It does not apply to direct-fired steam boilers, which are governed by other specific codes. Core Objectives of the Standard
: A detailed technical manual including ISO 23251 sizing formulas. Fire Case and Hydraulic Thermal Expansion Report iso 23251 pdf
: Primarily designed for oil refineries, it also applies to petrochemical facilities, gas plants, LNG facilities, and upstream oil and gas production. It does not apply to direct-fired steam boilers,
ISO 23251 is a global technical standard for pressure-relieving and depressuring systems it also applies to petrochemical facilities