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.

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.

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.

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.

Demonstrating Nutrient Cost Gradients: A Brooklyn Case Study

2014 ◽  
Vol 84 (5-6) ◽  
pp. 244-251 ◽  
Author(s):  
Robert J. Karp ◽  
Gary Wong ◽  
Marguerite Orsi
Keyword(s):  
Low Income ◽  
Energy Content ◽  
Food Selection ◽  
The United States ◽  
United States Department ◽  
Micronutrient Deficiencies ◽  
Caloric Density ◽  
Low Income Families ◽  
The Cost ◽  
The Impact

Abstract. Introduction: Foods dense in micronutrients are generally more expensive than those with higher energy content. These cost-differentials may put low-income families at risk of diminished micronutrient intake. Objectives: We sought to determine differences in the cost for iron, folate, and choline in foods available for purchase in a low-income community when assessed for energy content and serving size. Methods: Sixty-nine foods listed in the menu plans provided by the United States Department of Agriculture (USDA) for low-income families were considered, in 10 domains. The cost and micronutrient content for-energy and per-serving of these foods were determined for the three micronutrients. Exact Kruskal-Wallis tests were used for comparisons of energy costs; Spearman rho tests for comparisons of micronutrient content. Ninety families were interviewed in a pediatric clinic to assess the impact of food cost on food selection. Results: Significant differences between domains were shown for energy density with both cost-for-energy (p < 0.001) and cost-per-serving (p < 0.05) comparisons. All three micronutrient contents were significantly correlated with cost-for-energy (p < 0.01). Both iron and choline contents were significantly correlated with cost-per-serving (p < 0.05). Of the 90 families, 38 (42 %) worried about food costs; 40 (44 %) had chosen foods of high caloric density in response to that fear, and 29 of 40 families experiencing both worry and making such food selection. Conclusion: Adjustments to USDA meal plans using cost-for-energy analysis showed differentials for both energy and micronutrients. These differentials were reduced using cost-per-serving analysis, but were not eliminated. A substantial proportion of low-income families are vulnerable to micronutrient deficiencies.

Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction

2010 ◽  
Author(s):  
Steve Kerber ◽  
Keyword(s):  
Homeland Security ◽  
Fire Behavior ◽  
The United States ◽  
Fire Service ◽  
United States Department ◽  
Department Of Homeland Security ◽  
Front Door ◽  
Fire Environment ◽  
Open Floor ◽  
The Impact

Under the United States Department of Homeland Security (DHS) Assistance to Firefighter Grant Program, Underwriters Laboratories examined fire service ventilation practices as well as the impact of changes in modern house geometries. There has been a steady change in the residential fire environment over the past several decades. These changes include larger homes, more open floor plans and volumes and increased synthetic fuel loads. This series of experiments examine this change in fire behavior and the impact on firefighter ventilation tactics. This fire research project developed the empirical data that is needed to quantify the fire behavior associated with these scenarios and result in immediately developing the necessary firefighting ventilation practices to reduce firefighter death and injury. Two houses were constructed in the large fire facility of Underwriters Laboratories in Northbrook, IL. The first of two houses constructed was a one-story, 1200 ft, 3 bedroom, 
bathroom house with 8 total rooms. The second house was a two-story 3200 ft, 4 bedroom, 2.5 bathroom house with 12 total rooms. The second house featured a modern open floor plan, two- story great room and open foyer. Fifteen experiments were conducted varying the ventilation locations and the number of ventilation openings. Ventilation scenarios included ventilating the front door only, opening the front door and a window near and remote from the seat of the fire, opening a window only and ventilating a higher opening in the two-story house. One scenario in each house was conducted in triplicate to examine repeatability. The results of these experiments provide knowledge for the fire service for them to examine their thought processes, standard operating procedures and training content. Several tactical considerations were developed utilizing the data from the experiments to provide specific examples of changes that can be adopted based on a departments current strategies and tactics.

Abstract P078: Contribution of Nutrients from Consumption of Low/Non-Fat/Light Ice Cream and Frozen Yogurt versus Regular Ice Cream to Total Daily Nutrient Intake

Circulation ◽  
2012 ◽  
Vol 125 (suppl_10) ◽  
Author(s):  
Jessica Smerling ◽  
Douglas Balentine ◽  
Mary Kearney ◽  
Carolyn Scrafford ◽  
Leila Barraj ◽  
...  
Keyword(s):  
Nutrient Intake ◽  
Saturated Fat ◽  
Ice Cream ◽  
The United States ◽  
United States Department ◽  
Nutrient Intakes ◽  
Frozen Yogurt ◽  
Dietary Nutrient ◽  
Nationally Representative ◽  
The Impact

