This book presents a guidance on a large range of decision aids for risk analysts and decision makers in industry so that vital decisions can be made in a more consistent, logical, and rigorous manner. It provide good industry practices on how risk decision making is conducted in the chemical industry from many risk information sources as well as all the elements that need to be addressed to ensure good decisions are being made.
Topics Include: Identifying Risk Decisions, A Risk Decision Strategy for Process Safety, Case Studies in Risk Decision Making Failures, Guidance on Selecting Decision Aids, Templates for Decision Making in Risk-Based Process Safety, Understanding Process Hazards & Worst Possible Consequences, Management of Change as an Exercise in Risk Identification, Inherently Safer Design as an Exercise in Risk Tradeoff Analysis, Using LOPA and Risk Matrices in Risk Decisions, Using CPQRA and Safety Risk Criteria in Risk Decisions, Group Decision Making, Avoiding Decision Traps, Documentation of Process Safety Risk DecisionsTable of Contents
Contents v
List of Tables xi
List of Figures xiii
Acronyms and Abbreviations xv
Glossary xix
Acknowledgements xxxi
Preface xxxiii
Introduction 35
1.1 History of Approaches to Process Safety Management 35
1.2 The Paradigm of Risk-Based Process Safety Management 36
1.2.1 Risk Based Process Safety (RBPS) Management 36
1.2.2 Risk Decisions Characteristics 39
1.3 A Risk Decision Making Method 40
1.4 Road Map and Relationship of this Book with Other Material 41
1.5 Risk Decisions during Process Life Cycle 43
1.6 Pros and cons 44
1.7 Summary 44
Key Concepts in Risk Management 47
2.1 Risk Management Process 47
2.2 Risk Identification - Risk Scenario 47
2.2.1 Risk Identification 49
2.3 Risk Analysis - Consequences and Frequency 49
2.3.1 Consequences and Impacts 50
2.3.2 Frequency 50
2.3.3 Risk Estimation 51
2.4 Risk Evaluation 56
2.4.1 Decision criteria 56
2.4.2 Qualitative, Semi-Quantitative and Quantitative Risk Criteria 59
2.4.3 Risk Reduction Factor 61
2.5 Summary 62
Understanding Process Hazards, Consequences and Risks 63
3.1 Process Hazards 63
3.1.1 Acute Toxicity 63
3.1.2 Flammability and Explosivity 67
3.1.3 Chemical Reactivity 70
3.1.4 Significant or Large Environmental Release Hazards 72
3.1.5 Other Process Hazards 72
3.2 Risk Identification 73
3.3 Consequences and Impacts 73
3.4 Frequency 74
3.5 Risk 76
Risk Decisions and Strategies 79
4.1 Objectives and attributes 79
4.1.1 Objectives 79
4.1.2 Attributes 79
4.2 Process Life Cycle and Alternatives 81
4.3 The Decision Process 82
4.3.1 Define the Problem 82
4.3.2 Evaluate the Baseline Risk 83
4.3.3 Identify the Alternatives 83
4.3.4 Screen the Alternatives 84
4.3.5 Make the Decision 84
4.4 Objectives and Outcomes 84
4.5 Tradeoffs 85
4.6 Uncertainty 87
4.7 Risk Tolerance 90
4.8 Linked Decisions 91
4.9 Decision trees 92
Decision Making 95
5.1 Defining the Decision Problem 95
5.1.1 Types of Decisions 95
5.2 Selecting a Decision Tool 97
5.2.1 Progression of Risk Analysis Tools 97
5.2.2 Factors in Decision Tool Selection 98
5.3 Assembling the Appropriate Assessment Resources 101
5.3.1 Team Members 101
5.3.2 Opening Meeting 104
5.3.2 Tools/Methods 104
5.3.3 Time 105
5.4 Define decision criteria 105
5.4.1 Process Safety Risk Criteria 105
5.4.2 Other Criteria 107
5.5 Making the decision 107
5.5.1 Characteristics of Decision Aids 107
5.5.2 Appling the Decision Tools, Aids, and Criteria 108
5.5.3 Recognizing and Dealing with Uncertainties 111
5.5.4 Recognizing the Need to Escalate the Decision 113
5.6 Finalizing decision and the approval process 114
5.7 Communicating, Documenting, and implementing the Decision 114
