Analysis of spring operated pressure relief valve proof test data: Findings and implications

Ten years of research into spring operated pressure relief valve (SOPRV) proof test data are reviewed. Previously unpublished results are also presented. The principle findings are: proof test data alone are insufficient to properly analyze SOPRV safety behavior; root cause analysis (RCA) of all failed SOPRV is also required; probability of initial failure is a real and concerning phenomenon in both new (not previously installed) as well as used (previously installed) SOPRV but does not affect all SOPRV equally; SOPRV failure rates and safety performances depend on many variables including set pressure, SOPRV design and manufacturing specifics, and end user safety and maintenance practices; certain SOPRV require shorter proof test intervals (2-3 years) to maintain desired safety ratings but others can endure much longer proof test intervals with only small additional safety risks. Understanding all of the parameters which impact SOPRV safety performance and collecting safety performance data (including RCA of failed SOPRV) at the individual facility level are the keys to optimizing commissioning and pre-installation proof testing and proof test intervals, and potentially to extending turnaround times. (c) 2018 American Institute of Chemical Engineers Process Saf Prog 37: 467-477, 2018