A guide for plant engineers in the design, installation, and operation of pressure-relieving and depressuring systems. Supplements API Recommended Practice 520, Part I. Guidelines are provided for examining principal causes of overpressure; determining individual relieving rates; and selecting and designing disposal systems, including such component parts as vessels, flares, and vent stacks. Suggested solutions to the immediate design and economic and safety problems involved in pressure-relieving discharge systems are presented. Includes a new section on flare gas recovery.