ISO 23251:2019 pdf free.Petroleum, petrochemical and natural gas industries – Pressure-relieving
and depressuring systems.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in API Std 521, 6th edition (2014) and the following apply.
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3.1 pressure-relief valve safety valve valve designed to open and relieve excess pressure and to reclose and prevent the further flow of fluid after normal conditions have been restored
ISOURCE: API Std 521, 6th edition (2014), 3.1.59, modified — Admitted term was added.]
Note ito entry: “Pressure-relief valve” is equivalent to 3.1.59 in API Std 521, 6th edition (2014). It is reproduced here for clarity.
3.2 rupture disc device bursting disc safety device non reclosing pressure-relief device actuated by static differential pressure between the inlet and outlet of the device and designed to function by the bursting of a rupture disc [SOURCE: API Std 521, 6th edition (2014), 3.1.71, modified — Admitted term was added.] Note 1 to entry: “Rupture disc device” is equivalent to 3.1.71 in API Std 521, 6th edition (2014). It is reproduced here for clarity.
3.3 safety valve pressure-relief valve spring-loaded pressure-relief valve actuated by the static pressure upstream of the valve and characterized by rapid opening or pop action
[SOURCE: API Std 521, 6th edition (2014), 3.1.75, moditied — Admitted term was added.]
Note 1 to entry: “Safety valve” is equivalent to 3.1.75 In API Std 521, 6th editIon (2014). It is reproduced here for clarity.
4 Supplements to API Std 521, 6th edition (2014)
4.1 General requirements The requirements specified in API Std 521, 6th edition (2014) shall apply, with the exceptions specified in 42 to 4.
4.2 Chemical reaction The requirements specified in API Std 521, 6th edition (2014), 4.4.11.1 c) apply with the following exceptions. An additional methodology for sizing an emergency vent for chemical reactions and other two-phase flow applications is given in Iso 4126-10.
4.3 Fires The requirements specified in API Std 521, 6th edition (2014), 4.4.13.2.1, Paragraph 2 and 4.4.13.2.3, Table 4 apply with the following exceptions. For the purpose of this provision, ISO 28300 shall be used in place of API Std 2000. The requirements specified in API Std 521, 6th edition (2014), 4.4.13.2.4.3, Formula (9) with the following exceptions. For the purpose of this provision, the ISO 4126 series shall be used in place of API RP 520-1. The requirements specified in API Std 521, 6th edition (2014), 4.4.13.2.4.3, Formula (10) with the following exceptions. The coefficient, C, in Formula (10) is different from the coefficient, C, given in Iso 4126-7. Users should ensure that whenever the coefficient, C, is used in this document, it is the C from Formula (10) that applies and not the one mentioned in ISO 4126-7. The requirements specified in API Std 521,6th edition (2014), 4.4.13.2.5.4 with the following exceptions. An additional methodology for sizing PRV or emergency vent on mixed phase flow applications is given in ISO 41 26-10. 4.4 Causes for vacuum
The requirements specified in API Std 521, 6th edition (2014), 4.5.2 c) and h) apply with the following exceptions. For the purpose of this provision, Iso 28300 shall be used in place of API Std 2000. 4.5 Considerations for individual PRDs 4.5.1 General The requirements specified in API Std 521, 6th edition (2014), 4.9.1 apply with the following exceptions. For the purpose of this provision, the ISO 4126 series shall be used in place of API RP 520-1. 4.5.2 Multiple PRDs The requirements specified in API Std 521, 6th edition (2014), 4.9.4.1 apply with the following exceptions. For the purpose of this provision, EN 764-7 shall be used in place of ASME Code, Section VIII, Division 1. The requirements specified in API Std 521, 6th edition (2014), 4.9.4.3 apply with the following exceptions. For the purpose of this provision, EN 764-7 shall be used in place of API RP 520-1 and API RP 520-2.ISO 23251 pdf download.