EN ISO 23251:2007
(Main)Petroleum, petrochemical and natural gas industries - Pressure-relieving and depressuring systems (ISO 23251:2006)
Petroleum, petrochemical and natural gas industries - Pressure-relieving and depressuring systems (ISO 23251:2006)
ISO 23251:2006 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. ISO 23251:2006 is intended to supplement the practices set forth in ISO 4126 or API RP 520-1 for establishing a basis of design.
ISO 23251:2006 specifies requirements and gives guidelines for examining the principal causes of overpressure; and determining individual relieving rates; and selecting and designing disposal systems, including such component parts as piping, vessels, flares, and vent stacks.
ISO 23251:2006 does not apply to direct-fired steam boilers.
Erdöl-, petrochemische und Erdgasindustrie - Druckentlastungs- und Druckausgleichssysteme (ISO 23251:2006)
Industries du pétrole, de la pétrochimie et du gaz naturel - Systèmes de dépressurisation et de protection contre les surpressions (ISO 23251:2006)
L'ISO 23251:2006 est applicable aux systèmes de protection contre les surpressions et de dépressurisation des phases gazeuses. Bien qu'elle soit principalement destinée à être utilisée dans les raffineries de pétrole, elle est également applicable aux installations pétrochimiques, aux usines de traitement de gaz, aux installations pour gaz naturel liquéfié (GNL) et aux installations de production de pétrole et de gaz. Les informations fournies sont conçues pour faciliter le choix du système le plus approprié, compte tenu des risques et des circonstances associés à diverses installations. L'ISO 23251:2006 a pour objet de compléter les pratiques énoncées dans l'ISO 4126 ou l'API RP 520-I en vue d'établir une base de conception.
L'ISO 23251:2006 spécifie les exigences et donne des lignes directrices pour étudier les principales causes de surpression, déterminer les débits de décharge individuels et sélectionner et concevoir des systèmes d'évacuation, y compris des composants tels que tuyauteries, récipients, torches et colonnes d'évent.
L'ISO 23251:2006 ne s'applique pas aux chaudières à vapeur à flamme directe.
Petrokemična industrija ter industrija za predelavo nafte in zemeljskega plina - Sistemi za sproščanje in izravnavanje tlaka (ISO 23251:2006)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2007
3HWURNHPLþQDLQGXVWULMDWHULQGXVWULMD]DSUHGHODYRQDIWHLQ]HPHOMVNHJDSOLQD
6LVWHPL]DVSURãþDQMHLQL]UDYQDYDQMHWODND ,62
Petroleum, petrochemical and natural gas industries - Pressure-relieving and
depressuring systems (ISO 23251:2006)
Erdöl-, petrochemische und Erdgasindustrie - Druckentlastungs- und
Druckausgleichssysteme (ISO 23251:2006)
Industries du pétrole, de la pétrochimie et du gaz naturel - Systemes de dépressurisation
et de protection contre les surpressions (ISO 23251:2006)
Ta slovenski standard je istoveten z: EN ISO 23251:2007
ICS:
75.180.20 Predelovalna oprema Processing equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 23251
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2007
ICS 75.180.20
English Version
Petroleum, petrochemical and natural gas industries - Pressure-
relieving and depressuring systems (ISO 23251:2006)
Industries du pétrole, de la pétrochimie et du gaz naturel - Erdöl-, petrochemische und Erdgasindustrie -
Systèmes de dépressurisation et de protection contre les Druckentlastungs- und Druckausgleichssysteme (ISO
surpressions (ISO 23251:2006) 23251:2006)
This European Standard was approved by CEN on 12 July 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 23251:2007: E
worldwide for CEN national Members.
Foreword
The text of ISO 23251:2006 has been prepared by Technical Committee ISO/TC 67 "Materials,
equipment and offshore structures for petroleum and natural gas industries” of the International
Organization for Standardization (ISO) and has been taken over as EN ISO 23251:2007 by
Technical Committee CEN/TC 12 "Materials, equipment and offshore structures for petroleum,
petrochemical and natural gas industries", the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by January 2008, and conflicting national
standards shall be withdrawn at the latest by January 2008.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
Kingdom.
Endorsement notice
The text of ISO 23251:2006 has been approved by CEN as EN ISO 23251:2007 without any
modifications.
INTERNATIONAL ISO
STANDARD 23251
First edition
2006-08-15
Corrected version
2006-10-01
Petroleum, petrochemical and natural gas
industries — Pressure-relieving and
depressuring systems
Industries du pétrole, de la pétrochimie et du gaz naturel — Systèmes
de dépressurisation et de protection contre les surpressions
Reference number
ISO 23251:2006(E)
©
ISO 2006
ISO 23251:2006(E)
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ii © ISO 2006 – All rights reserved
ISO 23251:2006(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Causes of overpressure. 10
4.1 General. 10
4.2 Overpressure protection philosophy. 10
4.3 Potentials for overpressure . 11
4.4 Recommended minimum relief system design content . 17
4.5 List of items required in flare-header calculation documentation . 20
4.6 Guidance on vacuum relief. 20
5 Determination of individual relieving rates. 22
5.1 Principal sources of overpressure. 22
5.2 Sources of overpressure . 24
5.3 Effects of pressure, temperature, and composition . 24
5.4 Effect of operator response. 24
5.5 Closed outlets . 24
5.6 Cooling or reflux failure . 25
5.7 Absorbent flow failure. 26
5.8 Accumulation of non-condensables. 26
5.9 Entrance of volatile material into the system . 26
5.10 Failure of process stream automatic controls. 27
5.11 Abnormal process heat input . 29
5.12 Internal explosion (excluding detonation) .30
5.13 Chemical reaction. 30
5.14 Hydraulic expansion. 31
5.15 External pool fires. 36
5.16 Jet fires . 51
5.17 Opening manual valves. 51
5.18 Electric power failure. 51
5.19 Heat-transfer equipment failure . 52
5.20 Vapour depressuring. 55
5.21 Special considerations for individual pressure-relief devices . 63
5.22 Dynamic simulation. 64
6 Selection of disposal systems . 65
6.1 General. 65
6.2 Fluid properties that influence design. 65
6.3 Atmospheric discharge. 66
6.4 Disposal by flaring. 76
6.5 Disposal to a lower-pressure system . 95
6.6 Disposal of liquids and condensable vapours . 96
7 Disposal systems. 97
7.1 Definition of system design load . 97
7.2 System arrangement . 100
7.3 Design of disposal system components. 102
7.4 Flare gas recovery systems. 137
ISO 23251:2006(E)
Annex A (informative) Determination of fire relief requirements. 142
Annex B (informative) Special system design considerations . 146
Annex C (informative) Sample calculations for sizing a subsonic flare stack. 149
Annex D (informative) Typical details and sketches. 166
Annex E (informative) High integrity protection systems (HIPS) . 169
Bibliography . 176
iv © ISO 2006 – All rights reserved
ISO 23251:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft Internationa
...
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