Thank you Chris, very insightful point of view. However, I'm not sure about your high demand statement. I know many such units which work without stoppage for long time and a high demand mode is not appropriate to their protection systems in my opinion.

Hello everyone. Quite long time without answer so maybe I can trigger this topic once again. I really wonder your opinion about above high demand statement for the SIFs with breakers as final element. I have many doubts about this approach in the context of real possible demand for SIFs which protect rotating machines in process industry. My experience says that these critical ones usually work for long time without any stoppage, so should be treated as low demand. And one more: good quality breakers have a high operational reliability but usually don't have IEC61508 compliance documentation.

I agree with Anth. A banefit of your proposal is very minimal. Look at the failure rate of safety PLC in comparison to other elements - it's a very small part of overall system PFDavg. So you should aim at improving other parts rather the best one.

I want to return to the topic of legacy systems, because I've just read your additional article on LI about this topic :) We're talking about systems that typically have dozens or even hundreds of SIF functions and even more devices. The problem certainly arises when we look at the devices installed before IEC61511. Let's assume they've all been operating for decades without any problems but for some reasons we want to do sth with their compliance. Doing assessment and relying 100% on generic reliability data can be a trap. Let's look at current equipment reliability data declared by manufacturers. Their expected lifetimes show that devices in legacy systems have typically exceeded these values ​​long time ago. Without evidence of testing, servicing, and refreshes, there's no way to formally confirm that these systems have the reliability we're aiming for. I think the approach you're presenting is based on common sense. There's probably no better method than successive analysis of individual system components and categorizing their importance based on risk assessment. And, whenever possible, upgrade to newer solutions based on real needs with cost-effective way.

Anth, thank you for your comment. That's not quite what I meant. This issue concerns the preparation of internal documents that will be consistent with selected FSM tasks and their implementation into the existing ISO 9001 system. I'm referring mostly to internal procedures that address, for example, the use of FS analysis tools, the approval process for analysis reports, competency management within a team, etc. Of course this will be subject to audit, but in scope of quality ISO audit as some internal part of it. All within the company offering its services as part of FS activities. I remember Ed Marszal from Kenexis mentioned something like this when discussing FSM on his blog.

@Richard Kelly That' great. I haven't read all these available templates yet. So a task for this week ahead of me :)