Principles for proof testing of safety instrumented systems in the chemical industry Prepared by ABB Ltd for the Health and Safety Executive

Guiding principles for the proof testing of safety instrumented systems (SIS) in the chemical industry have been developed through research into the practices of proof testing. The proof testing of SIS is an integral component of the management of functional safety. Its purpose is to confirm the continued operation of the required safety instrumented function and to contribute to the maintenance of the required safety integrity level of the safety function. The guiding principles were developed through direct contact with industrial end-users and suppliers of SIS components, and through searches of incident data available within the public domain. Consideration has been given to good practices as defined by international publications such as IEC 61508 and by sector guidance such as that provided by EEMUA. The guiding principles therefore provide independent guidance on proof testing issues which are of interest and concern to chemical industry end-users. Examples of proof test practices and procedures have been provided together with a proposed checklist of recommended practices which can be used by Field Inspectors. More detailed recommendations are presented in the body of the report. This 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 not necessarily reflect HSE policy. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner.