Pressure Relief System Reaction Forces – the Importance of Evaluating Existing Installations

Overpressure protection analysis has evolved significantly since the inception of the PSM standard, but one aspect that appears to have been overlooked is the mechanical stress applied to the piping during overpressure events.  Recent events have led several facilities to request more attention be paid to the effects relief device discharges have on their piping.  A series of representative installations were evaluated in order to determine which parameters associated with pressure relief have the strongest impact on the installations, with particular attention being paid to the dynamic effects of the release.  Criteria for identifying pressure relief device installations which may exceed the allowable stress levels were developed from these systems.  This criteria was then evaluated against a petrochemical facility’s pressure relief systems and benchmarked for its validity as a first pass tool to identify potential installations that may require physical supports.