (b) determining the stem/stem-nut coefficient of friction using new research-based techniques, (c) adding the ability to evaluate globe valves, and (d) incorporating new methods to account for the effects of high ambient temperature on the output torque of alternating current (ac) motors

Analysis of flow induced valve operation and pressure wave propagation for single and two-phase flow conditions

International Nuclear Information System (INIS)

Nagel, H.

1986-01-01

The flow induced valve operation is calculated for single and two-phase flow conditions by the fluid dynamic computer code DYVRO and results are compared to experimental data. The analysis show that the operational behaviour of the valves is not only dependent on the condition of the induced flow, but also the pipe flow can cause a feedback as a result of the induced pressure waves. For the calculation of pressure wave propagation in pipes of which the operation of flow induced valves has a considerable influence it is therefore necessary to have a coupled analysis of the pressure wave propagation and the operational behaviour of the valves. The analyses of the fast transient transfer from steam to two-phase flow show a good agreement with experimental data. Hence even these very high loads on pipes resulting from such fluid dynamic transients can be calculated realistically. (orig.)

Rapid repair advisor for motor-operated valves

International Nuclear Information System (INIS)

Somsel, J.K.

1991-01-01

This paper reports on the initial proposed application for the Rapid Repair Advisor project for motor-operated valves (MOVs). The expected benefits from an MOV testing expert system depend on the purpose of the testing. Straight acceptance testing (post-maintenance and surveillance) could benefit from field verification of test validity. Troubleshooting of failed operators is seldom difficult. Intermittent problems are difficult to resolve suggesting that trace recording capabilities are needed. Predictive diagnosis places the most demands on the interpretive skills of the engineer. However, the limit to predictive capabilities seems to lie in the design of the MOV and the measurable parameters. Utilities are expected to require a knowledgeable MOV maintenance engineer to make decisions on MOV maintenance and operability. The economics of developing an expert system are comparable to improved training for the end-users

Application of diagnostics to determine operational readiness of aged motor-operated valves

International Nuclear Information System (INIS)

Eissenberg, D.M.

1987-01-01

Oak Ridge National Laboratory (ORNL) has been carrying out an aging assessment of motor-operated valves (MOVs) with the primary objective of recommending diagnostic methods for detecting and trending aging. As a result of experimental investigations at ORNL, it was discovered that the motor current during a valve stroke was a very useful diagnostic parameter for detecting and trending many MOV drive train load variations. The motor current signatures were analyzed at four levels: mean value for a stroke, gross trends during a stroke, transients, and noise frequency spectra. Examples illustrating the use of this technique are presented. The use of motor current signature analysis was also shown to apply to other electric motor driven equipment. Future work includes developing a data base of MOV diagnostics, including criteria for determining the extent of degradation and application of the technique to other LWR motor driven safety equipment

SEBIM pilot operated tandems. A new solution for Darlington NGS bleed condenser relief valves

International Nuclear Information System (INIS)

Paetzold, H.; Hera, V.; Schaumburg, G.

1996-01-01

Following incidents at Pickering, Wolsung and Bruce NGS, involving instability of bleed condenser relief valves, Darlington station decided to replace the spring loaded RV's by new pilot operated SEBIM tandem valves. This paper is presenting the approach taken, the design and the testing of the new solution, as well as some of the computer modeling work performed in connection with this project. The SEBIM tandems, following successful testing in France, will be installed in Darlington Unit 2, this spring. The new valves can perform with absence of instability and prevent a LOCA incident due to their design, which includes a protection and a redundant valve in series. (author)

Valve monitoring ITI-MOVATS

International Nuclear Information System (INIS)

Moureau, S.

1993-01-01

ITI-MOVATS provides a wide range of test devices to monitor the performance of valves: motor operated gate or globe valve, butterfly valve, air operated valve, and check valve. The ITI-MOVATS testing equipment is used in the following three areas: actuator setup/baseline testing, periodic/post-maintenance testing, and differential pressure testing. The parameters typically measured with the MOVATS diagnostic system as well as the devices used to measure them are described. (Z.S.)

A study of air-operated valves in U.S. nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Rothberg, O. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (United States); Khericha, S. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (United States); Watkins, J. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (United States); Holbrook, M. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (United States)

2000-02-01

A study of air-operated valves in nuclear power plant applications was conducted for the NRC Office of Research (the project was initiated by NRC/AEOD). The results of the study were based on visits to seven nuclear power plant sites, literature studies, and examinations of event records in databases available to the NRC. The purpose is to provide information to the NRC staff concerning capabilities and performance of air-operated valves (AOVs). Descriptions of air systems and AOVs were studied along with the support systems and equipment. Systems and equipment that contain AOVs and SOVs were studied to determine their dependencies. Applications of AOVs and SOVs were listed along with current NRC requirements.

Assessment of reliability and maintenance of motor operated valves at Finnish NPPS

International Nuclear Information System (INIS)

Laakso, K.; Haenninen, S.; Simola, K.

1994-01-01

This paper summarizes two studies on motor operated valve (MOV) failure and maintenance experiences in Finnish nuclear power plants. In the first study, described in section 2 of this paper, the failure reports of MOVs at Finnish BWR units from a nine years' time period were analyzed in a systematic way. The dominant failure mechanisms were identified and time-dependencies in failure occurrence were studied. This study initiated an experience based reliability centered maintenance (RCM) analysis of motor operated valve drives, which is summarized in chapter 3 of this paper. The RCM analysis resulted in the identification and proposal of the most suitable and effective maintenance tasks for consideration. 9 refs, 3 figs, 1 tab

A study of air-operated valves in U.S. nuclear power plants

International Nuclear Information System (INIS)

Rothberg, O.; Khericha, S.; Watkins, J.; Holbrook, M.

2000-01-01

A study of air-operated valves in nuclear power plant applications was conducted for the NRC Office of Research (the project was initiated by NRC/AEOD). The results of the study were based on visits to seven nuclear power plant sites, literature studies, and examinations of event records in databases available to the NRC. The purpose is to provide information to the NRC staff concerning capabilities and performance of air-operated valves (AOVs). Descriptions of air systems and AOVs were studied along with the support systems and equipment. Systems and equipment that contain AOVs and SOVs were studied to determine their dependencies. Applications of AOVs and SOVs were listed along with current NRC requirements.

NRC valve performance test program - check valve testing

International Nuclear Information System (INIS)

Jeanmougin, N.M.

1987-01-01

The Valve Performance Test Program addresses the current requirements for testing of pressure isolation valves (PIVs) in light water reactors. Leak rate monitoring is the current method used by operating commercial power plants to survey the condition of their PIVs. ETEC testing of three check valves (4-inch, 6-inch, and 12-inch nominal diameters) indicates that leak rate testing is not a reliable method for detecting impending valve failure. Acoustic emission monitoring of check valves shows promise as a method of detecting loosened internals damage. Future efforts will focus on evaluation of acoustic emission monitoring as a technique for determining check valve condition. Three gate valves also will be tested to evaluate whether the check valve results are applicable to gate type PIVs

Nuclear valves latest development

International Nuclear Information System (INIS)

Isaac, F.; Monier, M.

1993-01-01

In the frame of Nuclear Power Plant upgrade (Emergency Power Supply and Emergency Core Cooling), Westinghouse had to face a new valve design philosophy specially for motor operated valves. The valves have to been designed to resist any operating conditions, postulated accident or loss of control. The requirements for motor operated valves are listed and the selected model and related upgrading explained. As part of plant upgrade and valves replacement, Westinghouse has sponsored alternative hardfacing research programme. Two types of materials have been investigated: nickel base alloys and iron base alloys. Programme requirements and test results are given. A new globe valve model (On-Off or regulating) is described developed by Alsthom Velan permitting the seat replacement in less than 10 min. (Z.S.) 2 figs

Identification Trouble Valve Destruction On Hidroulic Press Breaker Model MPV.1620 ''DAVY-ITALlA''

International Nuclear Information System (INIS)

Paidjo; Pinitojo; Hafid, Abdul; Musa, Tamsil; Sagino

2000-01-01

To 'utility instalation examination and operation test, how long capacity to appear on the severaly valve.Torned valve on hidroulic press breaker is three sample: The first directional control valve type. 4 WE 10 H 32 / CE 24 N 9 Z4. Coil: Hydronorma GZ . 63-4 -A. 476. 24VDC, 1,46 A. For two and three is boll spriral spring valve Process operation explanation a short is oil lubrication to pump from reception center tank in to directional control valve then distributed. anything to boll spiral spring valve continued to hidroulic piston for pressed the sample job / plate thickness maximum = 16 mm with to different corner model, maximum press = 160 bar.Hindrance principle is to utilize operation test, hidroulic piston movement botom-up is smothly 0 whereas botom-down went no smoothly. Operation test property to utilize repeated resutls of the aqua. Hindrance / broken the fist estimate that the hole oil works at the directional control valve to threadbore hidroulic piston, wherever preasure not maximum to manometer indicate = 0 bar, at the moment to utilize operation. The second on the boll spiral spring valve no maximum, then to utilize servise detail and to utilize operation test againt. The results from operation test to concende destruction at the boll spiral spring valve, wherever after over houling to appear boll massive place position possessed spring wire> 3 mm to twist of couse preasure to press hidroulic piston no maximum because from leaking

Risk evaluation for motor operated valves in an Inservice Testing Program at a PWR nuclear power plant in Taiwan

International Nuclear Information System (INIS)

Li, Y.C.; Chen, K.T.; Su, Y.L.; Ting, K.; Chien, F.T.; Li, G.D.; Huang, S.H.

2012-01-01

Safety related valves such as Motor Operated Valves (MOV), Air Operated Valves (AOV) or Check Valves (CV) play an important role in nuclear power plant. Functioning of these valves mainly aim at emergency reactivity control, post-accident residue heat removal, post-accident radioactivity removal and containment isolation when a design basis accident occurred. In order to maintain these valves under operable conditions, an Inservice Testing Program (IST) is defined for routine testing tasks based on the ASME Boiler and Pressure Vessel Code section XI code requirements. Risk based Inservice Testing Programs have been studied and developed extensively in the nuclear energy industry since the 1990s. Risk Based evaluations of IST can bring positive advantages to the licensee such as identifying the vulnerability of the system, reducing unnecessary testing burden, concentrating testing resources on the critical pass oriented valves and saving plant’s personnel dose exposure. This risk evaluation is incorporated with quantitative and qualitative analyses to the Motor Operated Valves under current Inservice Testing Program for PWR nuclear power plant in Taiwan. With the outcome of the risk classifications for the safety related MOVs through numerical or deterministic analyses, a risk based testing frequency relief is suggested to demonstrate the benefits received from the risk based Inservice Testing Program. The goal made of this study, it could be as a reference and cornerstone for the licensee to perform overall scope Risk-Informed Inservice Testing Program (RI-IST) evaluation by referring relevant methodologies established in this study.

Correctness of multi-detector-row computed tomography for diagnosing mechanical prosthetic heart valve disorders using operative findings as a gold standard

Energy Technology Data Exchange (ETDEWEB)

Tsai, I.Chen [Taichung Veterans General Hospital, Department of Radiology, Taichung (China); Institute of Clinical Medicine and Faculty of Medicine, National Yang-Ming University, Taipei (China); Lin, Yung-Kai; Chang, Yen; Wang, Chung-Chi; Hsieh, Shih-Rong; Wei, Hao-Ji; Tsai, Hung-Wen [Taichung Veterans General Hospital, Section of Cardiovascular Surgery, Cardiovascular Center, Taichung (China); Fu, Yun-Ching; Jan, Sheng-Ling [Institute of Clinical Medicine and Faculty of Medicine, National Yang-Ming University, Taipei (China); Taichung Veterans General Hospital, Section of Pediatric Cardiology, Department of Pediatrics, Taichung (China); Wang, Kuo-Yang [Taichung Veterans General Hospital, Section of General Cardiology, Cardiovascular Center, Taichung (China); Chung-Shan Medical University, Department of Medicine, Taichung (China); Chen, Min-Chi; Chen, Clayton Chi-Chang [Taichung Veterans General Hospital, Department of Radiology, Taichung (China); Central Taiwan University of Science and Technology, Department of Radiological Technology, Taichung (China)

2009-04-15

The purpose was to compare the findings of multi-detector computed tomography (MDCT) in prosthetic valve disorders using the operative findings as a gold standard. In a 3-year period, we prospectively enrolled 25 patients with 31 prosthetic heart valves. MDCT and transthoracic echocardiography (TTE) were done to evaluate pannus formation, prosthetic valve dysfunction, suture loosening (paravalvular leak) and pseudoaneurysm formation. Patients indicated for surgery received an operation within 1 week. The MDCT findings were compared with the operative findings. One patient with a Bjoerk-Shiley valve could not be evaluated by MDCT due to a severe beam-hardening artifact; thus, the exclusion rate for MDCT was 3.2% (1/31). Prosthetic valve disorders were suspected in 12 patients by either MDCT or TTE. Six patients received an operation that included three redo aortic valve replacements, two redo mitral replacements and one Amplatzer ductal occluder occlusion of a mitral paravalvular leak. The concordance of MDCT for diagnosing and localizing prosthetic valve disorders and the surgical findings was 100%. Except for images impaired by severe beam-hardening artifacts, MDCT provides excellent delineation of prosthetic valve disorders. (orig.)

Application Of Light Valves For Continuous-Tone Printing

Science.gov (United States)

Vergona, Albert B.

1989-07-01

New opportunities are emerging in the graphic-arts pre-press market stimulated by the need for digitally created images. To meet this need, we have designed a cost-effective three-color digital printer using PLZT light valves. Transparent lead lanthanum zirconate titanate (PLZT) ceramic crystals when used as a linear modulator offer a number of significant benefits. The primary advantage is that the light valve is an efficient modulator of incoherent light providing a broad spectral output ranging from 400nm to well into the infrared region. In addition, light valves offer the advantages of being small, low cost, have a wide dynamic range (>1000 to 1), and can be used with simple optical designs. The characteristics of the PLZT material plays an important role in the performance of the light valve. A number of variables such as ceramic composition, electrode spacing, and ceramic thickness can be altered to affect its quadratic electrooptic behavior. Additionally, the modulator design requires a closed-loop servo to eliminate the errors caused by the device's remanent polarization and nonlinear behavior.

Scissor thrust valve actuator

Science.gov (United States)

DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

2006-08-29

Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

Apparatus and method for non-invasive diagnosis and control of motor operated valve condition

Science.gov (United States)

Lyon, R.H.; Chai, J.; Lang, J.H.; Hagman, W.H.; Umans, S.D.; Saarela, O.J.

1997-01-14

An apparatus compares the torque from an MOV motor with the valve displacement, and from the comparison assesses MOV operating condition. A transducer measures the vibration of the housing of an MOV. The vibrations are due to the motions of the rotating elements within the housing, which motions are directly related to the motion of the valve relative to its seat. Signal processing apparatus analyzes the vibrations to recover the rotations of the rotating elements and thus the motion of the valve plug. Lost motion can also be determined (if a lost motion connection exists) by demodulating the vibration signal and thus taking into account also the lost motion. Simultaneously, the forces applied to the valve are estimated by estimating the torque between the stator and the rotor of the motor. Such torque can be estimated from measuring the input current and voltage alone, using a forgetting factor and a correction for the forgetting factor. A signature derived from relating the torque to the valve position can be used to assess the condition of the MOV, by comparing the signature to signatures for MOVs of known conditions. The vibration analysis components generate signals that relate to the position of elements in the operator. Similarly, the torque estimator estimates the torque output by any type of electric motor, whether or not part of an MOV analysis unit. 28 figs.

Methodology for risk assessment and reliability applied for pipeline engineering design and industrial valves operation

Energy Technology Data Exchange (ETDEWEB)

Silveira, Dierci [Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil). Escola de Engenharia Industrial e Metalurgia. Lab. de Sistemas de Producao e Petroleo e Gas], e-mail: dsilveira@metal.eeimvr.uff.br; Batista, Fabiano [CICERO, Rio das Ostras, RJ (Brazil)

2009-07-01

Two kinds of situations may be distinguished for estimating the operating reliability when maneuvering industrial valves and the probability of undesired events in pipelines and industrial plants: situations in which the risk is identified in repetitive cycles of operations and situations in which there is a permanent hazard due to project configurations introduced by decisions during the engineering design definition stage. The estimation of reliability based on the influence of design options requires the choice of a numerical index, which may include a composite of human operating parameters based on biomechanics and ergonomics data. We first consider the design conditions under which the plant or pipeline operator reliability concepts can be applied when operating industrial valves, and then describe in details the ergonomics and biomechanics risks that would lend itself to engineering design database development and human reliability modeling and assessment. This engineering design database development and reliability modeling is based on a group of engineering design and biomechanics parameters likely to lead to over-exertion forces and working postures, which are themselves associated with the functioning of a particular plant or pipeline. This approach to construct based on ergonomics and biomechanics for a more common industrial valve positioning in the plant layout is proposed through the development of a methodology to assess physical efforts and operator reach, combining various elementary operations situations. These procedures can be combined with the genetic algorithm modeling and four elements of the man-machine systems: the individual, the task, the machinery and the environment. The proposed methodology should be viewed not as competing to traditional reliability and risk assessment bur rather as complementary, since it provides parameters related to physical efforts values for valves operation and workspace design and usability. (author)

Valve-sparing operation for aortic root aneurysm in patients with Marfan syndrome.

Science.gov (United States)

Wang, R; Ma, W G; Tian, L X; Sun, L Z; Chang, Q

2010-03-01

We report our experience with aortic valve-sparing procedures in patients with Marfan syndrome and aortic root aneurysm. Between August 2003 and July 2007, we performed aortic valve-sparing procedures in 20 patients with aortic root aneurysm resulting from Marfan syndrome. Mean age was 28 +/- 10 years (range, 10 to 57 years), and there were 9 females and 11 males. A reimplantation technique was used in 9 cases, a remodeling technique in 8 and a patch technique in 3 cases. Additional procedures included total aorta replacement in 1 patient, and aortic arch replacement plus stented elephant trunk in 2 patients. The mean follow-up time was 46 +/- 16 months (range, 17 to 64 months). No in-hospital or late death occurred. Reexploration for bleeding was required in one case on postoperative day 1. No valve-related complications occurred during the follow-up period. At the end of follow-up, trivial or no aortic regurgitation was demonstrated in 14 patients, mild in 4 patients, moderate in 1 and severe in 1. Two patients with moderate and severe aortic regurgitation required reoperation. The early and mid-term results of the valve-sparing operations were favorable, and the durability of the preserved valve should encourage use of this technique in patients with Marfan syndrome.

Aortic root reimplantation procedure: a new milestone in aortic valve-sparing operations

Directory of Open Access Journals (Sweden)

А. М. Чернявский

2016-08-01

Full Text Available Aim: Emphasis in this study was placed on clinical and functional assessment of a modified "Florida Sleeve" procedure during surgical correction of ascending aorta aneurysms with concomitant aortic insufficiency.Methods: 32 patients with an aneurysm of the ascending aorta and aortic insufficiency underwent a modified "Florida Sleeve" procedure. The average follow-up was 17 (0-60 months. The average age of patients was 57±13 (23-73 years 56±13 years.Results: The expected 4-year cumulative survival rate was 84.3%. Overall freedom from aortic insufficiency in the late period was 88.9%. Median aortic regurgitation was 1+ (1; 2. Long-term follow-up revealed no valve-associated complications.Conclusion: The aortic root reimplantation procedure enables optimal correction of the existing lesions of the aortic root without performing aortic valve replacement and demonstrates stable clinical and functional outcomes in the long-term period.Key words: aortic aneurysm; aortic valve; valve-sparing operations.FundingThe study had no sponsorship.Conflict of interestThe authors declare no conflict of interest.

Simulation of Valve Operation for Flow Interrupt Test in Nuclear Power Plant

International Nuclear Information System (INIS)

Kim, Jae Hyung; Shin, Dae Yong; Shin, Dong Woo; Kim, Charn Jung; Lee, Jung Hee

2012-01-01

The valve used in nuclear power plant must be qualified for the function according to the KEPIC MF. The test valve must be selected by shape and size, which is given by KEPIC MF. In the functional test, the mathematical model for the valve operation is needed. The mathematical model must be verified by the test, whose method and procedure is defined in KEPIC MF. The lack of analytical technique has lead to the poor mathematical model, with which the functional test for the big valve is impossible with analytical method. Especially, the tank and rupture disk in the flow test is not considered and the result of the analysis is so different to the real one. In these days, the 3D model for the flow interrupt test makes more accurate analysis. And no facility about functional test reduces the research will for the nuclear power plant valve. For this problem, the test facility for the functional test of the valve and pump in nuclear power plant has been made until 2012. With the test facility, the research project related the valve were initiated in KIMM( Korea Institute of Machinery and Materials). And the joint project to SNU(Seoul National University) has been going on the numerical analysis for the valve in nuclear power plant. Using the commercial software and user subroutine, UDF, the co-simulation with multi-body dynamic and fluid flow analysis and the addition of tank and rupture disk to the user subroutine make possible to simulate the flow interrupt test numerically. This is not simple and regular analysis, which was introduced in user subroutine. In order to simulate the real situation, the engineering work, related mathematical model, and the programming in the user subroutine are needed. This study is on the making the mathematical model for the functional test of the valve in nuclear power plan. The functional test is the real test procedure and defined in KEPIC MF

Resurgery for recurrent heart valve diseases

Directory of Open Access Journals (Sweden)

Chong-lei REN

2017-02-01

Full Text Available Objective　To summarize the experience with resurgery for recurrent valvular heart diseases. Methods　From June 2004 to June 2015, 28 patients (15 males and 13 females with ages ranging from 44 to 67 years (55.6±6.5 years with recurrent heart valve disease underwent resurgery. The reasons for resurgery included perivalvular leakage (7 cases, bioprosthetic valve decline (6 cases in mitral valve and 3 in tricuspid valve, mechanical prostheses dysfunction (2cases, infective endocarditis after valve replacement (2 cases, restenosis of repaired native valve (1 case, and severe tricuspid insufficiency after left-side valve surgery (7 cases. Resurgery included mitral valve replacement in 18 patients and tricuspid valve replacement in 10. All the patients underwent third or fourth or even fifth cardiac surgery for valve replacement. Results　There were 2 hospital deaths with a mortality of 7.1% (2/28. The main causes of early-stage deaths were low cardiac output syndrome. The main postoperative complications were respiratory failure in 3, low cardiac output syndrome in 2, reexploration for bleeding in 2 and serious infectious shock in 1. All the patients were found with the great improvement in heart function and the re-implanted prostheses worked well during follow-up. Conclusions　Although resurgery for recurrent heart valve disease poses a continuing challenge to cardiac surgeon, it could be performed with the satisfactory results. The keys to a successful cardiac resurgery include appropriate operational timing, refined surgical technique and reasonable perioperative managements. DOI: 10.11855/j.issn.0577-7402.2017.01.11

Modified Sleeve Technique in Aortic Valve-Sparing Operation for Marfan Syndrome.

Science.gov (United States)

Wu, Yung-Szu; Hsieh, Shih-Rong; Wang, Chung-Chi; Tsai, Chung-Lin

2018-03-22

We devised a simple modification of the Florida Sleeve procedure to perform aortic valve-sparing surgery. This technique is simple, quick, effective, and safe. We used this technique in operations performed on two young patients with Marfan syndrome. The initial and short-term results were satisfactory.

Relief valve testing study

International Nuclear Information System (INIS)

BROMM, R.D.

2001-01-01

Reclosing pressure-actuated valves, commonly called relief valves, are designed to relieve system pressure once it reaches the set point of the valve. They generally operate either proportional to the differential between their set pressure and the system pressure (gradual lift) or by rapidly opening fully when the set pressure is reached (pop action). A pop action valve allows the maximum fluid flow through the valve when the set pressure is reached. A gradual lift valve allows fluid flow in proportion to how much the system pressure has exceeded the set pressure of the valve (in the case of pressure relief) or has decreased below the set pressure (vacuum relief). These valves are used to protect systems from over and under pressurization. They are used on boilers, pressure vessels, piping systems and vacuum systems to prevent catastrophic failures of these systems, which can happen if they are under or over pressurized beyond the material tolerances. The construction of these valves ranges from extreme precision of less than a psi tolerance and a very short lifetime to extremely robust construction such as those used on historic railroad steam engines that are designed operate many times a day without changing their set pressure when the engines are operating. Relief valves can be designed to be immune to the effects of back pressure or to be vulnerable to it. Which type of valve to use depends upon the design requirements of the system

Computed Tomography Helps to Plan Minimally Invasive Aortic Valve Replacement Operations.

Science.gov (United States)

Stoliński, Jarosław; Plicner, Dariusz; Grudzień, Grzegorz; Kruszec, Paweł; Fijorek, Kamil; Musiał, Robert; Andres, Janusz

2016-05-01

This study evaluated the role of multidetector computed tomography (MDCT) in preparation for minimally invasive aortic valve replacement (MIAVR). An analysis of 187 patients scheduled for MIAVR between June 2009 and December 2014 was conducted. In the study group (n = 86), MDCT of the thorax, aorta, and femoral arteries was performed before the operation. In the control group (n = 101), patients qualified for MIAVR without receiving preoperative MDCT. The surgical strategy was changed preoperatively in 12.8% of patients from the study group and in 2.0% of patients from the control group (p = 0.010) and intraoperatively in 9.9% of patients from the control group and in none from the study group (p = 0.002). No conversion to median sternotomy was necessary in the study group; among the controls, there were 4.0% conversions. On the basis of the MDCT measurements, optimal access to the aortic valve was achieved when the angle between the aortic valve plane and the line to the second intercostal space was 91.9 ± 10.0 degrees and to the third intercostal space was 94.0 ± 1.4 degrees, with the distance to the valve being 94.8 ± 13.8 mm and 84.5 ± 9.9 mm for the second and third intercostal spaces, respectively. The right atrium covering the site of the aortotomy was present in 42.9% of cases when MIAVR had been performed through the third intercostal space and in 1.3% when through the second intercostal space (p = 0.001). Preoperative MDCT of the thorax, aorta, and femoral arteries makes it possible to plan MIAVR operations. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Outlet strut fracture of Björk-Shiley convexo-concave valves: can valve-manufacturing characteristics explain the risk?

Science.gov (United States)

Omar, R Z; Morton, L S; Beirne, M; Blot, W J; Lawford, P V; Hose, R; Taylor, K M

2001-06-01

Björk-Shiley 60 degrees convexo-concave prosthetic heart valves (Shiley, Inc, Irvine, Calif, a subsidiary of Pfizer, Inc) continue to be a concern for approximately 35,000 nonexplanted patients worldwide, with approximately 600 events reported to the manufacturer to date. Fractures of the outlet struts of the valves began to appear in the early 1980s and have continued to the present, but their causes are only partially understood. A matched case-control study was conducted evaluating manufacturing records for 52 valves with outlet strut fractures and 248 control subjects matched for age at implantation, valve size, and valve position. In addition to the risk factors recognized as determinants of outlet strut fracture, the United Kingdom case-control study has observed 7- to 9-fold increased risk with performance of multiple hook deflection tests. This test was performed more than once, usually after rework on the valve. Six valves in this study underwent multiple hook deflection tests, of which 4 experienced an outlet strut fracture. Cracks and further rework were noted for these valves. Significant associations were also observed between outlet strut fracture and disc-to-strut gap measurements taken before the attachment of the sewing ring. It is our view that a combination of factors related to valve design, manufacturing process, and patient characteristics are responsible for outlet strut fractures of Björk-Shiley convexo-concave valves. Multiple hook deflection tests have emerged as a potential new risk factor for outlet strut fracture in both The Netherlands and the United Kingdom. This factor appears to be correlated with the presence of other abnormalities. A further study is needed to investigate the factors correlated with multiple hook deflection tests. On confirmation of risk, the presence of multiple hook deflection tests may be added to equations, quantifying the risk of outlet strut fracture for comparison against risk of mortality and serious

Analysis of failure and maintenance experiences of motor operated valves in a Finnish nuclear power plant

International Nuclear Information System (INIS)

Simola, K.; Laakso, K.

1992-01-01

Operating experiences from 1981 up to 1989 of totally 104 motor operated closing valves (MOV) in different safety systems at TVO I and II nuclear power units were analysed in a systematic way. The qualitative methods used were failure mode and effects analysis (FMEA) and maintenance effects and criticality analysis (MECA). The failure descriptions were obtained from power plant's computerized failure reporting system. The reported 181 failure events were reanalysed and sorted according to specific classifications developed for the MOV function. Filled FMEA and MECA sheets on individual valves were stored in a microcomputer data base for further analyses. Analyses were performed for the failed mechanical and electrical valve parts, ways of detection of failure modes, failure effects, and repair and unavailability times

Motor-operated Valve Program at NPP Krsko (NEK) - Status and Overview

International Nuclear Information System (INIS)

Nikolic, M; Jagodar, N.; Cerjak, J.; Butkovic, V.

2002-01-01

On the basics of US NRC Generic Letter 89-10 Safety-related Motor-operated Valve Testing and Surveillance and subsequent generic letters, Motor-operated Valve (MOV) Program at NEK has been developing. Namely, the holders of nuclear power plant operating licenses has to verify the design basis capability of safety-related e.g. important-to-safety MOVs, as well as to ensure the same for the life of the plant. In light of that, each plant should establish a program to address stressed issues for each program MOV (124 at NEK). Such comprehensive task requires significant effort in many aspects, and basically multidisciplinary skills. NEK MOV Program represents a blend of engineering and in-plant testing, comprised of three phases: Phase I Engineering, Phase II Field Implementation and Phase III Trending. Currently, the program is about the end of Phase I and II, as well as in development of engineering basis for launching Phase III. Overview of the major programmatic issues will be given in this paper along with ongoing activities: testing process, gear-ratio modification, pressure locking/thermal binding susceptibility screening and preventive maintenance. (author)

Air-operated valve diagnostics: requirements, programmes and experiences

International Nuclear Information System (INIS)

Cervilla, Remedios; Vallana, Fernando; Laporta, Jose Maria

2014-01-01

The aim of this paper is to present some elements in the field of air-operated valve (AOV) diagnostics from the perspective of Tecnatom, as a testing services provider in the national and international nuclear park. Throughout the following lines, we summarize the regulatory framework existing in Spain and the current practices in Spanish nuclear power plants regarding the AOV programs, the role of Tecnatom as a service provider and our testing techniques. Finally, a real test case is presented, to illustrate the value of diagnostic as predictive maintenance and early degradation detection tool. (authors)

Analysis of aortic root surgery with composite mechanical aortic valve conduit and valve-sparing reconstruction.

Science.gov (United States)

Dias, Ricardo Ribeiro; Mejia, Omar Asdrubal Vilca; Fiorelli, Alfredo Inácio; Pomerantzeff, Pablo Maria Alberto; Dias, Altamiro Ribeiro; Mady, Charles; Stolf, Noedir Antonio Groppo

2010-01-01

Comparative analysis of early and late results of aortic root reconstruction with aortic valve sparing operations and the composite mechanical valve conduit replacement. From November 2002 to September 2009, 164 consecutive patients with mean age 54 ± 15 years, 115 male, underwent the aortic root reconstruction (125 mechanical valve conduit replacements and 39 valve sparing operations). Sixteen percent of patients had Marfan syndrome and 4.3% had bicuspid aortic valve. One hundred and forty-four patients (88%) were followed for a mean period of 41.1 ± 20.8 months. The hospital mortality was 4.9%, 5.6% in operations with valved conduits and 2.6% in the valve sparing procedures (P valve sparing operations, respectively (95% CI = 70% - 95%, P = 0.001), (95% CI = 82% - 95% P = 0.03) and (95% CI = 81% - 95%, P = 0.03). Multivariate analysis showed that creatinine greater than 1.4 mg/dl, Cabrol operation and renal dialysis were predictors of mortality, respectively, with occurrence chance of 6 (95% CI = 1.8 - 19.5, P = 0.003), 12 (95% CI = 3 - 49.7, P = 0.0004) and 16 (95% CI = 3.6 - 71.3, P = 0.0002). The aortic root reconstruction has a low early and late mortality, high survival free of complications and low need for reoperation. During the late follow-up, valve sparing aortic root reconstructions presented fewer incidences of bleeding, thromboembolic events and endocarditis.

Evaluation of isolation valve leakage in alternate charging piping

International Nuclear Information System (INIS)

Strauch, P.L.; Roarty, D.H.; Brice-Nash, R.L.

