Oil and Gas Processing Equipment Risk Assessment with Bayesian N etworks Oil and Gas Processing Equipment Risk Assessment with Bayesian Networks G. Unnikrishnan First edition published 2021 by CRC Press 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742 and by CRC Press 2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN © 2021 Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, LLC Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this p ublication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. 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Title: Oil and gas processing equipment : risk assessment with Bayesian networks / authored by G. Unnikrishnan. Description: First edition. | Boca Raton : CRC Press, 2021. | Includes bibliographical references and index. Identifiers: LCCN 2020019126 | ISBN 9780367254407 (hardback) | ISBN 9780429287800 (ebook) Subjects: LCSH: Gas manufacture and works—Risk assessment—Mathematics. | Petroleum refineries—Risk assessment—Mathematics. | Gas manufacture and works—Equipment and supplies—Safety measures—Mathematics. | Petroleum refineries—Equipment and supplies—Safety measures—Mathematics. | Bayesian statistical decision theory. Classification: LCC TP752 .U66 2021 | DDC 620.1/07—dc23 LC record available at https://lccn.loc.gov/2020019126 ISBN: 978-0-367-25440-7 (hbk) ISBN: 978-0-429-28780-0 (ebk) Typeset in Palatino by codeMantra This book is dedicated to my parents and wife For a safer world Contents Preface ......................................................................................................................xi Author ...................................................................................................................xiii 1. Introduction .....................................................................................................1 1.1 Application of BNs for Risk Assessment ...........................................1 1.2 The Readership ......................................................................................2 1.3 Major Limitations of QRA ...................................................................2 1.4 BN and Its Advantages .........................................................................3 1.5 Scope of the Book ..................................................................................4 1.6 Structure of the Book ............................................................................5 2. Bayes Theorem, Causality and Building Blocks for Bayesian Networks .........................................................................................7 2.1 Probability Basics ..................................................................................7 2.1.1 Law of Total Probability ........................................................10 2.1.2 Bayes Formula for Conditional Probability .......................11 2.2 Bayes Theorem and Nature of Causality .........................................13 2.3 Bayesian Network (BN) ......................................................................14 2.3.1 General Expression for Full Joint Probability Distribution of a BN ..............................................................15 2.3.2 Illustrative Example of Application ....................................15 2.4 Oil and Gas Separator ........................................................................18 2.5 Sensitivity to Findings ........................................................................22 2.6 Use of Probability Density Functions and Discretization ............24 2.7 Framework for BN Application for Major Hazards .......................25 2.8 Sources of Failure Data ......................................................................25 2.8.1 Published Data .......................................................................25 2.8.2 Industry Reports ....................................................................28 2.9 Chapter Summary...............................................................................28 3. Bayesian Network for Loss of Containment from Oil and Gas Separator..................................................................................29 3.1 Oil and Gas Separator Basics .............................................................29 3.2 Causes for Loss of Containment ......................................................30 3.3 Bayesian Network for LOC in Oil and Gas Separator ...................30 3.4 Sensitivities ..........................................................................................35 3.5 Application of BN to Safety Integrity Level Calculations for Oil and Gas Separator ........................................................................36 vii viii Contents 3.5.1 The Independent Protection Layers (IPLs) .........................37 3.5.2 ET for Layer of Protection Analysis (LOPA) ......................38 3.6 C hapter Summary...............................................................................40 4. Bayesian Network for Loss of Containment from Hydrocarbon Pipeline..................................................................................41 4.1 Causes of Pipeline Failures ................................................................41 4.2 M itigation Measures ...........................................................................43 4.3 BN for Loss of Containment from Pipeline .....................................44 4.4 N oisyOr Distribution .........................................................................49 4.5 S ensitivities ..........................................................................................56 4.6 Event Tree for Pipeline LOC ..............................................................56 4.7 Case Study Using BN for Pipeline: Natural Gas Pipeline, Andhra Pradesh, India .......................................................................58 4.7.1 B ackground .............................................................................58 4.7.2 K ey Findings ...........................................................................59 4.7.3 Application of the BN Model ...............................................63 4.7.4 BN for the Case Study ...........................................................63 4.8 C hapter Summary...............................................................................63 5. Bayesian Network for Loss of Containment from Hydrocarbon Storage Tank .........................................................................67 5.1 Storage Tank Basics .............................................................................67 5.2 Causal Factors for Loss of Containment ..........................................68 5.3 Methodology for the Development of BN for LOC and Evaluation .............................................................................................69 5.3.1 Quality of Design ...................................................................70 5.3.2 Quality of Maintenance and Inspection .............................76 5.3.3 Quality of Construction ........................................................77 5.3.4 Quality of Equipment Selection ...........................................78 5.3.5 Quality of Risk Assessments ................................................80 5.3.6 Quality of Systems and Procedures ....................................81 5.3.7 Quality of Human and Organizational Factors ................81 5.3.8 I ntermediate Causes ..............................................................84 5.3.9 Other Root Causes .................................................................85 5.3.10 BN for LOC Scenarios from Floating Roof Tank ...............85 5.3.11 S ensitivities .............................................................................88 5.4 Event Tree for the Post LOC Scenario in Floating Roof (FR) Tank ..............................................................................................92 5.5 BN for LOC in Cone Roof (CR) Tank ................................................93 5.6 C hapter Summary...............................................................................96 6. The Jaipur Tank Farm Accident .................................................................97 6.1 What Happened at IOC Jaipur Tank Farm: Predictability of Bayesian Network ...............................................................................97 Contents ix 6.2 Summary of the Investigation Committee Findings .....................99 6.3 BN for Post LOC ET ..........................................................................100 6.4 Chapter Summary.............................................................................102 7. Bayesian Network for Centrifugal Compressor Damage ..................103 7.1 Compressor Failure Modes ..............................................................103 7.2 Compressor Failure Rates ................................................................104 7.3 Findings from the BN for Compressor Damage...........................106 7.4 Sensitivity of Compressor Damage Node to Parent Nodes ........109 7.5 LOC and Its Consequences ..............................................................110 7.6 C hapter Summary.............................................................................111 8. Bayesian Network for Loss of Containment from a Centrifugal Pump .............................................................................................................113 8.1 I ntroduction .......................................................................................113 8.2 Causes of LOC a Centrifugal Pump ...............................................114 8.2.1 Mechanical Seal ...................................................................114 8.2.2 Casing ....................................................................................114 8.2.3 Suction or Discharge Gasket/s ...........................................114 8.3 BN for LOC in a Centrifugal Pump ...............................................116 8.3.1 Consequences of LOC from a Centrifugal Pump ...........117 8.4 Chapter Summary.............................................................................119 9. Other Related Topics ..................................................................................121 9.1 Introduction .......................................................................................121 9.2 Bayesian Inference ............................................................................121 9.2.1 Computational Aspects .......................................................122 9.3 Comparison between Traditional QRA and BN Methods .........124 References ...........................................................................................................129 Index .....................................................................................................................135