Layers of protection analysis (LOPA) is a semi-quantitative methodology that can be used to identify safeguards that meet the independent protection layer (IPL) criteria established by CCPS in 1993.
LOPA can be used at any point in the lifecycle of a project or process, but it is most cost effective when implemented during front-end loading when process flow diagrams are complete and the P&IDs are under development. For existing processes, LOPA should be used during or after the HAZOP review or revalidation. LOPA is typically applied after qualitative hazards analysis has been completed, which provides the LOPA team with a listing of hazard scenarios with associated consequence description and potential safeguards for consideration.
