Petroleum, petrochemical and natural gas industries — Pressure-relieving and depressuring systems

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 supplements API Std 521, 6th edition (2014), the requirements of which are applicable with the exceptions specified in this document.

Industries du pétrole, de la pétrochimie et du gaz naturel — Systèmes de dépressurisation et de protection contre les surpressions

General Information

Status
Published
Publication Date
17-Mar-2019
Current Stage
6060 - International Standard published
Start Date
18-Mar-2019
Completion Date
18-Mar-2019
Ref Project

RELATIONS

Buy Standard

Standard
ISO 23251:2019 - Petroleum, petrochemical and natural gas industries -- Pressure-relieving and depressuring systems
English language
5 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

INTERNATIONAL ISO
STANDARD 23251
Second edition
2019-03
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 23251:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 23251:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23251:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Supplements to API Std 521, 6th edition (2014)................................................................................................................. 2

4.1 General requirements ....................................................................................................................................................................... 2

4.2 Chemical reaction ................................................................................................................................................................................. 2

4.3 Fires .................................................................................................................................................................................................................. 2

4.4 Causes for vacuum ............................................................................................................................................................................... 3

4.5 Considerations for individual PRDs ...................................................................................................................................... 3

4.5.1 General...................................................................................................................................................................................... 3

4.5.2 Multiple PRDs ..................................................................................................................................................................... 3

4.6 Piping .............................................................................................................................................................................................................. 3

4.6.1 General...................................................................................................................................................................................... 3

4.6.2 Backpressure ....................................................................................................................................................................... 3

4.6.3 Line sizing .............................................................................................................................................................................. 3

4.6.4 Multiple relief scenarios ............................................................................................................................................ 3

4.6.5 Reaction forces .................................................................................................................................................................. 3

4.7 Disposal to flare ...................................................................................................................................................................................... 4

4.7.1 General...................................................................................................................................................................................... 4

4.7.2 Combustion properties .............................................................................................................................................. 4

4.7.3 Combustion methods ................................................................................................................................................... 4

4.7.4 Flare systems designs .................................................................................................................................................. 4

4.7.5 Sizing .......................................................................................................................................................................................... 4

4.7.6 Ignition of flare gases ................................................................................................................................................... 4

4.7.7 Liquid seal drum drums ............................................................................................................................................ 4

4.8 Single PRD protecting several components in a process system ................................................................. 4

Bibliography ................................................................................................................................................................................................................................ 5

© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23251:2019(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore

structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 6, Processing

equipment and systems.

This second edition cancels and replaces the first edition (ISO 23251:2006), which has been technically

revised. It also incorporates the Technical Corrigendum ISO 23251:2006/Cor.1:2007 and the Amendment

ISO 23251:2006/Amd.1:2008.
This document supplements API Std 521, 6th edition (2014).

The technical requirements of this document and API Std 521 used to be identical. In the meantime

API Std 521 has been technically revised as API Std 521, 6th edition (2014). The purpose of this document

is to bring it up to date, by referencing the current edition of API Std 521 and adding supplementary

content.
The main changes compared to the previous edition are as follows:

— Permission to use administrative controls such as car-sealing or chain-locking valves to prevent an

over-pressure only if the corrected hydrotest pressures are not exceeded;
— Addition of requirements to cover choke valve failures and acoustic fatigue;

— Strengthening of the requirements to evaluate check valve reverse flow failures;

— Addition of guidance on the use of alternative method for fire relief and blowdown system design.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23251:2019(E)
Introduction
Users of this document are in
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.