HAZOP: Guide to Best Practice Guidelines to Best Practice for the Process and Chemical Industries HAZOP: Guide to Best Practice Guidelines to Best Practice for the Process and Chemical Industries Third Edition Frank Crawley Atkins, University of Strathclyde Brian Tyler S&T Consultants (based upon the earlier editions by Frank Crawley, Malcolm Preston, and Brian Tyler) AMSTERDAM(cid:129)BOSTON(cid:129)HEIDELBERG(cid:129)LONDON(cid:129)NEWYORK(cid:129)OXFORD PARIS(cid:129)SANDIEGO(cid:129)SANFRANCISCO(cid:129)SINGAPORE(cid:129)SYDNEY(cid:129)TOKYO Elsevier Radarweg29,POBox211,1000AEAmsterdam,Netherlands TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UK 225WymanStreet,Waltham,MA02451,USA ThirdEdition2015 Copyrightr2015ElsevierLtd.Allrightsreserved. Previouseditions:Copyrightr2008,2000PublishedbyInstitutionofchemical Engineers.(IChemE.) 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Practitionersandresearchersmustalwaysrelyontheirownexperienceandknowledgein evaluatingandusinganyinformationormethodsdescribedherein.Inusingsuchinformationor methodstheyshouldbemindfuloftheirownsafetyandthesafetyofothers,includingpartiesfor whomtheyhaveaprofessionalresponsibility. Tothefullestextentofthelaw,neitherthePublishernortheauthors,contributors,oreditors, assumeanyliabilityforanyinjuryand/ordamagetopersonsorpropertyasamatterofproducts liability,negligenceorotherwise,orfromanyuseoroperationofanymethods,products, instructions,orideascontainedinthematerialherein. ISBN:978-0-323-39460-4 LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress BritishLibraryCataloguing-in-PublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ForInformationonallElsevierpublications visitourwebsiteathttp://store.elsevier.com/ FOREWORD FOREWORD TO THIRD EDITION It is with great pleasure that I have been invited to offer a preface to this, the third edition of HAZOP Guide to Best Practice which is cer- tainly one of the most popular IChemE texts that has been developed by EPSC members since the inception of the Centre in 1992. This particular book has fond personal memories because several years ago when working in industry I attended an IChemE HAZOP for Team Leaders course with one of its authors, Brian Tyler, which was heldattheformerUMISTcampusinManchester.Theopportunitypre- sented during that course of managing a HAZOP study team gave me thenecessaryconfidencebackattheworkplacetotrainfrontlinestaffin theuseofthetechnique,thenleadateaminastudyonafullyfunction- ing gin distillery, and finally present the recommendations to the site executive team. I still have the course folder, and I am glad to see that muchofthatcontentstillformsthecoreofthiscurrenttext. Nevertheless much has happened since the first edition and nothing stands still for long and so for the technique of HAZOP. There is now much greater appreciation in HAZOP studies of human error in acci- dent causation and more broadly human factors and the role of automation.HAZOPstudiesarenowperformedroutinelyoncontinuous plants at various stages of operation such as start-up and shutdown, batch processing plants, and even packaging plants. The technique of deviation analysis inherent in the method lends itself with care and imaginationtomanydiversemajorhazardenvironments. Asforthisthirdedition,theauthors,BrianTylerandFrankCrawley, aretobepraisedfortheircollectiveeffortsinrevisingthisbookyetagain and keeping the content as fresh and topical as possible. HAZOP pro- videsbothastructurefortheteamidentificationofhazards,accidentsce- narios, and operability issues while offering the chance for an element of creative thinking for a team whose time and effort is well managed. IfanythingthepressureinrecentyearshasgrownonthetypicalHAZOP team to identify and address all conceivable hazards arising from x Foreword dangerousoperationswhichmakesthisneweditionparticularlywelcome forstudentsandpractitionersalike. I have no doubt that EPSC members who contributed to the first edition will be immensely proud to see that this book has become a standard reference among the process safety community. Lee Allford EPSC Operations Manager IChemE Davis Building Rugby CV21 3HQ December 2014 FOREWORD TO EARLIER EDITIONS Hazard and Operability Studies (later shortened to HAZOP) were devised by ICI in the late 