Executing IEC 61511 Process Safety Projects

ControlGlobal.com has an excellent article on the global process safety standard, IEC 61511. The article, IEC 61511 Implementation – The Execution Challenge, shares the experiences of two Mustang Engineering process automation project veterans.

I turned to one of Emerson’s certified functional safety experts (CFSE) and long-time process safety veteran, Len Laskowski, for his thoughts on the article. You may recall Len from numerous process safety-related posts.

In our phone conversation, Len’s first comment after reading the article was, “This sounds like the voices of experience. One does not just declare, ‘On the next project we will implement IEC 61511’ and have life be happy ever after. As the article suggests, a company needs to adopt the IEC 61511 Safety Life Cycle. This takes time and resources that many process manufacturers underestimate.” Len noted that by following the Safety Life Cycle and doing the needed work will give process manufacturers the foundation to properly execute a project–and more importantly, a safe facility.

He agreed with the authors of the large challenges confronting process manufacturers when planning, designing, executing, and maintaining their operations using the IEC 61511 process safety lifecycle. The article’s authors frame these challenges:

The Safety Instrumented System (SIS) standard, IEC 61511, is driving the need for new engineering tools and Project Execution Plans (PEPs). The standard is a lifecycle approach to defining, implementing and managing a safety instrumented system (SIS). Industry discussions tend to focus on the technical aspects of the standard, but project execution is proving to have an equal or perhaps greater impact on the quality and success of an IEC 61511 project. This article describes a few of the challenges from the EPC [engineering, procurement, and construction] and MAC [main automation contractor] perspective, and suggests approaches to enhance IEC 61511 execution and technical outcomes.

I asked Len what most caused these project to go awry and without hesitation he said it was giving the upfront planning the time it requires–especially if this is the first time the process manufacturer has executed the project using the IEC 61511 approach or if the process is new. Even with completed Hazard and Operability (HAZOP) studies and validated layers of protection analysis (LOPA), it takes a lot of time and there is usually quite a bit of recycle. One example Len cited was a pressure relief valve. When walking through the hazard scenarios, discoveries may come up, such as insufficient sizing for reverse flow conditions. Changes may have to be made which ripple to other safety instrumented functions (SIFs).

Another example Len offered is alarm level settings for standalone alarms that are used as an independent layer of protection. Questions must be asked and answered if operators really have the required minimum amount of time to do something as a result of the alarm condition. It also must be clear exactly what the operator must do to alleviate the alarm condition. And ultimately, can all this be done within the process safety time for the given condition? Resolving these questions takes cross-departmental participation and it all adds up to increased time required on the project’s front end.

Len’s guidance to project engineers is to resist the temptation to shortcut this front end planning. It will cost more on the backend of the project in terms of rework, will increase project timelines, and will increase the difficulty in testing the safety instrumented functions over time.

Len shared more than I can fit in a single blog post so I’ll hold some back for future posts. If you have some wisdom to share based on your project experiences, add your thoughts below.

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