LOPA: Performed When and By Who

Layer of protection analysis (LOPA) was introduced in the mid-1990s by Art Dowell at Rohm & Haas Chemical Company (now Dow Chemical) and by William Bridges at ARCO Chemical (not Lyondell-Basel) and JBF Associates. The first textbook was published in 2001. Since then, the method has swiftly grown in popularity for use in making risk judgments and in deciding on the SIL rating for an SIF. But, many users of LOPA do not know when to use LOPA and so they overuse this tool; and they do not know who should be doing LOPA, so they many times use a team, similar to or the same as a PHA/HAZOP team. This presentation explains what the originators of LOPA intended and why, and also brings the industry up-to-date on the lessons learned from different approaches to using LOPA, related to when to do LOPA and who should do LOPA.