1995-01-01

The chemical and volume control system (CVCS) alternate charging flow path at an operating pressurized water reactor (PWR) plant was determined to be susceptible to adverse stresses from isolation valve leakage. Isolation valve leakage had resulted in pipe cracks at several nuclear units worldwide, as described in United States Nuclear Regulatory Commission Bulletin 88-08 and its supplements. To provide for continuing assurance that cracks would not initiate over the plant life, the operators considered performing fatigue evaluation to demonstrate structural integrity of the system. This evaluation included heat transfer, stress and fatigue analysis, using methods described in Electric Power Research Institute Report ''Thermal Stratification, Cycling, and Striping (TASCS),'' March 1994. The evaluation concluded that the fatigue usage would be less than 1.0 under worst case isolation valve leakage conditions, and therefore a significant investment in permanent temperature monitoring was avoided

Development of an integrated condition monitoring and diagnostic system for motor-operated valves used in nuclear power plant

International Nuclear Information System (INIS)

Carneiro, Alvaro Luiz Guimaraes

2003-01-01

The reliability question of the components, specifically of motor operated valves, became one of the most important issues to be investigated in nuclear power plants, considering security and life plant extension. Therefore, the necessity of improvements in monitoring and diagnosis methods started to be of extreme relevance in the maintenance predictive field, establishing as main goal the reliability and readiness of the system components. Specially in nuclear power plants, the predictive maintenance contributes in the security factor in order to diagnosis in advance the occurrence of a possible failure, preventing severe situations. It also presents a contribution on the economic side by establishing a better maintenance programming, and reducing unexpected shutdown. The development of non intrusive monitoring and diagnostic method makes it possible to identify malfunctions in plant components during normal plant operation. This dissertation presents the development of an integrated condition monitoring system for motor-operated valves used in nuclear power plants. The methodology used in this project is based on the electric motor power signatures analysis, during the closing and opening stroke time of the valve. Once the measurements baseline diagnostic of the motor-operated valve is taken, it is possible to detect long-term deviations during valve lifetime, detecting in advance valve failures. The system implements two parallel techniques for detection and categorization of anomalies: expert system using fuzzy logic based on rules and knowledge base, providing a systematic approach for decision making, and the Wavelet Transform Technique, where the main goal is to obtain more detailed information contained in the measured data, identifying and characterizing the transients phenomena in the time and frequency domains, correlating them to failures situations in the incipient stage. The conditioning monitoring and diagnostic system was designed and implemented at

46 CFR 108.443 - Controls and valves.

Science.gov (United States)

2010-10-01

... COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Fire Extinguishing Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.443 Controls and valves. (a) At least one control for operating a CO2 system must be outside the space or spaces that the...

Pilot program to identify valve failures which impact the safety and operation of light water nuclear power plants

International Nuclear Information System (INIS)

Tsacoyeanes, J.C.; Raju, P.P.

1980-04-01

The pilot program described has been initiated under the Department of Energy Light Water Reactor Safety Research and Development Program and has the following specific objectives: to identify the principal types and causes of failures in valves, valve operators and their controls and associated hardware, which lead to, or could lead to plant trip; and to suggest possible remedies for the prevention of these failures and recommend future research and development programs which could lead to minimizing these valve failures or mitigating their effect on plant operation. The data surveyed cover incidents reported over the six-year period, beginning 1973 through the end of 1978. Three sources of information on valve failures have been consulted: failure data centers, participating organizations in the nuclear power industry, and technical documents

Assessment of diagnostic methods for determining degradation of motor-operated valves

International Nuclear Information System (INIS)

Haynes, H.D.; Farmer, W.S.

1992-01-01

The Oak Ridge National Laboratory (ORNL) has carried out a comprehensive aging assessment of motor-operated valves (MOVs) in support of the Nuclear Plant Aging Research (NPAR) program. This paper provides a summary of the ORNL MOV aging assessment with emphasis on the identification, evaluation, and application of MOV monitoring methods and techniques. The diagnostic information available from any MOV measurable parameters was evaluated by ORNL using MOVs that were mounted on test stands. Those tests led to the conclusion that the single most informative MOV measurable parameter was also the one which was most easily acquired, namely the motor current. Motor current signature analysis (MCSA) was found to provide detailed information related to the condition of the motor, motor operator, and valve across a wide range of levels. As part of the MOV aging assessment, several tests were carried out by ORNL on MOVs having implanted defects and degradations. Tests were also performed on many MOVs located within a nuclear power plant. In addition, ORNL participated in the Gate Valve Flow Interruption Blowdown Test program carried out at Wyle Laboratories in Huntsville, Alabama. Results from all of these tests are summarized in this paper and several selected examples are given. Other areas covered in this paper include descriptions of relevant regulatory issues and activities, other related diagnostics research at ORNL, and interactions ORNL has had with outside organizations for the purpose of disseminating research results

Swing check valve

International Nuclear Information System (INIS)

Eminger, H.E.

1977-01-01

A swing check valve which includes a valve body having an inlet and outlet is described. A recess in the valve body designed to hold a seal ring and a check valve disc swingable between open and closed positions. The disc is supported by a high strength wire secured at one end in a support spacer pinned through bearing blocks fixed to the valve body and at its other end in a groove formed on the outer peripheral surface of the disc. The parts are designed and chosen such to provide a lightweight valve disc which is held open by minimum velocity of fluid flowing through the valve which thus reduces oscillations and accompanying wear of bearings supporting the valve operating parts. (Auth.)

AREVA's innovative solutions for valve diagnostics and in-situ valve repair

International Nuclear Information System (INIS)

Damies, H.; Breitenberger, U.; Munoz, L.; Kostroun, F.

2012-01-01

Optimized maintenance strategies are a key aspect for safe and undisturbed plant operation. Innovative valve service solutions can support that in an efficient way. The ADAM®/SIPLUG® valve monitoring system allows full online monitoring of valves and actuators with automatic evaluation and assessment. Especially for safety-related and operation-related valves this provides valuable information on components condition to ensure proper function and contribute to optimization of maintenance strategies as well as effective maintenance performance. More than 25 years of experience in various plants worldwide show that application of ADAM®/SIPLUG® valve diagnostics solution leads to increased plant safety and availability. With the innovative AVARIS technology an in-situ valve repair is possible. It has the unique ability to conduct several steps in-situ, to maintain the sealing seat of gate or check valves. By applying AVARIS, the valve is restored in its original state, the system remains unchanged. Thus, all original documents remain valid and applicable. In comparison to previous procedures like cutting valves out of the pipeline and repairing hard facings or damaged seal seats in a separate workshop or alternatively replacement by a new valve body the new AVARIS technology avoids costs, risk and effort. (author)

Remote actuated valve implant

Science.gov (United States)

McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

2014-02-25

Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

Operation of Two-Shaft Gas Turbine in the Range of Open Anti-Surge Valve

Directory of Open Access Journals (Sweden)

Dzida Marek

2017-12-01

Full Text Available This paper presents experimental tests of full-scale two-shaft gas turbine in the range of open anti-surge valve (ASV. The tests were carried out in a laboratory gas- turbine test stand belonging to Department of Automation and Power Engineering , Faculty of Ocean Engineering and Ship Technology , Gdańsk University of Technology. The tests covered the start-up and low load operation of the turbine set in the range of open anti-surge valve.

State-of-the-Art Report on Pilot Operated Safety Relief Valve

International Nuclear Information System (INIS)

Lee, Jun; Yoon, Ju Hyeon

2003-12-01

The pilot operated safety relief valve(POSRV) is a overpressure protection device. But the POSRV is additionally designed to be functioned as a fast depressurization device differently from the pressurizer safety valve(PSV). So, the POSRV assembly takes on the complicated configuration differently from the PSV, and also its configuration and component parts are much different according to its manufacturers. The objective of the study is to investigate the state of the art for POSRV. We want that the findings of the study are put to practical use as a selection guide to the utilities or system designers which want to purchase the POSRV. In this study, we selected the SEBIM and CCI made goods as the subject of investigation, and have investigated the technical characteristics and operating principles of the goods. However, in this report, the comparative contents with other company which were issued by one company were not handled. Also the advantages or disadvantages between two companies were not handled. Only the technical characteristics and operating principles with each company were described. For reference, the main considerations to select the POSRV' type are follows. - the characteristics of the system that the POSRV is to be installed - the fitness of the POSRV for the system - the requirements related to the function and operation of the POSRV - the vender's opinion

Prediction of coronary artery disease in patients undergoing operations for mitral valve degeneration

Science.gov (United States)

Lin, S. S.; Lauer, M. S.; Asher, C. R.; Cosgrove, D. M.; Blackstone, E.; Thomas, J. D.; Garcia, M. J.

2001-01-01

OBJECTIVES: We sought to develop and validate a model that estimates the risk of obstructive coronary artery disease in patients undergoing operations for mitral valve degeneration and to demonstrate its potential clinical utility. METHODS: A total of 722 patients (67% men; age, 61 +/- 12 years) without a history of myocardial infarction, ischemic electrocardiographic changes, or angina who underwent routine coronary angiography before mitral valve prolapse operations between 1989 and 1996 were analyzed. A bootstrap-validated logistic regression model on the basis of clinical risk factors was developed to identify low-risk (coronary atherosclerosis was defined as 50% or more luminal narrowing in one or more major epicardial vessels, as determined by means of coronary angiography. RESULTS: One hundred thirty-nine (19%) patients had obstructive coronary atherosclerosis. Independent predictors of coronary artery disease include age, male sex, hypertension, diabetes mellitus,and hyperlipidemia. Two hundred twenty patients were designated as low risk according to the logistic model. Of these patients, only 3 (1.3%) had single-vessel disease, and none had multivessel disease. The model showed good discrimination, with an area under the receiver-operating characteristic curve of 0.84. Cost analysis indicated that application of this model could safely eliminate 30% of coronary angiograms, corresponding to cost savings of $430,000 per 1000 patients without missing any case of high-risk coronary artery disease. CONCLUSION: A model with standard clinical predictors can reliably estimate the prevalence of obstructive coronary atherosclerosis in patients undergoing mitral valve prolapse operations. This model can identify low-risk patients in whom routine preoperative angiography may be safely avoided.

[Remote results of plastic operations on the tricuspid valve in patients with cardiac insufficiency at terminal stage].

Science.gov (United States)

Habriielian, A V; Smorzhevs'kyĭ, V I; Onishchenko, V F; Beleĭovych, V V; Topchu, Ie I; Domans'kyĭ, T M; Myroniuk, O I

2011-07-01

Comparative analysis of the results of plastic operations performance on a tricuspid valve (TV) in patients, suffering cardiac insufficiency in terminal stage, was conducted. In late postoperative period the indices of intracardial hemodynamics (cardiac output fraction, regurgitation on TV) and clinical features (severity of symptoms, quality of life) after plastic operations, using a support ring, have differed significantly from those after performance of a sutured plasty. The valve function during five years was secured in 91.1% of patients.

PATs Operating in Water Networks under Unsteady Flow Conditions: Control Valve Manoeuvre and Overspeed Effect

Directory of Open Access Journals (Sweden)

Modesto Pérez-Sánchez

2018-04-01

Full Text Available The knowledge of transient conditions in water pressurized networks equipped with pump as turbines (PATs is of the utmost importance and necessary for the design and correct implementation of these new renewable solutions. This research characterizes the water hammer phenomenon in the design of PAT systems, emphasizing the transient events that can occur during a normal operation. This is based on project concerns towards a stable and efficient operation associated with the normal dynamic behaviour of flow control valve closure or by the induced overspeed effect. Basic concepts of mathematical modelling, characterization of control valve behaviour, damping effects in the wave propagation and runaway conditions of PATs are currently related to an inadequate design. The precise evaluation of basic operating rules depends upon the system and component type, as well as the required safety level during each operation.

10 Years of operating experience of the valves in the safety systems on Caorso plant

International Nuclear Information System (INIS)

Curcuruto, S.; Pasquini, M.

1990-01-01

The Operating Experience (O.E.) of the valves in the safety related systems on Caorso plant has been analysed. The valves have been grouped according to system, type and manufacturer. All the data on the failures have been respectively drawn out by the O.E. data bank and, in some cases, they have been integrated by informations collected directly on the plant. The events and the relevant causes have been analysed, particularly taking into account the repetitive events. Most of the failures were discovered during the surveillance tests, giving a positive indication of the effectiveness of the periodic test program. It was also that concluded hardware problems caused more failures than human errors both during operation and maintenance. Abnormal distributions of failures on the valves and on their components have been found out. Weak components both mechanical and electrical and pertinent corrective measures have been identified, aimed to eliminate the recurring failure modes

Integration of continuous-flow sampling with microchip electrophoresis using poly(dimethylsiloxane)-based valves in a reversibly sealed device.

Science.gov (United States)

Li, Michelle W; Martin, R Scott

2007-07-01

Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39 nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n = 10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90 s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions.

Statistical analysis on failure-to-open/close probability of motor-operated valve in sodium system

International Nuclear Information System (INIS)

Kurisaka, Kenichi

1998-08-01

The objective of this work is to develop basic data for examination on efficiency of preventive maintenance and actuation test from the standpoint of failure probability. This work consists of a statistical trend analysis of valve failure probability in a failure-to-open/close mode on time since installation and time since last open/close action, based on the field data of operating- and failure-experience. In this work, the terms both dependent and independent on time were considered in the failure probability. The linear aging model was modified and applied to the first term. In this model there are two terms with both failure rates in proportion to time since installation and to time since last open/close-demand. Because of sufficient statistical population, motor-operated valves (MOV's) in sodium system were selected to be analyzed from the CORDS database which contains operating data and failure data of components in the fast reactors and sodium test facilities. According to these data, the functional parameters were statistically estimated to quantify the valve failure probability in a failure-to-open/close mode, with consideration of uncertainty. (J.P.N.)

A nonintrusive method for measuring the operating temperature of a solenoid-operated valve

International Nuclear Information System (INIS)

Kryter, R.C.

1990-01-01

Experimental data are presented to show that the in-service operating temperature of a solenoid-operated valve (SOV) can be interred simply and nondisruptively by using the copper winding of the solenoid coil as a self-indicating, permanently available resistance thermometer. The principal merits of this approach include (a) there is no need for an add-on temperature sensor, (b) the true temperature of a critical --- and likely the hottest --- part of the SOV (namely, the electrical coil) is measured directly, (c) temperature readout can be provided at any location at which the SOV electrical lead wires are accessible (even though remote from the valve), (d) the SOV need not be disturbed (whether normally energized or deenergized) to measure its temperature in situ, and (e) the method is applicable to all types of SOVs, large and small, ac- and dc-powered. Laboratory tests comparing temperatures measured both by coil resistance and by a conventional thermometer placed in contact with the external surface of the potted solenoid coil indicate that temperature within the coil may be on the order of 40 degree C higher than that measured externally, a fact that is important to life-expectancy calculations made on the basis of Arrhenius theory. Field practicality is illustrated with temperature measurements made using this method on a SOV controlling the flow of refrigerant in a large chilled-water air-conditioning system. 5 refs., 7 figs

Preliminary assessment of valve IST effectiveness

International Nuclear Information System (INIS)

Grove, E.; DiBiasio, A.; Carbonaro, J.

1994-01-01

A preliminary review of inservice testing effectiveness for Code Class 1,2, and 3 valves at nuclear power plants was performed. These requirements are specified by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI, and the Operations and Maintenance Standard. The Institute of Nuclear Power Operations Nuclear Plant Reliability Data System (NPRDS) database was used to provide failure reports for these components for 1988 to 1992. This time period coincides with the issuance of Generic Letter 89-04, which resulted in a more consistent application of the requirements by the licensees. For this time period, 8,593 valve failures were identified. From the review of the NPRDS database, the primary failure causes and failure modes for motor-operated valves (MOV), air-operated valves (AOV), and check valves (CV) were identified. Solenoid-operated valves were not reviewed in this study. Plant testing programs were effective in identifying approximately 60% of the CV failures, 46% of the AOV failures, and 44% of the MOV failures

Which valve is which?

Directory of Open Access Journals (Sweden)

Pravin Saxena

2015-01-01

Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

Overflow control valve

International Nuclear Information System (INIS)

Kessinger, B.A.; Hundal, R.; Parlak, E.A.

1982-01-01

An overflow control valve for use in a liquid sodium coolant pump tank which can be remotely engaged with and disengaged from the pump tank wall to thereby permit valve removal. An actuating shaft for controlling the valve also has means for operating a sliding cylinder against a spring to retract the cylinder from sealing contact with the pump tank nozzle. (author)

Prediction of coronary artery disease in patients undergoing operations for mitral valve degeneration

Science.gov (United States)

Lin, S. S.; Lauer, M. S.; Asher, C. R.; Cosgrove, D. M.; Blackstone, E.; Thomas, J. D.; Garcia, M. J.

2001-01-01

OBJECTIVES: We sought to develop and validate a model that estimates the risk of obstructive coronary artery disease in patients undergoing operations for mitral valve degeneration and to demonstrate its potential clinical utility. METHODS: A total of 722 patients (67% men; age, 61 +/- 12 years) without a history of myocardial infarction, ischemic electrocardiographic changes, or angina who underwent routine coronary angiography before mitral valve prolapse operations between 1989 and 1996 were analyzed. A bootstrap-validated logistic regression model on the basis of clinical risk factors was developed to identify low-risk (< or =5%) patients. Obstructive coronary atherosclerosis was defined as 50% or more luminal narrowing in one or more major epicardial vessels, as determined by means of coronary angiography. RESULTS: One hundred thirty-nine (19%) patients had obstructive coronary atherosclerosis. Independent predictors of coronary artery disease include age, male sex, hypertension, diabetes mellitus,and hyperlipidemia. Two hundred twenty patients were designated as low risk according to the logistic model. Of these patients, only 3 (1.3%) had single-vessel disease, and none had multivessel disease. The model showed good discrimination, with an area under the receiver-operating characteristic curve of 0.84. Cost analysis indicated that application of this model could safely eliminate 30% of coronary angiograms, corresponding to cost savings of $430,000 per 1000 patients without missing any case of high-risk coronary artery disease. CONCLUSION: A model with standard clinical predictors can reliably estimate the prevalence of obstructive coronary atherosclerosis in patients undergoing mitral valve prolapse operations. This model can identify low-risk patients in whom routine preoperative angiography may be safely avoided.

Redo mitral valve surgery

Directory of Open Access Journals (Sweden)

Redoy Ranjan

2018-03-01

Full Text Available This study is based on the findings of a single surgeon’s practice of mitral valve replacement of 167 patients from April 2005 to June 2017 who developed symptomatic mitral restenosis after closed or open mitral commisurotomy. Both clinical and color doppler echocardiographic data of peri-operative and six months follow-up period were evaluated and compared to assess the early outcome of the redo mitral valve surgery. With male-female ratio of 1: 2.2 and after a duration of 6 to 22 years symptom free interval between the redo procedures, the selected patients with mitral valve restenosis undergone valve replacement with either mechanical valve in 62% cases and also tissue valve in 38% cases. Particular emphasis was given to separate the adhered pericardium from the heart completely to ameliorate base to apex and global contraction of the heart. Besides favorable post-operative clinical outcome, the echocardiographic findings were also encouraging as there was statistically significant increase in the mitral valve area and ejection fraction with significant decrease in the left atrial diameter, pressure gradient across the mitral valve and pulmonary artery systolic pressure. Therefore, in case of inevitable mitral restenosis after closed or open commisurotomy, mitral valve replacement is a promising treatment modality.

A shut-off valve for flexible tubing

Science.gov (United States)

Reyburn, W. W.

1972-01-01

Design of light weight valve for flexible tubing is described. Valve is hand operated and provides positive sealing in normally closed position. Diagram is provided to show construction of valve. Principles of operation are explained.

Minimally invasive aortic valve replacement

DEFF Research Database (Denmark)

Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

2009-01-01

In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy...... operations were completed as mini-sternotomies, 4 died later of noncardiac causes. The aortic cross-clamp and perfusion times were significantly different across all groups (P replacement...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

Design and characterization of poly(dimethylsiloxane)-based valves for interfacing continuous-flow sampling to microchip electrophoresis.

Science.gov (United States)

Li, Michelle W; Huynh, Bryan H; Hulvey, Matthew K; Lunte, Susan M; Martin, R Scott

2006-02-15

This work describes the fabrication and evaluation of a poly(dimethyl)siloxane (PDMS)-based device that enables the discrete injection of a sample plug from a continuous-flow stream into a microchannel for subsequent analysis by electrophoresis. Devices were fabricated by aligning valving and flow channel layers followed by plasma sealing the combined layers onto a glass plate that contained fittings for the introduction of liquid sample and nitrogen gas. The design incorporates a reduced-volume pneumatic valve that actuates (on the order of hundreds of milliseconds) to allow analyte from a continuously flowing sampling channel to be injected into a separation channel for electrophoresis. The injector design was optimized to include a pushback channel to flush away stagnant sample associated with the injector dead volume. The effect of the valve actuation time, the pushback voltage, and the sampling stream flow rate on the performance of the device was characterized. Using the optimized design and an injection frequency of 0.64 Hz showed that the injection process is reproducible (RSD of 1.77%, n = 15). Concentration change experiments using fluorescein as the analyte showed that the device could achieve a lag time as small as 14 s. Finally, to demonstrate the potential uses of this device, the microchip was coupled to a microdialysis probe to monitor a concentration change and sample a fluorescein dye mixture.

Theoretical analysis of steady state operating forces in control valves

Directory of Open Access Journals (Sweden)

Basavaraj Hubballi

2018-01-01

Full Text Available The controlling components, such as valves are used to regulate controlled fluid power. It is not always possible to calculate valve forces accurately, and with some types of valves even the existence of certain types of forces cannot be predicted with certainty. In many cases, however, the analysis can be made fairly completely and accurately. The assumption of steady state conditions is valid for the valve alone, but transient effects in the rest of the system may be large. These effects are particularly important with regard to the instability of valves, where the system may react on the valve in such a way as to make it squeal or oscillate, sometimes with large amplitude. The origin of the steady state flow force understood from a brief qualitative explanation. The following paper will summarize much of what is known about valve forces in the spool type controlling element.

Preventive maintenance basis: Volume 1 -- Air-operated valves. Final report

International Nuclear Information System (INIS)

Worledge, D.; Hinchcliffe, G.

1997-07-01

US nuclear plants are implementing preventive maintenance (PM) tasks with little documented basis beyond fundamental vendor information to support the tasks or their intervals. The Preventive Maintenance Basis project provides utilities with the technical basis for PM tasks and task intervals associated with 40 specific components such as valves, electric motors, pumps, and HVAC equipment. This report provides an overview of the PM Basis project and describes use of the PM Basis database. This document provides a program of PM tasks suitable for application to Air Operated Valves (AOV's) in nuclear power plants. The PM tasks that are recommended provide a cost-effective way to intercept the causes and mechanisms that lead to degradation and failure. They can be used, in conjunction with material from other sources, to develop a complete PM program or to improve an existing program. Users of this information will be utility managers, supervisors, craft technicians, and training instructors responsible for developing, optimizing, or fine-tuning PM programs

Cavitation guide for control valves

Energy Technology Data Exchange (ETDEWEB)

Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

1993-04-01

This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

Cavitation guide for control valves

International Nuclear Information System (INIS)

Tullis, J.P.

1993-04-01

This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation

250 kV aim for hvdc valves

Energy Technology Data Exchange (ETDEWEB)

1966-06-01

Development now being carried out by ASEA is aimed at increasing the normal operating voltage for a mercury arc valve to 250 kV dc. The maximum direct voltage per valve group, with one valve in each arm of the bridge, is 125 kV for equipment already in operation in New Zealand, Japan, and Konti Scan. Valves for 130 kV and 133 kV operation are under construction for the Vancouver and the Pacific Intertie 1 links.

Door valve for fuel handling path

International Nuclear Information System (INIS)

Makishima, Katsuhiko.

1969-01-01

A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. A valve plate is suspended from the box press by four guide wheels mounted thereon. The guide wheels are fitted into inclined guide grooves formed at the valve plate and into grooved formed in the inner wall of a valve casing. A locking ball is provided at each side of the valve plate. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing, thus releasing the locking balls. The valve plate does not contact the bottom of the casing. When the box press reaches the home position, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not slide over other parts. (Yamaguchi, T.)

Assessment of nonintrusive methods for monitoring the operational readiness of solenoid-operated valves

International Nuclear Information System (INIS)

Kryter, R.C.

1988-01-01

Solenoid-operated valves (SOVs) are being studied at Oak Ridge National Laboratory as part of the USNRC Nuclear Plant Aging Research (NPAR) Program. The primary objective of the study is to identify and recommend methods for inspection, surveillance, and maintenance of SOVs that can ensure their operational readiness-- that is, their ability to perform required safety functions under all anticipated operating conditions. An earlier (Phase I) study described SOV failure modes and causes and identified measurable parameters that might be used to monitor the various degradations that lead to functional failure. The present (Phase II) study focuses on devising and then demonstrating the effectiveness of techniques and/or equipment with which to measure the previously identified performance parameters and thus detect and trend the progress of any degradation. Several nonintrusive techniques are currently under investigation. Recent experimental results which demonstrate the feasibility and practicality of the techniques being studied are presented. 4 refs., 6 figs., 2 tabs

Frequency probabilistic analysis of a small break LOCA due to a power operated relief valve (PORV) for Angra-1 pre-TMI and post-TMI

International Nuclear Information System (INIS)

Onusic Junior, J.

1986-01-01

After the TMI event efforts were aimed towards improvements in the operational and administrative procedures related to the power operated relief valves (PORVs) in order to decrease the probability of a small-break loss-of-coolant accident (LOCA) caused by stuck-open power operated relief valve. This paper presents a frequency probabilistic analysis of a small break LOCA due to a stuck open PORV and safety valve to the Angra I nuclear power plant in operating conditions pre-TMI and post-TMI. (Author) [pt

Simulant Development for Hanford Tank Farms Double Valve Isolation (DVI) Valves Testing

Energy Technology Data Exchange (ETDEWEB)

Wells, Beric E.

2012-12-21

Leakage testing of a representative sample of the safety-significant isolation valves for Double Valve Isolation (DVI) in an environment that simulates the abrasive characteristics of the Hanford Tank Farms Waste Transfer System during waste feed delivery to the Waste Treatment and Immobilization Plant (WTP) is to be conducted. The testing will consist of periodic leak performed on the DVI valves after prescribed numbers of valve cycles (open and close) in a simulated environment representative of the abrasive properties of the waste and the Waste Transfer System. The valve operations include exposure to cycling conditions that include gravity drain and flush operation following slurry transfer. The simulant test will establish the performance characteristics and verify compliance with the Documented Safety Analysis. Proper simulant development is essential to ensure that the critical process streams characteristics are represented, National Research Council report “Advice on the Department of Energy's Cleanup Technology Roadmap: Gaps and Bridges”

VALIDATION OF MITRAL VALVE ANNULUS DIMENSIONS MEASURED BY 2D TRANS-THORACIC ECHOCARDIOGRAPHY WITH GOLD STANDARD DIRECT INTRA-OPERATIVE MEASUREMENT

OpenAIRE

Praveen; Yadav; Ankur; Saket; Kaushal

2014-01-01

CONTEXT: Precise estimation of Mitral valve annulus dimensions preoperatively through Echocardiography is of paramount importance in replacement/repair surgeries. However a frequent disagreement was experienced between anticipated size of prosthetic valve based on echocardiography and actual valve size. This fact encouraged the authors to validate the measurements through echocardiography with gold-standard direct intra operative measurement. AIM: To compare the mitral val...

Automatic fire hydrant valve development

International Nuclear Information System (INIS)

Drumheller, K.

1976-01-01

The development of a remotely-controlled valve to operate a fire hydrant is described. Assembled from off-the-shelf components, the prototype illustrates that a valve light enough to be handled by one man is possible. However, it does not have the ruggedness or reliability needed for actual fire-fighting operations. Preliminary testing by City of Tacoma fire department personnel indicates that the valve may indeed contribute significantly to fire-fighting efficiency

Aortic valve-sparing in 37 patients with Marfan syndrome: midterm results with David operation.

Science.gov (United States)

Forteza, Alberto; De Diego, Javier; Centeno, Jorge; López, Maria Jesus; Pérez, Enrique; Martín, Carlos; Sánchez, Violeta; Rufilanchas, Juan J; Cortina, Jose

2010-01-01

We reviewed our experience with aortic valve-sparing operations in Marfan syndrome during last 5 years. Between March 2004 and June 2009, 94 patients with aortic root aneurysms underwent valve-sparing operations. Of these, 37 (68% male) were diagnosed with Marfan syndrome, according to the Ghent diagnostic criteria. Mean age was 30 +/- 10 years (range, 11 to 59 years). Moderate/severe aortic regurgitation was present in 13%, and the mean diameter of the Valsalva sinuses was 50 +/- 4 mm (range, 42 to 62 mm). The David V modification was performed in the last 28 patients. Additional procedures were mitral valve repair in 6, tricuspid valve repair in 3, closure of septal atrial defect in 2, and closure of a patent foramen ovale in 13. Mean follow-up was 27 +/- 16 months (range, 1 to 61 months). There were no in-hospital deaths and no major adverse outcomes. One patient required implantation of a mechanical prosthesis during the same procedure because of moderate aortic regurgitation. One late death occurred. No patients required reoperation. In the last follow-up, 23 patients did not have aortic regurgitation, 12 had grade I, and 1 had grade II. No thromboembolic complications have been documented, and 97% of the patients are free from anticoagulation. Short-term and midterm results with the reimplantation technique for aortic root aneurysms in Marfan patients are excellent. If long-term results are similar, this technique could be the treatment of choice for these patients. 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Valve thrombosis following transcatheter aortic valve implantation: a systematic review.

Science.gov (United States)

Córdoba-Soriano, Juan G; Puri, Rishi; Amat-Santos, Ignacio; Ribeiro, Henrique B; Abdul-Jawad Altisent, Omar; del Trigo, María; Paradis, Jean-Michel; Dumont, Eric; Urena, Marina; Rodés-Cabau, Josep

2015-03-01

Despite the rapid global uptake of transcatheter aortic valve implantation, valve trombosis has yet to be systematically evaluated in this field. The aim of this study was to determine the clinical characteristics, diagnostic criteria, and treatment outcomes of patients diagnosed with valve thrombosis following transcatheter aortic valve implantation through a systematic review of published data. Literature published between 2002 and 2012 on valve thrombosis as a complication of transcatheter aortic valve implantation was identified through a systematic electronic search. A total of 11 publications were identified, describing 16 patients (mean age, 80 [5] years, 65% men). All but 1 patient (94%) received a balloon-expandable valve. All patients received dual antiplatelet therapy immediately following the procedure and continued to take either mono- or dual antiplatelet therapy at the time of valve thrombosis diagnosis. Valve thrombosis was diagnosed at a median of 6 months post-procedure, with progressive dyspnea being the most common symptom. A significant increase in transvalvular gradient (from 10 [4] to 40 [12] mmHg) was the most common echocardiographic feature, in addition to leaflet thickening. Thrombus was not directly visualized with echocardiography. Three patients underwent valve explantation, and the remaining received warfarin, which effectively restored the mean transvalvular gradient to baseline within 2 months. Systemic embolism was not a feature of valve thrombosis post-transcatheter aortic valve implantation. Although a rare, yet likely under-reported complication of post-transcatheter aortic valve implantation, progressive dyspnea coupled with an increasing transvalvular gradient on echocardiography within the months following the intervention likely signifies valve thrombosis. While direct thrombus visualization appears difficult, prompt initiation of oral anticoagulation therapy effectively restores baseline valve function. Copyright © 2014

Aortic valve-sparing operations in aortic root aneurysms: remodeling or reimplantation?

Science.gov (United States)

Rahnavardi, Mohammad; Yan, Tristan D; Bannon, Paul G; Wilson, Michael K

2011-08-01

A best evidence topic was written according to a structured protocol. The question addressed was whether the reimplantation (David) technique or the remodeling (Yacoub) technique provides the optimum event free survival in patients with an aortic root aneurysm suitable for an aortic valve-sparing operation. In total, 392 papers were found using the reported search criteria, of which 14 papers provided the best evidence to answer the clinical question. A total of 1338 patients (Yacoub technique in 606 and David technique in 732) from 13 centres were included. In most series, cardiopulmonary bypass time and aortic cross-clamp time were longer for the David technique compared to the Yacoub technique. Early mortality was comparable between the two techniques (0-6.9% for the Yacoub technique and 0-6% for the David technique). There is a tendency for a higher freedom from significant long-term aortic insufficiency in the David group than the Yacoub group, which does not necessarily result in a higher reoperation rate in the Yacoub group. In the largest series reported, freedom from a moderate-to-severe aortic insufficiency at 12 years was 82.6 ± 6.2% in the Yacoub and 91.0 ± 3.8% in the David group (P=0.035). Freedom from reoperation at the same time point was 90.4 ± 4.7% in the Yacoub group and 97.4 ± 2.2% in the David group (P=0.09). In another series, freedom from reoperation at a follow-up time of about four years was 89 ± 4% in the Yacoub group and 98 ± 2% in the David group. Although some authors merely preferred the Yacoub technique for a bicuspid aortic valve, the accumulated evidence in the current review indicates comparable results for both techniques in a bicuspid aortic valve. Current evidence is in favour of the David rather than the Yacoub technique in pathologies such as Marfan syndrome, acute type A aortic dissection, and excessive annular dilatation that may impair aortic root integrity. Careful selection of patients for each technique and

Valve testing for UK PWR safety applications

International Nuclear Information System (INIS)

George, P.T.; Bryant, S.

