Functional Safety Assessments and Audits
Functional Safety Assessments (FSAs) are an integral part of the Safety Life Cycle. IEC 61511 defines five FSA’s, of which FSA Stage 3 and Stage 4 are considered to be mandatory. In addition to verification, validation and FSA, independent Audits confirm compliance with the Site FSM Plan.
Functional Safety Assessments (FSAs) are specific review stages during the Safety Life Cycle. These are independent cross-checks to confirm that functional safety is achieved in accordance with the corresponding SLC stage.
There are five stages of FSA identified in IEC 61511, of which FSA Stage 3 and Stage 4 are considered mandatory (FSA-3 prior to introduction of hazards and FSA-4 during operation). However, in order to maintain a robust FSM system it is strongly recommended to also carry out FSA Stages 1, 2 and 5 in order to identify systematic deficiencies before they develop into potential hazards.
The FSA team shall comprise expertise with the appropriate competence corresponding to the assessment stage. PSC can provide independent expertise as per IEC 61511-1 and can lead / coordinate and document the FSA. The assessment shall be carried out on the basis of a pre-prepared procedure and checklist corresponding to the FSA Stage and appropriate to the SIF criticality. The result of the FSA shall be a statement of compliance to IEC 61511 corresponding to the life cycle stage.
In addition to FSA, IEC 61511 also recommends independent audits. Such audits shall provide an appraisal of whether the required documentation according to a particular SLC phase is available, but not an overall declaration of functional safety status (as required in FSA). Where gaps are identified, recommendations for improvements are made. Audits may be carried out separately and in addition to verification, validation and FSA in line with the Audit Plan. Again, PSC can provide independent expertise to carry out audits as per IEC 61511.