1960s, following some major problems with new, large process plants. The study was an evolution of method study and was used during the design stage of a project to identify and correct design faults which might lead to Hazard or Operability problems. Over thelastfewdecades,theneedforhighstandardsinsafetyandtheenviron- mentisfullyrecognizedbytheRegulator,theindustry,andthepublic. HAZOPisnowthefirstchoicetoolfortheidentificationofweaknesses in the process design and is used worldwide within the process industry. Ithasbeenusedinamodifiedformoutsidetheprocessindustry. The first definitive guide on Hazard and Operability Studies was issued by the Chemical Industries Association in 1974 when the tool hadbeenfullydeveloped.Thisremainedthemainguidancefor26years. However, in that period, new ideas on HAZOPs had been developed and equally some poor practices had been adopted. In 1998, it was decided that a new guide, using best practice, should be written. The first edition of this guide was published in 2000. For the second edition, the authors took the opportunity of reviewing that guide and incorpo- rating better practices and giving more guidance on how these might be applied. In particular the new guide addresses Computer-Controlled Processes. Although the basic approach of HAZOP is unchanged, there is now considerable experience in how the technique can be used most Foreword xi effectively. This experience has been drawn upon in preparing this guide, with a total of 31 companies contributing to its preparation. Finally, the guide is important as a joint project which has the sup- port of the Institution of Chemical Engineers (IChemE), the Chemical Industries Association (CIA), and the European Process Safety Centre (EPSC). Our thanks are due both to the authors of the guide and to the many industrial members who assisted in its development. Richard Gowland Technical Director European Process Safety Centre ACKNOWLEDGMENTS This first edition of this guide would not have been possible without the contributions of the following individuals and the support of their companies: M. Dennehy Air Products plc J. Snadden Air Products plc A Jacobsson AJ Risk Engineering AB D. Hackney Akcros Chemicals K. Brookes Akcros Chemicals R. Vis van Heemst Akzo Nobel Engineering bv K. Gieselburg BASF AG K-O. Falke Bayer AG V. Pilz Bayer AG H. Crowther BP Chemicals H. Jenkins BP Chemicals J-H. Christiansen Borealis M. Scanlon Chemical Industries Association F. Altorfer Ciba Specialty Chemicals T. Gillard Consultant S. Duffield EC JRC J-C. Adrian Elf Atochem P. Lawrie EniChem UK Ltd M. Powell-Price EPSC R. Turney EPSC R. Carter Eutech A. Ormond Eutech C. Swann Eutech S. Turner Foster Wheeler H. Wakeling Foster Wheeler T. Maddison Health and Safety Executive (UK) A. Rushton Health and Safety Executive (UK) K. Patterson Hickson and Welch J. Hopper Huntsman Polyurethanes M. Wilkinson Institution of Chemical Engineers xiv Acknowledgments J. Geerinck Janssen Pharmaceutica NV G. Gillett Kvaerner Water A. Poot Lyondell Chemie Nederland Ltd E. Dyke Merck C. Downie Merck and Co Ltd K. Dekker Montell Polyolefins bv J. Ytreeide Norsk Hydro AS D. Moppett Proctor and Gamble European Technical Centre ^ P. Rouyer Rho ne-Poulenc C. Caputo Rohm and Haas Italia G. Dilley Rohm and Hass (Scotland) Ltd F. de Luca Snamprogetti S.p.A (cid:2) C. Bartholome Solvay SA P. Depret Solvay SA J. Ham TNO K. Ling Zurich International The initiative of the IChemE Safety and Loss Prevention Subject GroupandthesupportoftheIChemESafetyHealthandEnvironmental PolicyCommitteearerecognized. While all of the above contributed to this guide, the authors would like to give special thanks to the following for their contributions and support: Rob Carter, Howard Crowther, Martin Dennehy, Julian Hooper, Hedley Jenkins, Ken Patterson, Chris Swann, Simon Turner, and Robin Turney. The authors would also like to give special thanks to Phil Aspinall of VECTRA Group Limited for his help and contribution in preparing the second edition of this guide, in particular for the development of Section 10.1 on HAZOP Study of Computer-Controlled Processes. The authors of the third edition wish to thank Jerry Lane (Optimus) for his help during the preparation of this revision. 