Pressure-relieving and Depressuring Systems

7th Edition

Includes all amendments and changes through Errata , November 2022

Published by American Petroleum Institute, 05/31/2020


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API 521, 7th Edition – Pressure-relieving and Depressuring Systems

API 521 is applicable to pressure-relieving and vapor 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 standard specifies requirements and gives guidelines for the following:

— examining the principal causes of overpressure;

— determining individual relieving rates;

— selecting and designing disposal systems, including such component parts as piping, vessels, flares, and vent stacks.

This standard does not apply to direct-fired steam boilers.

General Product Information:

Revision 7th Edition
Document Type PDF
Pages 247
Document Language English
Publisher American Petroleum Institute (API)
Status Current


Document History