EN 61511-3:2004
(Main)Functional safety - Safety instrumented systems for the process industry sector - Part 3: Guidance for the determination of the required safety integrity levels
Functional safety - Safety instrumented systems for the process industry sector - Part 3: Guidance for the determination of the required safety integrity levels
provides information on the underlying concepts of risk, the relationship of risk to safety integrity, the determination of tolerable risk and a number of different methods that enable the safety integrity levels for the safety instru-mented functions to be determined
Funktionale Sicherheit - Sicherheitstechnische Systeme für die Prozessindustrie - Teil 3: Anleitung für die Bestimmung der erforderlichen Sicherheits-Integritätslevel
Sécurité fonctionnelle - Systèmes instrumentés de sécurité pour le secteur des industries de transformation - Partie 3: Conseils pour la détermination des niveaux exigés d'intégrité de sécurité
fournit des informations sur les concepts sous-jacents de risque et la relation entre risque et intégrité, la détermination du risque tolérable, différentes méthodes permettant de déterminer les niveaux d'intégrité de sécurité des fonctions instrumentées de sécurité. 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 - 3. del: Smernice za ugotavljanje zahtevanih nivojev celovite varnosti (IEC 61511-3:2003)
General Information
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Standards Content (Sample)
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EUROPEAN STANDARD
EN 61511-3 NORME EUROPÉENNE EUROPÄISCHE NORM
December 2004 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 61511-3:2004 E
ICS 25.040.01
English version
Functional safety –
Safety instrumented systems for the process industry sector Part 3: Guidance for the determination
of the required safety integrity levels (IEC 61511-3:2003 + corrigendum 2004)
Sécurité fonctionnelle –
Systèmes instrumentés de sécurité
pour le secteur des industries
de transformation Partie 3: Conseils pour la détermination des niveaux d'intégrité de sécurité (CEI 61511-3:2003)
Funktionale Sicherheit - Sicherheitstechnische Systeme
für die Prozessindustrie Teil 3: Anleitung für die Bestimmung
der erforderlichen Sicherheits-Integritätslevel (IEC 61511-3:2003 + 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.
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 __________ Endorsement notice The text of the International Standard IEC 61511-3:2003 + corrigendum October 2004 was approved by CENELEC as a European Standard without any modification. __________
NORME INTERNATIONALECEIIEC INTERNATIONAL STANDARD 61511-3Première éditionFirst edition2003-03 Sécurité fonctionnelle – Systèmes instrumentés de sécurité pour
le secteur des industries de transformation – Partie 3: Conseils pour la détermination des niveaux exigés d'intégrité de sécurité
Functional safety – Safety instrumented systems for the process industry sector – Part 3: Guidance for the determination of the required safety integrity levels
Pour prix, voir catalogue en vigueur For price, see current catalogue IEC 2004
Droits de reproduction réservés
Copyright - all rights reserved Aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission,
3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, SwitzerlandTelephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch
Web: www.iec.ch CODE PRIX PRICE CODE XA Commission Electrotechnique InternationaleInternational Electrotechnical Commission
61511-3 IEC:2004 – 3 –
CONTENTS FOREWORD.7 INTRODUCTION.11 1 Scope.17 2 Terms, definitions and abbreviations.19 3 Risk and safety integrity – general guidance.19 3.1 General.19 3.2 Necessary risk reduction.21 3.3 Role of safety instrumented systems.21 3.4 Safety integrity.23 3.5 Risk and safety integrity.25 3.6 Allocation of safety requirements.27 3.7 Safety integrity levels.27 3.8 Selection of the method for determining the required safety integrity level.29
Annex A
(informative)
As Low As Reasonably Practicable (ALARP)
and tolerable risk concepts.31 Annex B (informative) Semi-quantitative method.39 Annex C (informative) The safety layer matrix method.55 Annex D (informative) Determination of the required safety integrity levels –
a semi-qualitative method: calibrated risk graph.67 Annex E (informative)
Determination of the required safety integrity levels –
a qualitative method: risk graph.85 Annex F (informative)
Layer of protection analysis (LOPA).97
Figure 1 – Overall framework of this standard.15 Figure 2 – Typical risk reduction methods found in process plants.19 Figure 3 – Risk reduction: general concepts.25 Figure 4 – Risk and safety integrity concepts.27 Figure 5 – Allocation of safety requirements to the Safety Instrumented Systems,
non-SIS prevention/mitigation protection layers and other protection layers.29 Figure A.1 – Tolerable risk and ALARP.33 Figure B.1 – Pressurized vessel with existing safety systems.41 Figure B.2 – Fault tree for overpressure of the vessel.47 Figure B.3 – Hazardous events with existing safety systems.49 Figure B.4 – Hazardous events with redundant protection layer.51 Figure B.5 – Hazardous events with SIL 2 SIS safety function.53 Figure C.1 – Protection layers.55 Figure C.2 – Example safety layer matrix.63 Figure D.1 – Risk graph: general scheme.77 Figure D.2 – Risk graph: environmental loss.83 Figure E.1 – DIN V 19250 risk graph – personnel protection (see Table E.1).91 Figure E.2 – Relationship between IEC 61511 series, DIN 19250 and VDI/VDE 2180.95 Figure F.1 – Layer of Protection Analysis (LOPA) Report.99
61511-3 © IEC:2004 – 5 –
Table A.1 – Example of risk classification of incidents.37 Table A.2 – Interpretation of risk classes.37 Table B.1 – HAZOP study results.43 Table C.1 – Frequency of hazardous event likelihood (without considering PLs).61 Table C.2 – Criteria for rating the severity
of impact of hazardous events.61 Table D.1 – Descriptions of process industry risk graph parameters.69 Table D.2 – Example calibration of the general purpose risk graph.79 Table D.3 – General environmental consequences.81 Table E.1 – Data relating to risk graph (see Figure E.1).93 Table F.1 – HAZOP developed data for LOPA.99 Table F.2 – Impact event severity levels.101 Table F.3 – Initiation Likelihood.101 Table F.4 – Typical protection layer (prevention and mitigation) PFDs.103
61511-3 IEC:2004 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
FUNCTIONAL SAFETY– SAFETY INSTRUMENTED SYSTEMS
FOR THE PROCESS INDUSTRY SECTOR –
Part 3: Guidance for the determination
of the required safety integrity levels
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 61511-3 has been prepared by subcommittee 65A: System aspects, of IEC technical committee 65: Industrial-process measurement and control. This bilingual version (2004-10) replaces the English version. The text of this standard is based on the following documents: FDIS Report on voting 65A/367/FDIS 65A/370/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.
61511-3 IEC:2004 – 9 –
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 requ
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