CONTRACT RESEARCH REPORT 428/2002 - HSE: …

1 HSEH ealth & SafetyExecutivePrinciples for proof testing of safety instrumented systems in the chemical industryPrepared by ABB Ltdfor the Health and Safety ExecutiveCONTRACT RESEARCH REPORT428/2002 HSEH ealth & SafetyExecutivePrinciples for proof testing of safety instrumented systems in the chemical industryStuart NunnsBSc, C Eng, FIEE, FInstMCABB LtdPavillion 9 Byland WayBelasis Hall Technology ParkBillinghamCleveland TS23 4 YSGuiding principles for the proof testing of safety instrumented systems (SIS) in the chemical industryhave been developed through RESEARCH into the practices of proof testing. The proof testing of SIS is anintegral component of the management of functional safety. Its purpose is to confirm the continuedoperation of the required safety instrumented function and to contribute to the maintenance of therequired safety integrity level of the safety guiding principles were developed through direct contact with industrial end-users and suppliers ofSIS components, and through searches of incident data available within the public has been given to good practices as defined by international publications such as IEC61508 and by sector guidance such as that provided by EEMUA.

2 The guiding principles thereforeprovide independent guidance on proof testing issues which are of interest and concern to chemicalindustry of proof test practices and procedures have been provided together with a proposedchecklist of recommended practices which can be used by Field Inspectors. More detailedrecommendations are presented in the body of the REPORT and the work it describes were funded by the Health and Safety Executive. Its contents,including any opinions and/or conclusions expressed, are those of the author(s) alone and do notnecessarily reflect HSE BOOKSii Crown copyright 2002 Applications for reproduction should be made in writing to:Copyright Unit, Her Majesty s Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1 BQFirst published 2002 ISBN 0 7176 2346 7 All rights reserved.

3 No part of this publication may bereproduced, stored in a retrieval system, or transmittedin any form or by any means (electronic, mechanical,photocopying, recording or otherwise) without the priorwritten permission of the copyright CONTENTS EXECUTIVE SUMMARY IV 1. INTRODUCTION 1 2. RESEARCH METHOD 2 3. PRESENTATION OF RESULTS 4 4. GUIDING PRINCIPLES 5 Proof Test Practices 5 Content of Proof Test Procedures 17 Format of Proof Test Procedures 23 Planning and Scheduling 26 Records of Proof Testing 27 Competence 31 Awareness of Hazard and Risk 36 Management of Change 38 5. SEARCHES 41 Loss Prevention Journal 41 IChemE Loss Prevention Bulletin 41 Miscellaneous Literature Searches 41 Industry Incident Database 43 Major Accident Reporting System (MARS) Database Search 44 HSE Prosecutions Database ( ) 44 General Conclusions from Searches 44 APPENDIX 1 : GUIDING PRINCIPLES FOR PROOF TESTING 45 APPENDIX 2 : PROPOSED CHECKLIST FOR USE BY INSPECTORS 47 APPENDIX : EXAMPLE OF A FORMATTED PROOF TEST PROCEDURE 55 APPENDIX : EXAMPLE OF THE RECORDING OF PROOF TEST RESULTS 60 APPENDIX.

4 EXAMPLE OF PROOF TEST DOCUMENT CONTROL 63 REFERENCES 65 GLOSSARY 66 iv EXECUTIVE SUMMARY A set of guiding principles upon which the proof testing safety instrumented systems (SIS) should be based has been developed via RESEARCH into chemical industry practices, experience and views and via searches of data in the public domain.

5 Interviews, questionnaires, workshops and searches identified a set of issues relating to proof testing which were of particular interest to a cross-section of the chemical industry. These issues have been used to generate guiding principles, which address the following: proof testing practices; content of proof testing procedures; format of proof testing procedures; planning and scheduling; proof test records; competence; awareness of hazard and risk; management of change. The RESEARCH indicated that the proof testing of SIS is common practice but that some organisations take a more structured and focused approach than others. The size of an organisation, and therefore its ability to deploy engineering resources, was significant as was a commonly held view that the reducing numbers of competent, experienced technical personnel is beginning to have an impact on proof testing practices.

6 The RESEARCH confirmed the existence of conflict between the need for realistic proof testing and the need to minimise downtime, particularly within high throughput continuous processes such as refining and bulk chemical manufacture. The increasing profile of IEC615081 was a common theme throughout the RESEARCH with manufacturing organisations expressing trepidation over its potential impact on existing installations, notwithstanding its non-retrospective nature. Examples of good and poor practice were encountered and have been highlighted in this REPORT , however, searches of published literature and incident databases provided no tangible evidence that incidents have been directly attributed to issues relating to proof testing.

7 1 1. INTRODUCTION This REPORT relates to the proof testing of safety instrumented systems (SIS). It has been produced as part of a RESEARCH project funded by the Health and Safety Executive. The CONTRACT was placed with Eutech Engineering Solutions Limited. The objectives of the RESEARCH were to define a set of guiding principles upon which proof tests of SIS should be developed, to provide independent advice to HSE Field Inspectors and to REPORT on current practices, highlighting examples of good and poor practice where relevant. The RESEARCH gathered data from industry via interviews, workshops and questionnaires and executed searches of data within the public domain. This REPORT presents the findings of the RESEARCH .

8 The target audiences for the REPORT are industrial end-users of SIS and HSE Field Inspectors. Industrial end users should benefit from the communication and illustration of current practices. The collation of experiences, views and examples gives an indication of what is practicable and of the issues of concern to different sectors within the chemical industry. The data generated by the industrial RESEARCH is presented 'as found' in an attempt to provide a genuine indication of the practices, experiences and concerns within industry. The data collected during the RESEARCH was analysed and the results used to generate and support a set of guiding principles for the proof testing of SIS. Each principle is presented in this REPORT and is supported by the RESEARCH data and a rationale based on recognised standards and guidance.

9 The current high profile of IEC615081 amongst end-users was evident throughout the RESEARCH . Its principles have been used to construct the rationales supporting the guiding principles. Detailed recommendations have been generated to provide practical guidance on the application of the guiding principles. The recommendations have been used to create a checklist for use by HSE inspectors. The checklist is presented in Appendix 2. 2 2. RESEARCH METHOD The RESEARCH consisted of five activities: interviews with industrial end-user organisations; follow-up questionnaires, discussions and interviews; workshops attended by end-user organisations; workshops attended by equipment suppliers; searches of data and documentation, in the public domain.

10 The industrial RESEARCH targeted a cross section of medium to large scale chemical manufacturing organisations covering continuous and batch operators from the chemical, petrochemical, refining, fine chemical and pharmaceutical sectors. Interviews with representatives of end-user organisations were carried out via face-to-face discussions by engineering consultants using a common interview script. An analysis of the interview coverage is shown in Table 1. The reported distribution of SIS across the sectors examined is shown in Figure 1. The interviews targeted personnel involved in the proof testing of SIS, specifically those with responsibility for the management of proof testing and those responsible for its execution.