Knowing the Fitness-for-Service Limit Is NOT Enough – PHA Scenario Development and Validation Against Equipment Limitations

This presentation will review examples of fitness-for-service limitations and the potential process safety hazards presented if the limits are exceeded.  Utilizing the aviation term “black-box” to reflect the process data historian; the use of a “black-box” historical operating data review methodology as a part of the process hazards analysis (PHA) scenario development and validation will be discussed.  Fitness-for-service evaluation of equipment under a time dependent failure mechanisms (auto-refrigeration, hydrogen damage, etc.) will also be presented.  For example; utilizing a vessel minimum design metal temperature (MDMT) as the single low-temperature fitness-for-service criteria value, under auto-refrigeration conditions, can incorrectly indicate an at risk brittle condition because the reduced equipment pressure loading is not accounted for in the MDMT value.