Functional safety - Safety instrumented systems for the process industry sector -- Part 1: Framework, definitions, system, hardware and software requirements

Gives requirements for the specification, design, installation, operation and maintenance of a safety instrumented system, so that it can be confidently entrusted to place and/or maintain the process in a safe state. This standard has been developed as a process sector implementation of IEC 61508. Experts in IEC Subcommittee 65A (System aspects) explain that this sector specific standard of IEC 61508 addresses the functional safety of safety instrumented systems (SIS) for the process sector. "The purpose is to ensure that the safety integrity of safety instrumented systems is adequate taking into account the associated hazards & risks. It falls under the generic IEC 61508 standard and thus required adjustment to the requirements found in IEC 61508 (generic in content since it covers all sectors) to cover process sector needs." The standard will mainly be used by integrators and operators of chemical, petro-chemical and gas process plants. It also has applications in non-nuclear power generation. It will also be used as a benchmark by those responsible for assessing the adequacy of such plants including certification bodies and regulators. IEC 61511-2 Ed. 1.0: Functional safety instrumented systems for the process industry;Part 2: Guidelines in the application of Part 1 wil be published shortly and IEC 61511-3 Ed. 1.0: Functional safety: Safety instrumented systems for the process industry sector;Part 3: Guidance for the determination of safety integrity levels is scheduled to appear in June 2003.

Funktionale Sicherheit - Sicherheitstechnische Systeme für die Prozessindustrie -- Teil 1: Allgemeines, Begriffe, Anforderungen an Systeme, Software und Hardware

Sécurité fonctionnelle - Systèmes instrumentés de sécurité pour le secteur des industries de transformation -- Partie 1: Cadre, définitions, exigences pour le système, le matériel et le logiciel

permet de définir des prescriptions relatives aux spécifications, à la conception, à l'installation, à l'exploitation et à l'entretien d'un système instrumenté de sécurité, de telle manière qu'il puisse être mis en oeuvre en toute confiance, et ainsi établir et/ou maintenir les processus dans un état de sécurité convenable. La présente norme a été conçue pour être une mise en uvre de la norme internationale CEI 61508 "Sécurité fonctionnelle des systèmes électriques/électroniques/ électroniques programmables relatifs à la sécurité" dans le domaine de l'industrie des processus. Le contenu du corrigendum de novembre 2004 a été pris en considération dans cet exemplaire. Elle a le statut d'une norme horizontale conformément au Guide 108 de la CEI.

Funkcijska varnost - Sistemi z varnostnimi instrumenti za sektor procesne industrije - 1. del: Okvirno, definicije, sistem, zahteve za strojno in programsko opremo (IEC 61511-1:2003 + popravek 2004)

General Information

Status
Published
Publication Date
31-Dec-2006
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jan-2007
Due Date
01-Jan-2007
Completion Date
01-Jan-2007

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---------------------- Page: 1 ----------------------
EUROPEAN STANDARD EN 61511-1
NORME EUROPÉENNE
EUROPÄISCHE NORM December 2004
ICS 13.110; 25.040.01
English version
Functional safety –
Safety instrumented systems for the process industry sector
Part 1: Framework, definitions, system,
hardware and software requirements
(IEC 61511-1:2003 + corrigendum 2004)
Sécurité fonctionnelle – Funktionale Sicherheit -
Systèmes instrumentés de sécurité Sicherheitstechnische Systeme
pour le secteur des industries für die Prozessindustrie
de transformation Teil 1: Allgemeines, Begriffe,
Partie 1: Cadre, définitions, exigences Anforderungen an Systeme,
pour le système, le matériel et le logiciel Software und Hardware
(CEI 61511-1:2003 + corrigendum 2004) (IEC 61511-1:2003 + Corrigendum 2004)

This European Standard was approved by CENELEC on 2004-10-01. CENELEC 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 Central Secretariat or to any CENELEC 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 CENELEC member into its own language and

notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,

Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61511-1:2004 E
---------------------- Page: 2 ----------------------
EN 61511-1:2004 - 2 -
Foreword

The text of the International Standard IEC 61511-1:2003, prepared by SC 65A, System aspects, of

IEC TC 65, Industrial-process measurement and control, was submitted to the Unique Acceptance

Procedure and was approved by CENELEC as EN 61511-1 on 2004-10-01 without any modification.

