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
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:
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.
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.
Telephone now to speak to someone about your FSA project
Functional safety assessment is an important review activity which is required in IEC 61511 and IEC 61508 to be carried out at least once prior to start-up of a new or modified automated safety system.
The activity must be led by a senior, competent person, who is not involved with the step or steps being assessed.
The end expectation of a functional safety assessment is that a judgement is made about the functional safety conformance and safety integrity achieved by every safety instrumented function within the system(s) being assessed.
The hope is that duty holders will implement functional safety assessment planning at the outset of a new project or modification process. Every organisation involved in delivering functional safety equipment or services must be aware of their responsibilities.
Functional safety audit is intentionally separated from functional safety assessment in the IEC series of functional safety standards.
The goal is for an audit of procedures and records to determine whether an appropriate functional safety management system is in place, and it is being followed.
Somewhat like a Quality or Gap audit, a functional safety audit cannot be conducted until functional safety procedures are in place. The assessor is looking for sufficient evidence that procedures are being followed.
An audit alongside a functional safety assessment activity is an entirely valid prospect for an existing installation.
The timing of a functional safety assessment depends largely on what type of project or installation is being assessed, and to which standard.
Projects looking at conformance with IEC 61511 have 5 recommended stages - see FSA 1 to FSA 5 in the remaining FAQ's in this section.
Stage 1 FSA - When the hazard and risk assessment is complete, and SIL target has been selected. Technically, it is possible to wait until the safety requirements are completed before starting functional safety assessment stage one, but only if this is available immediately following the SIL target allocation or SIL determination stage.
DO NOT WAIT FOR REQUIREMENTS TO FULLY STABILIZE BEFORE STARTING FUNCTIONAL SAFETY ASSESSMENT.
Stage 2 FSA - This is best completed alongside Factory Acceptance Testing, although it is advisable to start the stage two functional safety assessment activity when the instrumentation and logic solver selection has been made. Logic solver software review should commence when the software detailed design specification is available.
Stage 3 FSA - This must be complete before the safety instrumented system enters into service. To achieve this in practice, it is crucial that FSA 1 and FSA 2 stage actions are closed out.
Key documents for this stage include the installation, commissioning and validation planning, and witnessed records that validation testing of each SIS and SIF is complete.
Also known as an FSA stage 4 - since IEC 61511 edition 2 was published, it has been a requirement to conduct functional safety assessment of existing safety instrumented systems after some time in operation and maintenance.
This activity must led by someone independent of the operations and maintenance team.
FSA stage 5 - this is an assessment of any modification of a safety instrumented system (SIS) or safety instrumented function (SIF) hardware or software.
Except for fully like-for-like hardware changes, an FSA 5 may repeat elements of FSA 1, 2 and 3 for a limited part of the system.
ALL changes to software MUST undergo FSA 5.
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.