1989-01-01

Extensive testing and development has been done by the Central Electricity Generating Board (CEGB) to support the design, construction and operation of Sizewell B, the UK's first PWR. A Blowdown Rig for the Assessment of Valve Operability - (BRAVO) has been constructed at the CEGB Marchwood Engineering Laboratory to reproduce PWR Pressurizer fluid conditions for the full scale testing of Pressurizer Relief System (PRS) valves. A full size tandem pair of Pilot Operated Safety Relief Valves (POSRVs) is being tested under the full range of pressurizer fluid conditions. Tests to date have produced important data on the performance of the valve in its Cold Overpressure protection mode of operation and on methods for the in-service testing of the valve. Also, a full size pressurizer safety valve has been tested under full PRS fluid conditions to develop a methodology for the pre-service testing of the Sizewell valves. Further work will be carried out to develop procedures for the in-service testing of the valve. In the Main Steam Safety Valve test program carried out at the Siemens-KWU Test Facilities, a single MSSV from three potential suppliers was tested under full secondary system conditions. The test results have been analyzed and are reflected in the CEGB's arrangements for the pre-service and in-service testing of the Sizewell MSSVs. Valves required to interrupt pipebreak flow must be qualified for this duty by testing or a combination of testing and analysis. To obtain guidance on the performance of such tests gate and globe valves have been subjected to simulated pipebreaks under PWR primary circuit conditions. In the light of problems encountered with gate valve closure under these conditions, further tests are currently being carried out on the BRAVO facility on a gate valve, in preparation for the full scale flow interruption qualification testing of the Sizewell main steam isolation valve

The patient inflating valve in anaesthesia and resuscitation breathing systems.

Science.gov (United States)

Fenton, P M; Bell, G

2013-03-01

Patient inflating valves combined with self-inflating bags are known to all anaesthetists as resuscitation devices and are familiar as components of draw-over anaesthesia systems. Their variants are also commonplace in transfer and home ventilators. However, the many variations in structure and function have led to difficulties in their optimal use, definition and classification. After reviewing the relevant literature, we defined a patient inflating valve as a one-way valve that closes an exit port to enable lung inflation, also permitting exhalation and spontaneous breathing, the actions being automatic. We present a new classification based on the mechanism of valve opening/closure; namely elastic recoil of a flexible flap/diaphragm, sliding spindle opened by a spring/magnet or a hollow balloon collapsed by external pressure. The evolution of these valves has been driven by the difficulties documented in critical incidents, which we have used along with information from modern International Organization for Standardization standards to identify 13 ideal properties, the top six of which are non-jamming, automatic, no bypass effect, no rebreathing or air entry at patient end, low resistance, robust and easy to service. The Ambu and the Laerdal valves have remained popular due to their simplicity and reliability. Two new alternatives, the Fenton and Diamedica valves, offer the benefits of location away from the patient while retaining a small functional dead space. They also offer the potential for greater use of hybrid continuous flow/draw-over systems that can operate close to atmospheric pressure. The reliable application of positive end-expiratory pressure/continuous positive airway pressure remains a challenge.

Dangers of bypassing thermal overload relays in nuclear power plant motor operated valve circuits

International Nuclear Information System (INIS)

Baxter, F.D.

1980-01-01

Operation of motor operated valves is analyzed under various abnormal conditions such as frozen bearing, tight packing, mid-travel obstruction, torque switch failure, limit switch failure, and post-accident operation. Each condition has been reviewed to show that an adverse situation results if the thermal overload relays in the circuit are bypassed. In conclusion, there appears to be no technical basis for bypassing or oversizing the thermal overload relay provided it is selected correctly

Safety and relief valves in light water reactors

International Nuclear Information System (INIS)

Singh, A.

1985-12-01

Information is presented to: provide an introduction to and descriptions of various types of safety and relief valves in both PWR and BWR plants; describe anticipated operating conditions for these valves; describe the test facilities, procedures, and major results for both types of valves; present an extensive discussion of modeling and analysis of safety and relief valve performance, including the prediction of flow capacity and stability during operation; deal with the analyses related to the prediction of thermal-hydraulic loads on discharge piping and comparison against test data; discuss results of small-scale valve tests and flow visualization studies through transparent valve models; and describe an EPRI study for optimizing a typical PWR over-pressure protection system to enhance the availability and reliability of plant operation and thus reduce operation costs

CFD simulations of flow erosion and flow-induced deformation of needle valve: Effects of operation, structure and fluid parameters

Energy Technology Data Exchange (ETDEWEB)

Zhu, Hongjun, E-mail: ticky863@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China); State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, Sichuan (China); Pan, Qian; Zhang, Wenli; Feng, Guang; Li, Xue [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China)

2014-07-01

Highlights: • A combined FSI–CFD and DPM computational method is used to investigate flow erosion and deformation of needle valve. • The numerical model is validated with the comparison of measured and predicted erosion rate. • Effects of operation, structure and fluid parameters on flow erosion and flow-induced deformation are discussed. • Particle diameter has the most significant effect on flow erosion. • Inlet rate has the most obvious effect on flow-induced deformation. - Abstract: A three-dimensional fluid–structure interaction (FSI) computational model coupling with a combined continuum and discrete model has been used to predict the flow erosion rate and flow-induced deformation of needle valve. Comparisons with measured data demonstrate good agreement with the predictions of erosion rate. The flow field distribution of gas-particle flow and the erosion rate and deformation of valve core are captured under different operating and structural conditions with different fluid parameters. The effects of inlet velocity, valve opening and inlet valve channel size, particle concentration, particle diameter and particle phase components are discussed in detail. The results indicate that valve tip has the most severe erosion and deformation, and flow field, erosion rate and deformation of valve are all sensitive to inlet condition changes, structural changes and fluid properties changes. The effect of particle diameter on erosion is the most significant, while the influence of inlet rate on deformation is the greatest one.

Steam turbine power plant having improved testing method and system for turbine inlet valves associated with downstream inlet valves preferably having feedforward position managed control

International Nuclear Information System (INIS)

Lardi, F.; Ronnen, U.G.

1981-01-01

A throttle valve test system for a large steam turbine functions in a turbine control system to provide throttle and governor valve test operations. The control system operates with a valve management capability to provide for pre-test governor valve mode transfer when desired, and it automatically generates feedforward valve position demand signals during and after valve tests to satisfy test and load control requirements and to provide smooth transition from valve test status to normal single or sequential governor valve operation. A digital computer is included in the control system to provide control and test functions in the generation of the valve position demand signals

40 CFR 63.175 - Quality improvement program for valves.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Quality improvement program for valves... alternative quality improvement programs specified in paragraphs (d) and (e) of this section. The decision to... § 63.168 and § 63.175. (1) If the owner or operator elects to continue the quality improvement program...

Door valve for fuel handling path

International Nuclear Information System (INIS)

Makishima, Katsuhiko.

1969-01-01

A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. From the box press a valve plate is suspended by four linkage bars, one for each corner. Each linkage bar is provided with two wheels which are respectively mounted at the connections with the box press and the valve plate. The wheels are carried on the horizontal grooves formed in a door valve casing. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing while the valve plate does not contact the casing. When the box press reaches the home position, the wheels drop into the recesses which are disposed at the ends of the grooves, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not over other parts. (Yamaguchi, T.)

BWR control rod drive scram pilot valve monitoring system

International Nuclear Information System (INIS)

Soden, R.A.; Kelly, V.

1984-01-01

The control rod drive system in a Boiling Water Reactor is the most important safety system in the power plant. All components of the system can be verified except the solenoid operated, scram pilot valves without scramming a rod. The pilot valve mechancial works is the weak link to the control rod drive system. These pilot valves control the hydraulic system which applies pressure to the ''insert'' side of the control rod piston and vents the ''withdraw'' side of the piston causing the rods to insert during a scam. The only verification that the valve is operating properly is to scram the rod. The concern for this portion of the system is demonstrated by the high number of redundant components and complete periodic testing of the electrical circuits. The pilot valve can become hung-up through wear, fracture of internal components, mechanical binding, foreign material or chemicals left in the valve during maintenance, etc. If the valve becomes hung-up the electrical tests performed will not indicate this condition and scramming the rod is in jeopardy. Only an attempt to scram a rod will indicate the hung-up valve. While this condition exists the rod is considered inoperative. This paper describes a system developed at a nuclear power plant that monitors the pilot valves on the control rod drive system. This system utilizes pattern recognition to assure proper internal workings of the scram pilot valves to plant operators. The system is totally automatic such that each time the valve is operated on a ''half scram'', a printout is available to the operator along with light indication that each of the 370 valves (on one unit of a BWR) is operating properly. With this monitoring system installed, all components of the control rod drive system including the solenoid pilot valves can be verified as operational without scramming any rods

BWR control rod drive scram pilot valve monitoring program

International Nuclear Information System (INIS)

Soden, R.A.; Kelly, V.

1986-01-01

The control rod drive system in a Boiling Water Reactor is the most important safety system in the power plant. All components of the system can be verified except the solenoid operated, scram pilot valves without scramming a rod. The pilot valve mechanical works is the weak link to the control rod drive system. These pilot valves control the hydraulic system which applies pressure to the insert side of the control rod piston and vents the withdraw side of the piston causing the rods to insert during a scram. The only verification that the valve is operating properly is to scram the rod. The concern for this portion of the system is demonstrated by the high number of redundant components and complete periodic testing of the electrical circuits. The pilot valve can become hung-up through wear, fracture of internal components, mechanical binding, foreign material or chemicals left in the valve during maintenance, etc. If the valve becomes hung-up the electrical tests performed will not indicate this condition and scramming the rod is in jeopardy. Only an attempt to scram a rod will indicate the hung-up valve. While this condition exists the rod is considered inoperative. This paper describes a system developed at a nuclear power plant that monitors the pilot valves on the control rod drive system. This system utilizes pattern recognition to assure proper internal workings of the scram pilot valves to plant operators. The system is totally automatic such that each time the valve is operated on a half scram, a printout is available to the operator along with light indication that each of the 370 valves (on one unit of a BWR) is operating properly. With this monitoring system installed, all components of the control rod drive system including the solenoid pilot valves can be verified as operational without scramming any rods

Gate valve performance prediction

International Nuclear Information System (INIS)

Harrison, D.H.; Damerell, P.S.; Wang, J.K.; Kalsi, M.S.; Wolfe, K.J.

1994-01-01

The Electric Power Research Institute is carrying out a program to improve the performance prediction methods for motor-operated valves. As part of this program, an analytical method to predict the stem thrust required to stroke a gate valve has been developed and has been assessed against data from gate valve tests. The method accounts for the loads applied to the disc by fluid flow and for the detailed mechanical interaction of the stem, disc, guides, and seats. To support development of the method, two separate-effects test programs were carried out. One test program determined friction coefficients for contacts between gate valve parts by using material specimens in controlled environments. The other test program investigated the interaction of the stem, disc, guides, and seat using a special fixture with full-sized gate valve parts. The method has been assessed against flow-loop and in-plant test data. These tests include valve sizes from 3 to 18 in. and cover a considerable range of flow, temperature, and differential pressure. Stem thrust predictions for the method bound measured results. In some cases, the bounding predictions are substantially higher than the stem loads required for valve operation, as a result of the bounding nature of the friction coefficients in the method

NRC Information Notice No. 93-01: Accuracy of motor-operated valve diagnostic equipment manufactured by Liberty Technologies

International Nuclear Information System (INIS)

Grimes, B.K.

1993-01-01

Most licensees rely on MOV diagnostic equipment to provide information on the thrust delivered by the motor actuator in opening or closing its valve. The various types of MOV diagnostic equipment estimate valve stem thrust using different parameters, such as displacement of the spring pack or strain in the stem, mounting bolts, or yoke. Liberty Technologies has developed MOV diagnostic equipment, referred to as the Valve Operation Test and Evaluation System (VOTES), that estimates the thrust needed to open or close a valve based on strain of the valve yoke. The VOTES equipment derives thrust from yoke strain that has been calibrated to stem thrust using measured diametral strain of the valve stem and nominal engineering material properties. On October 2, 1992, Liberty Technologies notified the NRC that it had determined that two new factors can affect the thrust values obtained with its equipment. Those factors involve (1) the possible use of improper stem material constants and (2) the failure to account for a torque effect when the VOTES equipment is calibrated by measuring strain in the threaded portion of the valve stem. Liberty Technologies provided information on performing manual calculations to address these factors and stated that its new software, Version 2.3, assists in performing corrections to the thrust data

Review and analysis of check valve failure data

International Nuclear Information System (INIS)

Todd, M.D.; Casada, D.A.

1992-01-01

Check valve operating problems in recent years have resulted in significant operating transients, increased cost and decreased system availability. There has been, in response, additional attention given to check valves by utilities, as well as the US Nuclear Regulatory Commission and the American Society of Mechanical Engineers Operation and Maintenance Committee. All these organizations have the fundamental goal of ensuring reliable operation of check valves. A key ingredient to an engineering-oriented reliability improvement effort is a thorough understanding of relevant historical experience. Oak Ridge National Laboratory is currently conducting a detailed review of historical failure data available through the Institute of Nuclear Power Operation's Nuclear Plant Reliability Data System. The focus of the review is on check valve failures that have involved significant degradation of the valve internal parts. A variety of parameters are being considered during the review, including size, age, system of service, method of failure discovery, the affected valve parts, attributed causes, and corrective actions

Remotely handled and remotely operated valve, particularly for the hot part of radioactive plants. Fernhantierbare und fernbedienbare Armatur, insbesondere fuer den heissen Bereich radioaktiver Anlagen

Energy Technology Data Exchange (ETDEWEB)

Radovan, G.; Sandling, M.J.; Davidson, J.W.; Blaseck, K.; Hoffmeister, L.; Westendorf, H.

1988-01-21

The valve consists of a valve whose valve housing is built into a pipeline. The wear parts of the valve to be replaced, such as the valve body and valve seat, are combined into a replacement part. The replacement part and a clamp act together so that the replacement part is interlocked with the valve housing in the closed operating position. The exchange can be made by undoing a single central screw.

Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

Science.gov (United States)

Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

2016-06-20

The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation.

Aortic valve-sparing operation in Marfan syndrome: what do we know after a decade?

Science.gov (United States)

Kallenbach, Klaus; Baraki, Hassina; Khaladj, Nawid; Kamiya, Hiroyuki; Hagl, Christian; Haverich, Axel; Karck, Matthias

2007-02-01

We assessed the outcome in patients with Marfan syndrome operated on exclusively with the aortic valve-sparing reimplantation technique for aortic root aneurysms during more than a decade. Between July 1993 and April 2005, the aortic valve-sparing reimplantation technique (David I) was used in 325 patients. In 59 patients with clinical evidence of Marfan syndrome, procedures were done for aortic root aneurysm (n = 55) or aortic dissection type A (n = 4). Their mean age was 30 +/- 12 years (range, 9 to 62 years), and 37 (63%) were male. Additional procedures were arch replacement in 4 patients, coronary artery bypass grafting in 1, mitral valve surgery in 9, and closure of atrial septal defect in 3. Mean follow-up was 54 +/- 37 months (range, 0 to 139 months). No patient died during the first 30 days postoperatively. Mean bypass time was 163 +/- 34 minutes (range, 99 to 248 minutes), and mean aortic cross clamp time was 126 +/- 28 minutes (range, 78 to 202 minutes). Four patients (6.8%) required rethoracotomy for postoperative bleeding. Five late deaths (8.5%) occurred during follow-up. Reoperation of the reconstructed valve was required in 7 patients. Freedom from reoperation was 88% +/- 5% at 5 years and 80% +/- 9% at 10 years. Mean grade of aortic insufficiency was 1.81 preoperatively compared with 0.20 early postoperatively (p valve should encourage use of this technique in patients with Marfan syndrome.

Development of an effective valve packing program

Energy Technology Data Exchange (ETDEWEB)

Hart, K.A.

1996-12-01

Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

Oil pipeline valve automation for spill reduction

Energy Technology Data Exchange (ETDEWEB)

Mohitpour, Mo; Trefanenko, Bill [Enbridge Technology Inc, Calgary (Canada); Tolmasquim, Sueli Tiomno; Kossatz, Helmut [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

2003-07-01

Liquid pipeline codes generally stipulate placement of block valves along liquid transmission pipelines such as on each side of major river crossings where environmental hazards could cause or are foreseen to potentially cause serious consequences. Codes, however, do not stipulate any requirement for block valve spacing for low vapour pressure petroleum transportation, nor for remote pipeline valve operations to reduce spills. A review of pipeline codes for valve requirement and spill limitation in high consequence areas is thus presented along with a criteria for an acceptable spill volume that could be caused by pipeline leak/full rupture. A technique for deciding economically and technically effective pipeline block valve automation for remote operation to reduce oil spilled and control of hazards is also provided. In this review, industry practice is highlighted and application of the criteria for maximum permissible oil spill and the technique for deciding valve automation thus developed, as applied to ORSUB pipeline is presented. ORSUB is one of the three initially selected pipelines that have been studied. These pipelines represent about 14% of the total length of petroleum transmission lines operated by PETROBRAS Transporte S.A. (TRANSPETRO) in Brazil. Based on the implementation of valve motorization on these three pipeline, motorization of block valves for remote operation on the remaining pipelines is intended, depending on the success of these implementations, on historical records of failure and appropriate ranking. (author)

Sliding spool design for reducing the actuation forces in direct operated proportional directional valves: Experimental validation

International Nuclear Information System (INIS)

Amirante, Riccardo; Distaso, Elia; Tamburrano, Paolo

2016-01-01

Highlights: • An innovative procedure to design a commercial proportional directional valve is shown. • Experimental tests are performed to demonstrate the flow force reduction. • The design is improved by means of a previously made optimization procedure. • Great reduction in the flow forces without reducing the flow rate is demonstrated. - Abstract: This paper presents the experimental validation of a new methodology for the design of the spool surfaces of four way three position direct operated proportional directional valves. The proposed methodology is based on the re-design of both the compensation profile (the central conical surface of the spool) and the lateral surfaces of the spool, in order to reduce the flow forces acting on the spool and hence the actuation forces. The aim of this work is to extend the application range of these valves to higher values of pressure and flow rate, thus avoiding the employment of more expensive two stage configurations in the case of high-pressure conditions and/or flow rate. The paper first presents a theoretical approach and a general strategy for the sliding spool design to be applied to any four way three position direct operated proportional directional valve. Then, the proposed approach is experimentally validated on a commercially available valve using a hydraulic circuit capable of measuring the flow rate as well as the actuation force over the entire spool stroke. The experimental results, performed using both the electronic driver provided by the manufacturer and a manual actuation system, show that the novel spool surface requires remarkably lower actuation forces compared to the commercial configuration, while maintaining the same flow rate trend as a function of the spool position.

Development of multilayer piezoelectric actuator valve for JT-60

International Nuclear Information System (INIS)

Miyo, Yasuhiko; Hiratsuka, Hajime; Masui, Hiroshi; Hosogane, Nobuyuki; Miya, Naoyuki

2001-11-01

In order to improve the gas injection valve used for the operation of JT-60, a new type of valve (multilayer piezoelectric actuator valve) was developed. The conventional valve (bimorph piezoelectric valve) has been used for 15 years since the beginning of experimental operation in April, 1985. However, it came to be hard to keep the performance of the valve because of the deterioration of the driving source, i.e. piezoelectric element. Developments of the new valve were carried out based on experiences through experimental operations in JT-60. Requirements for the design are: (1) to be hard structure for making a sheet leak, (2) to allow a repair work at atmosphere side without an air vent of the vacuum vessel, (3) to be more smaller and lighter compared with the conventional one, and (4) to have a high maintenance efficiency by utilizing of the commercial piezoelectric elements and power supplies. The newly developed valve was examined with various tests such as gas flow characteristic test, high magnetic field proof test, high temperature proof test and gas flow rate test for aged deterioration. Results, confirm that the performance of the valve is applicable for JT-60 operations. (author)

Early beneficial effect of preservation of papillo-annular continuity in mitral valve replacement on left ventricular function.

Science.gov (United States)

Dilip, D; Chandra, A; Rajashekhar, D; Padmanabhan, M

2001-05-01

Impairment of left ventricular (LV) function after mitral valve replacement (MVR) has been the most important factor to determine morbidity and mortality. With this in mind, LV performance in the postoperative period was assessed with and without preservation of papillo-annular continuity in MVR. Between March 1994 and August 1998, a total of 383 valve prostheses (202 MVR, 65 AVR, 58 MVR+AVR) were implanted in 325 patients, 177 of whom underwent MVR with Starr Edwards ball cage prostheses (the study group). Of these 177 patients, 105 had MVR with preservation of the posterior mitral leaflet (group I), and 72 had conventional MVR (group II). Predominant lesions were mitral stenosis in 81, mitral regurgitation in 42, and mixed mitral lesion (MS/MR) in 54. Concomitant tricuspid valve annuloplasty was performed in 13, and atrial septal defect repair in five. Sixteen patients underwent MVR for mitral restenosis. In-vivo performance of the prostheses and LV function was evaluated by M-mode and Doppler echocardiography. At 3-6 months clinical improvement was seen in NYHA class, with reduction in cardiothoracic ratio among patients with preserved papillo-annular continuity, irrespective of lesion type. Significant reductions (p versus 44.64 +/- 8.54 postop.; p versus 41.21 +/- 7.16 postop.; p versus 28.81 +/- 5.79 postop.; p versus 64.47 +/- 7.93; p <0.05). Further analysis of data in group I patients showed significant reductions in left atrial dimensions, LVESD and peak gradient, along with improved ejection fraction compared with conventional (group II) patients. Deterioration in LV function in patients undergoing conventional MVR indicates chordal resection as a putative mechanism. This study supports the concept that maintenance of continuity between the mitral annulus and papillary muscles has a beneficial effect on postoperative LV function, and is particularly important in patients with mitral stenosis with depressed preoperative LV systolic function.

3-D analysis of reactor loop isolation valves

International Nuclear Information System (INIS)

Dietrich, D.E.

1975-01-01

A full three-dimensional analysis for the design and operational loading conditions was performed on a 29 inch loop isolation valve using the Westinghouse finite element computer code. The 3-D analysis was employed for the valve design in place of utilizing the standard ASME valve design criteria. The valve design employs the design by analysis concept allowed for nuclear class valve. The valve design was evaluated for a set of independent load including pipe reactions and internal pressure. The design pipe reaction loads were based upon maximum fiber pipe stresses at yield for the bending moments, pipe membrane stresses at half yield for the axial load, and pipe maximum shear stress at half yield for the torsional moment. The valve design pressure was the system loop design pressure. The operating and accident condition evaluation included pipe reactions, extended structure forces, system pressure, and system thermal transients. The valve was analyzed for the normal operating, upset, emergency, and faulted loading conditions. These operating and accident conditions used various specified combinations of the supplied generic system pressure, deadweight, thermal, seismic, and LOCA pipe load components. The generic pipe loads are the worst possible postulated loads for any system design. These generic pipe load components were supplied as maximums and minimums so a simplified nozzle analysis was performed to determine the worst case combination for each loading condition. The valve design was shown to meet the design, operating, and accident condition requirements of the ASME code. The design by analysis concept for nuclear class 1 valves gave a significant reduction in required minimum wall thickness, 3.75 inches vs. 5.4 inches. These translate into significant material savings

Diagnostic for two-mode variable valve activation device

Science.gov (United States)

Fedewa, Andrew M

2014-01-07

A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

Demonstration of containment purge and vent valve operability for the Hope Creek Generating Station, Unit 1 (Docket No. 50-354)

International Nuclear Information System (INIS)

Kido, C.

1985-05-01

The containment purge and vent valve qualification program for the Hope Creek Generating Station has been reviewed by the NRC Licensing Support Section. The review indicates that the licensee has demonstrated the dependability of containment isolation against the buildup of containment pressure due to a LOCA/DBA with the restrictions that during operating conditions 1, 2, and 3 all purge and vent valves will be sealed closed and under administrative control, and during power ascension and descension conditions the 26 in. inboard valve (1-GS-HV-4952) will be used in series with the 2 in. bypass valve (1-GS-HV-4951) to control the release of containment pressure

Disc dislodgment in Björk Shiley mitral valve prosthesis: two successfully operated cases.

Science.gov (United States)

Dubernet, J; Irarrázaval, M J; Urzúa, J; Maturana, G; Morán, S; Lema, G; Asenjo, F; Fajuri, A

1986-02-01

Two patients with Björk Shiley mitral valve replacement had migration and embolization of the occluding disc. One patient suffered migration of the disc a few hours after surgery and the other had a strut fracture with disc translocation six years after the initial operation. Clinical signs in both cases were pulmonary edema, cardiogenic shock, and absence of prosthetic sounds. Both patients were reoperated on an emergency basis, recovering after a complicated postoperative course. They are on functional Class I, 8 and 1 years later, respectively, with their dislodged discs still in the abdominal aorta. The only hope for survival in these patients is emergency reoperation, once the prosthetic mitral valve dysfunction is confirmed.

Latest design of gate valves

Energy Technology Data Exchange (ETDEWEB)

Kurzhofer, U.; Stolte, J.; Weyand, M.

1996-12-01

Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

Thermal fatigue behavior of valves

International Nuclear Information System (INIS)

Moinereau, D.; Scliffet, L.; Capion, J.C.; Genette, P.

1991-01-01

This paper reports that valves of pressurized water reactors are exposed to thermal shocks during transient operations. The numerous thermal shock tests performed on valves on the EDF test facilities have shown the sensibility of fillets and geometrical discontinuities to thermal fatigue: cracks can appear in those areas and grow through the valve body. Valves systems designated as level 1 must be designed to withstand fatigue up to the second isolation valve: the relevant rule is specified in the paragraph B 3500 of the French RCCM code. It is a simplified method which doesn't require finite element calculations. Many valve systems have been designed according to this rule and have been operated without accident. However, in one case, important cracks were found in the fillet of a check-valve after numerous thermal shocks. Calculation of the valve's behavior according to the RCCM code to estimate the fatigue damage resulting from thermal shocks led to a low damage factor, which doesn't agree with the experimental results. This was confirmed by new testings and showed the inadequacy of B 3500 rule for thermal transients. On this base a new rule is proposed to estimate fatigue damage resulting from thermal shocks. An experimental program has been realized to validate this rule. Axisymetrical analytical mock-ups with different geometries and one check-valve in austenitic stainless steel 316 L have been submitted to hot thermal shocks of 210 degrees C magnitude

Early and long-term results of a valve-sparing operation for Marfan syndrome.

Science.gov (United States)

Birks, E J; Webb, C; Child, A; Radley-Smith, R; Yacoub, M H

1999-11-09

We have previously described the experience, rationale, and development of a valve preserving technique, but its role in patients with Marfan syndrome has not previously been defined. Here, we attempt to determine the early and long-term results, timing, and determinants of outcome of this operation in patients with Marfan syndrome. Since 1979, 82 patients (73.2% of all patients with Marfan syndrome undergoing resection of aneurysm of the ascending aorta) were operated on using this technique. Ages ranged from 2 to 69 years (mean, 33.9 years). In all, there were 4 early deaths (4.9%), 2 with acute dissection and 2 with chronic aneurysm operated on as emergencies. There were no early deaths in 67 patients operated on electively. Actuarial survival for patients operated for chronic aneurysm was 94.2%, 94.2%, and 94.2% at 1, 5, and 10 years, respectively; that for acute dissection was 72.7%, 63. 6%, and 63.6%; and that for chronic dissection was 100%, 85.7%, and 75.0%. The probability of needing reoperation was 5.7%, 17.3%, and 17.3% at 1, 5, and 10 years. There were no instances of infective endocarditis or thromboembolic complications except in 2 patients operated on early in the series who had cusp extension. At the end of the follow-up, trivial or no aortic regurgitation was demonstrated in 33.3%, mild in 45.6%, moderate in 21.1%, and severe in 0. Valve-sparing operations are feasible in most patients with Marfan syndrome; they are applicable to patients with both dissection and chronic aneurysm. The early and long-term results are encouraging. Results are better in the absence of dissection, and prophylactic operation is warranted in some cases.

VALIDATION OF SPRING OPERATED PRESSURE RELIEF VALVE TIME TO FAILURE AND THE IMPORTANCE OF STATISTICALLY SUPPORTED MAINTENANCE INTERVALS

Energy Technology Data Exchange (ETDEWEB)

Gross, R; Stephen Harris, S

2009-02-18

The Savannah River Site operates a Relief Valve Repair Shop certified by the National Board of Pressure Vessel Inspectors to NB-23, The National Board Inspection Code. Local maintenance forces perform inspection, testing, and repair of approximately 1200 spring-operated relief valves (SORV) each year as the valves are cycled in from the field. The Site now has over 7000 certified test records in the Computerized Maintenance Management System (CMMS); a summary of that data is presented in this paper. In previous papers, several statistical techniques were used to investigate failure on demand and failure rates including a quantal response method for predicting the failure probability as a function of time in service. The non-conservative failure mode for SORV is commonly termed 'stuck shut'; industry defined as the valve opening at greater than or equal to 1.5 times the cold set pressure. Actual time to failure is typically not known, only that failure occurred some time since the last proof test (censored data). This paper attempts to validate the assumptions underlying the statistical lifetime prediction results using Monte Carlo simulation. It employs an aging model for lift pressure as a function of set pressure, valve manufacturer, and a time-related aging effect. This paper attempts to answer two questions: (1) what is the predicted failure rate over the chosen maintenance/ inspection interval; and do we understand aging sufficient enough to estimate risk when basing proof test intervals on proof test results?

Leaky valves : New operation improves the heart's pumping action

NARCIS (Netherlands)

Pistecky, P.; Havlik, P.; Van Kasteren, J.

2003-01-01

The action of any pump will start to decline when the valves no longer close properly. The same goes for the heart, the pump that maintains the circulation in our vascular system. Consequently, a major field of focus of open heart surgery is the repair or replacement of heart valves. Petr Havl a

A study on the development of the computerized safety evaluation system of the motor operated valve

International Nuclear Information System (INIS)

Kim, J. C.; Park, S. G.; Lee, D. H.; Ahn, N. S.; Bae, H. J.; Hong, J. S.

2001-01-01

The MOVIDIK (Motor-Operated Valves Integrated Database and Information of KEPCO) system was developed to assist the design basis safety evaluation and to manage the overall data made by evaluation on the safety-related Motor-operated Valves(MOV) in the nuclear power plant. The huge amount of safety evaluation data of the MOV is being piled up as the safety evaluation work goes on. Much time and manpower was needed to do safety evaluation works without computerized system and it was not easy to obtain the statistic information from the evaluation data. The MOVIDIK will improve the efficiency of safety evaluation works and standardize the analysis process. But the some process which needs specific evaluation codes and engineering calculation by the specialists was not computerized. The MOVIDIK was developed by JAVA/JSP language known by the flexibility of language and the easiness of transplantation between operating systems. The Oracle 8i which is the world's most popular database was used for MOVIDIK database

Check valves aging assessment

International Nuclear Information System (INIS)

Haynes, H.D.

1991-01-01

In support of the NRC Nuclear Plant Aging Research (NPAR) program, the Oak Ridge National Laboratory (ORNL) has carried out an assessment of several check value diagnostic monitoring methods, in particular, those based on measurements of acoustic emission, ultrasonics, and magnetic flux. The evaluations have focussed on the capabilities of each method to provide information useful in determining check valve aging and service wear effects, check valve failures, and undesirable operating modes. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data, including data obtained from the vendors who recently participated in a comprehensive series of tests directed by a nuclear industry users group. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two novel nonintrusive monitoring methods were developed that provide several unique capabilities. These methods, based on external ac- an dc-magnetic monitoring are also described. None of the examined methods could, by themselves, monitor both the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information

Butterfly valves for seawater

International Nuclear Information System (INIS)

Yamanaka, Katsuto

1991-01-01

Recently in thermal and nuclear power stations and chemical plants which have become large capacity, large quantity of cooling water is required, and mostly seawater is utilized. In these cooling water systems, considering thermal efficiency and economy, the pipings become complex, and various control functions are demanded. For the purpose, the installation of shut-off valves and control valves for pipings is necessary. The various types of valves have been employed, and in particular, butterfly valves have many merits in their function, size, structure, operation, maintenance, usable period, price and so on. The corrosion behavior of seawater is complicated due to the pollution of seawater, therefore, the environment of the valves used for seawater became severe. The structure and the features of the butterfly valves for seawater, the change of the structure of the butterfly valves for seawater and the checkup of the butterfly valves for seawater are reported. The corrosion of metallic materials is complicatedly different due to the locating condition of plants, the state of pipings and the condition of use. The corrosion countermeasures for butterfly valves must be examined from the synthetic viewpoints. (K.I.)

