(128c) Auditing PHA Quality

Process Hazard Analyses (PHAs) are widely used in the process industries to identify process deviations that could lead to a catastrophic fire, explosion, and/or toxic release. Their use predates OSHA’s Process Safety Management regulation. Over the past 40+ years, PHA techniques have been improved to include a review of a wider range of information, better documentation, and a more thorough consideration of risk.

Sometimes, we see PHAs that have not kept up with these improvements or are simply lacking critical information. When revalidating PHAs, PHA Leaders must assess the quality of the previous PHA in order to decide how best to conduct the revalidation. If the previous PHA is sound, including all elements in accordance with best practices, the PHA can be reviewed and updated with current information and process changes. If the PHA is missing a few critical elements, it may be possible to retrofit the study to include these elements. Lastly, due to significant defects in the previous study, redoing some studies from scratch is the best course of action.

The question becomes, “What constitutes a good PHA?” The activities undertaken to conduct the study are, of course, critically important; nearly as important is the documentation of the study. Remember that the study will be used in the future by individuals who were not on the study team and during the next revalidation. For these reasons, the documentation of what was done, and the outcomes are very important. This article reviews the elements of a sound PHA, covering all aspects of a quality PHA.