The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2005-10-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2007-10-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 61511-1:2003 + corrigendum November 2004 was

approved by CENELEC as a European Standard without any modification.
__________
---------------------- Page: 3 ----------------------
- 3 - EN 61511-1:2004
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.
Publication Year Title EN/HD Year
IEC 60654-1 1993 Industrial-process measurement and EN 60654-1 1993
control equipment - Operating conditions
Part 1: Climatic conditions
IEC 60654-3 1983 Part 3: Mechanical influences EN 60654-3 1997
1) 2)
IEC 61326 - Electrical equipment for measurement, EN 61326 1997
control and laboratory use - EMC
requirements
1) 2)
IEC 61508-2 - Functional safety of EN 61508-2 2001
electrical/electronic/programmable
electronic safety-related systems
Part 2: Requirements for
electrical/electronic/programmable
electronic safety-related systems
- 1) 2)
IEC 61508-3 Part 3: Software requirements EN 61508-3 2001
- 1) 2)
IEC 61511-2 Functional safety - Safety instrumented EN 61511-2 2004
systems for the process industry sector
Part 2: Guidelines for the application of
IEC 61511-1
Undated reference.
Valid edition at date of issue.
---------------------- Page: 4 ----------------------
NORME CEI
INTERNATIONALE
IEC
61511-1
INTERNATIONAL
Première édition
STANDARD
First edition
2003-01
Sécurité fonctionnelle –
Systèmes instrumentés de sécurité pour
le secteur des industries de transformation –
Partie 1:
Cadre, définitions, exigences pour le système,
le matériel et le logiciel
Functional safety –
Safety instrumented systems
for the process industry sector –
Part 1:
Framework, definitions, system,
hardware and software requirements
 IEC 2003 Droits de reproduction réservés  Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any

utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including

électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from

microfilms, sans l'accord écrit de l'éditeur. the publisher.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch

CODE PRIX
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International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 5 ----------------------
61511-1  IEC:2003 – 3 –
CONTENTS

FOREWORD...........................................................................................................................9

INTRODUCTION...................................................................................................................13

1 Scope.............................................................................................................................19

2 Normative references.....................................................................................................31

3 Abbreviations and definitions..........................................................................................31

3.1 Abbreviations........................................................................................................31

3.2 Definitions.............................................................................................................33

4 Conformance to this International Standard ....................................................................65

5 Management of functional safety ....................................................................................65

5.1 Objective...............................................................................................................65

5.2 Requirements........................................................................................................65

6 Safety life-cycle requirements.........................................................................................75

6.1 Objective...............................................................................................................75

6.2 Requirements........................................................................................................75

7 Verification.....................................................................................................................81

7.1 Objective...............................................................................................................81

8 Process hazard and risk analysis ...................................................................................81

8.1 Objectives.............................................................................................................81

8.2 Requirements........................................................................................................83

9 Allocation of safety functions to protection layers ...........................................................85

9.1 Objective...............................................................................................................85

9.2 Requirements of the allocation process .................................................................85

9.3 Additional requirements for safety integrity level 4.................................................87

9.4 Requirements on the basic process control system as a protection layer...............89

9.5 Requirements for preventing common cause, common mode and dependent

failures ..................................................................................................................91

10 SIS safety requirements specification .............................................................................91

10.1 Objective...............................................................................................................91

10.2 General requirements............................................................................................91

10.3 SIS safety requirements ........................................................................................91

11 SIS design and engineering............................................................................................95

11.1 Objective...............................................................................................................95

11.2 General requirements............................................................................................95

11.3 Requirements for system behaviour on detection of a fault ....................................97

11.4 Requirements for hardware fault tolerance ..........................................................101

11.5 Requirements for selection of components and subsystems ................................103

11.6 Field devices.......................................................................................................111

11.7 Interfaces............................................................................................................111

11.8 Maintenance or testing design requirements........................................................115

11.9 SIF probability of failure ......................................................................................117

---------------------- Page: 6 ----------------------
61511-1  IEC:2003 – 5 –

12 Requirements for application software, including selection criteria for utility software ...119

12.1 Application software safety life-cycle requirements..............................................119

12.2 Application software safety requirements specification ........................................131

12.3 Application software safety validation planning....................................................135

12.4 Application software design and development .....................................................135

12.5 Integration of the application software with the SIS subsystem ............................147

12.6 FPL and LVL software modification procedures ...................................................149

12.7 Application software verification..........................................................................149

13 Factory acceptance testing (FAT) .................................................................................151

13.1 Objectives...........................................................................................................151

13.2 Recommendations...............................................................................................153

14 SIS installation and commissioning...............................................................................155

14.1 Objectives...........................................................................................................155

14.2 Requirements......................................................................................................155

15 SIS safety validation.....................................................................................................157

15.1 Objective.............................................................................................................157

