Is a reliable plant a safe plant?

Reliability does not always equal safety.

By William L. Mostia, Jr.

Noted and well-respected safety guru and author of Engineering a Safer World, Nancy Leveson, once stated in a presentation on "The Path to More Cost-Effective System Safety" that reliability does not equal safety: Reliability ≠ Safety. This is based on the observation that many accidents occur without any component or equipment hardware or software failure, leading to the conclusion that systems of highly reliable components or equipment alone are not necessarily safe. She also said that complexity compounds this issue.

So how does this statement relate to the process industries? Reliability and safety are many times treated differently, as if they're dissimilar concepts or philosophies. It seems certain that we want a reliable and safe plant, but how do these concepts interact in a process plant?

Reliability as a plant function depends somewhat on one's perspective and goals. Reliability from the perspective of the maintenance department may not be the same as reliability in the process safety management (PSM) or engineering departments.

Read the whole story on Control Global

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