What is Layers of Protection Analysis (LOPA)?

Risk

Layers of Protection AnalysisLOPA

A semi-quantitative method for evaluating whether risk reduction is adequate.

LOPA assigns a probability of failure on demand (PFD) to each independent protection layer (IPL) and calculates mitigated event frequency. If the mitigated frequency exceeds the tolerable risk target, additional layers — often a Safety Instrumented System (SIS) — are required. LOPA is the primary method for determining SIL requirements per IEC 61511.

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Layers of Protection Analysis (LOPA) · Glossary · QEHS — QEHS