Hazard and operability studies (HAZOP studies) - Application guide

IEC 61882:2016 is available as IEC 61882:2016 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 61882:2016 provides a guide for HAZOP studies of systems using guide words. It gives guidance on application of the technique and on the HAZOP study procedure, including definition, preparation, examination sessions and resulting documentation and follow-up. Documentation examples, as well as a broad set of examples encompassing various applications, illustrating HAZOP studies are also provided. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- clarification of terminology as well as alignment with terms and definitions within ISO 31000:2009 and ISO Guide 73:2009;
- addition of an improved case study of a procedural HAZOP. Keywords: HAZOP, risks and operability problems

Études de danger et d'exploitabilité (études HAZOP) - Guide d'application

L'IEC 61882:2016 constitue un guide pour les études HAZOP de systèmes qui utilisent des mots-guides. Elle donne des lignes directrices relatives à l'application de la technique et à la procédure de l'étude HAZOP, y compris la définition, la préparation, les sessions d'examen ainsi que les documents et le suivi qui en résultent. Elle fournit également des exemples de documentation ainsi qu'un grand choix d'exemples concernant diverses applications qui présentent les études HAZOP. Cette deuxième édition annule et remplace la première édition parue en 2001. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- terminologie clarifiée, et alignement sur les termes et définitions de l'ISO 31000:2009 et du Guide ISO 73:2009;
- ajout d'une étude de cas améliorée d'un HAZOP de procédure. Mots clés: HAZOP, risques et les problèmes d'exploitabilité

General Information

Status
Published
Publication Date
09-Mar-2016
Technical Committee
Current Stage
PPUB - Publication issued
Start Date
10-Mar-2016
Completion Date
10-Mar-2016
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IEC 61882
Edition 2.0 2016-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Hazard and operability studies (HAZOP studies) – Application guide
Études de danger et d'exploitabilité (études HAZOP) – Guide d'application
IEC 61882:2016-03(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61882
Edition 2.0 2016-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Hazard and operability studies (HAZOP studies) – Application guide
Études de danger et d'exploitabilité (études HAZOP) – Guide d'application
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 03.100.50; 03.120.01; 13.020.30 ISBN 978-2-8322-3208-8

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61882:2016 © IEC 2016
CONTENTS

FOREWORD......................................................................................................................... 4

INTRODUCTION ................................................................................................................... 6

1 Scope ............................................................................................................................ 7

2 Normative references .................................................................................................... 7

3 Terms, definitions and abbreviations .............................................................................. 7

3.1 Terms and definitions ............................................................................................ 7

3.2 Abbreviations ........................................................................................................ 9

4 Key features of HAZOP ................................................................................................ 10

4.1 General ............................................................................................................... 10

4.2 Principles of examination..................................................................................... 11

4.3 Design representation ......................................................................................... 12

4.3.1 General ....................................................................................................... 12

4.3.2 Design requirements and design intent ......................................................... 13

5 Applications of HAZOP ................................................................................................ 13

5.1 General ............................................................................................................... 13

5.2 Relation to other analysis tools ............................................................................ 14

5.3 HAZOP study limitations ...................................................................................... 14

5.4 Risk identification studies during different system life cycle stages ....................... 15

5.4.1 Concept stage .............................................................................................. 15

5.4.2 Development stage ...................................................................................... 15

5.4.3 Realization stage ......................................................................................... 15

5.4.4 Utilization stage ........................................................................................... 15

5.4.5 Enhancement stage ..................................................................................... 16

5.4.6 Retirement stage.......................................................................................... 16

6 The HAZOP study procedure ....................................................................................... 16

6.1 General ............................................................................................................... 16

6.2 Definitions ........................................................................................................... 17

6.2.1 Initiate the study .......................................................................................... 17

6.2.2 Define scope and objectives ......................................................................... 17

6.2.3 Define roles and responsibilities ................................................................... 18

6.3 Preparation ......................................................................................................... 19

6.3.1 Plan the study .............................................................................................. 19

6.3.2 Collect data and documentation ................................................................... 20

6.3.3 Establish guide words and deviations ........................................................... 20

6.4 Examination ........................................................................................................ 21

6.4.1 Structure the examination ............................................................................ 21

6.4.2 Perform the examination .............................................................................. 22

6.5 Documentation and follow up ............................................................................... 24

6.5.1 General ....................................................................................................... 24

6.5.2 Establish method of recording ...................................................................... 25

6.5.3 Output of the study....................................................................................... 25

6.5.4 Record information ....................................................................................... 25

6.5.5 Sign off the documentation ........................................................................... 26

6.5.6 Follow-up and responsibilities ...................................................................... 26

Annex A (informative) Methods of recording ....................................................................... 27

---------------------- Page: 4 ----------------------
IEC 61882:2016 © IEC 2016 – 3 –

A.1 Recording options ............................................................................................... 27

A.2 HAZOP worksheet ............................................................................................... 27

A.3 Marked-up representation .................................................................................... 28