A WEAR MODEL FOR DIESEL ENGINE EXHAUST VALVES

Energy Technology Data Exchange (ETDEWEB)

Blau, Peter Julian [ORNL

2009-11-01

The work summarized here comprises the concluding effort of a multi-year project, funded by the U.S. Department of Energy, Office of Vehicle Technologies. It supports the development of a better understanding of advanced diesel engine designs in which enhanced power density, energy efficiency, and emissions control place increasing demands upon the durability of engine materials. Many kinds of metallic alloys are used in engines depending on the operating stresses, temperatures, and chemical environments. Exhaust valves, for example, are subjected to high temperatures and repetitive surface contacts that place demands on durability and frictional characteristics of the materials. Valves must continue to seal the combustion chamber properly for thousands of hours of cyclic engine operation and under varying operating conditions. It was the focus of this effort to understand the wear processes in the valve-seat area and to develop a model for the surface deformation and wear of that important interface. An annotated bibliography is provided to illustrate efforts to understand valve wear and to investigate the factors of engine operation that affect its severity and physical manifestation. The project for which this modeling effort was the final task, involved construction of a high-temperature repetitive impact test system as well as basic tribology studies of the combined processes of mechanical wear plus oxidation at elevated temperatures. Several publications resulted from this work, and are cited in this report. The materials selected for the experimental work were high-performance alloys based on nickel and cobalt. In some cases, engine-tested exhaust valves were made available for wear analysis and to ensure that the modes of surface damage produced in experiments were simulative of service. New, production-grade exhaust valves were also used to prepare test specimens for experimental work along with the other alloy samples. Wear analysis of valves and seats

Intra-operative Vector Flow Imaging Using Ultrasound of the Ascending Aorta among 40 Patients with Normal, Stenotic and Replaced Aortic Valves

DEFF Research Database (Denmark)

Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper

2016-01-01

Stenosis of the aortic valve gives rise to more complex blood flows with increased velocities. The angleindependent vector flow ultrasound technique transverse oscillation was employed intra-operatively on the ascending aorta of (I) 20 patients with a healthy aortic valve and 20 patients with aor...... replacement corrects some of these changes. Transverse oscillation may be useful for assessment of aortic stenosis and optimization of valve surgery. (E-mail: lindskov@gmail.com) 2016 World Federation for Ultrasound in Medicine & Biology...... with aortic stenosis before (IIa) and after (IIb) valve replacement. The results indicate that aortic stenosis increased flow complexity (p , 0.0001), induced systolic backflow (p , 0.003) and reduced systolic jet width (p , 0.0001). After valve replacement, the systolic backflow and jet width were normalized...

Double-reed exhaust valve engine

Science.gov (United States)

Bennett, Charles L.

2015-06-30

An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a double reed outlet valve for controlling the flow of low-pressure working fluid out of the engine. The double reed provides a stronger force resisting closure of the outlet valve than the force tending to open the outlet valve. The double reed valve enables engine operation at relatively higher torque and lower efficiency at low speed, with lower torque, but higher efficiency at high speed.

Miniature piezo electric vacuum inlet valve

Science.gov (United States)

Keville, Robert F.; Dietrich, Daniel D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

FEATURES OF CONTROLLING ELECTROPNEUMATIC VALVES OF ACTUATOR TO CONTROL ITS CLUTCH WITH ACCELERATION VALVE

Directory of Open Access Journals (Sweden)

O. A. Yaryta

2018-01-01

Full Text Available The article deals with one of the ways to control an actuator of the automated clutch control system. The aim is to design control of the electropneumatic actuator, to control its coupling with the acceleration valve on the basis of experimental research as well as to provide rational parameters of the automated clutch control system for the robotic transmission. The feature of the system is an acceleration valve in the design of the electropneumatic actuator to control the clutch. New links demand to adjust the way to control the actuator. The connection of Pulse-Width Modulation (PWM with single power supply pulses to control electropneumatic valves is substantiated. The quantitative characteristics of single control pulses and PWM ones are determined. The error of operation accuracy for various ways of the control of the electropneumatic actuator to control the clutch of the robotic transmission is determined. Obtained separate PWM area is designed to suppress the initial hysteresis when the rod of the clutch actuator is moved. An algorithm for the operation of a clutch control system is proposed, taking into account the use of two modes of operation of solenoid valves. A graphical interpretation of the clutch control algorithm is presented, which gives an idea of the location of the constant signal feeding zones to the solenoid valve, as well as the operation areas of the solenoid valve in PWM mode. The control algorithm of the clutch booster provides a mode of guaranteed absence of excess pressure in the pneumatic cylinder after releasing the clutch pedal, provided that two normally closed solenoid valves are used. This configuration of the electro-pneumatic clutch control system allows the use of an emergency clutch release system in case of voltage absence. The reference algorithm for filtering the array of data coming from the feedback sensor, as well as the numerical values of the delay caused by the presence of a filter, are given.

Aging and service wear of air-operated valves used in safety-related systems at nuclear power plants

International Nuclear Information System (INIS)

Cox, D.F.; McElhaney, K.L.; Staunton, R.H.

1995-05-01

Air-operated valves (AOVs) are used in a variety of safety-related applications at nuclear power plants. They are often used where rapid stroke times are required or precise control of the valve obturator is required. They can be designed to operate automatically upon loss of power, which is often desirable when selecting components for response to design basis conditions. The purpose of this report is to examine the reported failures of AOVs and determine whether there are identifiable trends in the failures related to predictable causes. This report examines the specific components that comprise a typical AOV, how those components fail, when they fail, and how such failures are discovered. It also examines whether current testing frequencies and methods are effective in predicting such failures

Characteristics of electrostatic gas micro-pump with integrated polyimide passive valves

International Nuclear Information System (INIS)

Han, Jeahyeong; Yeom, Junghoon; Mensing, Glennys; Flachsbart, Bruce; Shannon, Mark A

2012-01-01

We report on the fabrication and characterization of electrostatic gas micro-pumps integrated with polyimide check valves. Touch-mode capacitance actuation, enabled by a fixed silicon electrode and a metal/polyimide diaphragm, creates the suction and push-out of the ambient gas; the gas flow is rectified by the check valves located at the inlet and outlet of the pump. The fabricated pumps were tested with various actuation voltages at different frequencies and duty cycles; an emphasis was placed on investigating the effect of valve flow conductance on the gas pumping characteristics. The pump with higher valve conductance could increase the operating frequency of the pump and affect the pumping characteristics from a pulsating flow to a continuous flow, leading to a higher gas flow rate. This electrostatic pump has a flow control resolution of 1 µL min −1 ; it could generate a gas flow up to 106 µL min −1 . (paper)

IE Information Notice No. 85-47: Potential effect of line-induced vibration on certain Target Rock solenoid-operated valves

International Nuclear Information System (INIS)

Jordan, E.L.

1992-01-01

On November 14, 1984, Arizona Public Services Company provided the NRC with a final report on a 10 CFR 50.55(e) reportable condition relating to qualification testing of certain TR (Target Rock), solenoid-operated valves. Four TR valves, procured by Combustion Engineering (CE) for use at Palo Verde Nuclear Generating Station Unit 3, were tested to the requirements of NUREG-0588, Category 1. Test valves included two 1-inch TR valves, model 77L-001 and two 2-inch TR valves, model 77L-003. The qualification test involved irradiation to 50 megarads, thermal aging at 260 F for 635 hours, mechanical cycling, vibrational aging to represent normal service vibration, seismic testing, and finally, testing in a simulated LOCA environment. The licensee reported that during the qualification testing, a number of anomalies were identified, and the test was discontinued when the test valves failed to function for different reasons during the seismic testing. CE an TR appraised the overall safety significance of the observed test anomalies for the licensee. They considered the failure of the valve to open on demand as a result of solenoid lead shorting caused by line-induced vibrational wear to be a common mode of failure that, in a seismic event, could potentially disable several redundant valves at the same time. This failure of the valve to open on demand is the only observed test anomaly considered to have significant generic safety implications and is the subject of this information notice

New piezo driven gas inlet valve for fusion experiments

International Nuclear Information System (INIS)

Usselmann, E.; Hemmerich, J.L.; How, J.; Holland, D.; Orchard, J.; Winkel, T.; Schargitz, U.; Pocheim, N.

1989-01-01

The gas inlet valves used at the JET experiment are described and their performances are discussed. A new gas-valve development suitable to replace the existing valves at JET and for future use in large fusion experiments is presented. The new valve is equipped with a piezo-electric translator and has a dosing range of 0-800 mbarls -1 for D 2 . The operating mode of the valve is fail-safe closed with a leak-rate of ≤ 10 -9 mbarls -1 . The design, the test results and throughput values in dependence of filling pressure and control voltage are presented and experiences with the prototype valve as a new gas inlet valve for the JET operation are described

When operable patients become inoperable: conversion of a surgical aortic valve replacement into transcatheter aortic valve implantation

DEFF Research Database (Denmark)

Olsen, Lene Kjaer; Arendrup, Henrik; Engstrøm, Thomas

2009-01-01

. On extracorporal circulation it was reconized that the aortic annulus, the coronary ostiae and the proximal part of the ascending aorta were severely calcified making valve implantation impossible. Surgical closure without valve substitution was estimated to be associated with a high risk of mortality due...

A Complicated Case of Triple Valve Infective Endocarditis in an IV Drug User with a Bicuspid Aortic Valve Requiring Three Separate Salvage Operations: A Case Report and Literature Review

Directory of Open Access Journals (Sweden)

Shahzad Khan

2015-01-01

Full Text Available Infective endocarditis (IE is an infection of the endocardium that involves valves and adjacent mural endocardium or a septal defect. Local complications include severe valvular insufficiency, which may lead to intractable congestive heart failure and myocardial abscesses. If left untreated, IE is generally fatal. Diagnosing IE can be straightforward in patients with the typical oslerian manifestations such as bacteremia, evidence of active valvulitis, peripheral emboli, and immunologic vascular phenomena. In the acute course, however, the classic peripheral stigmata may be few or absent, particularly among intravenous drug abuse (IVDA patients in whom IE is often due to a S. aureus infection of right-sided heart valves. We present a complicated case of a very aggressive native aortic valve MSSA (methicillin sensitive Staphylococcus aureus IE in a young adult male with a past medical history of bicuspid aortic valve and IV drug abuse. His clinical course was complicated by aortic valve destruction and development of third-degree AV block, as well as an aorto-left atrial fistula requiring emergent operation for AV replacement and patch repair. The patient required two reoperations for recurrent endocarditis and its complications.

40 CFR 63.4768 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Science.gov (United States)

2010-07-01

... device to the atmosphere. (ii) Car-seal or lock-and-key valve closures. Secure any bypass line valve in the closed position with a car-seal or a lock-and-key type configuration. You must visually inspect...) Automatic shutdown system. Use an automatic shutdown system in which the coating operation is stopped when...

Surgery of the aortic root: should we go for the valve-sparing root reconstruction or the composite graft-valve replacement is still the first choice of treatment for these patients?

Science.gov (United States)

Lamana, Fernando de Azevedo; Dias, Ricardo Ribeiro; Duncan, Jose Augusto; Faria, Leandro Batisti de; Malbouisson, Luiz Marcelo Sa; Borges, Luciano de Figueiredo; Mady, Charles; Jatene, Fábio Biscegli

2015-01-01

To compare the results of the root reconstruction with the aortic valve-sparing operation versus composite graft-valve replacement. From January 2002 to October 2013, 324 patients underwent aortic root reconstruction. They were 263 composite graft-valve replacement and 61 aortic valve-sparing operation (43 reimplantation and 18 remodeling). Twenty-six percent of the patients were NYHA functional class III and IV; 9.6% had Marfan syndrome, and 12% had bicuspid aortic valve. There was a predominance of aneurysms over dissections (81% vs. 19%), with 7% being acute dissections. The complete follow-up of 100% of the patients was performed with median follow-up time of 902 days for patients undergoing composite graft-valve replacement and 1492 for those undergoing aortic valve-sparing operation. In-hospital mortality was 6.7% and 4.9%, respectively for composite graft-valve replacement and aortic valve-sparing operation (ns). During the late follow-up period, there was 0% moderate and 15.4% severe aortic regurgitation, and NYHA functional class I and II were 89.4% and 94%, respectively for composite graft-valve replacement and aortic valve-sparing operation (ns). Root reconstruction with aortic valve-sparing operation showed lower late mortality (P=0.001) and lower bleeding complications (P=0.006). There was no difference for thromboembolism, endocarditis, and need of reoperation. The aortic root reconstruction with preservation of the valve should be the operation being performed for presenting lower late mortality and survival free of bleeding events.

Guidelines for valves in tritium service

International Nuclear Information System (INIS)

Weaver, W.W.

1994-01-01

Some undesirable practices and misapplications that caused valve-related failures are examined, and future courses of action are recommended to avoid repetition of these events. Desirable valve characteristics and practices that should be considered when selecting valves for use in tritium service are also discussed. Supporting logic for the desirability of these features is presented by discussing the mechanisms of valve degradation followed by examples of related events. Desirable valve and system features and operational actions are grouped into two categories: strongly recommended and recommended. 13 refs., 1 fig

Steel-fabricated butterfly valves for condenser circulating water system

International Nuclear Information System (INIS)

Kawase, Hiroshi; Yasuoka, Masahiro; Nanao, Teruaki.

1979-01-01

The steel-fabricated butterfly valves, which are large in general, and gave rubber linings inside to prevent the corrosion due to sea Water, are utilized for the condenser circulating water systems of thermal and nuclear power plants. Cast iron butterfly valves, having been used hitherto, have some technical irrationalities, such as corrosion prevention, the techniques for manufacturing large castings, severe thermal transient operation. On the contrary, the steel plate-fabricated butterfly valves have the following advantages; much superior characteristics in strength, rigidity and shock resistance, the streamline shape of valve plates, the narrow width between two flanges, superior execution of works for rubber lining, the perfect sealed structure, safety to vibration, light weight and easy maintenance. The structural design and the main specifications for the steel plate butterfly valves with the nominal bore from 1350 mm to 3500 mm are presented. Concerning the design criteria, the torque of operating butterfly valves and the strength of valve bodies, valve plates and valve stems are explained. The performance tests utilizing the mock-up valve were carried out for the measurements of stress distribution, the deformation of valve body, the endurance and the operating torque. In the welding standards for steel plate butterfly valves, three kinds of welded parts are classified, and the inspection method for each part is stipulated. The vibration of the valves induced by flow vortexes and cavitation is explained. (Nakai, Y.)

The use of check valve performance data to support new concepts (probabilistic risk assessment, condition monitoring) for check valve program

Energy Technology Data Exchange (ETDEWEB)

Hart, K.A.; Gower, D.

1996-12-01

The concept of developing an integrated check valve database based on the Nuclear Power Reliability Data System (NPRDS) data was presented at the last Symposium. The Nuclear Industry Check Valve Group (NIC), working in cooperation with the Oak Ridge National Laboratory (ORNL), has completed an operational database of check valve performance from 1984 to the present. NIC has committed to the nuclear industry to periodically update the data and maintain this information accessible. As the new concepts of probabilistic risk analysis and condition monitoring are integrated into the American Society of Mechanical Engineers (ASME) Code, a critical element will be performance data. From check valve performance data, feasible failure modes and rates can be established. When a failure rate or frequency of failures can be established based on a significant enough population (sampling), a more solid foundation for focusing resources and determining appropriate frequencies and testing can be determined. The presentation will give the updated status of the NIC Check Valve Performance Database covering (1) methodology used to combine the original ORNL data; (2) process/controls established for continuing update and refinement of the data; (3) discussion of how this data is being utilized by (a) OM-22 for condition monitoring, and (b) risk-based inservice testing work of Westinghouse Owners` Group; and (4) results/trends of data evaluations. At the 1994 Symposium, ORNL provided an update as of 1991 to their original work of 1984 -1990 which they had performed to characterize check valve degradations and failures in the nuclear industry. These characterizations will be updated to 1995 and additional reviews provided to give insight into the current condition and trends of check valve performance.

The use of check valve performance data to support new concepts (probabilistic risk assessment, condition monitoring) for check valve program

International Nuclear Information System (INIS)

Hart, K.A.; Gower, D.

1996-01-01

The concept of developing an integrated check valve database based on the Nuclear Power Reliability Data System (NPRDS) data was presented at the last Symposium. The Nuclear Industry Check Valve Group (NIC), working in cooperation with the Oak Ridge National Laboratory (ORNL), has completed an operational database of check valve performance from 1984 to the present. NIC has committed to the nuclear industry to periodically update the data and maintain this information accessible. As the new concepts of probabilistic risk analysis and condition monitoring are integrated into the American Society of Mechanical Engineers (ASME) Code, a critical element will be performance data. From check valve performance data, feasible failure modes and rates can be established. When a failure rate or frequency of failures can be established based on a significant enough population (sampling), a more solid foundation for focusing resources and determining appropriate frequencies and testing can be determined. The presentation will give the updated status of the NIC Check Valve Performance Database covering (1) methodology used to combine the original ORNL data; (2) process/controls established for continuing update and refinement of the data; (3) discussion of how this data is being utilized by (a) OM-22 for condition monitoring, and (b) risk-based inservice testing work of Westinghouse Owners' Group; and (4) results/trends of data evaluations. At the 1994 Symposium, ORNL provided an update as of 1991 to their original work of 1984 -1990 which they had performed to characterize check valve degradations and failures in the nuclear industry. These characterizations will be updated to 1995 and additional reviews provided to give insight into the current condition and trends of check valve performance

Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

Science.gov (United States)

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1999-01-01

A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

Plunger with simple retention valve

International Nuclear Information System (INIS)

Fekete, A.V.

1987-01-01

This patent describes a positive displacement retention valve apparatus in which the actual flow equals the theoretical maximum flow through the retention valve. The apparatus includes, in combination, a confined fluid flow conduit, a piston adapted for reciprocal movement within the fluid flow conduit between upstream and downstream limit positions, piston reciprocating means, and pressure responsive check valve means located upstream with respect to the piston in the fluid flow conduit. The pressure responsive check valve means operable to permit fluid flow therethrough in a downstream direction toward the piston, and to preclude fluid flow therethrough in an opposite direction. The piston is composed of parts which are relatively movable with respect to one another. The piston includes a simple retention valve consisting of a plug means, a cylinder having a minimum and a maximum internal cross section flow area therein and being reciprocal within the confined fluid flow conduit, and a seat on the cylinder for the plug means. The piston reciprocating means are operatively connected to the plug means

Preliminary observations of gate valve flow interruption tests, Phase 2

International Nuclear Information System (INIS)

Steele, R. Jr.; DeWall, K.G.

1990-01-01

This paper presents preliminary observations from the US Nuclear Regulatory Commission/Idaho National Engineering Laboratory Flexible Wedge Gate Valve Qualification and Flow Interruption Test Program, Phase 2. The program investigated the ability of selected boiling water reactor (BWR) process line valves to perform their containment isolation function at high energy pipe break conditions and other more normal flow conditions. The fluid and valve operating responses were measured to provide information concerning valve and operator performance at various valve loadings so that the information could be used to assess typical nuclear industry motor operator sizing equations. Six valves were tested, three 6-in. isolation valves representative of those used in reactor water cleanup systems in BWRs and three 10-in. isolation valves representative of those used in BWR high pressure coolant injection (HPCI) steam lines. The concern with these normally open isolation valves is whether they will close in the event of a downstream pipe break outside of containment. The results of this testing will provide part of the technical insights for NRC efforts regarding Generic Issue 87 (GI-87), Failure of the HPCI Steam Line Without Isolation, which includes concerns about the uncertainties in gate valve motor operator sizing and torque switch settings for these BWR containment isolation valves. As of this writing, the Phase 2 test program has just been completed. Preliminary observations made in the field confirmed most of the results from the Phase 1 test program. All six valves closing in high energy water, high energy steam, and high pressure cold water require more force to close than would be calculated using the typical variables in the standard industry motor operator sizing equations

Space Shuttle OMS engine valve technology. [Orbital Maneuvering System

Science.gov (United States)

Wichmann, H.

1974-01-01

Valve technology program to determine shutoff valve concepts suitable for the Orbital Maneuvering System (OMS) engine of the Space Shuttle. The tradeoff studies selected the electric torque motor operated dual poppet and ball valves as the most desirable valve concepts for the OMS Engine Shutoff Valve. A prototype of one of these concepts was built and subjected to a design verification program. A number of unique features were designed to include the required contamination insensitivity, operating fluid compatibility, decontamination capability, minimum maintenance requirement and long service life capability.

LANL continuity of operations plan

Energy Technology Data Exchange (ETDEWEB)

Senutovitch, Diane M [Los Alamos National Laboratory

2010-12-22

The Los Alamos National Laboratory (LANL) is a premier national security research institution, delivering scientific and engineering solutions for the nation's most crucial and complex problems. Our primary responsibility is to ensure the safety, security, and reliability of the nation's nuclear stockpile. LANL emphasizes worker safety, effective operational safeguards and security, and environmental stewardship, outstanding science remains the foundation of work at the Laboratory. In addition to supporting the Laboratory's core national security mission, our work advances bioscience, chemistry, computer science, earth and environmental sciences, materials science, and physics disciplines. To accomplish LANL's mission, we must ensure that the Laboratory EFs continue to be performed during a continuity event, including localized acts of nature, accidents, technological or attack-related emergencies, and pandemic or epidemic events. The LANL Continuity of Operations (COOP) Plan documents the overall LANL COOP Program and provides the operational framework to implement continuity policies, requirements, and responsibilities at LANL, as required by DOE 0 150.1, Continuity Programs, May 2008. LANL must maintain its ability to perform the nation's PMEFs, which are: (1) maintain the safety and security of nuclear materials in the DOE Complex at fixed sites and in transit; (2) respond to a nuclear incident, both domestically and internationally, caused by terrorist activity, natural disaster, or accident, including mobilizing the resources to support these efforts; and (3) support the nation's energy infrastructure. This plan supports Continuity of Operations for Los Alamos National Laboratory (LANL). This plan issues LANL policy as directed by the DOE 0 150.1, Continuity Programs, and provides direction for the orderly continuation of LANL EFs for 30 days of closure or 60 days for a pandemic/epidemic event. Initiation of COOP operations may

Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

Science.gov (United States)

Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

2017-11-01

Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

78 FR 21245 - Continuity of Operations Plan

Science.gov (United States)

2013-04-10

...; Order No. 778] Continuity of Operations Plan AGENCY: Federal Energy Regulatory Commission, DOE. ACTION: Final rule. SUMMARY: In this Final Rule the Commission revises its Continuity of Operations Plan... Commission's Continuity of Operations Plan (COOP) regulations to incorporate its regional offices into the...

Continuous PECS II block for postoperative analgesia in patients undergoing transapical transcatheter aortic valve implantation.

Science.gov (United States)

Shakuo, Tomoharu; Kakumoto, Shinichi; Kuribayashi, Junya; Oe, Katsunori; Seo, Katsuhiro

2017-01-01

It has been reported that PECS II block can alleviate postoperative pain following transapical transcatheter aortic valve implantation (TA-TAVI). However, the effectiveness of continuous PECS II block with catheterization has not yet been reported on the postoperative pain in patients undergoing TA-TAVI. We experienced two cases of TA-TAVI who received PECS II block with catheterization to manage postoperative pain. In the first case, a bolus injection for intraoperative pain and subsequent catheterization were performed before the implantation. However, the patient developed severe pain postoperatively in spite of the continuous block due to displacement of the catheter. In the second case, a bolus injection and the catheterization for the continuous block were performed before and after the implantation, respectively, which provided high-quality pain control. Continuous PECS II block may be useful to control perioperative pain associated with TA-TAVI. The insertion of the catheter after the implantation could be useful to avoid its displacement during the surgery.

Double-disc gate valve

International Nuclear Information System (INIS)

Wheatley, S.J.

1979-01-01

The invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewith, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separation of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve

A study on a characteristic of stem friction coefficient for motor operated flexible wedge gate valve

International Nuclear Information System (INIS)

Kim, Dae-Woong; Park, Sung-Geun; Lee, Sang-Guk; Kang, Shin-Cheul

2009-01-01

Stem friction coefficient is a coefficient that represents friction between thread leads of the stem and stem nut. It is an important factor to determine output thrust delivered from the actuator to the valve stem in assessing performance of motor operated valves. This study analyzes the effects of changes in differential pressure on stem friction coefficient, and determines the bounding value of stem friction coefficient. A dynamic test was conducted on multiple flexible wedge gate valves in various differential pressure conditions, and the test data was statistically analyzed to determine the bounding value. The results show that stem friction coefficient in middle and high differential pressure is influenced by fluid pressure, while stem friction coefficient in low differential pressure is almost not affected by fluid pressure. In addition, it is found that the bounding value of stem friction coefficient is higher in a closing stroke than in an opening stroke.

Bentall Procedure Using Cryopreserved Valved Aortic Homografts

Science.gov (United States)

Christenson, Jan T.; Sierra, Jorge; Trindade, Pedro T.; Didier, Dominique; Kalangos, Afksendiyos

2004-01-01

The Bentall procedure is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. In many cases, however, mechanical prosthetic conduits are not suitable. There are few reports in the English-language medical literature concerning the mid- to long-term outcome of Bentall operations with cryopreserved homografts. Therefore, we reviewed our experience with this procedure and valved homografts. From January 1997 through December 2002, 21 patients underwent a Bentall operation with cryopreserved homografts at our institution. There were 14 males and 7 females; the mean age was 36 ± 21 years (range, 15–74 years). Eleven patients had undergone previous aortic valve surgery. All patients had aortic dilatation or aneurysms involving the ascending aorta. Indications for surgery included aortic valve stenosis or insufficiency, and aortic valve endocarditis (native valve or prosthetic). One patient had Takayasu's arteritis and 3 had Marfan syndrome. There was 1 hospital death (due to sepsis), but no other major postoperative complications. The mean hospital stay was 14 ± 7 days. Follow-up echocardiographic and computed tomographic scans were performed yearly. The mean follow-up was 34 months (6–72 months). Follow-up imaging revealed no calcifications or degenerative processes related to the homograft. Four patients had minimal valve regurgitation. Two patients died during follow-up. The 3-year actuarial survival rate was 85.7%. Our data suggest that the Bentall procedure with a valved homograft conduit is a safe procedure with excellent mid- to long-term results, comparable to results reported with aortic valve replacement with a homograft. PMID:15745290

Control valve sizing and specification: The first step

International Nuclear Information System (INIS)

Harkins, J.F.; Hoyle, E.D.

1991-01-01

Today's modern control valve can satisfy almost any application. Special trim, materials, operators, and body configurations have been developed to meet the most severe operating conditions. The missing link in the chain connecting design to application is often the interpretation and communication of the requirements for determining the proper valve for each application. This paper addresses an important but often neglected requirement for proper selection and sizing of control valves: the determination of correct input data. It presents criteria necessary to ensure that the data given the manufacturer accurately reflects the conditions under which the control valve will operate. It highlights the importance of communication between the system design engineer, the valve specifying engineer, and the control valve supplier, to ensure that the final system design meets the true requirements of the application. An example is provided of a simple liquid-handling system, for which line losses and variations in flow and equipment capacities are tabulated and requirements shown graphically on typical control valve characteristic curves. The effects of seemingly harmless, conservative assumptions regarding line losses, equipment capacities and selection, sizing practices, and the selection of various flow data can have on the final valve selection are illustrated. Also discussed is the proper selection of equipment and input data, based on the example

Survival Prediction in Patients Undergoing Open-Heart Mitral Valve Operation After Previous Failed MitraClip Procedures.

Science.gov (United States)

Geidel, Stephan; Wohlmuth, Peter; Schmoeckel, Michael

2016-03-01

The objective of this study was to analyze the results of open heart mitral valve operations for survival prediction in patients with previously unsuccessful MitraClip procedures. Thirty-three consecutive patients who underwent mitral valve surgery in our institution were studied. At a median of 41 days, they had previously undergone one to five futile MitraClip implantations. At the time of their operations, patients were 72.6 ± 10.3 years old, and the calculated risk, using the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II, was a median of 26.5%. Individual outcomes were recorded, and all patients were monitored postoperatively. Thirty-day mortality was 9.1%, and the overall survival at 2.2 years was 60.6%. Seven cardiac-related and six noncardiac deaths occurred. Univariate survival regression models demonstrated a significant influence of the following variables on survival: EuroSCORE II (p = 0.0022), preoperative left ventricular end-diastolic dimension (p = 0.0052), left ventricular ejection fraction (p = 0.0249), coronary artery disease (p = 0.0385), and severe pulmonary hypertension (p = 0.0431). Survivors showed considerable improvements in their New York Heart Association class (p < 0.0001), left ventricular ejection fraction (p = 0.0080), grade of mitral regurgitation (p = 0.0350), and mitral valve area (p = 0.0486). Survival after mitral repair was not superior to survival after replacement. Indications for surgery after failed MitraClip procedures must be considered with the greatest of care. Variables predicting postoperative survival should be taken into account regarding the difficult decision as to whether to operate or not. Our data suggest that replacement of the pretreated mitral valve is probably the more reasonable concept rather than complex repairs. When the EuroSCORE II at the time of surgery exceeds 30%, conservative therapy is advisable. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc

Thermal overload protection for electric motors on safety-related motor-operated valves: Generic Issue II.E.6.1

International Nuclear Information System (INIS)

Rothberg, O.

1988-06-01

NRC regulatory positions, as stated in Regulatory Guide 1.106, Revision 1, have been identified by the Office for Analysis and Evaluation of Operational Data (AEOD) as potential contributors to valve motor burnout. AEOD is particularly concerned about the allowed policy of bypassing thermal overload devices during normal or accident conditions. Regulatory Guide 1.106 favors compromising the function of thermal overload devices in favor of completing the safety-related action of valves. The purpose of this study was to determine if the guidance contained in Regulatory Guide 1.106 is appropriate and, if not, to recommend the necessary changes. This report describes thermal overload devices commonly used to protect safety-related valve operator motors. The regulatory guidelines stated in Regulatory Guide 1.106 along with the limitations of thermal overload protection are discussed. Supplements and alternatives to thermal overload protection are also described. Findings and conclusions of several AEOD reports are discussed. Information obtained from the standard review plan, standard technical specifications, technical specifications from representative plants, and several papers are cited

A remotely operated drug delivery system with an electrolytic pump and a thermo-responsive valve

KAUST Repository

Yi, Ying

2015-07-22

Implantable drug delivery devices are becoming attractive due to their abilities of targeted and controlled dose release. Currently, two important issues are functional lifetime and non-controlled drug diffusion. In this work, we present a drug delivery device combining an electrolytic pump and a thermo-responsive valve, which are both remotely controlled by an electromagnetic field (40.5 mT and 450 kHz). Our proposed device exhibits a novel operation mechanism for long-term therapeutic treatments using a solid drug in reservoir approach. Our device also prevents undesired drug liquid diffusions. When the electromagnetic field is on, the electrolysis-induced bubble drives the drug liquid towards the Poly (N-Isopropylacrylamide) (PNIPAM) valve that consists of PNIPAM and iron micro-particles. The heat generated by the iron micro-particles causes the PNIPAM to shrink, resulting in an open valve. When the electromagnetic field is turned off, the PNIPAM starts to swell. In the meantime, the bubbles are catalytically recombined into water, reducing the pressure inside the pumping chamber, which leads to the refilling of the fresh liquid from outside the device. A catalytic reformer is included, allowing more liquid refilling during the limited valve\\'s closing time. The amount of body liquid that refills the drug reservoir can further dissolve the solid drug, forming a reproducible drug solution for the next dose. By repeatedly turning on and off the electromagnetic field, the drug dose can be cyclically released, and the exit port of the device is effectively controlled.

Full-root aortic valve replacement with stentless xenograft achieves superior regression of left ventricular hypertrophy compared to pericardial stented aortic valves.

Science.gov (United States)

Tavakoli, Reza; Auf der Maur, Christoph; Mueller, Xavier; Schläpfer, Reinhard; Jamshidi, Peiman; Daubeuf, François; Frossard, Nelly

2015-02-03

Full-root aortic valve replacement with stentless xenografts has potentially superior hemodynamic performance compared to stented valves. However, a number of cardiac surgeons are reluctant to transform a classical stented aortic valve replacement into a technically more demanding full-root stentless aortic valve replacement. Here we describe our technique of full-root stentless aortic xenograft implantation and compare the early clinical and midterm hemodynamic outcomes to those after aortic valve replacement with stented valves. We retrospectively compared the pre-operative characteristics of 180 consecutive patients who underwent full-root replacement with stentless aortic xenografts with those of 80 patients undergoing aortic valve replacement with stented valves. In subgroups presenting with aortic stenosis, we further analyzed the intra-operative data, early postoperative outcomes and mid-term regression of left ventricular mass index. Patients in the stentless group were younger (62.6 ± 13 vs. 70.3 ± 11.8 years, p regression of the left ventricular mass index in the stentless (p replacement can be performed without adversely affecting the early morbidity or mortality in patients operated on for aortic valve stenosis provided that the coronary ostia are not heavily calcified. The additional time necessary for the full-root stentless compared to the classical stented aortic valve replacement is therefore not detrimental to the early clinical outcomes and is largely rewarded in patients with aortic stenosis by lower transvalvular gradients at mid-term and a better regression of their left ventricular mass index.

