FALSE. The current version of the functional safety standard (IEC 61511:2026) recognises the possibility that risk reduction will be provided by means other than SIL rated SIF’s, but – as for H&RA – “no detailed requirements are given”. Again, we interpret this to mean that the approach should follow Functional Safety Management, but the implementation is outside of the scope of 61511.
=Method team members work in the development of various international standards and guidelines and are involved the development of the next edition of 61511. It is already clear that the new edition will have more to say about “other risk reduction measures”, which seems sensible, when the risk reduction that a relief valve delivers could be higher than that from a SIL rated SIF.