Considering External Fire to be a Non-Applicable Overpressure Scenario

An external fire is usually considered an applicable overpressure scenario as the necessary elements to fuel the ignition of a fire are almost always present within a refinery, gas plant, or petro-chemical plant.  This article will demonstrate the situations and conditions when it is acceptable to not consider external fire as an applicable scenario.  The primary circumstances that will be covered include: surrounding chemical inventory, ignition source distance, and equipment elevation.  In the event that these conditions are such that fire is considered an applicable scenario, the required flammable liquid pool conditions should be evaluated to ensure that an external fire can both be created and sustained to result in an overpressure occurrence.