Solution to valve failures at Braidwood induced by service water cavitation

International Nuclear Information System (INIS)

Ozol, J.; Schipiour, B.K.; Wix, J.E.

1994-01-01

Control valves throttle fluid from a high pressure to a lower pressure. On water systems, this throttling process may be accompanied by cavitation, which induces valve noise, vibration, and material damage. Extensive and significant caviation erosion has been experienced the last 10 years in most service water control valve bodies, downstream flanges, and reducers at Braidwood Station. There have been 40 different and distinct cavitation-induced failures in the service water system at Braidwood Station. These failures have created significant costs and continue to be a lingering source of operational maintenance costs to the Commonwealth Edison Company, which is incurring significant financial losses. It should be noted that almost all service water control valves experience some cavitation effects. Cavitation and cavitation damage are complex and elusive phenomena for which no single, simple analytical model exists. The purpose of this paper is to explain features of service water control valve cavitation failures and some of the solutions used by Commonwealth Edison at their six nuclear stations. The paper discusses the following: (1) Braidwood's history of erosion from cavitation; (2) Erosion-corrosion considerations; (3) The Instrument Society of America's valve sizing equations and how they relate to cavitation; (4) Methods to eliminate cavitation; (5) Corrective actions and practical approaches used by Commonwealth Edison to eliminate cavitation

An Operational Foundation for Delimited Continuations

DEFF Research Database (Denmark)

Biernacka, Malgorzata; Biernacki, Dariusz; Danvy, Olivier

2004-01-01

We present an abstract machine and a reduction semantics for the lambda-calculus extended with control operators that give access to delimited continuations in the CPS hierarchy. The abstract machine is derived from an evaluator in continuation-passing style (CPS); the reduction semantics (i.......e., a small-step operational semantics with an explicit representation of evaluation contexts) is constructed from the abstract machine; and the control operators are the shift and reset family. We also present new applications of delimited continuations in the CPS hierarchy: finding list prefixes...

Surgery of the aortic root: should we go for the valve-sparing root reconstruction or the composite graft-valve replacement is still the first choice of treatment for these patients?

Directory of Open Access Journals (Sweden)

Fernando de Azevedo Lamana

2015-09-01

Full Text Available AbstractObjective:To compare the results of the root reconstruction with the aortic valve-sparing operation versus composite graftvalve replacement.Methods:From January 2002 to October 2013, 324 patients underwent aortic root reconstruction. They were 263 composite graft-valve replacement and 61 aortic valve-sparing operation (43 reimplantation and 18 remodeling. Twenty-six percent of the patients were NYHA functional class III and IV; 9.6% had Marfan syndrome, and 12% had bicuspid aortic valve. There was a predominance of aneurysms over dissections (81% vs. 19%, with 7% being acute dissections. The complete follow-up of 100% of the patients was performed with median follow-up time of 902 days for patients undergoing composite graft-valve replacement and 1492 for those undergoing aortic valve-sparing operation.Results:In-hospital mortality was 6.7% and 4.9%, respectively for composite graft-valve replacement and aortic valve-sparing operation (ns. During the late follow-up period, there was 0% moderate and 15.4% severe aortic regurgitation, and NYHA functional class I and II were 89.4% and 94%, respectively for composite graft-valve replacement and aortic valve-sparing operation (ns. Root reconstruction with aortic valve-sparing operation showed lower late mortality (P=0.001 and lower bleeding complications (P=0.006. There was no difference for thromboembolism, endocarditis, and need of reoperation.Conclusion:The aortic root reconstruction with preservation of the valve should be the operation being performed for presenting lower late mortality and survival free of bleeding events.

Survey of industrial coal conversion equipment capabilities: valves

Energy Technology Data Exchange (ETDEWEB)

Bush, W. A.; Slade, E. C.

1978-06-01

A survey of the industrial capabilities of the valve and valve-actuator industry to supply large, high-pressure stop valves for the future coal conversion industry is presented in this report. Also discussed are development and testing capabilities of valve and valve-actuator manufacturers and anticipated lead times required to manufacture advanced design valves for the most stringent service applications. Results indicate that the valve and valve-actuator industry is capable of manufacturing in quantity equipment of the size and for the pressure and temperature ranges which would be required in the coal conversion industry. Valve manufacturers do not, however, have sufficient product application experience to predict the continuing functional ability of valves used for lock-hopper feeders, slurry feeders, and slag-char letdown service. Developmental and testing efforts to modify existing valve designs or to develop new valve concepts for these applications were estimated to range from 1 to 6 years. A testing facility to simulate actuation of critical valves under service conditions would be beneficial.

Self-actuated Polymeric Valve for Autonomous Sensing and Mixing

DEFF Research Database (Denmark)

Häfliger, Daniel; Marie, Rodolphe Charly Willy; Boisen, Anja

2005-01-01

We present an autonomously operated microvalve array for chemical sensing and mixing, which gains the actuation energy from a chemical reaction on the valve structure. An 8-μm-thick flapper valve made in SU-8 is coated with stress-loaded Al on one side and Ti on the other side. The metal films ke...... a reservoir. Calculations reveal that valve operation with stress originating from biochemical processes will require considerable enhancement of the actuation efficiency.......We present an autonomously operated microvalve array for chemical sensing and mixing, which gains the actuation energy from a chemical reaction on the valve structure. An 8-μm-thick flapper valve made in SU-8 is coated with stress-loaded Al on one side and Ti on the other side. The metal films keep...

Proving test on the reliability for nuclear valves

International Nuclear Information System (INIS)

Kajiyama, Yasuo; Tashiro, Hisao; Uga, Takeo; Maeda, Shunichi.

1986-01-01

Since valves are the most common components, they could be the most frequent causes of troubles in nuclear power plants. This proving test, therefore, has an important meaning to examine and verify the reliability of various valves under simulating conditions of abnormal and transient operations of the nuclear power plant. The test was performed mainly for the various types and pressure ratings of valves which were used in the primary and secondary systems in BWR and PWR nuclear power plants and which had major operating or safety related functions in those nuclear power plants. The results of the proving test, confirmed for more than four years, showed relatively favourable performance of the tested valves. It is concluded that performances of valves including operability, seat sealing and structural integrity were proved under the thermal cycling, vibration and pipe reaction load conditions. Operating functions during and after accident such as loss of coolant accident were satisfactory. From these results, it was considered that the purpose of this proving test was satisfactorily fulfilled. Several data accumulated by the test would be useful to get better reliability if it was evaluated with the actually experienced data of valves in the nuclear power plants. (Nogami, K.)

Prioritization of motor operated valves based on risk importances

International Nuclear Information System (INIS)

Vesely, W.E.; Weidenhamer, G.H.

1994-01-01

The plant Probabilistic Risk Assessment (PRA) can be a potentially useful and powerful tool for helping to define an effective response to GL 89-10. The plant PRA can be used to prioritize the Motor Operated Valves (MOV) dynamic test. The plant PRA can also be used to determine test schedules for the MOVs. In order for the PRA to be validly used to respond to GL 89-10, various issues need to be validly addressed. Eleven issues are specifically identified and responses to these issues are outlined. The issues of joint MOV importance, PRA truncation, and validation of the proposed approach are specifically highlighted and more detailed response considerations are described. As in all PRA applications, sensitivity studies and uncertainty considerations should be incorporated in the PRA evaluations. 4 refs, 3 tabs

Valve-Sparing Root Replacement Compared With Composite Valve Graft Procedures in Patients With Aortic Root Dilation.

Science.gov (United States)

Ouzounian, Maral; Rao, Vivek; Manlhiot, Cedric; Abraham, Nachum; David, Carolyn; Feindel, Christopher M; David, Tirone E

2016-10-25

Although aortic valve-sparing (AVS) operations are established alternatives to composite valve graft (CVG) procedures for patients with aortic root aneurysms, comparative long-term outcomes are lacking. This study sought to compare the results of patients undergoing AVS procedures with those undergoing CVG operations. From 1990 to 2010, a total of 616 patients age Marfan syndrome and lower rates of bicuspid aortic valve than those undergoing bio-CVG or m-CVG procedures. In-hospital mortality (0.3%) and stroke rate (1.3%) were similar among groups. After adjusting for clinical covariates, both bio-CVG and m-CVG procedures were associated with increased long-term major adverse valve-related events compared with patients undergoing AVS (hazard ratio [HR]: 3.4, p = 0.005; and HR: 5.2, p valve-related complications when compared with bio-CVG and m-CVG. AVS is the treatment of choice for young patients with aortic root aneurysm and normal or near-normal aortic cusps. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Early results of gate valve flow interruption blowdown tests

International Nuclear Information System (INIS)

DeWall, K.G.

1988-01-01

The preliminary results of the USNRC/INEL high-energy BWR line break flow interruption testing are presented. Two representative nuclear valve assemblies were cycled under design basis Reactor Water Cleanup pipe break conditions to provide input for the technical basis for resolving the Nuclear Regulatory Commission's Generic Issue 87. The effects of the blowdown hydraulic loadings on valve operability, especially valve closure stem forces, were studied. The blowdown tests showed that, given enough thrust, typical gate valves will close against the high flow resulting from a line break. The tests also showed that proper operator sizing depends on the correct identification of values for the sizing equation. Evidence exists that values used in the past may not be conservative for all valve applications. The tests showed that improper operator lock ring installation following test or maintenance can invalidate in-situ test results and prevent the valve from performing its design function. 2 refs., 12 figs., 2 tabs

Selection and evaluation of an ultra high vacuum gate valve for Isabelle beam line vacuum system

International Nuclear Information System (INIS)

Foerster, C.L.; McCafferty, D.

1980-01-01

A minimum of eighty-four (84) Ultra High Vacuum Gate Valves will be utilized in ISABELLE to protect proton beam lines from catastrophic vacuum failure and to provide sector isolation for maintenance requirements. The valve to be selected must function at less than 1 x 10 -11 Torr pressure and be bakeable to 300 0 C in its open or closed position. In the open position, the valve must have an RF shield to make the beam line walls appear continuous. Several proposed designs were built and evaluated. The evaluation consisted mainly of leak testing, life tests, thermal cycling, mass spectrometer analysis, and 10 -12 Torr operation. Problems with initial design and fabrication were resolved. Special requirements for design and construction were developed. This paper describes the tests on two final prototypes which appear to be the best candidates for ISABELLE operation

Valve for gas centrifuges

Science.gov (United States)

Hahs, Charles A.; Burbage, Charles H.

1984-01-01

The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

3D Printed Multimaterial Microfluidic Valve.

Directory of Open Access Journals (Sweden)

Steven J Keating

Full Text Available We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deformation spatially, through combinations of stiff and flexible materials, to enable intricate geometries in an actuated, functionally graded device. Research presented marks a shift towards 3D printing multi-property programmable fluidic devices in a single step, in which integrated multimaterial valves can be used to control complex fluidic reactions for a variety of applications, including DNA assembly and analysis, continuous sampling and sensing, and soft robotics.

Preventive maintenance basis: Volume 16 -- Power operated relief valves, solenoid actuated. Final report

International Nuclear Information System (INIS)

Worledge, D.; Hinchcliffe, G.

1997-07-01

US nuclear plants are implementing preventive maintenance (PM) tasks with little documented basis beyond fundamental vendor information to support the tasks or their intervals. The Preventive Maintenance Basis project provides utilities with the technical basis for PM tasks and task intervals associated with 40 specific components such as valves, electric motors, pumps, and HVAC equipment. This report provides an overview of the PM Basis project and describes use of the PM Basis database. This volume 16 of the report provides a program of PM tasks suitable for application to power operated relief valves (PORV's) that are solenoid actuated. The PM tasks that are recommended provide a cost-effective way to intercept the causes and mechanisms that lead to degradation and failure. They can be used, in conjunction with material from other sources, to develop a complete PM program or to improve an existing program. Users of this information will be utility managers, supervisors, craft technicians, and training instructors responsible for developing, optimizing, or fine-tuning PM programs

Constraints of using thermostatic expansion valves to operate air-cooled chillers at lower condensing temperatures

International Nuclear Information System (INIS)

Yu, F.W.; Chan, K.T.; Chu, H.Y.

2006-01-01

Thermostatic expansion valves (TXVs) have long been used in air-cooled chillers to implement head pressure control under which the condensing temperature is kept high at around 50 o C by staging condenser fans as few as possible. This paper considers how TXVs prevent the chillers from operating with an increased COP at lower condensing temperatures when the chiller load or outdoor temperature drops. An analysis on an existing air-cooled reciprocating chiller showed that the range of differential pressures across TXVs restricts the maximum heat rejection airflow required to increase the chiller COP, though the set point of condensing temperature is reduced to 22 o C from a high level of 45 o C. It is possible to use electronic expansion valves to meet the differential pressure requirements for maximum chiller COP. There is a maximum of 28.7% increase in the chiller COP when the heat rejection airflow is able to be maximized in various operating conditions. The results of this paper emphasize criteria for lowering the condensing temperature to enhance the performance of air-cooled chillers

[Pannus Formation Six-years after Aortic and Mitral Valve Replacement with Tissue Valves;Report of a Case].

Science.gov (United States)

Nakamura, Makoto; Muraoka, Arata; Aizawa, Kei; Akutsu, Hirohiko; Kurumisawa, Soki; Misawa, Yoshio

2015-07-01

A 77-year-old man presented with exertional dyspnea. He had undergone aortic and mitral valve replacement with tissue valves 6-years earlier. The patient's hemoglobin level was 9.8 g/dl and serum aspartate aminotransferase (70 mU/ml) and lactate dehydrogenase (1,112 mU/ml) were elevated. Echocardiography revealed stenosis of the prosthetic valve in the aortic position with peak flow velocity of 3.8 m/second and massive mitral regurgitation. The patient underwent repeat valve replacement. Pannus formation around both implanted valves was observed. The aortic valve orifice was narrowed by the pannus, and one cusp of the prosthesis in the mitral position was fixed and caused the regurgitation, but they were free from cusp laceration or calcification. The patient's postoperative course was uneventful, and he continues to do well 14 months after surgery.

Bistable fluidic valve is electrically switched

Science.gov (United States)

Fiet, O.; Salvinski, R. J.

1970-01-01

Bistable control valve is selectively switched by direct application of an electrical field to divert fluid from one output channel to another. Valve is inexpensive, has no moving parts, and operates on fluids which are relatively poor electrical conductors.

Design of the Modular Pneumatic Valve Terminal

Directory of Open Access Journals (Sweden)

Jakub E. TAKOSOGLU

2015-11-01

Full Text Available The paper presents design of the modular pneumatic valve terminal, which was made on the basis of the patent application No A1 402905 „A valve for controlling fluid power drives, specially for pneumatic actuators, and the control system for fluid power drives valves”. The authors describe a method of operation of the system with double-acting valve and 5/2 (five ways and two position valve. Functions of the valve, and an example of application of the valve terminal in the production process were presented. 3D solid models of all the components of the valve were made. The paper presents a complete 3D model of the valve in various configurations. Using CAD-embedded SOLIDWORKS Flow Simulation computational fluid dynamics CFD analysis was also carried out of compressed air flow in the ways of the valve elements

A review of historical check valve failure data

International Nuclear Information System (INIS)

Casada, D.A.; Todd, M.D.

1992-01-01

Check valve operating problems in recent years have resulted in significant operating transients, increased cost, and decreased system availability. In response, additional attention has been given to check valves by utilities, as well as the US Nuclear Regulatory Commission (NRC) and the American Society of Mechanical Engineers Operation and Maintenance Committee. All these organizations have the fundamental goal of ensuring reliable operation of check valves. A key ingredient of an engineering-oriented reliability improvement effort is a thorough understanding of relevant historical experience. Oak Ridge National Laboratory is currently conducting a detailed review of historical failure data available through the Institute of Nuclear Power Operation's Nuclear Plant Reliability Data System. The focus of the review is on check valve failures that have involved significant degradation of the valve internal parts. A variety of parameters are being considered during the review, including size, age, system of service, method of failure discovery, the affected valve parts, attributed causes, and corrective actions. This work is being carried out under the auspices of the NRC's Nuclear Plant Aging Research program. At this time, the study is approximately 50% complete. All failure records have been reviewed and categorized, and preliminary tabulation and correlation of data is underway. The bulk of the tabulation and correlation portion of the work is expected to be completed by the end of June 1992. A report draft is expected in the fall of 1992

Recent experience with testing of parallel disc gate valves under accident flow conditions

International Nuclear Information System (INIS)

LaPointe, P.A.; Clayton, J.K.

1992-01-01

This paper presents the nuclear valve industry's latest and most extensive valve qualification test program experience. The test program includes a variety of 25 different gate and globe valves. All the test valves are power operated using either air, electric, or gas/hydraulic operators. The valves are categorized in size and pressure class so as to form a group of appropriate parent valve assemblies. Parent valve assembly qualification is used as the basis for qualification of candidate valve assemblies. The parent and candidate valve assemblies are representative of a nuclear plant's safety-related valve applications. The test program was performed in accordance with ANSI B16.41-1983 'Functional Qualification Requirements for Power Operated Active Valve Assemblies for Nuclear Power Plants.' The focus of this paper is on functional valve qualification test experience and specifically flow interruption testing to Annex G of the aforementioned test standard. Results of the flow test are summarized, including the coefficient of friction for each of the gate type valves reported. Information on valve size, pressure class, and actuator are given for all valves in the program. Although all valves performed extremely well, only selected test data are presented. The effects of the speed of operation and the effects of different fluid flow rates as they relate to the coefficient of friction between the valve disc and seat are discussed. The variation in the coefficient of friction based on other variables in the thrust equation, namely, differential pressure area is cited

Additively Manufactured Main Fuel Valve Housing

Science.gov (United States)

Eddleman, David; Richard, Jim

2015-01-01

Selective Laser Melting (SLM) was utilized to fabricate a liquid hydrogen valve housing typical of those found in rocket engines and main propulsion systems. The SLM process allowed for a valve geometry that would be difficult, if not impossible to fabricate by traditional means. Several valve bodies were built by different SLM suppliers and assembled with valve internals. The assemblies were then tested with liquid nitrogen and operated as desired. One unit was also burst tested and sectioned for materials analysis. The design, test results, and planned testing are presented herein.

ADAM®/SIPLUG®: An innovative valve monitoring system

International Nuclear Information System (INIS)

Muñoz, L.; Krell, M.

2012-01-01

Optimized maintenance strategies are a key aspect for safe and undisturbed plant operation. Innovative valve service solutions, e.g. valve diagnostics can support this in an efficient way. The ADAM®/SIPLUG® valve monitoring system allows full online monitoring of valves and actuators with automatic evaluation and assessment. Especially for safety-related and operation-related valves this provides valuable information on components condition to ensure proper function and contribute to optimization of maintenance strategies as well as effective maintenance performance. The new SIPLUG®-4 modules are the evolutionary solution for valve diagnosis at the Motor Control Center (MCC). As the SIPLUG®-4 can be installed directly in the MCC outgoing actuator power cable it allows an easy installation in existing switchgear cabinets. Measurement at MCC means also zero effort for performance of diagnostics reducing the number of on-site activities. This results in decrease of maintenance costs and dose rates for deployed personnel. The ADAM® evaluation software and database was developed in parallel with the hardware. It provides automatic analysis of the monitoring results using the limit values specified for the valves. The measured data can be transmitted via the power plant’s local area network to the ADAM® data server, if the SIPLUG® online hardware is installed. With the mobile solution, the data can be transmitted via serial or USB interface to a PC or notebook. With this solution all measurement information will be available immediately in the offices of plant engineers. Also, with SIPLUG® online all operations of valves can be automatically recorded. More than 25 years of experience in various plants worldwide show that the application of ADAM®/SIPLUG® valve diagnostics solution leads to increased plant safety and availability. Some of the references for ADAM®/SIPLUG® are Germany, Switzerland, Brazil, Spain and Eastern Europe. (author)

BCE selector valves and flow proportional sampler

International Nuclear Information System (INIS)

Rippy, G.L.

1994-01-01

This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the Electrical/Instrumentation systems for the B-Plant Process Condensate Treatment Facility (BCE) function as required by project criteria. Tests will be run to: Verify the operation of the solenoid valve and associated limit switches installed for the BCE portion of W-007H; Operate the solenoid valve and verify the proper operation of the associated limit switches based on the position of the solenoid valve;and, Demonstrate the integrity of the Sample Failure Alarm Relay XFA-211BA-BCE-1, and Power Failure ALarm Relay JFA-211BA-BCE-1 located inside the Flow Proportional Sampler in Building 211 BA

Flow Characteristics and Sizing of Annular Seat Valves for Digital Displacement Machines

Directory of Open Access Journals (Sweden)

Christian Nørgård

2018-01-01

Full Text Available This paper investigates the steady-state flow characteristics and power losses of annular seat valves for digital displacement machines. Annular seat valves are promising candidates for active check-valves used in digital displacement fluid power machinery which excels in efficiency in a broad operating range. To achieve high machine efficiency, the valve flow losses and the required electrical power needed for valve switching should be low. The annular valve plunger geometry, of a valve prototype developed for digital displacement machines, is parametrized by three parameters: stroke length, seat radius and seat width. The steady-state flow characteristics are analyzed using static axi-symmetric computational fluid dynamics. The pressure drops and flow forces are mapped in the valve design space for several different flow rates. The simulated results are compared against measurements using a valve prototype. Using the simulated maps to estimate the flow power losses and a simple generic model to estimate the electric power losses, both during digital displacement operation, optimal designs of annular seat valves, with respect to valve power losses, are derived under several different operating conditions.

Recent improvements in check valve monitoring methods

International Nuclear Information System (INIS)

Haynes, H.D.

1991-01-01

In support of the NRC Nuclear Plant Aging Research (NPAR) program, ORNL has carried out an evaluation of three check valve monitoring methods: acoustic emission, ultrasonic inspection, and magnetic flux signature analysis (MFSA). This work has focussed on determining the capabilities of each method to provide diagnostic information useful in determining check valve aging and service wear effects (degradation) and undesirable operating modes. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two novel nonintrusive monitoring methods were developed (external ac- and dc-magnetic monitoring) that provide several improvements over the other methods. None of the examined methods could, by themselves, monitor the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data to illustrate the capabilities of these methods to detect simulated check valve degradation. 3 refs., 22 figs., 4 tabs

Recent improvements in check valve monitoring methods

International Nuclear Information System (INIS)

Haynes, H.D.

1990-01-01

In support of the NRC Nuclear Plant Aging Research (NPAR) program, ORNL has carried out an evaluation of three check valve monitoring methods: acoustic emission, ultrasonic inspection, and magnetic flux signature analysis (MFSA). This work has focused on determining the capabilities of each method to provide diagnostic information useful in determining check valve aging and service wear effects (degradation) and undesirable operating modes. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two noval nonintrusive monitoring methods were developed (external ac- and dc-magnetic monitoring) that provide several improvements over the other methods. None of the examined methods could, by themselves, monitor the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data to illustrate the capabilities of these methods to detect simulated check valve degradation. 3 refs., 22 figs., 4 tabs

High-risk Trans-Catheter Aortic Valve Replacement in a Failed Freestyle Valve with Low Coronary Height: A Case Report

OpenAIRE

Karimi, Ashkan; Pourafshar, Negiin; Dibu, George; Beaver, Thomas M.; Bavry, Anthony A.

2017-01-01

A 55-year-old male with a history of two prior cardiac surgeries presented with decompensated heart failure due to severe bioprosthetic aortic valve insufficiency. A third operation was viewed prohibitively high risk and valve-in-valve trans-catheter aortic valve replacement was considered. There were however several high-risk features and technically challenging aspects including low coronary ostia height, poor visualization of the aortic sinuses, and difficulty in identification of the copl...

Engine including hydraulically actuated valvetrain and method of valve overlap control

Science.gov (United States)

Cowgill, Joel [White Lake, MI

2012-05-08

An exhaust valve control method may include displacing an exhaust valve in communication with the combustion chamber of an engine to an open position using a hydraulic exhaust valve actuation system and returning the exhaust valve to a closed position using the hydraulic exhaust valve actuation assembly. During closing, the exhaust valve may be displaced for a first duration from the open position to an intermediate closing position at a first velocity by operating the hydraulic exhaust valve actuation assembly in a first mode. The exhaust valve may be displaced for a second duration greater than the first duration from the intermediate closing position to a fully closed position at a second velocity at least eighty percent less than the first velocity by operating the hydraulic exhaust valve actuation assembly in a second mode.

Nuclear reactor steam depressurization valve

International Nuclear Information System (INIS)

Moore, G.L.

1991-01-01

This patent describes improvement in a nuclear reactor plant, an improved steam depressurization valve positioned intermediate along a steam discharge pipe for controlling the venting of steam pressure from the reactor through the pipe. The improvement comprises: a housing including a domed cover forming a chamber and having a partition plate dividing the chamber into a fluid pressure activation compartment and a steam flow control compartment, the valve housing being provided with an inlet connection and an outlet connection in the steam flow control compartment, and a fluid duct in communication with a source of fluid pressure for operating the valve; a valve set mounted within the fluid flow control compartment comprising a cylindrical section surrounding the inlet connection with one end adjoining the connection and having a radially projecting flange at the other end with a contoured extended valve sealing flange provided with an annular valve sealing member, and a valve cylinder traversing the partition plate and reciprocally movable within an opening in the partition plate with one terminal and extending into the fluid pressure activation compartment and the other terminal end extending into the steam flow control compartment coaxially aligned with the valve seat surrounding the inlet connection, the valve cylinder being surrounded by two bellow fluid seals and provided with guides to inhibit lateral movement, an end of the valve cylinder extending into the fluid flow control compartment having a radially projecting flange substantially conterminous with the valve seat flange and having a contoured surface facing and complimentary to the contoured valve seating surface whereby the two contoured valve surfaces can meet in matching relationship, thus providing a pressure actuated reciprocatable valve member for making closing contact with the valve seat and withdrawing therefrom for opening fluid flow through the valve

Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

Science.gov (United States)

Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

2017-07-01

Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

Minimising life cycle costs of automated valves in offshore platforms

Energy Technology Data Exchange (ETDEWEB)

Yli-Petays, Juha [Metso Automation do Brasil Ltda., Rio de Janeiro, RJ (Brazil); Niemela, Ismo [Metso Automation, Imatra (Finland)

2012-07-01

Automated process valves play an essential role in offshore platforms operation. If you are able to optimize their operation and maintenance activities you can receive extensive operational savings with minimal investment. Valves used in offshore platforms doesn't differentiate that much from the valves used in downstream but there are certain specialties, which makes the operations more challenging in offshore: Process valves are more difficult to access and maintain because of space limitations. Also spare part inventories and deliveries are challenging because of offshore platform's remote location. To overcome these challenges usage of digital positioners with diagnostic features has become more common because predictive maintenance capabilities enable possibilities to plan the maintenance activities and this way optimise the spare part orders regarding to valves. There are intelligent controllers available for control valves, automated on/off valves as well as ESD-valves and whole network of automated valves on platforms can be controlled by intelligent valve controllers. This creates many new opportunities in regards of optimized process performance or predictive maintenance point-of-view. By means of intelligent valve controllers and predictive diagnostics, condition monitoring and maintenance planning can also be performed remotely from an onshore location. Thus, intelligent valve controllers provide good way to minimize spending related to total cost of ownership of automated process valves. When purchase value of control valve represent 20% of TCO, intelligent positioner and predictive maintenance methods can enable as high as 30% savings over the life cycle of asset so basically it benefit savings higher than whole investment of monitored asset over its life cycle. This is mainly achieved through the optimized maintenance activities since real life examples has shown that with time based maintenance (preventive maintenance) approach 70% of

Continuity of Accelerator Operations during an Extended Pandemic

International Nuclear Information System (INIS)

Noel Okay

2010-01-01

The Operations group for the Continuous Electron Accelerator Facility in Newport News Virginia has developed a Continuity of Operations plan for pandemic conditions when high absenteeism may impact accelerator control room operations. Protocols to address both the potential spread of illnesses in the control room environment as well as maintaining minimum staffing requirements for contiguous accelerator operation will be presented. During acute pandemic conditions local government restrictions may prevent continued operations but during extended periods of high absenteeism accelerator operations can continue when some added precautionary measures and staffing adjustments are made in the way business is done.

Evaluation of mispositioned ECCS valves

International Nuclear Information System (INIS)

Hill, R.A.; O'Brien, J.F.; McIntire, D.C.; Barlow, R.T.

1977-09-01

In October of 1975, Westinghouse submitted NS-CE-787, dated October 17, 1975, to the Nuclear Regulatory Commission (NRC) and entered into discussions with them concerning the spurious movement of certain motor-operated valves (MOV's) in the Emergency Core Cooling System (ECCS) to a position defeating the ECCS function at a time when this function is required. On November 25, 1975, the discussion turned to the possible movement of a manually controlled, motor-operated valve due to a fault in its electrical circuitry and the NRC staff expressed concerns about other possible failure modes that might lead to such a valve movement. The NRC meeting minutes document these concerns. This report is an item-by-item response to the concerns expressed by the NRC staff at that meeting and incorporates the original electrical fault analysis

Mechanical versus bioprosthetic aortic valve replacement.

Science.gov (United States)

Head, Stuart J; Çelik, Mevlüt; Kappetein, A Pieter

2017-07-21

Mechanical valves used for aortic valve replacement (AVR) continue to be associated with bleeding risks because of anticoagulation therapy, while bioprosthetic valves are at risk of structural valve deterioration requiring reoperation. This risk/benefit ratio of mechanical and bioprosthetic valves has led American and European guidelines on valvular heart disease to be consistent in recommending the use of mechanical prostheses in patients younger than 60 years of age. Despite these recommendations, the use of bioprosthetic valves has significantly increased over the last decades in all age groups. A systematic review of manuscripts applying propensity-matching or multivariable analysis to compare the usage of mechanical vs. bioprosthetic valves found either similar outcomes between the two types of valves or favourable outcomes with mechanical prostheses, particularly in younger patients. The risk/benefit ratio and choice of valves will be impacted by developments in valve designs, anticoagulation therapy, reducing the required international normalized ratio, and transcatheter and minimally invasive procedures. However, there is currently no evidence to support lowering the age threshold for implanting a bioprosthesis. Physicians in the Heart Team and patients should be cautious in pursuing more bioprosthetic valve use until its benefit is clearly proven in middle-aged patients. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Aging and defect characterization of motor-operated valves: progress based on NPAR strategy

International Nuclear Information System (INIS)

Eissenberg, D.M.

1984-01-01

The Nuclear Plant Aging Research (NPAR) program strategy is directed at carrying out comprehensive aging assessments in order to define and resolve issues related to aging (including service wear) of electrical and mechanical components and structures at operating reactor facilities and their possible impact on plant safety. This paper describes work recently completed at Oak Ridge National Laboratory which applied the NPAR strategy to motor-operated valves (MOVs). The objective of the work was primarily to develop an understanding of the operating history and conditions and the failure modes of MOVs in nuclear plant service as a preliminary to identifying and recommending methods for trending aging degradation. A second objective was to demonstrate, using MOVs as an example, that the NPAR strategy can be applied to many electrical and mechanical components of nuclear power plants

Design review report: AN valve pit upgrades for Project W-314, tank farm restoration and safe operations

International Nuclear Information System (INIS)

Boes, K.A.

1998-01-01

This Design Review Report (DRR) documents the contractor design verification methodology and records associated with project W-314's AN Valve Pit Upgrades design package. The DRR includes the documented comments and their respective dispositions for this design. Acceptance of the comment dispositions and closure of the review comments is indicated by the signatures of the participating reviewers. Project W-314, Tank Farm Restoration and Safe Operations, is a project within the Tank Waste Remediation System (TWRS) Tank Waste Retrieval Program. This project provides capital upgrades for the existing Hanford tank farms' waste transfer, instrumentation, ventilation, and electrical infrastructure systems. To support established TWRS programmatic objectives, the project is organized into two distinct phases. The initial focus of the project (i.e., Phase 1) is on waste transfer system upgrades needed to support the TWRS Privatization waste feed delivery system. Phase 2 of the project will provide upgrades to support resolution of regulatory compliance issues, improve tank infrastructure reliability, and reduce overall plant operating/maintenance costs. Within Phase 1 of the W-314 project, the waste transfer system upgrades are further broken down into six major packages which align with the project's work breakdown structure. Each of these six sub-elements includes the design, procurement, and construction activities necessary to accomplish the specific tank farm upgrades contained within the package. The first package to be performed is the AN Valve Pit Upgrades package. The scope of the modifications includes new pit cover blocks, valve manifolds, leak detectors, transfer line connections (for future planned transfer lines), and special protective coating for the 241-AN-A and 241-AN-B valve pits

High-risk Trans-Catheter Aortic Valve Replacement in a Failed Freestyle Valve with Low Coronary Height: A Case Report.

