Statistical Performance Evaluation of Soft (Elastomer) Seat Pressure Relief Valves

2013 ◽  
Author(s):  
Robert E. Gross ◽  
Stephen P. Harris
Keyword(s):  
South Carolina ◽  
Performance Evaluation ◽  
The United States ◽  
Probability Of Failure ◽  
United States Department ◽  
Relief Valve ◽  
Pressure Relief ◽  
On Demand ◽  
Pressure Relief Valves ◽  
Statistical Performance Evaluation

Risk-based inspection methods enable estimation of the probability of failure on demand for spring-operated pressure relief valves at the United States Department of Energy’s Savannah River Site in Aiken, South Carolina. This paper presents a statistical performance evaluation of soft seat spring operated pressure relief valves. These pressure relief valves are typically smaller and of lower cost than hard seat (metal to metal) pressure relief valves and can provide substantial cost savings in fluid service applications (air, gas, liquid, and steam) providing that probability of failure on demand (the probability that the pressure relief valve fails to perform its intended safety function during a potentially dangerous over pressurization) is at least as good as that for hard seat valves. The research in this paper shows that the proportion of soft seat spring operated pressure relief valves failing is the same or less than that of hard seat valves, and that for failed valves, soft seat valves typically have failure ratios of proof test pressure to set pressure less than that of hard seat valves.

Statististical Performance Evaluation of Soft Seat Pressure Relief Valves

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Robert E. Gross ◽  
Stephen P. Harris
Keyword(s):  
South Carolina ◽  
Performance Evaluation ◽  
Cost Savings ◽  
The United States ◽  
United States Department ◽  
Relief Valve ◽  
Pressure Relief ◽  
Safety Function ◽  
Test Pressure ◽  
Pressure Relief Valves

Risk-based inspection methods enable estimation of the probability of failure on demand (PFD) for spring-operated pressure relief valves at the United States Department of Energy's Savannah River Site in Aiken, South Carolina. This paper presents a statistical performance evaluation of soft seat elastomer spring operated pressure relief valves. These pressure relief valves are typically smaller and of lower cost than hard seat (metal to metal) pressure relief valves. They can provide substantial cost savings in certain fluid service applications providing that PFD is at least as good as that for hard seat valves. PFD is the probability that a pressure relief valve fails to perform its intended safety function during a potentially dangerous over pressurization. The research in this paper shows that the proportion of soft seat spring operated pressure relief valves failing is the same or less than that of hard seat valves, and that for failed valves, soft seat valves typically have failure ratios of proof test pressure to set pressure much less than that of hard seat valves.

scholarly journals Statistical Performance Evaluation of Spring Operated Pressure Relief Valve Reliability Improvements 2004 to 2014

2015 ◽  
Author(s):  
Holly L. Watson ◽  
Robert E. Gross ◽  
Stephen P. Harris
Keyword(s):  
South Carolina ◽  
The United States ◽  
Pressure Relief Valve ◽  
United States Department ◽  
Relief Valve ◽  
Pressure Relief ◽  
Maintenance Program ◽  
Operational Systems ◽  
Pressure Relief Valves ◽  
Improved Performance

The United States Department of Energy’s Savannah River Site (SRS) in Aiken, South Carolina, is dedicated to promoting site-level risk-based inspection (RBI) practices in order to maintain a safe and productive work environment. Inspecting component parts of operational systems, such as pressure relief valves (PRVs), is a vital part of SRS’s safe operating envelope. This paper is a continuation of a SRS program to minimize the risks associated with PRV failures. Spring operated pressure relief valve (SOPRV) test data accumulated over the past ten years resulted in over 11,000 proof tests of both new and used valves. Improved performance is seen for air service valves resulting from changes to the maintenance program. Although, statistically significant improvement was not seen for liquid, gas, or steam service valves, analysis shows that the overall probability of failure on demand is trending down. Current SRS practices are reviewed and the reasons for improved performance are explored.

Evaluating Risk and Safety Integrity Levels for Pressure Relief Valves Through Probabilistic Modeling

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Emily M. Mitchell ◽  
Robert E. Gross ◽  
Stephen P. Harris
Keyword(s):  
South Carolina ◽  
Probability Distributions ◽  
The United States ◽  
Process Equipment ◽  
United States Department ◽  
Pressure Relief ◽  
Safety Margins ◽  
Pressure Relief Valves ◽  
The Impact ◽  
Maintenance Plan

The probability of failure on demand (PFD) for spring-operated pressure relief valves (SORVs) is estimated by applying the Fréchet and Weibull probability distributions using proof test data from the United States Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. The data can be accessed through the Center for Chemical Process Safety (CCPS) Process Equipment Reliability Database (PERD). The probability distributions enable the evaluation of risk, estimation of ANSI/ISA-84.00.01 Safety Integrity Levels (SILs), and the impact of potential modifications of the maintenance plan. Current SRS practices are reviewed, and recommendations are made for risk-based adjustments to the maintenance plan. Subsets of valves are identified in which maintenance times can be extended and in which increased safety margins may be needed.

