How do you conduct a Functional Safety Assessment (FSA) for a new SIS installation?

Functional Safety Assessment methodology per IEC 61511: FSA Stage 1 - review safety requirements specification (SRS completeness, SIL determination adequacy, functional requirements clarity), assess competency of project team; FSA Stage 2 - review detailed design (architecture meets SIL, calculations correct, systematic capability adequate), verify application program against SRS; FSA Stage 3 - review installation and commissioning results, validate proof tests demonstrate SIF functionality; FSA Stage 4 - review operation and maintenance procedures, training records, bypass management. Assessment independence requirements increase with SIL level. Document findings in FSA report with conclusion on fitness for purpose. Address outstanding actions before placing SIS in service. Assessor must be competent and independent of design team.