Functional Safety Assessment -

FSA for your projects

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.

Experiences with FSA 1, 2, 3

Our experience shows that projects involving SIL-rated Safety Instrumented Systems (SIS) often fall short of meeting the requirements of IEC 61511.

This is a challenge for all concerned, but tackling functional safety head-on can bring huge side benefits in organisation improvement.


Compliant without comment


Require long-term improvement


Need action before start-up

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?

Read FSA Articles & Papers

If you own or operate any electrical / electronic or programmable system that has safety functions with a SIL (safety integrity level) rating, then you need to conduct periodic functional safety audit or FSA 4.I hear you say, "functional safety audits and functional safety assessments are not a requirement, our installation pre-dates these new-fangled standards!". Read

Functional Safety Assessment may be a dry topic even at the best of times, so much so that I took it as a personal challenge to try and write a paper about it!The paper highlights experiences from several different projects and concludes with some simple recommendations to save time, money and mistakes.The paper featured at

Achieving complete compliance with "risk-based" functional safety standards like IEC 61511 is a great objective to have, but is it, in fact, possible?

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

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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