Failure Probability

Failure Probability Is it very important to calculate very precisely the average probability of failure “PFDavg” of a Safety Instrumented Function? The short answer is “NO“, and we will try to explain it below. The first thing to say is that Functional Safety is much more than meeting the probability of failure. IEC 61511 defines …

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Partial Valve Stroke Test

Partial Valve Stroke Test (PVST) The Partial Valve Stroke Test is used in the Safety Instrumented Function (SIF) to diagnose valve failures without having to stop the process. The problem of the shut-off valves in low demand SIFs is that they remain in a position (open or closed) for many months, without knowing if they …

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