Objective: The impact on nutrient intake of replacing regular ice cream with low/non-fat/light ice cream and frozen yogurt (lower fat ice cream) is heretofore unknown. The objective of this study was to evaluate the contribution of daily nutrient intake from ice cream consumption to total daily dietary nutrient intake. Methods: Food intake and frequency of consumption data were based on the National Health and Nutrition Examination Survey (NHANES) (2003–2004 and 2005–2006) and nutrient composition data from the United States Department of Agriculture (USDA) Food and Nutrient Database for Dietary Studies (FNDDS). The NHANES datasets provide nationally representative nutrition and health data of the civilian U.S. population. A total of 16,783 individuals in the 2003–2006 survey periods provided 2 complete days of dietary recalls and nutrient intake estimates were derived using 2-day average intake analysis. Results: Mean consumption of regular and lower fat ice cream products in the US population was 68.5 and 77.1 grams/day, respectively and frequency of consumption was 0.2 and 0.22 eating occasion/day, respectively among consumers of ice cream. Figure 1 reveals that lower fat ice cream contributed equal or greater amounts of calcium, phosphorus, potassium, riboflavin, and niacin to daily nutrient intakes for the U.S. population when compared with regular ice cream, with the exception of vitamin D. Alternatively, lower fat ice cream contributed lesser amounts of energy, saturated fat, and added sugar to daily nutrient intakes when compared to regular ice cream; lower fat ice cream contributed 56% less saturated fat to daily nutrient intake compared to regular ice cream. Conclusion: Consumers of low/non-fat/light ice cream and frozen yogurt had lower percent contribution of saturated fat to total daily nutrient intake compared to users of regular ice cream. Figure 1

Shark Nursery Grounds of the Gulf of Mexico and the East Coast Waters of the United States

2007 ◽  
Keyword(s):  
South Carolina ◽  
The United States ◽  
North Inlet ◽  
Shark Species ◽  
Sandbar Shark ◽  
Catch Per Unit Effort ◽  
Salinity Regime ◽  
Carcharhinus Limbatus ◽  
Winyah Bay ◽  
The Impact

<em>Abstract.</em>—Winyah Bay is a 65-km<sup>2</sup> estuary in northeast South Carolina, and North Inlet is a 32- km<sup>2</sup>, high-salinity estuary connected to both Winyah Bay and the Atlantic Ocean. The objectives of this study were to survey the shark fauna of these systems, determine the potential of these estuaries as shark nurseries, and assess the impact of salinity structure on shark diversity and abundance in these two estuaries. From May to November in 2002 (a drier than average year) and 2003 (a wetter than average year), 227 bottom longlines (16/0 and 12/0 hooks) were set in Winyah Bay. In 2002 and 2003, a total of 119 trammel net sets were also conducted from June to October in North Inlet. A total of 196 sharks (38 adults, 158 juveniles) representing 10 species were captured in Winyah Bay in 2002, whereas 73 sharks (17 adults and 56 juveniles) representing four species were caught in 2003. Catch per unit effort (CPUE) for all sharks caught in Winyah Bay was not significantly different between 2002 and 2003. Blacktip shark <em>Carcharhinus limbatus </em>and finetooth shark <em>C. isodon </em>CPUE declined significantly on 16/0 hook longlines set in Winyah Bay from 2002 to 2003. For 12/0 hook longlines set in Winyah Bay, CPUE for three species (sandbar shark <em>C. plumbeus</em>, Atlantic sharpnose shark <em>Rhizoprionodon terraenovae</em>, and finetooth shark) out of five declined significantly from 2002 to 2003. Within Winyah Bay, CPUE for sharks on both longline configurations was not significantly different between lower and middle bay sites for 2002 but was for 2003. In both years, CPUE correlated positively with bottom salinity in Winyah Bay. In North Inlet, in 2002, 30 sharks (20 adults, 10 juveniles) comprising five species were caught, whereas 57 sharks (26 adults and 31 juveniles) representing three species were caught in 2003. The CPUE in 2002 was significantly less than in 2003 in North Inlet for Atlantic sharpnose sharks, bonnetheads <em>Sphyrna tiburo</em>, and all sharks combined. This study documented the presence of adults and juveniles (including neonates and young of the year) for 10 species of sharks in Winyah Bay and 5 in North Inlet and thus identified these areas as shark habitat and potential primary and secondary nurseries for some shark species. We also observed salinity-related differences in the distribution of sharks in both estuaries, including differences in abundance and age-class, as a result of normal salinity regime and precipitation-induced salinity changes.

scholarly journals Advocating for Structural Change? Exploring the Advocacy Activities of Immigrant-Serving Organizations in an Unwelcoming Policy Context

2018 ◽  
Vol 18 (3) ◽  
pp. 682-703 ◽  
Author(s):  
Benjamin Roth ◽  
Seo Yeon Park ◽  
Breanne Grace
Keyword(s):  
South Carolina ◽  
Social Service ◽  
Service Providers ◽  
The United States ◽  
Service Organizations ◽  
Future Research ◽  
Policy Advocacy ◽  
Social Service Organizations ◽  
State And Local ◽  
The Impact

The growth of the immigrant population in the United States has prompted a recent increase in the number of restrictive immigration policies at the state and local levels. The literature on policy advocacy and social service organizations suggests that these local providers can engage in political activities that challenge the restrictive nature of these contexts. This qualitative study explored how immigrant-serving social service organizations engage in policy advocacy in a state with restrictive, anti-immigrant policies. In-depth interviews with directors of 50 service providers in South Carolina clearly indicate a tension between the need for policy advocacy and the risks associated with engaging in such activities. Fifty percent (50%) of the providers in our sample reported engaging in some form of policy advocacy. However, their policy advocacy activities were often indirect, non-confrontational, and episodic. Most were engaged in coalitions and other forms of indirect advocacy tactics. We discuss implications for the social work profession and recommendations for future research, including the need to further explore the impact of policy advocacy efforts on changing the policy landscape in places that are unwelcoming to immigrants.

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.

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