Covers the sizing and selection of pressure relief devices employed in refineries and related industries, for apparatus with maximum allowable working pressure of 15 psig (103kPag) or more. These devices are meant to protect unfired pressure vessels and related apparatus from overpressure from operating and fire contingencies. Covers basic information and definitions about operational characteristics and applications of devices, and sizing procedures and methods based on steady state flow of Newtonian fluids. The devices only protect vessels against overpressure, and not against structural failure, when vessels are subjected to very high temperatures, such as fire.

API 520-1 Ed. 8 (2008)