Table of Contents

List of Tables ix

List of Figures xi

Acronyms and Abbreviations xiii

Glossary xv

Acknowledgments xxiii

Online Materials Accompanying this Book xxvii

Preface xxix

1 INTRODUCTION 1

1.1 Purpose 1

1.2 Scope and Intended Audience 1

1.3 Organization of this Concept Book 2

1.4 Introduction to the Bow Tie Concept 4

1.5 Conclusions 12

2 THE BOW TIE MODEL 15

2.1 Bow Tie Model Elements 15

2.2 Hazard 17

2.3 Top Event 20

2.4 Consequences 24

2.5 Threats 27

2.6 Barriers 32

2.7 Degradation actors and Degradation Controls 45

2.8 Conclusions 51

3 BOW TIE DEVELOPMENT 53

3.1 Rationale for Bow Tie Development 53

3.2 Bow Tie workshop 53

3.3 Postow Tie Workshop Activities and Quality Checks 64

Conclusions 51

4 ADDRESSING HUMAN FACTORS IN BOW TIE ANALYSIS 69

4.1 Human and Organiational Factors Fundamentals 69

4.2 Standard and MultiLevel Bow Tie Approaches 74

4.3 Human and Organiational Factors as a Barrier or Degradation Control 80

4.4 Validating Human Performance in Barriers and Degradation Controls 84

4.5 Quantifying Human Reliability in Bow Ties 86

4.6 Conclusions 86

5 PRIMARY USES OF BOW TIES 89

5.1 Primary Use Examples 89

5.2 Linking Bow Ties to the Risk Management System 89

5.3 Communication of Major Accident Scenarios and Degradation Controls 94

5.4 Use of Bow Ties in Design and Operations 101

5.5 Identification of Safety Critical Information 107

5.6 Conclusions 113

6 BARRIER MANAGEMENT PROGRAM 115

6.1 Barrier Management Strategy 115

6.2 Barrier and Degradation Control Management Program 118

6.3 Organizational Learning 127

6.4 Conclusions 128

7 ADDITIONAL USES OF BOW TIES 131

7.1 Additional Use Examples 131

7.2 Linking Bow Ties to HAZOP, LOPA and SIL 131

7.3 Integrating Bow Ties into ALARP Demonstrations 134

7.4 Operationalizing Bow Ties (MOPO / SOOB) 135

7.5 Incident Investigation using Bow Ties 139

7.6 Real-time Dashboards using Bow Ties 142

7.7 Barrier and Degradation Control Verification 143

7.8 Bow Tie Chaining 144

7.9 Enterprise-wide Analysis and Window on Systemic Risks 146

7.10 Conclusions 147

APPENDIX A – SOFTWARE TOOLS 149

Software used for Bow Tie Diagrams 149

APPENDIX B – CASE STUDY 153

Introduction 153

Volatile Hydrocarbons under Pressure in a Pipeline 153

APPENDIX C – MULTI-LEVEL BOW TIES 161

Multilevel Bow Tie for Tank Overfill 161

References 171

Index 177

About the Author

The Center for Chemical Process Safety (CCPS) has been the world leader in developing and disseminating information on process safety management and technology since 1985. The CCPS, an industry technology alliance of the American Institute of Chemical Engineers (AIChE), has published over 100 books in its process safety guidelines and process safety concepts series, and over 10 training modules through its Safety in Chemical Engineering Education (SAChE) series.