Non-Conformance of Existing Pressure Relief Systems With Recommended Practices: A Statistical Analysis

Abstract

This article presents a statistical analysis showing that the pressure relief systems on nearly half of the equipment in the oil, gas, and chemical industries lack adequate overpressure protection as defined by recognized and generally accepted good engineering practices. This analysis was based on data collected from a large number of government mandated (per OSHA 1910.119) pressure relief system design audits performed by an independent contractor. The vast majority of these deviations from good practice were not identified during conventional process hazard analyses (PHAs) performed on these same facilities. Most of the units had also been designed by reputable design firms. The authors conclude that, as a practical matter, conventional PHA methods are ineffective tools for evaluating pressure relief systems. They also conclude that the pressure relief system design process could be improved. Specifically, the authors recommend that, in order to reduce this deficiency rate in the future, the industry adopt an equipment-based approach to pressure relief system design and maintenance.