15.2 Requirements......................................................................................................157

16 SIS operation and maintenance....................................................................................163

16.1 Objectives...........................................................................................................163

16.2 Requirements......................................................................................................163

16.3 Proof testing and inspection ................................................................................167

17 SIS modification...........................................................................................................169

17.1 Objective.............................................................................................................169

17.2 Requirements......................................................................................................169

18 SIS decommissioning...................................................................................................171

18.1 Objectives...........................................................................................................171

18.2 Requirements......................................................................................................171

19 Information and documentation requirements ...............................................................171

19.1 Objectives...........................................................................................................171

19.2 Requirements......................................................................................................173

Annex A (informative) Differences......................................................................................175

Bibliography........................................................................................................................177

Figure 1 – Overall framework of this standard.......................................................................17

Figure 2 – Relationship between IEC 61511 and IEC 61508 .................................................23

Figure 3 – Relationship between IEC 61511 and IEC 61508 (see 1.2)...................................25

Figure 4 – Relationship between safety instrumented functions and other functions..............27

Figure 5 – Relationship between system, hardware, and software of IEC 61511-1 ................29

Figure 6 – Programmable electronic system (PES): structure and terminology ......................49

Figure 7 – Example SIS architecture.....................................................................................55

Figure 8 – SIS safety life-cycle phases and functional safety assessment stages .................71

Figure 9 – Typical risk reduction methods found in process plants ........................................89

---------------------- Page: 7 ----------------------
61511-1  IEC:2003 – 7 –

Figure 10 – Application software safety life cycle and its relationship to the SIS safety

life cycle .............................................................................................................................121

Figure 11 – Application software safety life cycle (in realization phase) ..............................125

Figure 12 − Software development life cycle (the V-model) .................................................125

Figure 13 – Relationship between the hardware and software architectures of SIS .............131

Table 1 – Abbreviations used in IEC 61511...........................................................................31

Table 2 – SIS safety life-cycle overview ................................................................................77

Table 3 – Safety integrity levels: probability of failure on demand .........................................85

Table 4 – Safety integrity levels: frequency of dangerous failures of the SIF .........................87

Table 5 – Minimum hardware fault tolerance of PE logic solvers .........................................101

Table 6 – Minimum hardware fault tolerance of sensors and final elements and non-PE

logic solvers .......................................................................................................................103

Table 7 – Application software safety life cycle: overview ...................................................127

---------------------- Page: 8 ----------------------
61511-1  IEC:2003 – 9 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY –
SAFETY INSTRUMENTED SYSTEMS
FOR THE PROCESS INDUSTRY SECTOR –
Part 1: Framework, definitions, system,
hardware and software requirements
FOREWORD

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

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

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

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

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

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

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

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

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

International Standard IEC 61511-1 has been prepared by subcommittee 65A: System

aspects, of IEC technical committee 65: Industrial-process measurement and control.

This bilingual version (2003-12) replaces the English version.
---------------------- Page: 9 ----------------------
61511-1  IEC:2003 – 11 –
The text of this standard is based on the following documents:
FDIS Report on voting
65A/368/FDIS 65A/372/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.
The French version of this standard has not been voted upon.

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

IEC 61511 consists of the following parts, under the general title Functional safety: Safety

instrumented systems for the process industry sector (see Figure 1):
Part 1: Framework, definitions, system, hardware and software requirements
Part 2: Guidelines in the application of IEC 61511-1
Part 3: Guidance for the determination of the required safety integrity levels

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

2007. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.

The contents of the corrigendum of November 2004 have been included in this copy.

---------------------- Page: 10 ----------------------
61511-1  IEC:2003 – 13 –
INTRODUCTION

Safety instrumented systems have been used for many years to perform safety instrumented

functions in the process industries. If instrumentation is to be effectively used for safety

instrumented functions, it is essential that this instrumentation achieves certain minimum

standards and performance levels.

This standard addresses the application of safety instrumented systems for the process

industries. It also requires a process hazard and risk assessment to be carried out to enable

the specification for safety instrumented systems to be derived. Other safety systems are only

considered so that their contribution can be taken into account when considering the

performance requirements for the safety instrumented systems. The safety instrumented

system includes all components and subsystems necessary to carry out the safety
instrumented function from sensor(s) to final element(s).

This standard has two concepts which are fundamental to its application; safety lifecycle and

safety integrity levels.

This standard addresses safety instrumented systems which are based on the use of

electrical/electronic/programmable electronic technology. Where other technologies are used

for logic solvers, the basic principles of this standard should be applied. This standard also

addresses the safety instrumented system sensors and final elements regardless of the

technology used. This standard is process industry specific within the framework of IEC 61508

(see Annex A).