Science.gov (United States)

Karimi, Ashkan; Pourafshar, Negiin; Dibu, George; Beaver, Thomas M; Bavry, Anthony A

2017-06-01

A 55-year-old male with a history of two prior cardiac surgeries presented with decompensated heart failure due to severe bioprosthetic aortic valve insufficiency. A third operation was viewed prohibitively high risk and valve-in-valve trans-catheter aortic valve replacement was considered. There were however several high-risk features and technically challenging aspects including low coronary ostia height, poor visualization of the aortic sinuses, and difficulty in identification of the coplanar view due to severe aortic insufficiency, and a highly mobile aortic valve mass. After meticulous peri-procedural planning, trans-catheter aortic valve replacement was carried out with a SAPIEN 3 balloon-expandable valve without any complication. Strategies undertaken to navigate the technically challenging aspects of the case are discussed.

77 FR 43488 - Continuity of Operations Plan

Science.gov (United States)

2012-07-25

...; Order No. 765] Continuity of Operations Plan AGENCY: Federal Energy Regulatory Commission, DOE. ACTION... Operations Plan to allow the Commission the discretion to better address not only long-term and catastrophic... discretion regarding: the activation and deactivation of the Continuity of Operations Plan and any suspension...

Effects of valve timing, valve lift and exhaust backpressure on performance and gas exchanging of a two-stroke GDI engine with overhead valves

International Nuclear Information System (INIS)

Dalla Nora, Macklini; Lanzanova, Thompson Diórdinis Metzka; Zhao, Hua

2016-01-01

Highlights: • Two-stroke operation was achieved in a four-valve direct injection gasoline engine. • Shorter valve opening durations improved torque at lower engine speeds. • The longer the valve opening duration, the lower was the air trapping efficiency. • Higher exhaust backpressure and lower valve lift reduced the compressor work. - Abstract: The current demand for fuel efficient and lightweight powertrains, particularly for application in downsized and hybrid electric vehicles, has renewed the interest in two-stroke engines. In this framework, an overhead four-valve spark-ignition gasoline engine was modified to run in the two-stroke cycle. The scavenging process took place during a long valve overlap period around bottom dead centre at each crankshaft revolution. Boosted intake air was externally supplied at a constant pressure and gasoline was directly injected into the cylinder after valve closure. Intake and exhaust valve timings and lifts were independently varied through an electrohydraulic valve train, so their effects on engine performance and gas exchanging were investigated at 800 rpm and 2000 rpm. Different exhaust backpressures were also evaluated by means of exhaust throttling. Air trapping efficiency, charging efficiency and scavenge ratio were calculated based on air and fuel flow rates, and exhaust oxygen concentration at fuel rich conditions. The results indicated that longer intake and exhaust valve opening durations increased the charge purity and hence torque at higher engine speeds. At lower speeds, although, shorter valve opening durations increased air trapping efficiency and reduced the estimated supercharger power consumption due to lower air short-circuiting. A strong correlation was found between torque and charging efficiency, while air trapping efficiency was more associated to exhaust valve opening duration. The application of exhaust backpressure, as well as lower intake/exhaust valve lifts, made it possible to increase

[Reoperative valve replacement in patients undergoing cardiac reoperation: a report of 104 cases].

Science.gov (United States)

Zou, Liang-jian; Xu, Zhi-yun; Wang, Zhi-nong; Lang, Xi-long; Han, Lin; Lu, Fang-lin; Xu, Ji-bin; Tang, Hao; Ji, Guang-yu; Wang, Er-song; Wang, Jun; Qu, Yi

2010-08-15

To review the experience of reoperative valve replacement for 104 patients. From January 2002 to December 2009, 104 patients underwent heart valve replacement in reoperations, accounting for 2.92% of the total patient population (3557 cases) who had valve replacement during this period. In this group, 53 male and 51 female patients were included with a median age of 46 years (ranged from 13 to 72 years). The reasons of reoperation included 28 cases suffered from another valve lesion after valve replacement, 10 cases suffered from valve lesion after mitral valvuloplasty, 19 cases suffered from perivalvular leakage after valve replacement, 18 cases suffered from valve lesion after previous correction of congenital heart defect, 7 cases suffered from bioprosthetic valve decline, 10 cases suffered from prosthetic valve endocarditis, 9 cases suffered from dysfunction of machine valve, and 3 cases suffered from other causes. The re-operations were mitral and aortic valve replacement in 2 cases, mitral valve replacement in 59 cases, aortic valve replacement in 24 cases, tricuspid valve replacement in 16 cases, and Bentall's operation in 3 cases. The interval from first operation to next operation was 1 month-19 years. There were 8 early deaths from heart failure, renal failure and multiple organ failure (early mortality 7.69%). Major complications were intraoperative hemorrhage in 2 cases, re-exploration for mediastinal bleeding in 2 cases and sternotomy surgical site infection in 1 case. Complete follow-up (3 months-7 years and 2 months) was available for all patients. Two patients died, one patient died of intracranial hemorrhage, and another cause was unknown. Satisfactory short-term and long-term results can be obtained in reoperative valve replacement with appropriate timing of operation control, satisfactory myocardial protection, accurate surgical procedure and suitable perioperative treatment.

Fairchild Stratos Division's Type II prototype lockhopper valve: METC Prototype Test Valve No. F-1 prototype lockhopper valve-testing and development project. Static test report

Energy Technology Data Exchange (ETDEWEB)

Goff, D. R.; Cutright, R. L.; Griffith, R. A.; Loomis, R. B.; Maxfield, D. A.; Moritz, R. S.

1981-10-01

METC Prototype Test Valve No. F-1 is a hybrid design, based on a segmented ball termed a visor valve, developed and manufactured by Fairchild Stratos Division under contract to the Department of Energy. The valve uses a visor arm that rotates into position and then translates to seal. This valve conditionally completed static testing at METC with clean gas to pressures of 1600 psig and internal valve temperatures to 600/sup 0/F. External leakage was excessive due to leakage through the stuffing box, purge fittings, external bolts, and other assemblies. The stuffing box was repacked several times and redesigned midway through the testing, but external leakage was still excessive. Internal leakage through the seats, except for a few anomalies, was very low throughout the 2409 cycles of testing. As shown by the low internal leakage, the visor valve concept appears to have potential for lock-hopper valve applications. The problems that are present with METC Prototype Test Valve No. F-1 are in the seals, which are equivalent to the shaft and bonnet seals in standard valve designs. The operating conditions at these seals are well within the capabilities of available seal designs and materials. Further engineering and minor modifications should be able to resolve the problems identified during static testing.

Risk Factors for Late Aortic Valve Dysfunction After the David V Valve-Sparing Root Replacement.

Science.gov (United States)

Esaki, Jiro; Leshnower, Bradley G; Binongo, Jose N; Lasanajak, Yi; McPherson, LaRonica; Guyton, Robert A; Chen, Edward P

2017-11-01

Valve-sparing root replacement (VSRR) is an established therapy for aortic root pathology. However, late aortic valve dysfunction requiring reoperation remains a primary concern of this procedure. This study examines risk factors for late aortic insufficiency (AI) and aortic stenosis (AS) after David V VSRR. A retrospective review from 2005 to 2015 at a US academic center identified 282 patients who underwent VSRR. Cox proportional hazards regression analysis was used to identify risk factors for late AI and AS after VSRR. The mean age was 46.4 years. Sixty-four patients (22.7%) had bicuspid valves, and 41 patients (14.5%) had Marfan syndrome. The incidence of reoperations was 27 (9.6%), and 42 cases (14.9%) presented with acute type A dissection. Operative mortality was 8 (2.8%). Seven-year survival was 90.9%. Seven-year cumulative incidence of reoperation, greater than 2+ AI and greater than moderate AS were 3.1%, 2.2%, and 0.8%, respectively. Multivariable analysis showed aortic root size 55 mm or larger (hazard ratio 3.44, 95% confidence interval: 1.27 to 9.29, p = 0.01) to be a risk factor for late AI whereas bicuspid valve (hazard ratio 16.07, 95% confidence interval: 3.12 to 82.68, p = 0.001) and cusp repair were found to be risk factors (hazard ratio 5.91, 95% confidence interval: 1.17 to 29.86, p = 0.03) for late AS. Valve-sparing root replacement can be performed with low operative risk and good overall long-term survival even in complex clinical settings. Durable valve function can be expected; however, aortic root size 55 cm or more, bicuspid valve anatomy, and cusp repair represent independent risk factors for late aortic valve dysfunction after these procedures. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Singular continuous spectrum for palindromic Schroedinger operators

International Nuclear Information System (INIS)

Hof, A.; Knill, O.; Simon, B.

1995-01-01

We give new examples of discrete Schroedinger operators with potentials taking finitely many values that have purely singular continuous spectrum. If the hull X of the potential is strictly ergodic, then the existence of just one potential x in X for which the operator has no eigenvalues implies that there is a generic set in X for which the operator has purely singular continuous spectrum. A sufficient condition for the existence of such an x is that there is a z element of X that contains arbitrarily long palindromes. Thus we can define a large class of primitive substitutions for which the operators are purely singularly continuous for a generic subset in X. The class includes well-known substitutions like Fibonacci, Thue-Morse, Period Doubling, binary non-Pisot and ternary non-Pisot. We also show that the operator has no absolutely continuous spectrum for all x element of X if X derives from a primitive substitution. For potentials defined by circle maps, x n =l J (θ 0 +nα), we show that the operator has purely singular continuous spectrum for a generic subset in X for all irrational α and every half-open interval J. (orig.)

Main feedwater valve diagnostics at Waterford 3 nuclear generating station

International Nuclear Information System (INIS)

Fitzgerald, W.V.

1991-01-01

Pneumatically-operated control valves are coming under increasing scrutiny in nuclear power plants because of their relatively high incident rate. The theory behind a device that could make performance evaluation of these valves simpler and more effective was first described at the original EPRI Power Plant Valve Symposium. The development of this Diagnostic System was completed in 1989, and it was recently used to troubleshoot two main feedwater valves at Louisiana Power and Light's Waterford 3 Power Station. During a cold snap last December, these valves failed to respond to the input signal and, as a result, the plant came off line. An incident report had to be filed, and the plant chose to contact the original equipment manufacturer (OEM) for assistance. This paper describes the original incident involving these valves and then gives a brief description of the diagnostic system and how it works. The balance of the paper then reviews how the OEM and plant personnel utilized the system to evaluate each component of the control valve assembly (I/P transducer, positioner, volume boosters, actuator, and valve body assembly). By simply stroking the valve and monitoring pneumatic signals and valve position, the problem was traced to a malfunctioning positioner and a volume booster that was leaking. The problems were corrected and new performance signatures run for the valves using the system to document their improved operation. This case study demonstrates how new Diagnostic Technology along with OEM involvement can effectively address problems with pneumatically-operated control valves so that root-cause solutions can be implemented

Operator continued fraction and bound states

International Nuclear Information System (INIS)

Pindor, M.

1984-01-01

The effective Hamiltonian of the model space perturbation theory (multilevel Rayleigh-Schroedinger theory) is expressed as an operator continued fraction. In the case of a nondegenerate model space the expression becomes an operator branched continued fraction. The method is applied to the harmonic oscillator with the kinetic energy treated as the perturbation and to the anharmonic oscillator

Investigations on pneumatically forced-actuated compressor valves

Science.gov (United States)

Stöckel, Christian; Thomas, Christiane; Nickl, Jörg; Hesse, Ullrich

2017-08-01

In the present paper the performance of a novel designed valve for reciprocating piston machines is investigated, which makes existing compressors utilizable for operating as expander. Three design parameters were identified as critical for the valves performance particularly in forced actuated mode. Within a numerical simulation a study on the crucial geometrical parameters, the influence could be observed. Afterwards the experimental setup for the integral test of the valve design is presented and also additional tests for single valve components.

Flow Characteristics and Sizing of Annular Seat Valves for Digital Displacement Machines

DEFF Research Database (Denmark)

Nørgård, Christian; Bech, Michael Møller; Andersen, Torben O.

2018-01-01

operating range. To achieve high machine efficiency, the valve flow losses and the required electrical power needed for valve switching should be low. The annular valve plunger geometry, of a valve prototype developed for digital displacement machines, is parametrized by three parameters: stroke length......This paper investigates the steady-state flow characteristics and power losses of annular seat valves for digital displacement machines. Annular seat valves are promising candidates for active check-valves used in digital displacement fluid power machinery which excels in efficiency in a broad...... a valve prototype. Using the simulated maps to estimate the flow power losses and a simple generic model to estimate the electric power losses, both during digital displacement operation, optimal designs of annular seat valves, with respect to valve power losses, are derived under several different...

Continuity of operations/continuity of government for state-level transportation organizations : brief.

Science.gov (United States)

2011-09-01

As a result of a federal requirement, all non-federal entities that own or operate critical : infrastructure are required to develop Continuity of Operations/Continuity of Government : (COOP/COG) Plans. Transportation is a critical infrastructure com...

Design and production of a hermetic bayonet isolation valve

International Nuclear Information System (INIS)

Fuerst, J.

1993-05-01

Fermilab is upgrading the Tevatron for lower temperature/higher beam energy operation. Portions of the satellite refrigeration system will operate below atmospheric pressure after the upgrade is complete. Contamination must be prevented by hermetically sealing the subatmospheric helium to air interfaces. Bayonet connections in the low pressure flow path require a reliable, leak tight isolation valve instead of the standard quarter turn ball valve. Design, development, and production of a new valve are described

Optimal results of aortic valve replacement with small mechanical valves (< 19 mm).

Science.gov (United States)

Kato, Yasuyuki; Hattori, Koji; Motoki, Manabu; Takahashi, Yosuke; Kotani, Shinsuke; Nishimura, Shinsuke; Shibata, Toshihiko

2013-07-01

Controversy exists regarding the optimal operative method or type of prosthesis for patients with a small aortic root. The aim of this retrospective study was to investigate the early and mid-term outcomes of standard aortic valve replacement (AVR) using 16 mm or 18 mm ATS Advanced Performance (AP) or 17 mm St. Jude Medical (SJM) Regent valves for a small aortic root. Between April 2003 and August 2009, 78 patients (age range: 50-86 years; 86% aged > or = 65 years) underwent AVR with 16 mm or 18 mm ATS AP valves (16AP group: n = 21, 18AP group: n = 32), or a 17 mm SJM Regent valve (17Regent group: n = 25). Fifty-six patients (72%) had a body surface area (BSA) of regression was similar among the groups (-30%, -25% and -28% in the 16AP, 17Regent and 18AP groups, respectively; p = 0.844). The early and mid-term results of AVR with 16 mm or 18 mm ATS AP valves, or with a 17 mm SJM Regent valve, were satisfactory. Therefore, standard AVR using these small mechanical prostheses, which avoids the need to enlarge the annulus or to conduct stentless bioprosthesis implantation, might represent an acceptable method, especially in elderly patients with a small aortic root.

Plant experience with check valves in passive systems

Energy Technology Data Exchange (ETDEWEB)

Pahladsingh, R R [GKN Joint Nuclear Power Plant, Dodewaard (Netherlands)

1996-12-01

In the design of the advanced nuclear reactors there is a tendency to introduce more passive safety systems. The 25 year old design of the GKN nuclear reactor is different from the present BWR reactors because of some special features, such as the Natural Circulation - and the Passive Isolation Condenser system. When reviewing the design, one can conclude that the plant has 25 years of experience with check valves in passive systems and as passive components in systems. The result of this experience has been modeled in a plant-specific ``living PSA`` for the plant. A data-analysis has been performed on components which are related to the safety systems in the plant. As part of this study also the check valves have been taken in consideration. At GKN, the check valves have shown to be reliable components in the systems and no catastrophic failures have been experienced during the 25 years of operation. Especially the Isolation Condenser with its operation experience can contribute substantially to the insight of check valves in stand-by position at reactor pressure and operating by gravity under different pressure conditions. With the introduction of several passive systems in the SBWR-600 design, such as the Isolation Condensers, Gravity Driven Cooling, and Suppression Pool Cooling System, the issue of reliability of check valves in these systems is actual. Some critical aspects for study in connection with check valves are: What is the reliability of a check valve in a system at reactor pressure, to open on demand; what is the reliability of a check valve in a system at low pressure (gravity), to open on demand; what is the reliability of a check valve to open/close when the stand-by check wave is at zero differential pressure. The plant experience with check valves in a few essential safety systems is described and a brief introduction will be made about the application of check valves in the design of the new generation reactors is given. (author). 6 figs, 1 tab.

Banking cryopreserved heart valves in Europe: assessment of a 5-year operation in an international tissue bank in Brussels.

Science.gov (United States)

Goffin, Y; Grandmougin, D; Van Hoeck, B

1996-01-01

The heart valve bank of the European Homograft Bank has been set up in 1988 to meet the growing demand of cardiac surgeons for various sized and quality controlled cryopreserved homografts. Heart valve donors less than 60 years of age were classified in 3 categories: multiorgan donors with non transplantable hearts, recipients of cardiac transplantation and non beating heart cadavers with a warm ischemic time of less than 6 hours. Past history and biology were checked for transmissible diseases. Preparation, progressive freezing and storage in liquid nitrogen vapors, and quality control were according to the standards of the Belgian Ministry of Health. From end January 1989 to end May 1994, 989 homograft valves were cryopreserved (514 pulmonary, 475 aortic and 3 mitral) whereas 962 valves were discarded. The first cause of rejection being a major macroscopic lesion (41.48%). 138 hearts accepted at inspection were contaminated and 43 cases remained so after antibiotics. 38 cases were positive for hepatitis B or C. Complication at distribution and thawing included 10 instances of bag rupture and 15 of transversal fracture through the wall of the conduit. 477 aortic, 474 pulmonary valves as well as one mitral were implanted between May 1989 and May 1994, either for left or right ventricular outflow tract reconstruction. In the left ventricular outflow tract series 111 aortic and 23 pulmonary homograft valves were used in cases of native endocarditis, prosthetic endocarditis or recurrent endocarditis after homograft implantation. 9.6% of the requests could no be satisfied. Regular follow up information was available from 382 implants-40.1% only. The assessment of 5 years operation of the heart valve bank indicates: 1) the efficiency of selecting, cryopreserving and allocating quality controlled homograft valves from a large pool of donor hearts provided by a network of hospitals; 2) the difficulty of obtaining regular follow up information on the implants.

Impact characteristics for high-pressure large-flow water-based emulsion pilot operated check valve reverse opening

Science.gov (United States)

Liu, Lei; Huang, Chuanhui; Yu, Ping; Zhang, Lei

2017-10-01

To improve the dynamic characteristics and cavitation characteristics of large-flow pilot operated check valve, consider the pilot poppet as the research object, analyses working principle and design three different kinds of pilot poppets. The vibration characteristics and impact characteristics are analyzed. The simulation model is established through flow field simulation software. The cavitation characteristics of large-flow pilot operated check valve are studied and discussed. On this basis, high-pressure large-flow impact experimental system is used for impact experiment, and the cavitation index is discussed. Then optimal structure is obtained. Simulation results indicate that the increase of pilot poppet half cone angle can effectively reduce the cavitation area, reducing the generation of cavitation. Experimental results show that the pressure impact is not decreasing with increasing of pilot poppet half cone angle in process of unloading, but the unloading capacity, response speed and pilot poppet half cone angle are positively correlated. The impact characteristics of 60° pilot poppet, and its cavitation index is lesser, which indicates 60° pilot poppet is the optimal structure, with the theory results are basically identical.

Guidelines for the application and use of valves in power plant systems

International Nuclear Information System (INIS)

Brooks, B.

1991-01-01

The improper application, incorrect use, and ineffective maintenance of valves in power plant systems have been determined to be the cause of significant losses in plant availability. Such practices may additionally impact the safe operation of the plant. Numerous programs have been initiated, particularly in the nuclear power generation industry, to address these problems and excellent strides have been taken in that direction. Plant operating data, however, continues to indicate major losses in plant availability attributable to these sources. Although there exists significant knowledge and expertise in valve technology in the valve industry and in the power generation industry, the application of these factors, in preventing and resolving problems, has not been effectively utilized. Detailed information is difficult to glean from numerous sources and may often be restricted by proprietary considerations. Lessons learned in resolving problems have not been broadly disseminated in the industry with the result that individual utilities may be addressing problems unaware that a neighbor utility has already effectively resolved this same problem. To aid the power generation industry in improving upon this condition, EPRI initiated a project to develop 'Guide for the Application and Use of Valves in Power Plant Systems' (RP2233-5). A draft of the document was reviewed by an industry group whose major comment was the need to achieve a more readable text in which information on specific areas of concern is readily accessible. This rewriting has been accomplished along the lines of valve functional requirements. This paper presents an introduction, a summary, and a road map on how to use the guidebook

A remotely operated drug delivery system with an electrolytic pump and a thermo-responsive valve

KAUST Repository

Yi, Ying; Zaher, Amir; Yassine, Omar; Kosel, Jü rgen; Foulds, Ian G.

2015-01-01

Implantable drug delivery devices are becoming attractive due to their abilities of targeted and controlled dose release. Currently, two important issues are functional lifetime and non-controlled drug diffusion. In this work, we present a drug delivery device combining an electrolytic pump and a thermo-responsive valve, which are both remotely controlled by an electromagnetic field (40.5 mT and 450 kHz). Our proposed device exhibits a novel operation mechanism for long-term therapeutic treatments using a solid drug in reservoir approach. Our device also prevents undesired drug liquid diffusions. When the electromagnetic field is on, the electrolysis-induced bubble drives the drug liquid towards the Poly (N-Isopropylacrylamide) (PNIPAM) valve that consists of PNIPAM and iron micro-particles. The heat generated by the iron micro-particles causes the PNIPAM to shrink, resulting in an open valve. When the electromagnetic field is turned off, the PNIPAM starts to swell. In the meantime, the bubbles are catalytically recombined into water, reducing the pressure inside the pumping chamber, which leads to the refilling of the fresh liquid from outside the device. A catalytic reformer is included, allowing more liquid refilling during the limited valve's closing time. The amount of body liquid that refills the drug reservoir can further dissolve the solid drug, forming a reproducible drug solution for the next dose. By repeatedly turning on and off the electromagnetic field, the drug dose can be cyclically released, and the exit port of the device is effectively controlled.

Wireless online position monitoring of manual valve types for plant configuration management in nuclear power plants

International Nuclear Information System (INIS)

Agarwal, Vivek; Buttles, John W.; Beaty, Lawrence H.; Naser, Joseph; Hallbert, Bruce P.

2016-01-01

In the current competitive energy market, the nuclear industry is committed to lower the operations and maintenance cost; increase productivity and efficiency while maintaining safe and reliable operation. The present operating model of nuclear power plants is dependent on large technical staffs that put the nuclear industry at long-term economic disadvantage. Technology can play a key role in nuclear power plant configuration management in offsetting labor costs by automating manually performed plant activities. The technology being developed, tested, and demonstrated in this paper will enable the continued safe operation of today’s fleet of light water reactors by providing the technical means to monitor components in plants today that are only routinely monitored through manual activities. The wireless enabled valve position indicators that are the subject of this paper are able to provide a valid position indication available continuously, rather than only periodically. As a result, a real-time (online) availability of valve positions using an affordable technologies are vital to plant configuration when compared with long-term labor rates, and provide information that can be used for a variety of plant engineering, maintenance, and management applications.

The outcome after aortic valve-sparing (David) operation in 179 patients: a single-centre experience.

Science.gov (United States)

Leontyev, Sergey; Trommer, Constanze; Subramanian, Sreekumar; Lehmann, Sven; Dmitrieva, Yaroslava; Misfeld, Martin; Mohr, Friedrich W; Borger, Michael A

2012-08-01

The David aortic valve-sparing reimplantation (AVr-D) operation is increasingly being used in patients with aortic root aneurysmal disease and pliable aortic cusps. The objective of this study was to assess our early and medium-term outcomes with the AVr-D operation. Between 2003 and 2011, a total of 179 patients underwent AVr-D procedures. The mean patient age was 49.7 ± 15.1 years, and 23.5% (n = 42) were females. Marfan syndrome was present in 17.3% of patients (n = 31), and acute Type A aortic dissection in 15.6% (n = 28). Clinical follow-up was 100% complete and was 1.8 ± 1.6 years (0 days to 7.5 years) long. Echocardiographic follow-up was performed 2.2 ± 1.5 years (0 days to 7.5 years) postoperatively and was 77% complete. Early mortality was 1.1% (n = 2), with both deaths occurring in patients with Type A dissection. Pre-discharge echocardiography revealed no patients with >2+ aortic insufficiency (AI), 19.6% of patients (n = 34) with 1+ or 2+ AI and 80.4% of patients (n = 145) with trace or no AI. Left ventricular end-diastolic diameters decreased significantly from 5.6 ± 0.9 to 5.1 ± 0.8 cm early postoperatively (P valve re-replacement during follow-up, two due to early endocarditis and two due to non-coronary leaflet prolapse in Marfan patients. Five-year freedom from aortic valve reoperation was 95.9 ± 2.0%. AVr-D is associated with a low mortality and morbidity rate, even in patients with Type A aortic dissection. Although a slightly higher rate of recurrent AI may be present in patients with Marfan syndrome, freedom from recurrent AI and reoperation remains excellent during medium-term follow-up. The David operation should be considered the gold standard for patients with proximal aortic root pathology (aneurysm or dissection) and pliable aortic cusps.

A characterization of check valve degradation and failure experience in the nuclear power industry

International Nuclear Information System (INIS)

Casada, D.A.; Todd, M.D.

1993-09-01

Check valve operating problems in recent years have resulted in significant operating transients, increased cost and decreased system availability. As a result, additional attention has beau given to check valves by utilities (resulting in the formation of the Nuclear Industry Check Valve Group), as well as the US Nuclear Regulatory Commission and the American Society of Mechanical Engineers Operation and Maintenance Committee. All these organizations have the fundamental goal of ensuring reliable operation of check valves. A key ingredient to an engineering-oriented reliability improvement effort is a thorough understanding of relevant historical experience. A detailed review of historical failure data, available through the Institute of Nuclear Power Operation's Nuclear Plant Reliability Data System, has been conducted. The focus of the review is on check valve failures that have involved significant degradation of the valve internal parts. A variety of parameters are considered, including size, age, system of service, method of failure discovery, the affected valve parts, attributed causes, and corrective actions

Should patients with Björk-Shiley valves undergo prophylactic replacement?

Science.gov (United States)

Birkmeyer, J D; Marrin, C A; O'Connor, G T

1992-08-29

About 85,000 patients have undergone replacement of diseased heart valves with prosthetic Björk-Shiley convexo-concave (CC) valves. These valves are prone to fracture of the outlet strut, which leads to acute valve failure that is usually fatal. Should patients with these valves undergo prophylactic replacement to avoid fracture? The incidence of strut fracture varies between 0% and 1.5% per year, depending on valve opening angle (60 degrees or 70 degrees), diameter (less than 29 mm or greater than or equal to 29 mm), and location (aortic or mitral). Other factors include the patient's life expectancy and the expected morbidity and mortality associated with reoperation. We have used decision analysis to identify the patients most likely to benefit from prophylactic reoperation. The incidence of outlet strut fracture was estimated from the data of three large studies on CC valves, and stratified by opening angle, diameter, and location. A Markov decision analysis model was used to estimate life expectancy for patients undergoing prophylactic valve replacement and for those not undergoing reoperation. Prophylactic valve replacement does not benefit patients with CC valves that have low strut fracture risks (60 degrees aortic valves and less than 29 mm, 60 degrees mitral valves). For most patients with CC valves that have high strut fracture risks (greater than or equal to 29 mm, 70 degrees CC), prophylactic valve replacement increases life expectancy. However, elderly patients with such valves benefit from prophylactic reoperation only if the risk of operative mortality is low. Patient age and operative risk are most important in recommendations for patients with CC valves that have intermediate strut fracture risks (less than 29 mm, 70 degrees valves and greater than or equal to 29 mm, 60 degrees mitral valves). For all patients and their doctors facing the difficult decision on whether to replace CC valves, individual estimates of operative mortality risk that

Design And Analysis Of A Camless Valve Mechanism For I.C Engines Using Rotary Disc Valves

Directory of Open Access Journals (Sweden)

Vivek Jitendra Panchal

2017-09-01

Full Text Available It is the object of the presented paper to provide an electromechanical rotary valve actuating system for opening and closing valves of an internal combustion engine capable of separately controlling both the inlet and exhaust valve operations of each individual cylinder in a multi-cylinder engine. This indicates that only one valve will be required for each cylinder of the engine. Previously published versions of this concept require a separate valve for intake and exhaust in each cylinder. The system provides an alternative to the camshaft assembly in an attempt to overcome the limitations and inadequacies inevitably posed by a fully mechanical system. The prototype development is approached in a theoretical manner beginning with the conceptualization and design of a rotating disk with a notches and corresponding closure surfaces to open and close the flow path. The actuated disk and notch design is then refined and followed by the design of an inlet and exhaust manifold to correspond to the valve design and the theorizing and design of a sealing gasket. The rotating speed of the valve is determined by a general idling speed and can be varied to provide variable valve timing with the motor. The final assembly eliminates a majority of the moving parts currently used in camshaft systems like the cam camshaft rocker arm push rod and springs and results in a significantly lighter valve actuation system. By eliminating the translatory motion of valves the problem of valves slamming on the valve seats at high velocities is eliminated thus greatly reducing engine wear.

MEMS Micro-Valve for Space Applications

Science.gov (United States)

Chakraborty, I.; Tang, W. C.; Bame, D. P.; Tang, T. K.

1998-01-01

We report on the development of a Micro-ElectroMechanical Systems (MEMS) valve that is designed to meet the rigorous performance requirements for a variety of space applications, such as micropropulsion, in-situ chemical analysis of other planets, or micro-fluidics experiments in micro-gravity. These systems often require very small yet reliable silicon valves with extremely low leak rates and long shelf lives. Also, they must survive the perils of space travel, which include unstoppable radiation, monumental shock and vibration forces, as well as extreme variations in temperature. Currently, no commercial MEMS valve meets these requirements. We at JPL are developing a piezoelectric MEMS valve that attempts to address the unique problem of space. We begin with proven configurations that may seem familiar. However, we have implemented some major design innovations that should produce a superior valve. The JPL micro-valve is expected to have an extremely low leak rate, limited susceptibility to particulates, vibration or radiation, as well as a wide operational temperature range.

Measurements on a PV solar pump equipped with a piston pump with a matching valve

NARCIS (Netherlands)

Smulders, P.T.; Ten Thije O.G. Boonkkamp, J.; Borg, van der N.J.C.M.; Beek, van M.

1997-01-01

The work on a simple high efficient solar pump equipped with a piston pump with a matching valve, reported at the Solar World Congress in Budapest, has been continued. Quasi-static and dynamic models of the solar pump have been derived with which the operation of the system is simulated. A test rig

Piezoelectric valve

Science.gov (United States)

Petrenko, Serhiy Fedorovich

2013-01-15

A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

Evaluation on operation of liquid relief valves for steam line break accidents by RELAP5/CANDU+ code

International Nuclear Information System (INIS)

Yang, C. Y.; Bang, Y. S.; Kim, H. J.

2001-01-01

A development of RELAP5/CANDU+ code for regulatory audits of accident analysis of CANDU nuclear power plants is on progress. This paper is undertaken in a procedure of a verification and validation for RELAP5/CANDU+ code by analyzing main steam line break accidents of WS 2/3/4. Following the ECC injection in sequence of the steam line breaks, the mismatch in heat transfer between the primary and the secondary systems makes pressure of the primary system instantly peaked to the open setpoint of liquid relief valves. The event sequence follows the result of WS 2/3/4 FSAR, but there is a difference in pressure transient after ECC injection. Sensitivity analysis for main factors dependent on the peak pressure such as control logics of liquid relief valves. ECC flow path and feedwater flow is performed. Because the pressure increase is continued for a long time and its peaking is high, open and close of the liquid relief valves are repeated several times, which is obviously different from those of WS 2/3/4 FSAR. As a result, it is evaluated that conservative modeling for the above variables is required in the analysis

Aortic root reconstruction by aortic valve-sparing operation (David type I reimplantation) in Marfan syndrome accompanied by annuloaortic ectasia and acute type-A aortic dissection.