A.4 HAZOP study report ............................................................................................ 28

Annex B (informative) Examples of HAZOP studies ............................................................ 29

B.1 General ............................................................................................................... 29

B.2 Introductory example ........................................................................................... 29

B.3 Procedures ......................................................................................................... 34

B.4 Automatic train protection system ........................................................................ 37

B.4.1 General ....................................................................................................... 37

B.4.2 Application ................................................................................................... 37

B.5 Example involving emergency planning ................................................................ 40

B.6 Piezo valve control system .................................................................................. 44

B.7 HAZOP of a train stabling yard horn procedure .................................................... 48

Bibliography ....................................................................................................................... 59

Figure 1 – The HAZOP study procedure .............................................................................. 17

Figure 2 – Flow chart of the HAZOP examination procedure – Property first sequence ........ 23

Figure 3 – Flow chart of the HAZOP examination procedure – Guide word first

sequence ............................................................................................................................ 24

Figure B.1 – Simple flow sheet ............................................................................................ 30

Figure B.2 – Train-carried ATP equipment ........................................................................... 37

Figure B.3 – Piezo valve control system .............................................................................. 44

Table 1 – Example of basic guide words and their generic meanings ................................... 11

Table 2 – Example of guide words relating to clock time and order or sequence ................... 12

Table 3 – Examples of deviations and their associated guide words ..................................... 21

Table B.1 – Properties of the system under examination ...................................................... 30

Table B.2 – Example HAZOP worksheet for introductory example ........................................ 31

Table B.3 – Example HAZOP worksheet for procedures example ......................................... 35

Table B.4 – Example HAZOP worksheet for automatic train protection system ..................... 38

Table B.5 – Example HAZOP worksheet for emergency planning ......................................... 41

Table B.6 – System design intent ........................................................................................ 45

Table B.7 – Example HAZOP worksheet for piezo valve control system................................ 46

Table B.8 – Operational breakdown matrix for train stabling yard horn procedure ................. 50

Table B.9 – Example HAZOP worksheet for train stabling yard horn procedure .................... 53

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– 4 – IEC 61882:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HAZARD AND OPERABILITY STUDIES (HAZOP STUDIES) –
APPLICATION GUIDE
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61882 has been prepared by IEC technical committee 56:

Dependability.

This second edition cancels and replaces the first edition published in 2001. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) clarification of terminology as well as alignment with terms and definitions within

ISO 31000:2009 and ISO Guide 73:2009;
b) addition of an improved case study of a procedural HAZOP.
---------------------- Page: 6 ----------------------
IEC 61882:2016 © IEC 2016 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
56/1653/FDIS 56/1666/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 7 ----------------------
– 6 – IEC 61882:2016 © IEC 2016
INTRODUCTION

This standard describes the principles for and approach to guide word-driven risk

identification. Historically this approach to risk identification has been called a hazard and

operability study or HAZOP study for short. This is a structured and systematic technique for

examining a defined system, with the objectives of:

• identifying risks associated with the operation and maintenance of the system. The

hazards or other risk sources involved can include both those essentially relevant only to

the immediate area of the system and those with a much wider sphere of influence, for

example some environmental hazards;

• identifying potential operability problems with the system and in particular identifying

causes of operational disturbances and production deviations likely to lead to non-

conforming products.

An important benefit of HAZOP studies is that the resulting knowledge, obtained by identifying

risks and operability problems in a structured and systematic manner, is of great assistance in

determining appropriate remedial measures.

A characteristic feature of a HAZOP study is the examination session during which a multi-

disciplinary team under the guidance of a study leader systematically examines all relevant

parts of a design or system. It identifies deviations from the system design intent utilizing a

set of guide words. The technique aims to stimulate the imagination of participants in a

systematic way to identify risks and operability problems. A HAZOP study should be seen as

an enhancement to sound design using experience-based approaches such as codes of

practice rather than a substitute for such approaches.

Historically, HAZOP and similar studies were described as hazard identification as their

primary purpose is to test in a systematic way whether hazards are present and, if so,

understand both how they could result in adverse consequences and how such consequences

could be avoided through process redesign. ISO 31000:2009 defines risk as the effect of

uncertainty on objectives, with a note that an effect is a deviation from the expected.

Therefore HAZOP studies, which consider deviations from the expected, their causes and

their effect on objectives in the context of process design, are now correctly characterized as

powerful risk identification tools.

There are many different tools and techniques available for the identification of risks, ranging

from checklists, failure modes and effects analysis (FMEA) to HAZOP. Some techniques, such

as checklists and what-if/analysis, can be used early in the system life cycle when little

information is available, or in later phases if a less detailed analysis is needed. HAZOP

studies require more detail regarding the systems under consideration, but produce more

comprehensive information on risks and weaknesses in the system design.

The term HAZOP is sometimes associated, in a generic sense, with some other hazard

identification techniques (e.g. checklist HAZOP, HAZOP 1 or 2, knowledge-based HAZOP).