This standard sets out an approach for safety life-cycle activities to achieve these minimum

standards. This approach has been adopted in order that a rational and consistent technical

policy is used.

In most situations, safety is best achieved by an inherently safe process design. If necessary,

this may be combined with a protective system or systems to address any residual identified

risk. Protective systems can rely on different technologies (chemical, mechanical, hydraulic,

pneumatic, electrical, electronic, programmable electronic). To facilitate this approach, this

standard

• requires that a hazard and risk assessment is carried out to identify the overall safety

requirements;

• requires that an allocation of the safety requirements to the safety instrumented system(s)

is carried out;

• works within a framework which is applicable to all instrumented methods of achieving

functional safety;

• details the use of certain activities, such as safety management, which may be applicable

to all methods of achieving functional safety.
This standard on safety instrumented systems for the process industry

• addresses all safety life-cycle phases from initial concept, design, implementation,

operation and maintenance through to decommissioning;

• enables existing or new country specific process industry standards to be harmonized with

this standard.
---------------------- Page: 11 ----------------------
61511-1  IEC:2003 – 15 –

This International Standard is intended to lead to a high level of consistency (for example, of

underlying principles, terminology, information) within the process industries. This should

have both safety and economic benefits.

In jurisdictions where the governing authorities (for example, national, federal, state, province,

county, city) have established process safety design, process safety management, or other

requirements, these take precedence over the requirements defined in this standard.

---------------------- Page: 12 ----------------------
61511-1  IEC:2003 – 17 –
Support
Technical
parts
requirements
PART 1 References
Clause 2
Development of the overall safety
PART 1
requirements (concept, scope definition,
hazard and risk assessment)
Definitions and
abbreviations
Clause 8
Clause 3
PART 1
PART 1
Conformance
Allocation of the safety requirements to
Clause 4
the safety instrumented functions and
development of safety requirements
PART 1
specification
Management of
Clauses 9 and 10
functional safety
Clause 5
PART 1
PART 1
Safety life-cycle
Design phase for Design phase for
requirements
safety
safety
Clause 6
instrumented instrumented
PART 1
system software
systems
Clause 12
Clause 11
Verification
Clause 7
PART 1
PART 1
Information
Factory acceptance testing,
requirements
installation and commissioning and
Clause 19
safety validation of safety
instrumented systems PART 1
Clauses 13, 14, and 15
Differences
Annex “A”
PART 1
PART 1
Operation and maintenance,
modification and retrofit, Guideline for the
application of part 1
decommissioning or disposal of
safety instrumented systems
PART 2
Clauses 16, 17, and 18
Guidance for the
determination of the
required safety
integrity levels
PART 3
IEC 3240/02
Figure 1 – Overall framework of this standard
---------------------- Page: 13 ----------------------
61511-1  IEC:2003 – 19 –
FUNCTIONAL SAFETY –
SAFETY INSTRUMENTED SYSTEMS
FOR THE PROCESS INDUSTRY SECTOR –
Part 1: Framework, definitions, system,
hardware and software requirements
1 Scope

This International Standard gives requirements for the specification, design, installation,

operation and maintenance of a safety instrumented system, so that it can be confidently

entrusted to place and/or maintain the process in a safe state. This standard has been

developed as a process sector implementation of IEC 61508.
In particular, this standard

a) specifies the requirements for achieving functional safety but does not specify who is

responsible for implementing the requirements (for example, designers, suppliers,

owner/operating company, contractor); this responsibility will be assigned to different

parties according to safety planning and national regulations;

b) applies when equipment that meets the requirements of IEC 61508, or of 11.5 of

IEC 61511-1, is integrated into an overall system that is to be used for a process sector

application but does not apply to manufacturers wishing to claim that devices are suitable

for use in safety instrumented systems for the process sector (see IEC 61508-2 and

IEC 61508-3);
c) defines the relationship between IEC 61511 and IEC 61508 (Figures 2 and 3);

d) applies when application software is developed for systems having limited variability or

fixed programmes but does not apply to manufacturers, safety instrumented systems

designers, integrators and users that develop embedded software (system software) or

use full variability languages (see IEC 61508-3);

e) applies to a wide variety of industries within the process sector including chemicals, oil

refining, oil and gas production, pulp and paper, non-nuclear power generation;

NOTE Within the process sector some applications, (for example, off-shore), may have additional

requirements that have to be satisfied.
f) outlines the relationship between safety instrumented functions an
...

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