Science.gov (United States)

Inamura, Shunichi; Furuya, Hidekazu; Yagi, Kentarou; Ikeya, Eriko; Yamaguchi, Masaomi; Fujimura, Takabumi; Kanabuchi, Kazuo

2006-09-20

To reconstruct the aortic root for aneurysm of the ascending aorta accompanied by aortic regurgitation, annuloaortic ectasia (AAE) and acute type-A dissection with root destruction, the Bentall operation using a prosthetic valve still is the standard procedure today. Valve-sparing procedures have actively been used for aortic root lesions, and have also been attempted in aortic root reconstruction for Marfan syndrome which may have abnormalities in the valve leaflets. We conducted a valve-sparing procedure in a female patient with Marfan syndrome who had AAE accompanied by type-A acute aortic dissection. The patient was a 37-year-old woman complaining of severe pain from the chest to the back. The limbs were long, and funnel breast was observed. Diastolic murmurs were heard. On chest computed tomography, a dissection cavity was present from the ascending aorta to the left common iliac artery, and the root dilated to 55 mm. Grade II aortic regurgitation was observed on ultrasound cardiography. Regarding her family history, her father had died suddenly at 54 years of age. She was diagnosed with type-A acute dissection concurrent with Marfan syndrome and AAE. The structure of the aortic valve was normal, and root reconstruction by a valve-sparing operation and total replacement of the aortic arch was conducted. On postoperative ultrasound cardiography, the aortic regurgitation was within the allowable range, and the shortterm postoperative results were good.

Mitral valve surgery in the adult Marfan syndrome patient.

Science.gov (United States)

Bhudia, Sunil K; Troughton, Richard; Lam, Buu-Khanh; Rajeswaran, Jeevanantham; Mills, William R; Gillinov, A Marc; Griffin, Brian P; Blackstone, Eugene H; Lytle, Bruce W; Svensson, Lars G

2006-03-01

Because mitral valve dysfunction in adults with Marfan syndrome is poorly characterized, this study compares mitral valve pathophysiology and morphology with that of myxomatous mitral disease, documents types of mitral valve operations, and assesses long-term survival and durability of mitral valve surgery in Marfan patients. From May 1975 to June 2000, 27 adults with Marfan syndrome underwent mitral valve surgery. Their valve pathophysiology and morphology was compared with that of 119 patients with myxomatous mitral disease undergoing surgery from September 1995 to March 1999. Survival and repair durability were assessed at follow-up. Compared with myxomatous disease patients, Marfan patients had less posterior leaflet prolapse (44% versus 70%, p = 0.01), more bileaflet (44% versus 28%, p = 0.09) and anterior leaflet prolapse (11% versus 3%, p = 0.07), and presented earlier for surgery (age 41 +/- 12 years versus 57 +/- 13, p Marfan patients had longer and thinner leaflets. Mitral valve repair was performed less frequently in Marfan (16 of 27, 59%) than myxomatous disease patients (112 of 119, 94%). There were no hospital deaths; at 10 years, survival was 80% and freedom from reoperation 96%, with only 1 reoperation among the 16 repairs. Mitral valve pathophysiology and morphology differ between Marfan and myxomatous mitral valve diseases. Valve repair in Marfan patients is durable and gives acceptable long-term results, even in adults who present with advanced mitral valve pathology. With increasing use of the modified David reimplantation operation and sparing of the aortic valve, mitral valve repair is a greater imperative, particularly since we have not had to reoperate on any Marfan patients with reimplantations.

Plastik på trikuspidalklappen (Tricuspid valve annuloplasty. The neglected valve)

DEFF Research Database (Denmark)

Pedersen, Thais A L; Wierup, Per; Pedersen, Lia Mendes

2010-01-01

INTRODUCTION: Tricuspid valve regurgitation (TVR) is often secondary to left-sided or congenital heart disease (CHD). Surgical correction of TVR is indicated when the primary abnormalities require operation. MATERIAL AND METHODS: Retrospective analysis of all 50 patients (mean age: 65 years (rang...

Depth of valve implantation, conduction disturbances and pacemaker implantation with CoreValve and CoreValve Accutrak system for Transcatheter Aortic Valve Implantation, a multi-center study.

Science.gov (United States)

Lenders, Guy D; Collas, Valérie; Hernandez, José Maria; Legrand, Victor; Danenberg, Haim D; den Heijer, Peter; Rodrigus, Inez E; Paelinck, Bernard P; Vrints, Christiaan J; Bosmans, Johan M

2014-10-20

Transcatheter Aortic Valve Implantation (TAVI) is now considered an indispensable treatment strategy in high operative risk patients with severe, symptomatic aortic stenosis. However, conduction disturbances and the need for Permanent Pacemaker (PPM) implantation after TAVI with the CoreValve prosthesis still remain frequent. We aimed to evaluate the implantation depth, the incidence and predictors of new conduction disturbances, and the need for PPM implantation within the first month after TAVI, using the new Accutrak CoreValve delivery system (ACV), compared to the previous generation CoreValve (non-ACV). In 5 experienced TAVI-centers, a total of 120 consecutive non-ACV and 112 consecutive ACV patients were included (n=232). The mean depth of valve implantation (DVI) was 8.4±4.0 mm in the non-ACV group and 7.1±4.0 mm in the ACV group (p=0.034). The combined incidence of new PPM implantation and new LBBB was 71.2% in the non-ACV group compared to 50.5% in the ACV group (p=0.014). DVI (p=0.002), first degree AV block (p=0.018) and RBBB (p<0.001) were independent predictors of PPM implantation. DVI (p<0.001) and pre-existing first degree AV-block (p=0.021) were identified as significant predictors of new LBBB. DVI is an independent predictor of TAVI-related conduction disturbances and can be reduced by using the newer CoreValve Accutrak delivery system, resulting in a significantly lower incidence of new LBBB and new PPM implantation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Fast Flux Test Facility primary sodium valves

International Nuclear Information System (INIS)

Rabe, G.B.; Ezra, B.C.

1977-01-01

The design and development of the valves used in the primary sodium coolant loop of the Fast Flux Test Facility is described. One tilting-disk check valve is used in the cold leg of the coolant loop. It is designed to limit flow reversal in the loop while maintaining a low pressure drop during forward flow. Two isolation valves are used in each coolant loop--one in the cold leg and one in the hot leg. They are of the motor-operated swinging-gate type. The design, analysis, and testing programs undertaken to develop and qualify these valves are described

A Study of System Pressure Transients Generated by Isolation Valve Open/Closure in Orifice Manifold

Energy Technology Data Exchange (ETDEWEB)

Kim, M. [KEPCO, Daejeon (Korea, Republic of); Bae, S. W.; Kim, J. I.; Park, S. J. [KHNP, Abu Dhabi (United Arab Emirates)

2016-05-15

In this study, we explore the effects of pressure transients on peak and minimal pressures caused by the actuation of isolation valve and control valve reacting to the combined orifice operation of orifice manifold with motor-operated valve installed in the rear of the orifice. We then use the collected data to direct our effort towards cause analysis and propose improvements to efficiency and safety of operation. This formation is used to by domestic and foreign nuclear power plants as a mean to control flow rate, producing required flow rate jointly together by combination of the orifices. No significant impacts on the internals of manifold orifice due to peak pressure has been observed, although chance of cavitation at the outlet of control valve is significant. Considering the peak pressure, as well as minimum pressure occurs in low flow rate conditions, the pressure transient is more so affected by the characteristics (modified equal percentage) of control valve. Isolation valve of the orifice and control valve operate organically, therefore stroke time for valves need to be applied in order for both valves to cooperatively formulate an optimized operation.

The use of valves in the SAGD process

Energy Technology Data Exchange (ETDEWEB)

Romano, Michael A. [Global Marketing, Oil and Gas, Tyco Valves and Controls (United States)

2011-07-01

Steam-assisted gravity drainage (SAGD) is a developing technology, the aim of which is to increase production of bitumen while minimizing its environmental footprint. Valves must meet the process conditions of the operations, which depend on weel depth: deeper reservoirs of bitumen require higher steam injection pressure. A wide range of valves is used throughout the SAGD process. In the water softening plant, butterfly and process lined valves are used. HP gate valves are used for isolation, globe valves for vents/drains/bypasses, along with ARC valves for steam and booster pump projection with steam traps on injection lines in steam injection. Isolation valves are used throughout the low pressure process including ball, gate and triple-offset valves. Pressure management is carried out on all pressure vessels and lines. Control and choke valves are installed on well pads and production. Instrumentation, actuation and controls are installed throughout. In the ideal situation, suppliers and process engineers would work together in the early stages of a project.

Function analysis of steam isolation valves

International Nuclear Information System (INIS)

Persson, R.; Sjoeberg, A.; Aakesson, H.; Kilpi, K.; Noro, H.; Siikonen, T.; Wallen, G.

1981-01-01

Function analysis of system-medium-operated steam isolation valves has been the objective of the Swedish-Finnish IVLS project, the results of which are presented in this report. Theoretical models were to be verified against available experimental data, to some extent from the HDR blowdown experiments, which are part of a German reactor safety program. Finnish hydraulic measurements on a valve model (scale 1:2.15) have been performed to give complementary data. The analysis work has covered the thermal-hydraulic behaviour of steam isolation valves as well as phenomena related to structural mechanics. (Auth.)

Right miniparasternotomy may be a good minimally invasive alternative to full sternotomy for cardiac valve operations: a propensity-adjusted analysis.

Science.gov (United States)

Chiu, Kuan M; Chen, Robert J; Lin, Tzu Y; Chen, Jer S; Huang, Jin H; Huang, Chun Y; Chu, Shu H

2016-02-01

Limited real-world data existed for mini-parasternotomy approach with good sample size in Asian cohorts and most previous studies were eclipsed by case heterogeneity. The goal of this study was to compare safety and quality outcomes of cardiac non-coronary valve operations by mini-parasternotomy and full sternotomy approaches on risk-adjusted basis. METHODS From our hospital database, we retrieved the cases of non-coronary valve operations from 1 January 2005 to 31 December 2012, including re-do, emergent, and combined procedures. Estimated EuroScore-II and propensity score for choosing mini-parasternotomy were adjusted for in the regression models on hospital mortality, complications (pneumonia, stroke, sepsis, etc.), and quality parameters (length of stay, ICU time, ventilator time, etc.). Non-complicated cases, defined as survival to discharge, ventilator use not over one week, and intensive care unit stay not over two weeks, were used for quality parameters. There were 283 mini-parasternotomy and 177 full sternotomy cases. EuroScore-II differed significantly (medians 2.1 vs. 4.7, P<0.001). Propensity scores for choosing mini-parasternotomy were higher with lower EuroScore-II (OR=0.91 per 1%, P<0.001), aortic regurgitation (OR=2.3, P=0.005), and aortic non-mitral valve disease (OR=3.9, P<0.001). Adjusted for propensity score and EuroScore-II, mini-parasternotomy group had less pneumonia (OR=0.32, P=0.043), less sepsis (OR=0.31, P=0.045), and shorter non-complicated length of stay (coefficient=-7.2 (day), P<0.001) than full sternotomy group, whereas Kaplan-Meier survival, non-complicated ICU time, non-complicated ventilator time, and 30-day mortality did not differ significantly. The propensity-adjusted analysis demonstrated encouraging safety and quality outcomes for mini-parasternotomy valve operation in carefully selected patients.

Aortic valve function after bicuspidization of the unicuspid aortic valve.

Science.gov (United States)

Aicher, Diana; Bewarder, Moritz; Kindermann, Michael; Abdul-Khalique, Hashim; Schäfers, Hans-Joachim

2013-05-01

Unicuspid aortic valve (UAV) anatomy leads to dysfunction of the valve in young individuals. We introduced a reconstructive technique of bicuspidizing the UAV. Initially we copied the typical asymmetry of a normal bicuspid aortic valve (BAV) (I), later we created a symmetric BAV (II). This study compared the hemodynamic function of the two designs of a bicuspidized UAV. Aortic valve function was studied at rest and during exercise in 28 patients after repair of UAV (group I, n = 8; group II, n = 20). There were no differences among the groups I and II with respect to gender, age, body size, or weight. All patients were in New York Heart Association class I. Six healthy adults served as control individuals. All patients were studied with transthoracic echocardiography between 4 and 65 months postoperatively. Systolic gradients were assessed by continuous wave Doppler while patients were at rest and exercising on a bicycle ergometer. Aortic regurgitation was grade I or less in all patients. Resting gradients were significantly elevated in group I compared with group II and control individuals (group I, peak 33.8 ± 7.8 mm Hg; mean 19.1 ± 5.4 mm Hg; group II, peak 15.8 ± 5.4, mean 8.2 ± 2.8 mm Hg; control individuals, peak 6.0 ± 1.6, mean 3.2 ± 0.8 mm Hg; p competence. A symmetric repair design leads to improved systolic aortic valve function at rest and during exercise. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Study on a self diagnostic monitoring system for an air-operated valve: development of a fault library

International Nuclear Information System (INIS)

Chai, Jang Bom; Kim, Yun Chul; Kim, Woo Shik; Cho, Hang Duke

2004-01-01

In the interest of nuclear power plant safety, a Self-Diagnostic Monitoring System (SDMS) is needed to monitor defects in safety-related components. An Air-Operated Valve (AOV) is one of the components to be monitored since the failure of its operation could potentially have catastrophic consequences. In this paper, a model of the AOV is developed with the parameters that affect the operational characteristics. The model is useful for both understanding the operation and correlating parameters and defects. Various defects are introduced in the experiments to construct a fault library, which will be used in a pattern recognition approach. Finally, the validity of the fault library is examined

Reliability analysis of a hydraulic on/off fast switching valve

DEFF Research Database (Denmark)

Bender, Niels Christian; Pedersen, Henrik Clemmensen; Plöckinger, Andreas

2017-01-01

allowed internal leakage across the valve seat (0.0005 and 0.5 L/min). The study shows that the probability of a low leakage failure is close to 100% before 5 years of operation and 10% risk of high leakage failure after 25 years of operation. Valve seat failure is therefore a potential threat to limit....... Specifically, the mechanical topology of Fast Switching hydraulic Valves (FSVs) are of interest since these undergo operating cycles in the gigacycle regime in theirs functional lifetime. Application of these FSVs is relevant in e.g. digital displacement units, which for the specific design considered...

Hydraulic High Pressure Valve Controller Using the In-Situ Pressure Difference

Science.gov (United States)

Bao, Xiaoqi (Inventor); Sherrit, Stewart (Inventor); Badescu, Mircea (Inventor); Bar-Cohen, Yoseph (Inventor); Hall, Jeffery L. (Inventor)

2016-01-01

A hydraulic valve controller that uses an existing pressure differential as some or all of the power source for valve operation. In a high pressure environment, such as downhole in an oil or gas well, the pressure differential between the inside of a pipe and the outside of the pipe may be adequately large to drive a linear slide valve. The valve is operated hydraulically by a piston in a bore. When a higher pressure is applied to one end of the bore and a lower pressure to the other end, the piston moves in response to the pressure differential and drives a valve attached to it. If the pressure differential is too small to drive the piston at a sufficiently high speed, a pump is provided to generate a larger pressure differential to be applied. The apparatus is conveniently constructed using multiport valves, which can be rotary valves.

Dysfunction of an On-X Heart Valve by Pannus.

Science.gov (United States)

Abad, Cipriano; Urso, Stefano; Gomez, Elsa; De la Vega, Maria

2016-09-01

A 68-year-old woman with a history of previous double-valve replacement with On-X mechanical heart valves presented with clinical, echocardiographic and cardiac catheterization signs of obstruction of the On-X tricuspid heart valve prosthesis. The patient was successfully reoperated, but at surgery the valve was seen to be invaded by an abnormal overgrowth of pannus that blocked one of the leaflets. A small amount of non-obstructive fresh thrombus was also observed. The valve was successfully replaced with a biological heart valve prosthesis. The patient was discharged home, and is doing well four months after the operation, when echocardiography demonstrated normal function in the tricuspid valve. The present case represents the first ever report of pannus formation and subsequent dysfunction in an On-X heart valve, and also the first case of tricuspid valve malfunction and obstruction using this type of heart valve substitute.

An improved gate valve for critical applications in nuclear power plants

International Nuclear Information System (INIS)

Kalsi, M.S.; Alvarez, P.D.; Wang, J.K.; Somagyi, D.

1996-01-01

U.S. Nuclear Regulatory Commission Generic Letters 89-10 for motor-operated valves (MOVs) and 95-07 for all power-operated valves document in detail the problems related to the performance of the safety-related valves in nuclear power plants. The problems relate to lack of reliable operation under design basis conditions including higher than anticipated stem thrust, unpredictable valve behavior, damage to the valve internals under blowdown/high flow conditions, significant degradation of performance when cycled under AP and flow, thermal binding, and pressure locking. This paper describes an improved motor-operated flexible wedge gate valve design, the GE Sentinel Valve, which is the outcome of a comprehensive and systematic development effort undertaken to resolve the issues identified in the NRC Generic Letters 89-10 and 95-07. The new design provides a reliable, long-term, low maintenance cost solution to the nuclear power industry. One of the key features incorporated in the disc permits the disc flexibility to be varied independently of the disc thickness (pressure boundary) dictated by the ASME Section III Pressure Vessel ampersand Piping Code stress criteria. This feature allows the desired flexibility to be incorporated in the disc, thus eliminating thermal binding problems. A matrix of analyses was performed using finite element and computational fluid dynamics approaches to optimize design for stresses, flexibility, leak-tightness, fluid flow, and thermal effects. The design of the entire product line was based upon a consistent set of analyses and design rules which permit scaling to different valve sizes and pressure classes within the product line. The valve meets all of the ASME Section III Code design criteria and the N-Stamp requirements. The performance of the valve was validated by performing extensive separate effects and plant in-situ tests. This paper summarizes the key design features, analyses, and test results

An improved gate valve for critical applications in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Kalsi, M.S.; Alvarez, P.D.; Wang, J.K.; Somagyi, D. [Kalsi Engineering, Inc., Sugar Land, TX (United States)] [and others

1996-12-01

U.S. Nuclear Regulatory Commission Generic Letters 89-10 for motor-operated valves (MOVs) and 95-07 for all power-operated valves document in detail the problems related to the performance of the safety-related valves in nuclear power plants. The problems relate to lack of reliable operation under design basis conditions including higher than anticipated stem thrust, unpredictable valve behavior, damage to the valve internals under blowdown/high flow conditions, significant degradation of performance when cycled under AP and flow, thermal binding, and pressure locking. This paper describes an improved motor-operated flexible wedge gate valve design, the GE Sentinel Valve, which is the outcome of a comprehensive and systematic development effort undertaken to resolve the issues identified in the NRC Generic Letters 89-10 and 95-07. The new design provides a reliable, long-term, low maintenance cost solution to the nuclear power industry. One of the key features incorporated in the disc permits the disc flexibility to be varied independently of the disc thickness (pressure boundary) dictated by the ASME Section III Pressure Vessel & Piping Code stress criteria. This feature allows the desired flexibility to be incorporated in the disc, thus eliminating thermal binding problems. A matrix of analyses was performed using finite element and computational fluid dynamics approaches to optimize design for stresses, flexibility, leak-tightness, fluid flow, and thermal effects. The design of the entire product line was based upon a consistent set of analyses and design rules which permit scaling to different valve sizes and pressure classes within the product line. The valve meets all of the ASME Section III Code design criteria and the N-Stamp requirements. The performance of the valve was validated by performing extensive separate effects and plant in-situ tests. This paper summarizes the key design features, analyses, and test results.

An application of the valve-leak monitoring system to the valves for the improved Korean standard nuclear power plant (KSNP+)

International Nuclear Information System (INIS)

Byeong-yeol AHN; Dae-sik CHOI; Sang-kook CHUNG

2006-01-01

The loss of steam due to valve leakage leads to the inefficiency of power generation at the nuclear power plants. Under the normal conditions of plant operation, it is difficult to detect valve leaks early enough to prevent consequential damages and losses. The capability of timely detection allows the plant adequate time to prepare repair plans, which would ultimately result in efficient power production. Therefore, timing of detection is one of the most important factors in dealing with valve leakage problems. The VLMS has been developed to meet such an industrial demand. It provides early detection of valve leakage by real-time monitoring through the acoustic sensors installed on the inlet and the outlet of the valve. The KSNP+ utilizes the VLMS to enhance the performance and maintenance of major valves at plants. The VLMS will enable the plant to detect the leakage of valve at an early stage. It can reduce the steam losses and save related valve maintenance cost by performing fast diagnosis of valve leakage. (authors)

Aortic Regurgitation in Patients Undergoing Transcatheter Aortic Valve Replacement With the Self-Expanding CoreValve Versus the Balloon-Expandable SAPIEN XT Valve.

Science.gov (United States)

Kiramijyan, Sarkis; Magalhaes, Marco A; Koifman, Edward; Didier, Romain; Escarcega, Ricardo O; Baker, Nevin C; Negi, Smita I; Minha, Sa'ar; Torguson, Rebecca; Jiaxiang, Gai; Asch, Federico M; Wang, Zuyue; Okubagzi, Petros; Gaglia, Michael A; Ben-Dor, Itsik; Satler, Lowell F; Pichard, Augusto D; Waksman, Ron

2016-05-01

The incidence of aortic regurgitation (AR) after transcatheter aortic valve replacement (TAVR) in a self-expanding and a balloon-expandable system is controversial. This study aimed to examine the incidence and severity of post-TAVR AR with the CoreValve (CV) versus the Edwards XT Valve (XT). Baseline, procedural, and postprocedural inhospital outcomes were compared. The primary end point was the incidence of post-TAVR AR of any severity, assessed with a transthoracic echocardiogram, in the CV versus XT groups. A multivariate logistic regression analysis was completed to evaluate for correlates of the primary end point. The secondary end points included the change in severity of AR at 30-day and 1-year follow-up. A total of 223 consecutive patients (53% men, mean age 82 years) who had transfemoral TAVR with either a CV (n = 119) or XT (n = 104) were evaluated. The rates of post-TAVR AR in the groups were similar, and there was no evidence of more-than-moderate AR in either group. There were significant differences in the rates of intraprocedural balloon postdilation with the CV (17.1%) versus XT valve (5.8%; p = 0.009) and in the rates of intraprocedural implantation of a second valve-in-valve prosthesis with the CV (9.9%) versus XT valve (2.2%; p = 0.036). There were no significant differences in inhospital safety outcomes between the 2 groups. In conclusion, the incidence of post-TAVR AR is similar between the CV and the XT valve when performed by experienced operators using optimal intraprocedural strategies, as deemed appropriate, to mitigate the severity of AR. Copyright © 2016 Elsevier Inc. All rights reserved.

Tricuspid valve endocarditis

Science.gov (United States)

Hussain, Syed T.; Witten, James; Shrestha, Nabin K.; Blackstone, Eugene H.

2017-01-01

Right-sided infective endocarditis (RSIE) is less common than left-sided infective endocarditis (IE), encompassing only 5–10% of cases of IE. Ninety percent of RSIE involves the tricuspid valve (TV). Given the relatively small numbers of TVIE cases operated on at most institutions, the purpose of this review is to highlight and discuss the current understanding of IE involving the TV. RSIE and TVIE are strongly associated with intravenous drug use (IVDU), although pacemaker leads, defibrillator leads and vascular access for dialysis are also major risk factors. Staphylococcus aureus is the predominant causative organism in TVIE. Most patients with TVIE are successfully treated with antibiotics, however, 5–16% of RSIE cases eventually require surgical intervention. Indications and timing for surgery are less clear than for left-sided IE; surgery is primarily considered for failed medical therapy, large vegetations and septic pulmonary embolism, and less often for TV regurgitation and heart failure. Most patients with an infected prosthetic TV will require surgery. Concomitant left-sided IE has its own surgical indications. Earlier surgical intervention may potentially prevent further destruction of leaflet tissue and increase the likelihood of TV repair. Fortunately, TV debridement and repair can be accomplished in most cases, even those with extensive valve destruction, using a variety of techniques. Valve repair is advocated over replacement, particularly in IVDUs patients who are young, non-compliant and have a higher risk of recurrent infection and reoperation with valve replacement. Excising the valve without replacing, it is not advocated; it has been reported previously, but these patients are likely to be symptomatic, particularly in cases with septic pulmonary embolism and increased pulmonary vascular resistance. Patients with concomitant left-sided involvement have worse prognosis than those with RSIE alone, due predominantly to greater likelihood of

46 CFR 78.47-38 - Valves and closing appliances.

Science.gov (United States)

2010-10-01

... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.47-38 Section 78.47-38... Fire and Emergency Equipment, Etc. § 78.47-38 Valves and closing appliances. (a) All valves and closing appliances, or other mechanisms which may be required to be operated for damage control purposes in case of...

Classification of heart valve condition using acoustic measurements

Energy Technology Data Exchange (ETDEWEB)

Clark, G. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

Prosthetic heart valves and the many great strides in valve design have been responsible for extending the life spans of many people with serious heart conditions. Even though the prosthetic valves are extremely reliable, they are eventually susceptible to long-term fatigue and structural failure effects expected from mechanical devices operating over long periods of time. The purpose of our work is to classify the condition of in vivo Bjork-Shiley Convexo-Concave (BSCC) heart valves by processing acoustic measurements of heart valve sounds. The structural failures of interest for Bscc valves is called single leg separation (SLS). SLS can occur if the outlet strut cracks and separates from the main structure of the valve. We measure acoustic opening and closing sounds (waveforms) using high sensitivity contact microphones on the patient`s thorax. For our analysis, we focus our processing and classification efforts on the opening sounds because they yield direct information about outlet strut condition with minimal distortion caused by energy radiated from the valve disc.

Experimental Investigation of a Multi-Cycle Single-Tube Pulse Detonation Rocket Engine with a Coaxial Rotary Valve

Science.gov (United States)

Matsuoka, Ken; Esumi, Motoki; Ikeguchi, Ken Bryan; Kasahara, Jiro; Matsuo, Akiko; Funaki, Ikkoh

We developed a novel coaxial rotary valve for a multi-tube PDE. Since this single valve can supply three different gases (fuel, oxidizer and purge gas) into a combustor, the unification of the valve systems for three different gases is possible by using our newly designed valve. A PDRE system can be simple and lightweight by using this valve, and thus its thrust-weight ratio can be increased. We proposed the design of a multi-tube rotary-valved PDRE system by this rotary valve. Moreover, in preparation for a multi-tube rotary-valved PDRE, we carried out the multi-cycle operation experiment by the single-tube rotary-valved PDRE system. The combustion wave velocity was measured to confirm the operation of the PDRE system. Deflagration-to-detonation transition (DDT) was confirmed and DDT distance decreased under the condition of high operation frequency. In addition, a maximum operation frequency was 159 Hz.

Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

Science.gov (United States)

Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

2017-10-13

Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

Valve-sparing and valve-replacing techniques for aortic root replacement in patients with Marfan syndrome: Analysis of early outcome.

Science.gov (United States)

Volguina, Irina V; Miller, D Craig; LeMaire, Scott A; Palmero, Laura C; Wang, Xing Li; Connolly, Heidi M; Sundt, Thoralf M; Bavaria, Joseph E; Dietz, Harry C; Milewicz, Dianna M; Coselli, Joseph S

2009-05-01

A prospective, international registry study was initiated to provide contemporary comparative data on short-term clinical outcomes after aortic valve-sparing and aortic valve-replacing root operations in patients with Marfan syndrome. The purpose of this initial report is to describe the study design and to compare early outcomes in the first 151 enrolled patients. We assessed 30-day outcomes in 151 patients who met strict Ghent diagnostic criteria for Marfan syndrome and underwent aortic root replacement with either valve-replacing (n = 46) or valve-sparing techniques (n = 105) at one of 18 participating centers. In the valve replacement group, a mechanical composite valve graft was used in 39 (85%) patients and a bioprosthetic valve in 7 (15%). In the valve-sparing group, David V procedures were performed in 57 (54%) patients, David I in 38 (36%), David IV in 8 (8%), Florida sleeve in 1 (1%), and Yacoub remodeling in 1 (1%). No in-hospital or 30-day deaths occurred. Despite longer crossclamp and cardiopulmonary bypass times in the valve-sparing group, there were no significant between-group differences in postoperative complications. Thirty-day valve-related complications occurred in 2 (4%) patients undergoing valve replacement and in 3 (3%) undergoing valve-sparing procedures (P = .6). The analysis of early outcomes revealed that valve-sparing techniques were the most common approach to root replacement in patients with Marfan syndrome in these centers. The complexity of valve-sparing root replacement did not translate into any demonstrable adverse early outcomes. Subsequent analysis will compare the 3-year durability of these two surgical approaches.

Transcatheter Replacement of Failed Bioprosthetic Valves

DEFF Research Database (Denmark)

Simonato, Matheus; Webb, John; Kornowski, Ran

2016-01-01

postprocedural gradients (mean >= 20 mm Hg). Optimal implantation depths were defined by receiver operating characteristic curve. A total of 292 consecutive patients (age, 78.9 +/- 8.7 years; 60.3% male; 157 CoreValve Evolut and 135 Sapien XT) were evaluated. High implantation was associated with significantly...... lower rates of elevated gradients in comparison with low implantation (CoreValve Evolut, 15% versus 34.2%; P=0.03 and Sapien XT, 18.5% versus 43.5%; P=0.03, respectively). Optimal implantation depths were defined: CoreValve Evolut, 0 to 5 mm; Sapien XT, 0 to 2 mm (0-10% frame height); sensitivities, 91...

Analysis on typical illegal events for nuclear safety class 1 valve

International Nuclear Information System (INIS)

Tian Dongqing; Gao Runsheng; Jiao Dianhui; Yang Lili; Chen Peng

2014-01-01

Illegal welding events of nuclear safety class l valve forging occurred to the manufacturer, while the valve was returned to be repaired. Illegal nondestructive test event of nuclear safety class valve occurred also to the manufacturer in the manufacturing process. The two events have resulted in quality incipient fault for the installed valves and the valves in the manufacturing process. It was reflected that operation of the factory quality assurance system isn't activated, and nuclear power engineering and operating company have insufficient supervision. The event-related parties should strengthen quality management and process control, get rid of the quality incipient fault, and experience feedback should be done well to guarantee quality of equipment in nuclear power plant. (authors)

[Minor strut fracture of the Björk-Shiley mitral valve].

Science.gov (United States)

Sugita, T; Yasuda, R; Watarida, S; Onoe, M; Tabata, R; Mori, A

1990-06-01

In May, 1982, a 49-year-old man underwent mitral valve replacement (MVR) in our hospital with a 31 mm Björk-Shiley prosthesis for mitral regurgitation. He had been doing well until his episode of palpitation and dyspnea of sudden onset, and was transferred to our ICU with severe cardiogenic shock in Aug, 1986. Chest X-ray film revealed pulmonary edema and breakage of the valve with migration of the disc and the minor strut of the prosthesis. He was operated upon 5 hours after the onset of his complaints. The minor strut was removed from the left upper pulmonary vein and mitral valve re-replacement was done with a 29 mm Björk-Shiley Monostrut valve. The disc which had dislocated into the abdominal aorta was also recovered on the twenty-third post operative day. His postoperative course was uneventful. Immediate diagnosis and subsequent re-operation is absolute indication for rescue from acute cardiac failure due to mechanical failure of any prosthetic valve.

Aortic valve ochronosis: a rare manifestation of alkaptonuria.

Science.gov (United States)

Steger, Christina Maria

2011-07-28

Alkaptonuric ochronosis is a heritable disorder of tyrosine metabolism, with various systemic abnormalities related to pigment deposition and degeneration of collagen and other tissues, including the heart and aorta. A 65-year-old woman with alkaptonuric ochronosis and a history of four joint replacements required aortic valve replacement for severe aortic stenosis. Operative findings included ochronosis of a partly calcified aortic valve and the aortic intima. The aortic valve was removed at surgery and histologically investigated. Light microscopic examination of the aortic valve revealed intracellular and extracellular deposits of ochronotic pigment and a chronic inflammatory infiltrate. Beside the case representation, the disease history, aetiology, pathogenesis, clinical presentation and treatment of aortic valve ochronosis are reviewed.

Dielectric elastomer actuators used for pneumatic valve technology

International Nuclear Information System (INIS)

Giousouf, Metin; Kovacs, Gabor

2013-01-01

Dielectric elastomer actuators have been investigated for applications in the field of pneumatic automation technology. We have developed different valve designs with stacked dielectric elastomer actuators and with integrated high voltage converters. The actuators were made using VHB-4910 material and a stacker machine for automated fabrication of the cylindrical actuators. Typical characteristics of pneumatic valves such as flow rate, power consumption and dynamic behaviour are presented. For valve construction the force and stroke parameters of the dielectric elastomer actuator have been measured. Further, benefits for valve applications using dielectric elastomers are shown as well as their potential operational area. Finally, challenges are discussed that are relevant for the use of elastomer actuators in valves for industrial applications. (paper)

Impact of valve failures on the safety and reliability of light water nuclear power plants

International Nuclear Information System (INIS)

Riddington, J.W.; Reyer, R.J.

