Performing a risk analysis as part of an IEC61508 / 61511 / ISA 84.01 safety lifecycle process can be quite challenging. How can you be sure you get what you need within budget and how can your team provide the best value for money? When these services are brought in from outside, it can be difficult to see high quality and the value of that quality in advance. But it is almost always easy to see the cost. Also the buying decision is often based on the project requirements rather than the overall life of the plant requirements. As a result, this situation can easily lead to a lower quality risk analysis. This problem is what classical economics calls “the market for lemons,” and the safety lifecycle risk analysis often falls into this trap.

In an ideal world, we would be able to not only carry out a risk analysis but translate that analysis into a true understanding of the risk with a process or machine application. Then from that understanding, we can go a step further and make improvements. Such improvements can consider both the inherent risk management elements in the process, as well as any auxiliary SIL rated safety functions we may need to meet our risk target. This risk management optimization and cost benefit analysis is unfortunately much too rare.


What is even worse, is that the analysis costs people are trying to save are usually small relative to the project equipment spend. They are negligible relative to the years of plant production at stake. I have often found, the best results come from being generous in the low cost areas such as HAZOP and LOPA risk identification workshops with enough time, and enough skilled resources to properly understand the risk first. Second, this should be coupled with the opportunity to implement improvements based on this understanding. When projects do provide such freedom, my experience has been that the benefits typically outweigh the costs by a factor of five to ten. After all, it does not take very many SIL 3 to SIL 1 SIF performance target reductions to pay for a few extra days of workshop time. So if you are in a position to provide input to a budget or schedule for hazard identification and risk analysis, look at both the opportunity to add significant value as well as the standard relatively modest costs.

Tagged as:     sil 1     SIL     SIF     safety lifecycle     risk management     risk analysis     lopa     iec6150861511isa 84.01     hazop     eric scharpf  

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