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IEC 61511 - FSA Stage 5 - Modification
Hi all, With regards to carrying out an FSA 5 assessment, is it deemed necessary to carry one out if you are only adding new SIFs into an existing Safety Logic Solver. In this example, the new SIF to be installed does not share any of the same elements (other than the logic solver) as any existing SIF's, and also the new SIF has no impact on any existing SIFs? My thoughts are no, but just wondering if anyone else can clarify if I am correct?
2 likes • Apr 3
Correct, adding a new SIF should go through the FSA lifecycle (1 to 3) and any modifications to an existing SIF go through an FSA5.
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Lee Johnson
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@lee-johnson-8017
Electrical & Instrumentation Design Engineer

Active 38d ago
Joined Mar 25, 2026