Facilities that are covered by PSM/RMP have in general grown over the years and are processing significantly more than a decade ago or even when they were built. As a result, the flare (or other) disposal system needs to be checked to ensure that it can still meet the facility’s needs.
PSM/RMP covered facilities typically hire a few engineers directly or contract this work out to a general engineering firm. A group of engineers take a smattering of desperate data and consolidate it into a flare report. Typically the result of the final product can be summarized as Garbage-In-Garbage-Out.
Our engineering project teams divide the work up in a manner that allows them to efficiently check the basis for the most important loads (the 80 / 20 rule applies here) while modelling the flare systems to ensure they are able to handle the loads. We don’t just look at some arbitrary Power Failure; in fact, we statistically model the flare system using one of many tools (QRA, Dynamics, Load Probability, etc.) to ensure that the final design case is not a “one in a billion scenario,” but hits a reasonable design basis from the risk matrix.