Reliability Testing of Pressure Relief Valves
Following a brief description of pressure relief valves, this paper presents as-found set point test results for pressure relief valves that have been in process or utility system service. The paper examines the reliability of the relief valve to open at set pressure as a function of several key parameters, including time in service, fluid, size, and valve design (vendor). Although it may be that steam and water service valves are affected adversely by service conditions, this analysis is focused primarily on clean air/gas service. The probable correlation between fluid cleanliness and reliability is not being made, but will be considered in future studies. Valves that discharge outside allowable ASME tolerances are evaluated to determine possible causes of the deviation. Three failure case studies are presented. A final summary of test results indicates that valve reliability is not a strong function of time in service for the one-to-five year operating periods investigated. Additionally, this data set indicates that less than one percent (0.96%) of all valves pop tested at greater than 1.4 times tag set pressure.