1980-01-01

A study of the causes of, and solutions for, recurrent valve failures has been performed. The frequency and root causes of valve problems were identified from licensee event reports and meetings with utility, NSSS, and valve manufacturer personnel. Three generic problems (stem leakage, seat leakage, and inadequate specification) and four valve specific problems were identified. The four valve specific problems and their principal causes are: (1) BWR pilot operated safety relief valves (pilot valve leakage); (2) spring loaded safety relief valves (water solid and two-phase flow behavior); (3) PWR feedwater regulating valves (trim degradation and packing failures); and (4) air operated solenoid valves (jamming due to foreign matter in service air). The first two valve specific problems are the subject of current industry programs. Programs intended to address stem leakage, seat leakage, timely exchange of valve failure information, testing of valves, and adequate specification, selection, and maintenance of valves will be outlined

Surgery for rheumatic mitral valve disease in sub-saharan African countries: why valve repair is still the best surgical option.

Science.gov (United States)

Mvondo, Charles Mve; Pugliese, Marta; Giamberti, Alessandro; Chelo, David; Kuate, Liliane Mfeukeu; Boombhi, Jerome; Dailor, Ellen Marie

2016-01-01

Rheumatic valve disease, a consequence of acute rheumatic fever, remains endemic in developing countries in the sub-Saharan region where it is the leading cause of heart failure and cardiovascular death, involving predominantly a young population. The involvement of the mitral valve is pathognomonic and mitral surgery has become the lone therapeutic option for the majority of these patients. However, controversies exist on the choice between valve repair or prosthetic valve replacement. Although the advantages of mitral valve repair over prosthetic valve replacement in degenerative mitral disease are well established, this has not been the case for rheumatic lesions, where the use of prosthetic valves, specifically mechanical devices, even in poorly compliant populations remains very common. These patients deserve more accurate evaluation in the choice of the surgical strategy which strongly impacts the post-operative outcomes. This report discusses the factors supporting mitral repair surgery in rheumatic disease, according to the patients' characteristics and the effectiveness of the current repair techniques compared to prosthetic valve replacement in developing countries.

Right mini-parasternotomy may be a good minimally invasive alternative to full sternotomy for cardiac valve operations-a propensity-adjusted analysis.

Science.gov (United States)

Chiu, K M; Chen, R J; Lin, T Y; Chen, J S; Huang, J H; Huang, C Y; Chu, S H

2014-03-26

Limited realworld data existed for miniparasternotomy approach with good sample size in Asian cohorts and most previous studies were eclipsed by case heterogeneity. The goal of this study was to compare safety and quality outcomes of cardiac noncoronary valve operations by miniparasternotomy and full sternotomy approaches on riskadjusted basis. From our hospital database, we retrieved the cases of non-coronary valve operations from 1 January 2005 to 31 December 2012, including re-do, emergent, and combined procedures. Estimated EuroScore-II and propensity score for choosing mini-parasternotomy were adjusted for in the regression models on hospital mortality, complications (pneumonia, stroke, sepsis, etc.), and quality parameters (length of stay, ICU time, ventilator time, etc.). Non-complicated cases, defined as survival to discharge, ventilator use not over one week, and intensive care unit stay not over two weeks, were used for quality parameters. There were 283 miniparasternotomy and 177 full sternotomy cases. EuroScore-II differed significantly (medians 2.1 vs. 4.7, p<0.001). Propensity scores for choosing miniparasternotomy were higher with lower EuroScore-II (OR=0.91 per 1%, p<0.001), aortic regurgitation (OR=2.3, p=0.005), and aortic non-mitral valve disease (OR=3.9, p<0.001). Adjusted for propensity score and EuroScore-II, mini-parasternotomy group had less pneumonia (OR=0.32, p=0.043), less sepsis (OR=0.31, p=0.045), and shorter non-complicated length of stay (coefficient=7.2 (day), p<0.001) than full sternotomy group, whereas Kaplan-Meier survival, non-complicated ICU time, non-complicated ventilator time, and 30-day mortality did not differ significantly. The propensity-adjusted analysis demonstrated encouraging safety and quality outcomes for mini-parasternotomy valve operation in carefully selected patients.

Reactor operating procedures for start up of continuously operated chemical plants

NARCIS (Netherlands)

Verwijs, J.W.; Verwijs, J.W.; Kösters, P.H.; van den Berg, Henderikus; Westerterp, K.R.; Kosters, P.G.H.

1995-01-01

Rules are presented for the startup of an adiabatic tubular reactor, based on a qualitative analysis of the dynamic behavior of continuously-operated vapor- and liquid-phase processes. The relationships between the process dynamics, operating criteria, and operating constraints are investigated,

Check valve

Science.gov (United States)

Upton, H.A.; Garcia, P.

1999-08-24

A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

Check valve

International Nuclear Information System (INIS)

Upton, H.A.; Garcia, P.

1999-01-01

A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs

The safety relief valve handbook design and use of process safety valves to ASME and International codes and standards

CERN Document Server

Hellemans, Marc

2009-01-01

The Safety Valve Handbook is a professional reference for design, process, instrumentation, plant and maintenance engineers who work with fluid flow and transportation systems in the process industries, which covers the chemical, oil and gas, water, paper and pulp, food and bio products and energy sectors. It meets the need of engineers who have responsibilities for specifying, installing, inspecting or maintaining safety valves and flow control systems. It will also be an important reference for process safety and loss prevention engineers, environmental engineers, and plant and process designers who need to understand the operation of safety valves in a wider equipment or plant design context. . No other publication is dedicated to safety valves or to the extensive codes and standards that govern their installation and use. A single source means users save time in searching for specific information about safety valves. . The Safety Valve Handbook contains all of the vital technical and standards informat...

Experimental and Numerical Analysis of a Water Emptying Pipeline Using Different Air Valves

Directory of Open Access Journals (Sweden)

Oscar E. Coronado-Hernández

2017-02-01

Full Text Available The emptying procedure is a common operation that engineers have to face in pipelines. This generates subatmospheric pressure caused by the expansion of air pockets, which can produce the collapse of the system depending on the conditions of the installation. To avoid this problem, engineers have to install air valves in pipelines. However, if air valves are not adequately designed, then the risk in pipelines continues. In this research, a mathematical model is developed to simulate an emptying process in pipelines that can be used for planning this type of operation. The one-dimensional proposed model analyzes the water phase propagation by a new rigid model and the air pockets effect using thermodynamic formulations. The proposed model is validated through measurements of the air pocket absolute pressure, the water velocity and the length of the emptying columns in an experimental facility. Results show that the proposed model can accurately predict the hydraulic characteristic variables.

Early post-operative pulmonary function tests after mitral valve replacement: Minimally invasive versus conventional approach. Which is better?

Directory of Open Access Journals (Sweden)

Magdy Gomaa

2016-12-01

Conclusion: Minimally invasive right anterolateral mini-thoracotomy is as safe as median sternotomy for mitral valve surgery, with fewer complications and postoperative pain, less ICU and hospital stay, fast recovery to work with no movement restriction after surgery. There was a highly significant difference denoting better post operative pulmonary function of the minimally invasive approach.

The use of transcatheter aortic valve replacement vs surgical aortic valve replacement for the treatment of aortic stenosis

Directory of Open Access Journals (Sweden)

Jensen HA

2015-08-01

Full Text Available Hanna A Jensen, Lillian L Tsai, Vinod H Thourani Division of Cardiothoracic Surgery, Joseph B Whitehead Department of Surgery, Structural Heart and Valve Center, Emory University School of Medicine, Atlanta, GA, USA Abstract: Severe aortic stenosis (AS is associated with considerable morbidity and mortality and is increasing in prevalence as the global population increases. Since AS primarily affects the elderly, many of these patients have comorbidities that make them poor candidates for the gold standard treatment for AS, surgical aortic valve replacement. Transcatheter aortic valve replacement has emerged as a novel technology for the management of AS in higher risk patients over the past decade. Randomized trials have established the safety and efficacy of transcatheter aortic valve replacement, and the medical community has rallied to identify the patients who are most suitable for this transformative treatment. This review focuses on outlining the key procedural differences, describing the unique challenges of both operations, and finally assessing and comparing outcomes both on a general level and in challenging patient subgroups. Keywords: aortic valve replacement, transcatheter aortic valve replacement, surgical aortic valve replacement 

Expert system for fault diagnosis in process control valves using fuzzy-logic

Energy Technology Data Exchange (ETDEWEB)

Carneiro, Alvaro L.G., E-mail: carneiro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Porto Junior, Almir C.S., E-mail: almir@ctmsp.mar.mil.br [Centro Tecnologico da Marinha em Sao Paulo (CIANA/CTMSP), Ipero, SP (Brazil). Centro de Instrucao e Adestramento Nuclear de ARAMAR

2013-07-01

The models of asset maintenance of a process plant basically are classified in corrective maintenance, preventive, predictive and proactive (online). The corrective maintenance is the elementary and most obvious way of the maintenance models. The preventive maintenance consists in a fault prevention work, based on statistical studies that can lead to low efficiency or even an unexpected shutdown of the plant. Predictive maintenance aims to prevent equipment or systems failures through monitoring and tracking of parameters, allowing continuous operation as long as possible. The proactive maintenance usually includes predictive maintenance, emphasizing the root cause analysis of the failure. The maintenance predictive/proactive planning frequently uses software that integrates data from different systems, which facilitates a quick and effective decision- making. In nuclear plants this model has an important role regarding the reliability of equipment and systems. The main focus of this work is to study the development of a model of non-intrusive monitoring and diagnosis applied to process control valves using artificial intelligence by fuzzy logic technique, contributing in the development of predictive methodologies identifying faults in incipient state. The control valve analyzed belongs to a steam plant which simulates the secondary circuit of a PWR nuclear reactor - Pressurized Water Reactor. This study makes use of MATLAB language through the fuzzy logic toolbox which uses the method of inference Mamdani, acting by fuzzy conjunction, through Triangular Norms (t-norm) and Triangular Conorms (t-conorm). As input variables are used air pressure and displacement of the valve stem. Input data coming into the fuzzy system by graph of the automation system Delta V ® available in the plant, which receives a signal of electric current from an 'intelligent' positioned installed on the valve. The output variable is the 'status' of the valve. Through a

Expert system for fault diagnosis in process control valves using fuzzy-logic

International Nuclear Information System (INIS)

Carneiro, Alvaro L.G.; Porto Junior, Almir C.S.

2013-01-01

The models of asset maintenance of a process plant basically are classified in corrective maintenance, preventive, predictive and proactive (online). The corrective maintenance is the elementary and most obvious way of the maintenance models. The preventive maintenance consists in a fault prevention work, based on statistical studies that can lead to low efficiency or even an unexpected shutdown of the plant. Predictive maintenance aims to prevent equipment or systems failures through monitoring and tracking of parameters, allowing continuous operation as long as possible. The proactive maintenance usually includes predictive maintenance, emphasizing the root cause analysis of the failure. The maintenance predictive/proactive planning frequently uses software that integrates data from different systems, which facilitates a quick and effective decision- making. In nuclear plants this model has an important role regarding the reliability of equipment and systems. The main focus of this work is to study the development of a model of non-intrusive monitoring and diagnosis applied to process control valves using artificial intelligence by fuzzy logic technique, contributing in the development of predictive methodologies identifying faults in incipient state. The control valve analyzed belongs to a steam plant which simulates the secondary circuit of a PWR nuclear reactor - Pressurized Water Reactor. This study makes use of MATLAB language through the fuzzy logic toolbox which uses the method of inference Mamdani, acting by fuzzy conjunction, through Triangular Norms (t-norm) and Triangular Conorms (t-conorm). As input variables are used air pressure and displacement of the valve stem. Input data coming into the fuzzy system by graph of the automation system Delta V ® available in the plant, which receives a signal of electric current from an 'intelligent' positioned installed on the valve. The output variable is the 'status' of the valve. Through a rule base

Test Rig for Valves of Digital Displacement Machines

DEFF Research Database (Denmark)

Nørgård, Christian; Christensen, Jeppe Haals; Bech, Michael Møller

2017-01-01

A test rig for the valves of digital displacement machines has been developed at Aalborg University. It is composed of a commercial radial piston machine, which has been modified to facilitate Digital Displacement operation for a single piston. Prototype valves have been optimized, designed and m...

Design Method for Fast Switching Seat Valves for Digital Displacement Machines

DEFF Research Database (Denmark)

Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.

2014-01-01

corresponding to the piston movement, which has been shown to facilitate superior part load efficiency combined with high bandwidth compared to traditional displacement machines. However, DD machines need fast switching on-off valves with low pressure loss for efficient operation, especially in fast rotating......Digital Displacement (DD) machines are upcoming technology where the displacement of each pressure chamber is controlled electronically by use of two fast switching seat valves. The effective displacement and operation type (pumping/motoring) may be controlled by manipulating the seat valves...... method for DD seat valves are presented, taking into account the significant aspects related to obtaining efficient DD valves with basis in a given DD machine specifications. The seat area is minimized and the stroke length is minimized to obtain fast switching times while considering the pressure loss...

Infective endocarditis following transcatheter aortic valve replacement-

DEFF Research Database (Denmark)

Loh, Poay Huan; Bundgaard, Henning; S�ndergaard, Lars

2013-01-01

Transcatheter aortic valve replacement (TAVR) can improve the symptoms and prognosis of patients with severe aortic stenosis who, due to a high expected operative risk, would not have otherwise been treated surgically. If these patients develop prosthetic valve endocarditis, their presentations may...... be atypical causing a delay in the diagnosis and treatment. The management is also complicated by their comorbidities, and surgical treatment may not be feasible leading to a significant morbidity and mortality. We describe a case of an 85-year-old man with TAVI prosthetic valve endocarditis successfully...

Development of a stainless steel check valve for cryogenic applications

NARCIS (Netherlands)

Veenstra, T.T.; Venhorst, G.C.F.; Venhorst, G.C.F.; Burger, Johannes Faas; Holland, Herman J.; ter Brake, Hermanus J.M.; Sirbi, A.; Rogalla, Horst

2007-01-01

This paper describes the development of a check valve for use in a sorption compressor that will drive a 10 mW 4.5 K Joule–Thomson cryocooler. For the check valve extremely low backflow rates are tolerable at an operating temperature of the valve of 50 K. To fulfill these requirements, the sealing

Butterfly valve torque prediction methodology

International Nuclear Information System (INIS)

Eldiwany, B.H.; Sharma, V.; Kalsi, M.S.; Wolfe, K.

1994-01-01

As part of the Motor-Operated Valve (MOV) Performance Prediction Program, the Electric Power Research Institute has sponsored the development of methodologies for predicting thrust and torque requirements of gate, globe, and butterfly MOVs. This paper presents the methodology that will be used by utilities to calculate the dynamic torque requirements for butterfly valves. The total dynamic torque at any disc position is the sum of the hydrodynamic torque, bearing torque (which is induced by the hydrodynamic force), as well as other small torque components (such as packing torque). The hydrodynamic torque on the valve disc, caused by the fluid flow through the valve, depends on the disc angle, flow velocity, upstream flow disturbances, disc shape, and the disc aspect ratio. The butterfly valve model provides sets of nondimensional flow and torque coefficients that can be used to predict flow rate and hydrodynamic torque throughout the disc stroke and to calculate the required actuation torque and the maximum transmitted torque throughout the opening and closing stroke. The scope of the model includes symmetric and nonsymmetric discs of different shapes and aspects ratios in compressible and incompressible fluid applications under both choked and nonchoked flow conditions. The model features were validated against test data from a comprehensive flowloop and in situ test program. These tests were designed to systematically address the effect of the following parameters on the required torque: valve size, disc shapes and disc aspect ratios, upstream elbow orientation and its proximity, and flow conditions. The applicability of the nondimensional coefficients to valves of different sizes was validated by performing tests on 42-in. valve and a precisely scaled 6-in. model. The butterfly valve model torque predictions were found to bound test data from the flow-loop and in situ testing, as shown in the examples provided in this paper

A study on the force balance of an unbalanced globe valve

International Nuclear Information System (INIS)

Yang, Sang Min; Cho, Taik Dong; Ko, Sung Ho; Lee, Ho Young

2007-01-01

A pneumatic control valve is a piping element that controls the volumetric flow rate and pressure of a fluid: it is necessary to analyze the characteristics of the forces with respect to the opening of the valve in order to evaluate its operating performance. The forces occurring during operation are: resisting force and actuator force, where the load resistance is mostly affected by the fluid pressure difference of the valve. In this study, a force balance equation derived from the equilibrium relationship between the resisting force and the actuator force of an unbalanced globe valve is proposed, and the force balance equations are used to model the dynamic equations of a pneumatic unbalanced globe valve installed in nuclear power plants. A CFD analysis is also carried out to evaluate the pressure distribution and forces acting on the top and bottom planes of the valve plug. The results of this analysis have been verified through experimentation. This study has shown that the fluid pressure difference between the inlet and outlet of the valve, measured from the force balance equation of an unbalanced valve, should actually be examined with the fluid-pressure difference between the top and bottom side of the valve plug

Numerical Research on Flow Characteristics around a Hydraulic Turbine Runner at Small Opening of Cylindrical Valve

Directory of Open Access Journals (Sweden)

Zhenwei Mo

2016-01-01

Full Text Available We use the continuity equation and the Reynolds averaged Navier-Stokes equations to study the flow-pattern characteristics around a turbine runner for the small-opening cylindrical valve of a hydraulic turbine. For closure, we adopt the renormalization-group k-ε two-equation turbulence model and use the computational fluid dynamics (CFD software FLUENT to numerically simulate the three-dimensional unsteady turbulent flow through the entire passage of the hydraulic turbine. The results show that a low-pressure zone develops around the runner blades when the cylindrical valve is closed in a small opening; cavitation occurs at the blades, and a vortex appears at the outlet of the runner. As the cylindrical valve is gradually closed, the flow velocity over the runner area increases, and the pressure gradient becomes more significant as the discharge decreases. In addition, the fluid flow velocity is relatively high between the lower end of the cylindrical valve and the base, so that a high-velocity jet is easily induced. The calculation and analysis provide a theoretical basis for improving the performance of cylindrical-valve operating systems.

Function analysis of steam isolation valves

International Nuclear Information System (INIS)

Persson, R.; Kilpi, K.; Noro, H.; Siikonen, T.; Sjoeberg, A.; Wallen, G.; Aakesson, H.

1981-01-01

Function analysis of system-medium-operated steam isolation valves has been the objective of the Swedish-Finnish IVLS project, the results of which are presented in this report. Theoretical models were to be verified against available experimental data, to some extent from the HDR blowdown experiments, which are part of a German reactor safety program. Finnish hydraulic measurements on a valve model (scale 1:2.15) have been performed to give complementary data. The analysis work has covered the thermal-hydraulic behaviour of steam isolation valves as well as phenomena related to structural mechanics. Work performed under contract with the Swedish Nuclear Power Inspectorate. (Author)

Development of Overflow-Prevention Valve with Trigger Mechanism.

Science.gov (United States)

Ishino, Yuji; Mizuno, Takeshi; Takasaki, Masaya

2016-09-01

A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore, the valve must be constructed only by mechanical parts. The conventional overflow-prevention valve uses fluid and pneumatic forces. It consists of a sensor probe, a cylinder, a main valve for shutting off the fluid and a locking mechanism for holding an open state of the main valve. The proposed overflow-prevention valve uses the pressure due to the height difference between the fluid level of the tank and the sensor probe. However, the force of the cylinder produced by the pressure is too small to release the locking mechanism. Therefore, a trigger mechanism is introduced between the cylinder and the locking mechanism. The trigger mechanism produces sufficient force to release the locking mechanism and close the main valve when the height of fluid exceeds a threshold value. A trigger mechanism is designed and fabricated. The operation necessary for closing the main valve is conformed experimentally.

European supply chain for valve springs

Energy Technology Data Exchange (ETDEWEB)

Barthold, G. [Scherdel GmbH, Marktredwitz (Germany); Thureborn, D.; Hallberg, M. [Haldex Garphyttan AB (Sweden); Janssen, P. [Mittal Steel Ruhrort GmbH / Mittal Steel Hochfeld GmbH (Germany)

2005-07-01

Forced by the Kobe earthquake in 1995 and the lack of valve spring steel on the world market due to damages of the Kobe steel plant, the development of a European supply chain has been sped up. End of 1994 a super clean valve spring steel with a reasonable quality from a European source was available. A strong relationship between the steel producer (Mittal), the wire manufacturer (Haldex Garphyttan) and the spring maker (Scherdel) was established. A working group of the three companies holds meetings on a regular basis to discuss quality and development issues. Over the last years the supply chain has achieved significant improvements in terms of cleanliness and decarburisation of the wire rod. The continuous common advancement of the valve spring quality has enabled the valve spring failures in the field to be reduced to < 0.1 ppm. The development and market launch of new grades has been prepared. (orig.)

Design and simulation of the operation of a rotary valve for a portable prototype of a 99mTc generator

International Nuclear Information System (INIS)

Gago, Javier; Baltuano, Oscar; Hernandez, Yuri; Montoya, Eduardo; Lopez, Yon

2013-01-01

The design of a specific purpose rotary valve for a 99m Tc generator by extraction, which is being developed at IPEN, in order to contribute to the decentralization of nuclear medicine with social inclusion, is described and discussed in this paper. The prototype is reliable, low cost, and consists of a set of three three-way rotating valves with two positions, in a single device of Teflon®, which is driven by a servomotor. Structural analysis is reported considering external loads applied to the prototype, plus simulation and testing operation using a 12 volts servomotor of 16 RPM provided of a CNY70 infrared sensor, for control purposes. (authors).

Methodological inaccuracies in clinical aortic valve severity assessment: insights from computational fluid dynamic modeling of CT-derived aortic valve anatomy

Science.gov (United States)

Traeger, Brad; Srivatsa, Sanjay S.; Beussman, Kevin M.; Wang, Yechun; Suzen, Yildirim B.; Rybicki, Frank J.; Mazur, Wojciech; Miszalski-Jamka, Tomasz

2016-04-01

Aortic stenosis is the most common valvular heart disease. Assessing the contribution of the valve as a portion to total ventricular load is essential for the aging population. A CT scan for one patient was used to create one in vivo tricuspid aortic valve geometry and assessed with computational fluid dynamics (CFD). CFD simulated the pressure, velocity, and flow rate, which were used to assess the Gorlin formula and continuity equation, current clinical diagnostic standards. The results demonstrate an underestimation of the anatomic orifice area (AOA) by Gorlin formula and overestimation of AOA by the continuity equation, using peak velocities, as would be measured clinically by Doppler echocardiography. As a result, we suggest that the Gorlin formula is unable to achieve the intended estimation of AOA and largely underestimates AOA at the critical low-flow states present in heart failure. The disparity in the use of echocardiography with the continuity equation is due to the variation in velocity profile between the outflow tract and the valve orifice. Comparison of time-averaged orifice areas by Gorlin and continuity with instantaneous orifice areas by planimetry can mask the errors of these methods, which is a result of the assumption that the blood flow is inviscid.

[Valve-sparing Replacement in Patients with Aortic Root Dilatation].

Science.gov (United States)

Yamazaki, Kazuhiro; Minatoya, Kenji; Ueda, Ryoma; Takehara, Masato; Sakamoto, Kazuhisa; Ide, Yujiro; Kanemitsu, Hideo; Ueyama, Koji; Ikeda, Tadashi

2018-01-01

Valve-sparing root replacement is increasingly used to overcome drawbacks associated with valvular prostheses. In our institution, 7 patients underwent valve-sparing root replacement from August 2016 to July 2017. The mean age was 45 years (range, 14~69 years). Three patients had Marfan syndrome and 1 had Loeys-Dietz syndrome with acute aortic dissection. All patients underwent surgery with reimplantation technique using a Valsalva graft. Two patients required repair of aortic valve leaflet prolapse. All patients had an excellent clinical course, with mild or no aortic regurgitation and a decrease in end-diastolic volume on echocardiography. These results support the continued use of valve-sparing root replacement in selected patients.

Surgical treatment of aortic valve endocarditis: a 26-year experience

Directory of Open Access Journals (Sweden)

Taylan Adademir

2014-03-01

Full Text Available Objective: We have retrospectively analyzed the results of the operations made for aortic valve endocarditis in a single center in 26 years. Methods: From June 1985 to January 2011, 174 patients were operated for aortic valve endocarditis. One hundred and thirty-eight (79.3% patients were male and the mean age was 39.3±14.4 (9-77 years. Twenty-seven (15.5% patients had prosthetic valve endocarditis. The mean duration of follow-up was 7.3±4.2 years (0.1-18.2 adding up to a total of 1030.8 patient/years. Results: Two hundred and eighty-two procedures were performed. The most frequently performed procedure was aortic valve replacement with mechanical prosthesis (81.6%. In-hospital mortality occurred in 27 (15.5% cases. Postoperatively, 25 (14.4% patients had low cardiac output and 17 (9.8% heart block. The actuarial survival rates for 10 and 15 years were 74.6±3.7% and 61.1±10.3%, respectively. In-hospital mortality was found to be associated with female gender, emergency operation, postoperative renal failure and low cardiac output. The long term mortality was significantly associated with mitral valve involvement. Male gender was found to be a significant risk factor for recurrence in the follow-up. Conclusion: Surgery for aortic valve endocarditis has significant mortality. Emergency operation, female gender, postoperative renal failure and low cardiac output are significant risk factors. Risk for recurrence and need for reoperation is low.

Analysis of vibration of exhaust valve pipeline in nuclear power plant

International Nuclear Information System (INIS)

Tan Ping

2005-01-01

Pipeline system for conveying pressurized steam often operates under time-varying conditions due to the valve operations. This may cause vibration problems as a result the pipeline system suffered vibration damage. In this paper, a finite element formulation for the exhaust dynamic equations that include the effect of all pipe supports, and hangers is introduced and applied to the dynamic analysis of the pipeline system used in a nuclear power plant. the vibration response of steam-conveying pipeline induced by valve exhaust has been studied. The model is validated with a fieldwork experimental pipeline system. the mechanical vibrations from steam exhaust valves can be eliminated by careful design of the valve plug and seat. (authors)

Oil Stiction in Fast Switching Annular Seat Valves for Digital Displacement Fluid Power Machines

DEFF Research Database (Denmark)

Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.

2014-01-01

Digital Displacement (DD) fluid power machines utilizes electronically controlled seat valves connected to pressure chambers to obtain variable displacement with high operational efficiency and high bandwidth. To achieve high efficiency, fast valve switching is essential and all aspects related...... to the dynamic behaviour of the seat valves must be considered to optimize the machine efficiency. A significant effect influencing the valves switching performance is the presence of oil stiction when separating the contact surfaces in valve opening movement. This oil stiction force is limited by cavitation...... for low pressure levels, e.g. valves connected to the low pressure manifold, however for valves operated at higher pressure levels, the oil stiction force is dominating when the separating surfaces are close to contact. This paper presents an analytic solution to the oil stiction force for annular seat...

Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves

Energy Technology Data Exchange (ETDEWEB)

Somogyi, D.; Alvarez, P.D.; Kalsi, M.S. [Kalsi Engineering, Inc., Sugar Land, TX (United States)

1996-12-01

Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the {open_quote}Thrust Rating Increase{close_quote} test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner`s rule. Model predictions were validated against actual cyclic loading test results.

Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves

International Nuclear Information System (INIS)

Somogyi, D.; Alvarez, P.D.; Kalsi, M.S.

1996-01-01

Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the open-quote Thrust Rating Increase close-quote test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner's rule. Model predictions were validated against actual cyclic loading test results

Gamma Ray Sterilization of Starr-Edwards Heart Valve Prostheses

Energy Technology Data Exchange (ETDEWEB)

Gibbons, J. R. P.; Alladine, M. F. [London Chest Hospital, London (United Kingdom)

1967-09-15

Starr-Edwards valves have normally been sterilized by exposure to ethylene oxide or by autoclaving. Patients having a prosthetic valve replacement are known to have a higher incidence of endocarditis in comparison with patients in which no prosthesis has been used. Ethylene oxide will only sterilize the surface of the valve and autoclaving has caused distortion of the polytetrafluorethylene ring. Work has been done on the effect of gamma radiation on the components of these valve prostheses and is given in detail. The bacteriological efficiency, at a total absorbed dose of 2. 5 Mrad, has been established. Thirty valves treated by this method have now been inserted and twelve patients have been examined post-operatively for a period of one to two years. All valves are working normally and there has been no evidence of blood-borne infection or malfunction of the valve. (author)

Heart valve surgery

Science.gov (United States)

... replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... surgery. Your heart valve has been damaged by infection ( endocarditis ). You have received a new heart valve ...

Valve which can be remotely handled and operated, particularly for the hot area of radioactive plants

International Nuclear Information System (INIS)

Radovan, G.; Sandling, M.J.; Davidson, J.W.; Blaseck, K.; Hoffmeister, L.; Westendorf, H.

1986-01-01

The valve is built up so that one replacement part contains all the wear parts of the valve, while the non-wearing parts and particularly the valve housing are solidly connected to the pipeline. The replacement part and the valve housing are fixed on alternate sides by a clamp. The replacement part has a central screw which can be moved relative to the other components, which is supported in both axial directions in a clamp which can be opened. The replacement part can thus be pressed into the valve housing and pulled out of it. (orig./HP) [de

Initial experience with xenograft bioconduit for the treatment of complex prosthetic valve endocarditis.

Science.gov (United States)

Roubelakis, Apostolos; Karangelis, Dimos; Sadeque, Syed; Yanagawa, Bobby; Modi, Amit; Barlow, Clifford W; Livesey, Steven A; Ohri, Sunil K

2017-07-01

The treatment of complex prosthetic valve endocarditis (PVE) with aortic root abscess remains a surgical challenge. Several studies support the use of biological tissues to minimize the risk of recurrent infection. We present our initial surgical experience with the use of an aortic xenograft conduit for aortic valve and root replacement. Between October 2013 and August 2015, 15 xenograft bioconduits were implanted for complex PVE with abscess (13.3% female). In 6 patients, concomitant procedures were performed: coronary bypass (n=1), mitral valve replacement (n=5) and tricuspid annuloplasty (n=1). The mean age at operation was 60.3±15.5 years. The mean Logistic European system for cardiac operating risk evaluation (EuroSCORE) was 46.6±23.6. The median follow-up time was 607±328 days (range: 172-1074 days). There were two in-hospital deaths (14.3% mortality), two strokes (14.3%) and seven patients required permanent pacemaker insertion for conduction abnormalities (46.7%). The mean length of hospital stay was 26 days. At pre-discharge echocardiography, the conduit mean gradient was 9.3±3.3mmHg and there was either none (n=6), trace (n=6) or mild aortic insufficiency (n=1). There was no incidence of mid-term death, prosthesis-related complications or recurrent endocarditis. Xenograft bioconduits may be safe and effective for aortic valve and root replacement for complex PVE with aortic root abscess. Although excess early mortality reflects the complexity of the patient population, there was good valve hemodynamics, with no incidence of recurrent endocarditis or prosthesis failure in the mid-term. Our data support the continued use and evaluation of this biological prosthesis in this high-risk patient cohort.

Bentall procedure using cryopreserved valved aortic homografts: mid- to long-term results.

Science.gov (United States)

Christenson, Jan T; Sierra, Jorge; Trindade, Pedro T; Dominique, Didier; Kalangos, Afksendiyos

2004-01-01

The Bentall procedure is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. In many cases, however, mechanical prosthetic conduits are not suitable. There are few reports in the English-language medical literature concerning the mid- to long-term outcome of Bentall operations with cryopreserved homografts. Therefore, we reviewed our experience with this procedure and valved homografts. From January 1997 through December 2002, 21 patients underwent a Bentall operation with cryopreserved homografts at our institution. There were 14 males and 7 females; the mean age was 36 +/- 21 years (range, 15-74 years). Eleven patients had undergone previous aortic valve surgery. All patients had aortic dilatation or aneurysms involving the ascending aorta. Indications for surgery included aortic valve stenosis or insufficiency, and aortic valve endocarditis (native valve or prosthetic). One patient had Takayasu's arteritis and 3 had Marfan syndrome. There was 1 hospital death (due to sepsis), but no other major postoperative complications. The mean hospital stay was 14 +/- 7 days. Follow-up echocardiographic and computed tomographic scans were performed yearly. The mean follow-up was 34 months (6-72 months). Follow-up imaging revealed no calcifications or degenerative processes related to the homograft. Four patients had minimal valve regurgitation. Two patients died during follow-up. The 3-year actuarial survival rate was 85.7%. Our data suggest that the Bentall procedure with a valved homograft conduit is a safe procedure with excellent mid- to long-term results, comparable to results reported with aortic valve replacement with a homograft.