Specifying Reliability Performance to Meet PSM Expectations

Process Hazard Analysis (PHA) and Mechanical Integrity (MI) programs are two of the fourteen elements that the Process Safety Management (PSM) Standard uses to prevent or minimize the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals. Experience proves that equipment with higher failure frequency is more likely to initiate a PSM failure. Incorporating equipment failure history in the PHA program makes it possible to establish individual equipment performance requirements needed to achieve desired process safety risk reduction goals. An effective MI program manages the potential for a catastrophic equipment failure above acceptable levels. Additional layers of protection are needed if an MI program cannot realistically achieve the minimum level of equipment performance needed to satisfy safety objectives itself. This paper explains how one refinery uses a quantitative approach to specify the equipment reliability needed to adequately control the process safety hazards associated with catastrophic pump failures.