PresentationIt is not uncommon to find that Process Hazard Analysis (PHA) scenarios and Process Safety Valve (PSV) calculation cases do not align. The intent of PHA studies, typically performed using the Hazard and Operability (HAZOP) method, is to identify all plausible hazard scenarios and the risk of those events occurring by assessing potential causes, consequences, safeguards, and independent protection layers. The intent of the PSV protection layer is to provide relief capacity for all plausible overpressure scenarios. Therefore, HAZOP scenarios related to overpressure and PSV calculation cases should align. Lack of alignment between the HAZOP and the PSV calculation file creates problems in completeness, quality, and clarity. Lack of alignment also creates engineering rework and “churn” as inconsistencies are discovered and resolution is needed. A simple solution is proposed. Each PSV calculation case that is considered plausible should contain a direct reference to the related HAZOP scenario, preferably in the summary matrix. Likewise, each HAZOP scenario should reference the related PSV case. New or modified PSV calculations and new or modified HAZOP summary sheets associated with plant modifications or engineering document corrections should include this cross- referencing. Where broader changes are introduced, such as changes to engineering assumptions for PSV calculations or changes to HAZOP scenario protocol, the Discipline Subject Matter Experts (SMEs) responsible for approving those changes must consider the impacts to the related documents and define the expectations for updating those documents in order to assure alignment