11 CHAPTER Introduction 1.1 AIMS AND OBJECTIVES This book is intended to provide guidance on a specific technique developed for use in the process and chemical industries. The technique described is HAZOP (hazard and operability) study, a detailed method for systematic examination of a well-defined process or operation, either planned or existing. The HAZOP study method was developed by ICI in the 1960s and its use and development was encouraged by the Chemical Industries Association (CIA) Guide published in 1977. Since then, it has become the technique of choice for many of those involved in the design of new processes and operations. In addition to its power in identifying safety, health, and environmental (SHE) hazards, a HAZOP study can also be used to search for potential operating problems. Not sur- prisingly, the method has been applied in many different ways within the process industries.1 While it is frequently used on new facilities, it is now often applied to existing facilities and modifications. It has also been successfully applied to process documentation, pilot plant, and hazardous labora- tory operations as well as tasks such as commissioning and decom- missioning, emergency operations, and incident investigation. The objective here is to describe and illustrate the HAZOP study method, showing a variety of uses and some of the approaches that have been successful within the process industry. An important input has come from European Process Safety Centre (EPSC) members where 22 member companies responded in a survey carried out prior to the first edition of this Guide (2000). This identified many features generally regarded as essential to a good study. In addition, many common variations were described. These variations are in part due to the range of problems encountered within industry but also reflect individual choices of style. HAZOP study is a versatile technique and HAZOP:GuidetoBestPractice.DOI:http://dx.doi.org/10.1016/B978-0-323-39460-4.00001-3 Copyright©2015ElsevierLtd.Allrightsreserved. 2 HAZOP:GuidetoBestPractice good results may be achieved by several different approaches provided the basic principles are followed. It is hoped that this Guide will help maintain a high standard for HAZOP study within the industry, both by raising quality and encouraging flexibility without putting any unnecessary constraints upon its use and development. The HAZOP study method is well developed and is useful in most applications. There are other methods, however, that may have to be considered depending on the complexity and hazards of the installation being constructed and the state of the design. This publication does not address these methods in detail but their importance is discussed in Chapter 2. A fuller account is given in the IChemE Guide, Hazard Identification Methods.2 Finally, three illustrations of process industry applications are given in Appendices 3, 4 and 5. These examples cannot fully represent all the possible applications and process industries and readers new to HAZOP study are advised to consult the reference list,3-6 the International Electrotechnical Commission (IEC) standard,7 or guidelines written specifically for other industries. It is hoped that this guide will help people within the process industries, including all those with responsibilities within safety man- agement systems. Although it is primarily written for HAZOP study leaders, scribes, and members, it may also be of use to those involved in training and plant management. 1.2 ESSENTIAL FEATURES OF HAZOP STUDY A HAZOP study is a structured analysis of a system, process, or operation for which detailed design information is available, carried out by a multidisciplinary team. The team proceeds on a line-by-line or stage-by-stage examination of a firm design for the process or operation. While being systematic and rigorous, the analysis also aims to be open and creative. This is done by using a set of guidewords in combination with the system parameters to seek meaningful deviations from the design intention. A meaningful deviation is one that is physi- cally possible—for example, no flow, high pressure, or reverse reaction. Deviations such as no temperature or reverse viscosity have no sen- sible, physical meaning and are not considered. The team concentrates