(117bd) Guidelines for Risk Ranking Hazardous Scenarios When Conducting PHAs

Most of the companies in the process industry use corporate guidelines, or dedicated criteria and principles for conducting Process Hazard Analysis (PHAs). Examples of factors addressed are the following: nodes selection, process deviations to be brainstormed, level of detail when writing causes/consequences, safeguards categorization, risk matrix to be used, and how to risk rank the identified scenarios.

This paper collects different approaches from leading PHAs at several companies. An analysis comparing these approaches is provided and strengths and weaknesses are identified. Finally, based on safeguards and consequences categorization, guidelines are proposed for consistently risk rank hazardous scenarios.