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Title: Pressure locking test results

Abstract

The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is funding the Idaho National Engineering Laboratory (INEL) in performing research to provide technical input for their use in evaluating responses to Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves.{close_quotes} Pressure locking and thermal binding are phenomena that make a closed gate valve difficult to open. This paper discusses only the pressure locking phenomenon in a flexible-wedge gate valve; the authors will publish the results of their thermal binding research at a later date. Pressure locking can occur when operating sequences or temperature changes cause the pressure of the fluid in the bonnet (and, in most valves, between the discs) to be higher than the pressure on the upstream and downstream sides of the disc assembly. This high fluid pressure presses the discs against both seats, making the disc assembly harder to unseat than anticipated by the typical design calculations, which generally consider friction at only one of the two disc/seat interfaces. The high pressure of the bonnet fluid also changes the pressure distribution around the disc in a way that can further contribute to the unseating load. If the combined loads associated withmore » pressure locking are very high, the actuator might not have the capacity to open the valve. The results of the NRC/INEL research discussed in this paper show that the relationship between bonnet pressure and pressure locking stem loads appears linear. The results also show that for this valve, seat leakage affects the bonnet pressurization rate when the valve is subjected to thermally induced pressure locking conditions.« less

Authors:
; ; ;  [1]
  1. Idaho National Engineering Lab., Idaho Falls, ID (United States); and others
Publication Date:
Research Org.:
American Society of Mechanical Engineers (ASME), New York, NY (United States)
OSTI Identifier:
402020
Report Number(s):
NUREG/CP-0152; CONF-9607103-
ON: TI96013645; TRN: 96:005268-0054
Resource Type:
Conference
Resource Relation:
Conference: 4. NRC/ASME symposium on valve and pump testing in nuclear power plants, Washington, DC (United States), 15-18 Jul 1996; Other Information: PBD: [1996]; Related Information: Is Part Of Proceedings of the 4th NRC/ASME symposium on valve and pump testing; PB: 719 p.
Country of Publication:
United States
Language:
English
Subject:
22 NUCLEAR REACTOR TECHNOLOGY; VALVES; PRESSURIZATION; TESTING; NUCLEAR POWER PLANTS; STATIC LOADS; OPERATION

Citation Formats

DeWall, K G, Watkins, J C, McKellar, M G, and Bramwell, D. Pressure locking test results. United States: N. p., 1996. Web.
DeWall, K G, Watkins, J C, McKellar, M G, & Bramwell, D. Pressure locking test results. United States.
DeWall, K G, Watkins, J C, McKellar, M G, and Bramwell, D. 1996. "Pressure locking test results". United States. https://www.osti.gov/servlets/purl/402020.
@article{osti_402020,
title = {Pressure locking test results},
author = {DeWall, K G and Watkins, J C and McKellar, M G and Bramwell, D},
abstractNote = {The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is funding the Idaho National Engineering Laboratory (INEL) in performing research to provide technical input for their use in evaluating responses to Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves.{close_quotes} Pressure locking and thermal binding are phenomena that make a closed gate valve difficult to open. This paper discusses only the pressure locking phenomenon in a flexible-wedge gate valve; the authors will publish the results of their thermal binding research at a later date. Pressure locking can occur when operating sequences or temperature changes cause the pressure of the fluid in the bonnet (and, in most valves, between the discs) to be higher than the pressure on the upstream and downstream sides of the disc assembly. This high fluid pressure presses the discs against both seats, making the disc assembly harder to unseat than anticipated by the typical design calculations, which generally consider friction at only one of the two disc/seat interfaces. The high pressure of the bonnet fluid also changes the pressure distribution around the disc in a way that can further contribute to the unseating load. If the combined loads associated with pressure locking are very high, the actuator might not have the capacity to open the valve. The results of the NRC/INEL research discussed in this paper show that the relationship between bonnet pressure and pressure locking stem loads appears linear. The results also show that for this valve, seat leakage affects the bonnet pressurization rate when the valve is subjected to thermally induced pressure locking conditions.},
doi = {},
url = {https://www.osti.gov/biblio/402020}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Dec 01 00:00:00 EST 1996},
month = {Sun Dec 01 00:00:00 EST 1996}
}

Conference:
Other availability
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