Process Hazard Analysis, Layers of Protection Analysis and the Human Factor

Process hazard analysis (PHA) and Layers of Protection Analysis (LOPA) studies address human failures in operating and maintaining processes and the human factors that influence them. However, much less attention has been paid to the human factors that influence the conduct of PHA and LOPA. People conduct PHA and LOPA studies and, therefore, such studies are subject to various possible human failures. Such failures should be of significant concern to PHA and LOPA practitioners as such studies are difficult and time-consuming activities that place significant demands on participants which increases the chances that errors will be made. Human factors such as willingness to rely on the unsubstantiated opinions of others, group think, underestimation of the frequencies of low-probability, high-consequence events, and allowing a false sense of accomplishment to distract from implementing study results must be recognized and addressed.

This paper identifies and discusses various human factors that can influence the quality of PHA and LOPA studies covering preparation, conduct and follow-up of studies. Guidelines are provided to help minimize the extent to which these human factors may impair study quality.