Functional Safety — Safety Instrumented Systems for the Process Industry Sector —
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BRITISH STANDARD BS EN 61511-2:2004 Incorporating Amendment No. 1 to BS IEC 61511-2:2003 (renumbers the BS IEC as BS EN 61511-2:2004) Functional safety — Safety instrumented systems for the process industry sector — Part 2: Guidelines for the application of IEC 61511-1 The European Standard EN 61511-2:2004 has the status of a British Standard ICS 13.110; 25.040.01 Licensed copy:PONTYPRIDD COLLEGE, 13/02/2008, Uncontrolled Copy, © BSI BS EN 61511-2:2004 National foreword This British Standard is the official English language version of EN 61511-2:2004. It is identical with IEC 61511-2:2003. The UK participation in its preparation was entrusted by Technical Committee GEL/65, Measurement and control, to Subcommittee GEL/65/1, System considerations, which has the responsibility to: — aid enquirers to understand the text; — present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; — monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 70, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication This British Standard was published under the authority Amd. No. Date Comments of the Standards Policy and Strategy Committee on 15577 11 May 2005 Implementation of the European Standard 4 August 2003 © BSI 11 May 2005 ISBN 0 580 42376 X Licensed copy:PONTYPRIDD COLLEGE, 13/02/2008, Uncontrolled Copy, © BSI EUROPEAN STANDARD EN 61511-2 NORME EUROPÉENNE EUROPÄISCHE NORM December 2004 ICS 25.040.01;13.110 English version Functional safety – Safety instrumented systems for the process industry sector Part 2: Guidelines for the application of IEC 61511-1 (IEC 61511-2:2003) Sécurité fonctionnelle – Funktionale Sicherheit - Systèmes instrumentés de sécurité Sicherheitstechnische Systeme pour le secteur des industries für die Prozessindustrie de transformation Teil 2: Anleitungen zur Anwendung Partie 2: Lignes directrices pour des Teils 1 l'application de la CEI 61511-1 (IEC 61511-2:2003) (CEI 61511-2:2003) www.bzfxw.com 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 61511-2:2004 E Licensed copy:PONTYPRIDD COLLEGE, 13/02/2008, Uncontrolled Copy, © BSI Page 2 EN 60511−2:2004 Foreword The text of the International Standard IEC 61511-2:2003, 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 61511-2 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 __________ Endorsement notice The text of the International Standard IEC 61511-2:2003 was approved by CENELEC as a European Standard without any modification. __________ www.bzfxw.com Licensed copy:PONTYPRIDD COLLEGE, 13/02/2008, Uncontrolled Copy, © BSI Page 3 EN 60511−2:2004 – 2 – 615-112 EI:C002(3)E CONTENTS INTRODUCTION....................................................................................................................5 1 Scope .............................................................................................................................. 7 2 Normative references....................................................................................................... 7 3 Terms, definitions and abbreviations................................................................................ 7 4 Conformance to this International Standard ..................................................................... 7 5 Management of functional safety...................................................................................... 8 5.1 Objective ................................................................................................................ 8 5.2 Requirements ......................................................................................................... 8 6 Safety lifecycle requirements ..........................................................................................14 6.1 Objective ...............................................................................................................14 6.2 Requirements ........................................................................................................14 7 Verification .....................................................................................................................14 7.1 Objective ...............................................................................................................14 8 Process hazard and risk assessment ..............................................................................15 8.1 Objectives .............................................................................................................15 8.2 Requirements ........................................................................................................15 9 Allocation of safety functions to protection layers............................................................18 9.1 Objective ...............................................................................................................18 9.2 Requirements of the allocation prowww.bzfxw.comcess .................................................................18 9.3 Additional requirements for safety integrity level 4.................................................20 9.4 Requirement on the basic process control system as a layer of protection.............20 9.5 Requirements for preventing common cause, common mode and dependent failures ..................................................................................................................22 10 SIS safety requirements specification .............................................................................22 10.1 Objective ...............................................................................................................22 10.2 General requirements ............................................................................................22 10.3 SIS safety requirements.........................................................................................22 11 SIS design and engineering ............................................................................................23 11.1 Objective ...............................................................................................................23 11.2 General requirements ............................................................................................23 11.3 Requirements for system behaviour on detection of a fault ....................................27 11.4 Requirements for hardware fault tolerance.............................................................27 11.5 Requirements for selection of components and subsystems ..................................29 11.6 Field devices .........................................................................................................31 11.7 Interfaces ..............................................................................................................31 11.8 Maintenance