Layer of Protection Analysis (LOPA)

Overview

HAZOP studies often end with recommendations to add safeguards, but they rarely answer the question that matters most: is the risk now low enough? Layer of protection analysis fills that gap. It is a semi-quantitative method that estimates how often a hazardous scenario will lead to its consequence, credits only those safeguards that are truly independent and effective, and compares the result with the company's tolerable risk criteria. LOPA is also the most common method for setting the required safety integrity level of safety instrumented functions under IEC 61511. This course teaches participants to carry out and review LOPA studies with confidence. They learn to select scenarios from HAZOP, estimate initiating event frequencies, test candidate independent protection layers against the core attributes, apply conditional modifiers and determine SIL targets. Common pitfalls, such as double counting and over-crediting human response, are examined in detail.

Objectives

• Explain the principles of LOPA and its link to HAZOP and SIL
• Select and define scenarios suitable for LOPA
• Estimate initiating event frequencies from credible data
• Test safeguards against IPL criteria and assign credits
• Apply enabling conditions and conditional modifiers correctly
• Compare results with tolerable risk criteria
• Determine SIL targets for safety instrumented functions
• Review LOPA studies and identify common errors

Who should attend

Training methodology

After each concept, participants work through LOPA worksheets for scenarios taken from real HAZOP studies of a gas compression system, a distillation column and a storage tank. They argue for and against IPL credits in small groups, then compare their results with a reference solution. Worked examples show how errors change the SIL target. On the final day, teams run a short LOPA session on a new scenario and present their findings.

Programme outline

Dates and fees

Certificate

Frequently asked questions