Functional Safety Assessment -

FSA for your projects

Experiences with FSA results

Our experience shows that projects involving SIL-rated Safety Intsrumented Systems often come short of meeting the requirements of IEC 61511.

This is a challenge, but also an opportunity for safety and productivity improvement.


Compliant without comment


Require long-term improvement


Need action before start-up

Why you may need a Functional Safety Assessment or Audit - FSA

You will need a functional safety assessment or audit if you are working on any project or industrial process plant that has safety functions with a safety integrity level (SIL) requirement. These occur in oil & gas, power generation, chemical and pharmaceutical production, pulp and paper and others.


FSA is often required for:

  • Emergency Shut Down - ESD systems
  • Burner Management Systems - BMS - on industrial boilers
  • Overfill Protection on Tanks
  • Pressure protection for piping and pressure vessels

Projects involving SIL-rated safety instrumented systems (SIS) need FSA by an independent competent person because of the relatively complex nature of applying international standards.

Stages of FSA have been defined; from FSA 1, where safety requirements are first assessed, to FSA 5, where a system has been installed.

The IEC 61511 (BS EN 61511) requirement for an operations FSA, called FSA 4, applies to existing running facilities, irrespective of age, even if there are no modifications being made to safety instrumented systems.

Steps for effective FSA

  1. 1
    Step 1:
    Gather documentation including the hazard and risk analysis, safety requirements specification, detailed equipment specifications for safety instrumented system (SIS) hardware, software and the full make-up of any planned or previously installed safety instrumented functions (SIF).
  2. 2
    Step 2:
    Appoint an independent competent person to lead the FSA. It is crucial that the person appointed is competent in the application domain and with the primary standards for FSA, namely IEC 61508 and IEC 61511. Request a CV/Resume, and look for previous experience of leading FSA on other similar projects or installations. The lead assessor must also be independent of the project for FSA 1 to FSA , and independent of the facility for FSA 4 or FSA 5.
  3. 3
    Step 3:
    Plan the FSA scope and methodology. In conjunction with the lead assessor, write an FSA plan which details what will be included and excluded from the FSA. Ensure that the plan includes a sound methodology and expected deliverables.
  4. 4
    Step 4:
    Communicate the FSA plan. Ensure that all stakeholders in the project understand their required input to the FSA. This may include engineering service contractors and suppliers, in addition to internal personnel.
  5. 5
    Step 5:
    Carry out the FSA. Support the lead assessor to conduct the FSA according to the methodology outlined in the FSA plan. This may take days, weeks or possibly many months to complete. The time taken depends highly on the complexity of the project or installation and the maturity of documentation.
  6. 6
    Step 6:
    Produce an FSA report and communicate it. Usually the job of the lead assessor, the results of the FSA applicable to each stakeholder should be fully communicated.
  7. 7
    Step 7:
    Plan actions for improvement. Recommendations for improvements will typically result from FSA activities. These should generate a plan towards improvong future projects and/or the existing installation.

Functional Safety Assessment and Audit Plan, Procedure and Checklist

If you need to complete a Functional Safety Assessment or Audit, then you may be thinking "where do I start?".

Our template includes a ready-made plan which you can adapt to fit your needs, including a set of detailed recommended work-flows for assessment and audit at FSA 1, FSA 2, FSA 3, FSA 4 and FSA 5.

Call us now in Cambridge, UK on +44 (0)1223 653 169

Telephone now to speak to someone about your FSA project

Frequently Asked Questions about FSA

What is a functional safety assessment?

What is a functional safety audit?

When is the best time to do a functional safety assessment?

Who should do a functional safety assessment?

Who should be involved with a functional safety audit?

What is FSA 1?

What is FSA 2?

What is FSA 3?

What is FSA 4?

What is FSA 5?

Functional Safety Assessment

A Stage 5 Functional Safety Assessment (FSA) was required for a safety instrumented system (SIS) undergoing upgrade on a Top Tier COMAH* chemical plant. We provided the lead assessor to scope, plan and deliver an independent assessment report. 

We reviewed the safety instrumented system modification scope, including a revised hazard study, layer of protection analysis, safety requirements and the design changes to hardware and software of the system. The FSA stage 4 concluded with witnessed validation of the entire SIS prior to start-up.

eFunctionalSafety also completed a Stage 4 FSA by reviewing operations and maintenance procedures and proof test records for the existing system.

*COMAH - Control of Major Accident Hazards - UK legislation.

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