The Effects of Maintenance Actions on the Average Probability of Failure on Demand of Spring Operated Pressure Relief Valves

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Julia V. Bukowski ◽  
William M. Goble ◽  
Robert E. Gross ◽  
Stephen P. Harris
Keyword(s):  
Probability Of Failure ◽  
Pressure Relief ◽  
Periodic Inspection ◽  
On Demand ◽  
Plant Safety ◽  
Safety Integrity Level ◽  
Proof Testing ◽  
Average Probability ◽  
Pressure Relief Valves ◽  
Inspection And Maintenance

The safety integrity level (SIL) of equipment used in safety instrumented functions is determined by the average probability of failure on demand (PFDavg) computed at the time of periodic inspection and maintenance, i.e., the time of proof testing. The computation of PFDavg is generally based solely on predictions or estimates of the assumed constant failure rate of the equipment. However, PFDavg is also affected by maintenance actions (or lack thereof) taken by the end user. This paper shows how maintenance actions can affect the PFDavg of spring operated pressure relief valves (SOPRV) and how these maintenance actions may be accounted for in the computation of the PFDavg metric. The method provides a means for quantifying the effects of changes in maintenance practices and shows how these changes impact plant safety.

scholarly journals Estimated SIL Levels and Risk Comparisons for Relief Valves as a Function of Time-in-Service

2012 ◽  
Author(s):  
Emily M. Mitchell ◽  
Robert E. Gross ◽  
Stephen P. Harris
Keyword(s):  
South Carolina ◽  
Risk Estimation ◽  
Probability Distributions ◽  
The United States ◽  
Process Equipment ◽  
United States Department ◽  
Safety Margins ◽  
Pressure Relief Valves ◽  
The Impact ◽  
Maintenance Plan

The probability of failure on demand for spring-operated pressure relief valves (SORVs) is estimated by applying the Fréchet and Weibull probability distributions using proof test data from the United States Department of Energy’s Savannah River Site (SRS) in Aiken, South Carolina. The data can be accessed through the Center for Chemical Process Safety (CCPS) Process Equipment Reliability Database (PERD). The probability distributions enable the evaluation of risk, estimation of ANSI/ISA-84.00.01 Safety Integrity Levels (SILs), and the impact of potential modifications of the maintenance plan. Current SRS practices are reviewed, and recommendations are made for risk-based adjustments to the maintenance plan. Subsets of valves are identified in which maintenance times can be extended and in which increased safety margins may be needed.

Dynamic Behavior of Transportation Pressure Relief Valves Under Simulated Fire Impingement Conditions

1999 ◽  
Vol 122 (1) ◽  
pp. 60-65 ◽  
Author(s):  
A. J. Pierorazio ◽  
A. M. Birk
Keyword(s):  
Dynamic Testing ◽  
Test Facility ◽  
Time Varying ◽  
Relief Valve ◽  
Pressure Relief ◽  
Flow Rates ◽  
Depth Analysis ◽  
Pressure Relief Valves ◽  
Accident Conditions ◽  
Insight Into

This paper presents the results of the first full test series of commercial pressure relief valves using the newly constructed Queen’s University/Transport Canada dynamic valve test facility (VTF) in Maitland, Ontario. This facility is unique among those reported in the literature in its ability to cycle the valves repeatedly and to measure the time-varying flow rates during operation. This dynamic testing provides much more insight into valve behavior than the single-pop or continuous flow tests commonly reported. The facility is additionally unique in its simulation of accident conditions as a means of measuring valve performance. Specimen valves for this series represent 20 each of three manufacturers’ design for a semi-internal 1-in. 312 psi LPG relief valve. The purpose of this paper is to present the procedure and results of these tests. No effort is made to perform in-depth analysis into the causes of the various behaviors, nor is any assessment made of the risk presented by any of the valves. [S0094-9930(00)01201-4]

scholarly journals Mapping Center Pivot Irrigation Fields in South Carolina with Google Earth Engine and the National Agricultural Imagery Program

2021 ◽  
Author(s):  
C. Alex Pellett
Keyword(s):  
South Carolina ◽  
The United States ◽  
Google Earth ◽  
Aerial Images ◽  
United States Department ◽  
Department Of Agriculture ◽  
Growing Seasons ◽  
Irrigated Area ◽  
Center Pivot ◽  
Irrigation Infrastructure

Aerial images taken during the growing seasons of 2009, 2011, 2013, 2015, and 2017 were visually inspected for evidence of irrigation. Center pivot irrigation was identified by the characteristic shape of the spans and the curved tracks left by the wheels. The author manually delineated a polygon over each agricultural area where signs of irrigation infrastructure were observed. The result is a map of 2,689 polygons covering 146,662 acres in South Carolina. Compared with the United States Department of Agriculture 2017 Census of Agriculture, the sampling results account for over 69% of total irrigated area and over 98% of area irrigated solely by center pivots. Most center pivots covered from 25 to 75 acres, while the largest center pivot extended over 300 acres. These results are an important contribution to the quantification of water use in South Carolina.

