This International Standard is applicable to pressure-relieving and vapour-depressuring systems. Although
intended for use primarily in oil refineries, it is also applicable to petrochemical facilities, gas plants, liquefied
natural gas (LNG) facilities and oil and gas production facilities. The information provided is designed to aid in
the selection of the system that is most appropriate for the risks and circumstances involved in various
installations. This international Standard is intended to supplement the practices set forth in ISO 4126 or
APl RP 520-! for establishing a basis of design.
This International Standard specifies requirements and gives guidelines for examining the principal causes of
overpressure; and determining individual relieving rates; and selecting and designing disposal systems,
including such component parts as piping, vessels, flares, and vent stacks. This international Standard does
not apply to direct-fired steam boilers.
Piping information pertinent to pressure-relieving systems is presented in 7.3.1.