ISO DIS 23251

Description / Abstract: This document 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 document is intended to supplement the practices set forth in ISO 4126 or API RP 520-1 for establishing a basis of design.

This document specifies requirements and gives guidelines for the following:

— for examining the principal causes of over-pressure;

— determining individual relieving rates;

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

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

This document is a supplement to API Std 521, 6th edition (2014), the requirements of which are applicable with the additions and exclusions specified in this document.