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Safeguards Protection Analysis (SPA)


Safeguards protect processes from process safety incidents. They are critically important. Consequently, every effort must be exerted to ensure they are functional, effective, and adequate.

Unfortunately, many process safety incidents have occurred in processes that were not adequately protected by safeguards or other controls. Needed safeguards were not present or those that were present were insufficient, unreliable or disabled. A safeguards protection analysis (SPA) should be performed before a PHA study and updated after the PHA study. A SPA should address Identification of process safeguards including safety critical equipment and safety critical actions. Performance of a hierarchy of controls analysis (HCA) that identifies the position of each designated safeguard in the hierarchy and justifies the use of the designated safeguards in protecting against the hazards of the process based on their position in the hierarchy. Preparation of a Safety Requirements Specification (SRS) for each safeguard. An SRS documents the functional and integrity requirements for a safeguard. Validation that safeguards adequately protect against the hazards of the process, have a specified integrity level, have been installed correctly, are functional, etc. Once the SPA has been performed, the PHA team can focus on the qualification of safeguards for specific hazard scenarios. Qualification of safeguards addresses whether safeguards are appropriate for each hazard scenario in a PHA study. Information developed in a PHA study may necessitate revisions to the SPA and SRSs. For example, it may be determined that a redundant power supply is needed to support the integrity required for an emergency shutdown system. SPAs should be updated during MOC reviews and when developing recommendations from incident investigations. The Division of Occupational Safety and Health within the California Department of Industrial Relations in amendments to current process safety management (PSM) regulations for petroleum refineries in California has proposed requirements for performing SPAs.