Steady-State Positions of a Pop Action Safety Valve

2011 ◽  
Author(s):  
Jean-Franc¸ois Rit ◽  
Pierre Moussou ◽  
Christophe Teygeman
Keyword(s):  
Steady State ◽  
Pressure Drop ◽  
Relief Valve ◽  
Pressure Relief ◽  
Working Pressure ◽  
Process Industries ◽  
Water Pipes ◽  
Upstream Pressure ◽  
Pressure Relief Valves ◽  
The Stability

Pressure relief valves in water pipes are known to sometimes chatter when the inlet pressure slightly exceeds the maximum allowable working pressure (MAWP) value. Though these devices are responsible for numerous fatigue issues in process industries, there is a relatively low number of technical publications describing well-established facts about them, especially for heavy fluids. The present study deals with the investigation of the stability of a pressure relief valve when a pressure drop device is arranged upstream. The valve is a simple spring device, with a 1″1/2 inlet diameter and a set pressure equal to 3 MPa. The 12% to 66% range of relative opening for this valve exhibit an unstable static equilibrium of the plug, designed to achieve the so called “pop action”; as soon as the pressure set point is reached, a runaway process leads to the full opening. The statically stable regimes were observed in former studies with respect to the upstream pressure and to the plug position, with a test rig arrangement which ensured an almost constant pressure upstream. In the present study, high pressure drop devices are arranged upstream, in order to stabilize the hydraulic regimes. It is found that the upstream pressure drop devices significantly enlarge the range of steady state plug positions and upstream pressures. Pressure and plug position measurements are shown with a time resolution lower than 2 ms. Comparison with hydraulic regimes of the former studies indicate that the presence of an upstream pressure drop modifies the plug balance. It is proposed that the arrangement of pressure drop device upstream may significantly reduce the risk of valve instability in water pipes.

scholarly journals Performance Evaluation of a Respirator Vortex Cooling Device

2017 ◽  
Author(s):  
Ashley D. Elizondo ◽  
Robert K. Iacovone
Keyword(s):  
South Carolina ◽  
Vortex Tube ◽  
Cost Savings ◽  
The United States ◽  
Statistical Test ◽  
United States Department ◽  
Test Plan ◽  
Product Analysis ◽  
New Model ◽  
Vortex Tubes

The United States Department of Energy’s Savannah River Site (SRS) in Aiken, South Carolina, is dedicated to promoting site-level risk-based inspection practices in order to maintain a safe and productive work environment. Protective suits are worn by personnel working in contaminated environments. These suits require that cooling be applied to keep the interior temperature within safe and comfortable limits. A vortex tube, also known as the Ranque-Hilsch vortex tube, can provide the necessary cooling. As mechanical devices void of moving components, vortex tubes separate a compressed gas into hot and cold streams; the air emerging from the “hot” end reaching a temperature of 320 degrees F, and the air emerging from the “cold” end reaching a temperature of negative 25 degrees F [1]. Routing the cold stream of the vortex tube to the user’s protective suit facilitates the required cooling. Vortex tubes currently in use at SRS are pre-set, through sole modification by and within the SRS Respiratory Equipment Facility (REF), to provide a temperature reduction between 40 and 45 deg F. When a new model of vortex tube capable of user adjustment during operation recently became available, prototype testing was conducted for product comparison. Similar cooling performance between the old and new models is achievable. Implementing the use of the new model of vortex tube at SRS will result in significant cost savings because the product could be shipped directly to the end user, circumventing adjustment by the REF. Production units were acquired to be subjected to complete product analysis at SRS utilizing a statistical test plan. The statistical test plan, data, thermodynamic calculations, and conclusions were reviewed.

The Design and Research of Automatic Micro-Pressure Relief Valves Used in Mine Rescue Cabin

2015 ◽  
Vol 752-753 ◽  
pp. 828-832
Author(s):  
Nian Yong Zhou ◽  
Yan Long Jiang ◽  
Lei Xu ◽  
Jun Li ◽  
He Xu Wang
Keyword(s):  
Fast Response ◽  
Pressure Relief Valve ◽  
Opening Pressure ◽  
Relief Valve ◽  
Pressure Relief ◽  
Advantages And Disadvantages ◽  
Sealing Performance ◽  
Pressure Relief Valves ◽  
Relief Rate ◽  
Mine Rescue

By analyzing the key technologies of pressure relief valve and comparing the advantages and disadvantages of existing products, liquid sealing automatic micro-pressure relief valve is designed with the properties of adjustable opening pressure, fast response rate, good sealing performance and long life, etc. Also, a reasonable mathematical model of liquid sealing automatic micro-pressure relief valve is developed, and the pressure relief valve’s opening pressure, reset pressure, relief rate and other key performance parameters is obtained. This work wil be helpful for the design and research of automatic micro-pressure relief valves used in mine rescue cabin.

Sign in / Sign up

Export Citation Format

Share Document