ANSI 84 - SIL Ratings - Manual Operations

[Rogers1936]

When a Client has a manual equipment operating procedure, or even if it is "...supervised-manual..." according to NFPA 85; what is the engineer's position on establinhing a SIL rating for LOPA?

 

[unSIL]

If an operating procedure exists (e.g. for startup) and the LOPA is for the startup case, it can be credited as a layer of protection. It's value is dependant on the quality of the procedure and the number of people involved to verify the steps are completed in the proper sequence. Normally the risk reduction factor of up to 0.1 would be considered reasonable.