Layers of Protection Analysis - LOPA -  is a risk assessment technique for all industrial-scale plants that store or process flammable, toxic or environmentally hazardous materials. Usually following on from a Process Hazard Analysis study like HAZOP, LOPA requires specialist support to correctly credit protection layers.

  • LOPA can be applied to new projects or existing plant
    Ideally starting after P&ID's are well developed and HAZOP is completed, our qualified LOPA experts will support your team to review scenarios of concern.
  • Existing processes with hazardous materials
    Depending where you are in the world, there may be slightly different local standards or requirements for the frequency of reviews. Most companies review HAZOP & LOPA studies at least every five years, even when major changes have not occurred.
  • Plant modifications and upgrades
    Any plant modifications or upgrades must re-complete HAZOP and potentially LOPA on proposed changes.

LOPA Frequently Asked Questions

What is LOPA?

LOPA - Layer Of Protection Analysis. LOPA is a risk study method first proposed by the AIChE (American Institute of Chemical Engineers) in the early 2000's to provide a simplified method for attributing risk reduction to protection layers.

Who needs LOPA?

End users in chemical, oil and gas, pharmaceuticals and others with major accident hazards.

Is LOPA a Process Hazard Identification Method?

No. LOPA gets done after hazards have been identified by other techniques such as HAZOP, What-If? or similar methods. A good guide is that Process Flow diagrams and P&ID's should be complete.

Is LOPA a Standardized Procedure?

No. LOPA is applied in many different ways, so there is no standard (correct as of July 2021). This makes defining a LOPA procedure a critical step for companies to agree and approve.

What's needed to start LOPA?

Clear terms of reference (procedure) plus information about the scenarios to be assessed. Data usually comes from a process hazard analysis e.g. HAZOP, coupled with detailed P&ID drawings and a knowledge of the process. LOPA is a team study, and should be led by someone trained in the technique.

Can LOPA be used for SIL?

Yes and No.

Yes: Safety Integrity Level TARGETS can be derived directly from a LOPA study with appropriate procedures.

No: It is not possible to use LOPA to calculate if a Safety Instrumented Function (SIF) meets the SIL target.

LOPA Software Support

We can support projects with your preferred LOPA software if you have already selected one, or with template spreadsheets optimized for delivering LOPA documentation.

Our specialist software experience spans all the major specialist tools, including aeShield, exSILentia PHAx, HAZOP Leader, PHA-Pro, SafetyInsight and SISSuite.

  • The relatively simple mathematics of Layer of Protection Analysis make it possible to complete without specialist support tools. We have spreadsheet templates that can calculate low demand and high demand scenarios to provide a concise record of a team LOPA review.
  • A number of specialist software tools are available to support LOPA. Such software tools are usually more cost-effective when considering fulfilling multiple aspects of the safety life-cycle.

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