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Addressing enablers in layers of protection analysis
Author(s) -
Baybutt Paul
Publication year - 2014
Publication title -
process safety progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.378
H-Index - 40
eISSN - 1547-5913
pISSN - 1066-8527
DOI - 10.1002/prs.11639
Subject(s) - risk analysis (engineering) , hazard , event (particle physics) , process (computing) , work (physics) , hazard analysis , process safety management , risk management , reliability engineering , engineering , risk assessment , computer science , business , computer security , mechanical engineering , chemistry , physics , organic chemistry , finance , quantum mechanics , waste management , hazardous waste , operating system
Layers of protection analysis (LOPA) is used to evaluate the risk of individual hazard scenarios by combining initiating event frequencies with failure probabilities of protection layers. Some practitioners include events and conditions that enable the occurrence of hazard scenarios in the analysis, such as conditional modifiers, but sometimes they are excluded to ensure conservative results. However, these events and conditions, and other factors that enable scenarios, are often key parts of hazard scenarios and their exclusion from the analysis can result in overly conservative results. This article broadens the definition of enabling events and conditions to include other factors that can have a significant impact on the risk of hazard scenarios. Such other factors include management systems to account for inadequacies in, and failure to follow, policies, procedures, and work instructions; at‐risk factors to account for the time period in which a process is at risk; incident outcomes to represent different possible consequences for the same initiating event; and release conditions to account for different release conditions or circumstances. Their inclusion in LOPA studies is described with examples. The determination of adjustment factors to account for their effect on scenario risk is also demonstrated. © 2014 American Institute of Chemical Engineers Process Saf Prog 33: 221–226, 2014