The use of the term with such techniques is considered to be inappropriate and is specifically

excluded from this document.

Before commencing a HAZOP study, it should be confirmed that it is the most appropriate

technique (either individually or in combination with other techniques) for the task in hand. In

making this judgment, consideration should be given to the purpose of the study, the possible

severity of any consequences, the appropriate level of detail, the availability of relevant data

and resources and the needs of decision-makers.

This standard has been developed to provide guidance across many industries and types of

system. There are more specific standards and guides within some industries, notably the

process industries where the technique originated, which establish preferred methods of

application for these industries. For details see the bibliography at the end of this standard.

---------------------- Page: 8 ----------------------
IEC 61882:2016 © IEC 2016 – 7 –
HAZARD AND OPERABILITY STUDIES (HAZOP STUDIES) –
APPLICATION GUIDE
1 Scope

This International Standard provides a guide for HAZOP studies of systems using guide

words. It gives guidance on application of the technique and on the HAZOP study procedure,

including definition, preparation, examination sessions and resulting documentation and

follow-up.
Documentation examples, as well as a broad set of examples encompassing various
applications, illustrating HAZOP studies are also provided.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.

IEC 60050-192, International electrotechnical vocabulary – Part 192: Dependability (available

at http://www.electropedia.org)
3 Terms, definitions and abbreviations
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-192 and the

following apply.
NOTE Within this clause, the terms defined are in italic type.
3.1.1
characteristic
qualitative or quantitative property
EXAMPLE Pressure, temperature, voltage.
3.1.2
consequence
outcome of an event affecting objectives
Note 1 to entry: An event can lead to a range of consequences.

Note 2 to entry: A consequence can be certain or uncertain and can have positive or negative effects on

objectives.
Note 3 to entry: Consequences can be expressed qualitatively or quantitatively.
Note 4 to entry: Initial consequences can escalate through knock-on effects.
[SOURCE: ISO Guide 73:2009, 3.6.1.3]
---------------------- Page: 9 ----------------------
– 8 – IEC 61882:2016 © IEC 2016
3.1.3
control
measure that is modifying risk (3.1.12)

Note 1 to entry: Controls include any process, policy, device, practice, or other actions which modify risk.

Note 2 to entry: Controls may not always exert the intended or assumed modifying effect.

[SOURCE: ISO Guide 73:2009, 3.8.1.1]
3.1.4
design intent

designer’s desired, or specified range of behaviour for properties which ensure that the item

fulfills its requirements
3.1.5
property
constituent of a part which serves to identify the part’s essential features

Note 1 to entry: The choice of properties can depend upon the particular application, but properties can include

features such as the material involved, the activity being carried out, the equipment employed, etc. Material should

be considered in a general sense and includes data, software, etc.
3.1.6
guide word

word or phrase which expresses and defines a specific type of deviation from a property’s

design intent
3.1.7
harm

physical injury or damage to the health of people or damage to assets or the environment

3.1.8
hazard
source of potential harm (3.1.7)
Note 1 to entry: Hazard can be a risk source (3.1.14).
[SOURCE: ISO Guide 73:2009, 3.5.1.4]
3.1.9
level of risk

magnitude of a risk (3.1.12) or combination of risks, expressed in terms of the combination of

consequences (3.1.2) and their likelihood
[SOURCE: ISO Guide 73:2009, 3.6.1.8]
3.1.10
manager
person with responsibility for a project, activity or organization.
3.1.11
part
section of the system which is the subject of immediate study

Note 1 to entry: A part can be physical (e.g. hardware) or logical (e.g. step in an operational sequence).

3.1.12
risk
effect of uncertainty on objectives
---------------------- Page: 10 ----------------------
IEC 61882:2016 © IEC 2016 – 9 –

Note 1 to entry: An effect is a deviation from the expected – positive and/or negative.

Note 2 to entry: Objectives can have different aspects (such as financial, health and safety, and environmental

goals) and can apply at different levels (such as strategic, organization-wide, project, product and process).

Note 3 to entry: Risk is often characterized by reference to potential events and consequences (3.1.2) or a

combination of these.

Note 4 to entry: Risk is often expressed in terms of a combination of the consequences of an event (including

changes in circumstances) and the associated likelihood of occurrence.

Note 5 to entry: Uncertainty is the state, even partial, or deficiency of information related to, understanding or

knowledge of an event, its consequence, or likelihood.
[SOURCE: ISO Guide 73:2009, 1.1]
3.1.13
risk identification
process of finding, recognizing and describing risks (3.1.12)

Note 1 to entry: Risk identification involves the identification of risk sources (3.1.14), events, their causes and

their potential consequences (3.1.2).

Note 2 to entry: Risk identification can involve historical data, theoretical analysis, informed and expert opinions,

and stakeholder's needs.
[SOURCE: ISO Guide 73:2009, 3.5.1]
3.1.14
risk source

element which alone or in combination has the intrinsic potential to give rise to risk (3.1.12)

Note 1 to entry: A risk source
...

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