5.7 Summary 116
Potential Decision Traps 117
6.1 Introduction 117
6.2 Anchoring Trap 117
6.2.1 Anchoring Trap Example, Titanic 118
6.2.2 Countering the Anchoring Trap 118
6.3 Status-Quo Trap 119
6.3.1 Status Quo Examples 119
6.3.2 Countering the Status-Quo Trap 120
6.4 Sunk-cost and escalation of commitment trap 120
6.4.1 Countering the Sunk-Cost Trap 121
6.5 Confirming-Evidence Trap 121
6.5.1 Countering the Confirming Evidence Trap 122
6.6 Framing Trap 122
6.6.1 Framing Example 123
6.6.2 Countering the Framing Trap 123
6.7 Estimating and Forecasting Trap 123
6.7.1 Overconfidence 123
6.7.2 Prudence 126
6.7.3 Recallability 127
6.7.4 Countering Estimating and Forecasting Traps 127
6.8 Groupthink Trap 128
6.8.1 Groupthink Example, Flixborough, UK Explosion 128
6.8.2 Countering the Groupthink Trap 128
6.9 Summary 129
Inherently Safer Design 131
7.1 Introduction to inherently safer design 131
7.2 Inherently Safer Design Strategies 131
7.3 Hierarchy of Risk Management Controls 132
7.4 ISD examples to illustrate decision Process 133
7.4.1 Example with minimization 135
7.4.2 Example with moderation 136
7.4.3 Example with simplification 137
7.4.3 Other tradeoffs 137
Make versus buy 138
Substitution 138
7.5 Summary 138
Management of Change 139
8.1 Introduction 139
8.2 Decision Approval level 143
8.3 Examples of Decision Process Applied to Changes 144
8.3.1 Equipment Change 144
8.3.2 Procedural Change 145
8.3.3 Process Parameter Change 146
8.3.4 Organizational Change 147
8.3.5 Raw Material Change 148
8.3.6 Vendor Change 149
8.4 Summary 150
Using LOPA and Risk Matrices in Risk Decisions 151
9.1 Introduction 151
9.2 Risk Matrices 151
9.2.1 Risk Matrix Format 152
9.3 Layer of Protection Analysis 155
9.3.1 Independent Protection Layers 158
9.3.2 LOPA Format 159
9.4 Phosgene Handling Process for Risk Decision Example 159
9.4.1 Description 159
9.4.2 Risk Matrix for Phosgene Handling Example 161
9.5 Phosgene Example Decision Process Using Risk Matrix 164
9.6 Decision Process for Phosgene Example Using LOPA 165
9.7 Summary 172
Using QRA and Safety Risk Criteria in Risk Decisions 173
10.1 Introduction to CPQRA 173
10.1.1 Calculate Frequencies 173
10.1.2 Calculate Consequences 178
10.1.3 Quantitative Risk Analysis (QRA) 179
10.2 Safety Risk Criteria 179
10.2.1 Scope of Risk Criteria 179
10.2.2 Individual and Societal Risk 180
10.2.3 Continual Improvement 184
10.3 High Consequence Low Probability (HCLP) Events 185
10.4 Examples 188
10.4.1 Comparing Design Options: Bromine Handling Facility 188
10.4.2 Compliance and Continual Improvement: Organic Acid Vent System 192
10.4.3 Special Case: The Domino Effect 193
10.5 Summary 195
Decision Implementation 197
11.1 Introduction 197
11.2 Implementation 197
11.3 Documentation 197
11.3.1 Importance of a decision document 197
11.3.2 Writing recommendations 197
11.3.3 Advice of legal counsel 198
11.3.4 Contents of the decision document 199
11.3.5 Retention of the decision document 199
11.4 Revalidation 200
11.4.1 Time based 200
11.4.2 Situation based 200
11.5 Summary 201
Summary and Lessons 203
12.1 Introduction 203
12.2 Case Studies in Risk: Decision Making Failures 203
12.2.1 Failure to Define the Problem 203
12.2.2 Failure to Establish Baseline Risk and Identify Alternatives 204
12.2.3 Make the Decision - Failure to consider tradeoffs 205
12.2.4 Make the Decision - Failure to understand uncertainty 206
12.2.5 Make the Decision - Failure to do risk identification and Failure to probe risk tolerance 206
12.2.6 Make the Decision - Failure to recognize linked decisions 207
12.3 Lessons and Summary 207
References 211
Index 219
