Basic Guide to System Safety

This book provides guidance on including prevention through design concepts within an occupational safety and health management system. Through the application of these concepts, decisions pertaining to occupational hazards and risks can be incorporated into the process of design and redesign of work premises, tools, equipment, machinery, substances, and work processes including their construction, manufacture, use, maintenance, and ultimate disposal or reuse. These techniques provide guidance for a life-cycle assessment and design model that balances environmental and occupational safety and health goals over the life span of a facility, process, or product.

The new edition is expanded to include primer information on the use of safety assurance techniques in design and construction.

Jeffrey W. Vincoli, CSP is currently the Manager of Environmental, Safety and Health Compliance Assurance for Bechtel Corporation. Jeff has over three decades of experience in the practice of occupational and environmental safety and health to include work in system safety analysis, accident and incident investigation, professional training and consulting services, and hazard recognition and assessment. He is a Professional Member of the American Society of Safety Engineers and has assisted in a number of task force assignments and appointed positions focusing on improving the practice of occupational safety and health on a global basis. He has conducted safety reviews and analyses, investigations and training at major construction and engineering projects located on six continents. Jeff is the author of eight published books with three different publishing houses and more than two dozen articles in professional trade journals.

PREFACE xiii

PART I THE SYSTEM SAFETY PROGRAM 1

1 System Safety: An Overview 3

Background 3

The Difference Between Industrial Safety and System Safety 7

System Safety and the Assessment of Risk 8

2 System Safety Concepts 15

Fundamentals 15

The System Safety Process 16

System Safety Criteria 18

Hazard Severity 18

Hazard Probability 18

The Hazard Risk Matrix 19

System Safety Precedence 20

Cost and Risk Acceptance 24

Quantitative Risk Assessment 25

Principles of Risk Management 27

Management Commitment 27

3 System Safety Program Requirements 29

The Safety Charter 29

Selling Safety to Management 30

The System Safety Effort 31

Closed-Loop Hazard Tracking System 32

Accident Risk Assessment 33

MishapAccidentIncident Reporting 33

Facility Inspection Reports 36

System Safety Analyses 36

Life Cycle Phases and the System Safety Process 36

Concept Phase 37

Design Phase 37

Production Phase 37

Operations Phase 39

Disposal Phase 39

4 The Industrial Safety Connection 41

The Occupational Safety and Health Act 41

The Human Factors Element 43

Accident Prevention Through System Design 44

The Process of Task Analysis 47

The Job Safety Analysis and System Safety 48

Guidelines for Preparing a Job Safety Analysis 50

Signatures and Approvals 56

Changes in HazardScope 56

System Safety: an Integral Part of the Overall Organization 57

5 Probability Theory and Statistical Analysis 61

Introduction 61

Probability 62

Statistics 64

Summary 67

PART II SYSTEM SAFETY ANALYSIS: TECHNIQUES AND METHODS 69

6 Preliminary Hazard Analysis 71

Introduction 71

The PHA Development Process 72

The PHA Report 78

PHA Example 78

System Description 79

System Operation 80

Preliminary Assessment 81

Evaluation of System Risk 81

Summary 90

7 Subsystem and System Hazard Analyses 91

Introduction 91

The Subsystem Hazard Analysis Report 92

SSHA Example 93

System Description 93

Evaluation of Subsystem Hazard Risk 95

Summary 98

8 Operating and Support Hazard Analysis 99

Introduction 99

Ergonomics 99

When to Perform the O&SHA 101

O&SHA Example 103

Scope and Purpose of the Example O&SHA 103

Risk Assessment 104

Risk Assessment 1: 1B 106

Risk Assessment 2: 1A 107

Risk Assessment 3: 2B 107

Summary 109

9 Energy Trace and Barrier Analysis 111

Introduction 111

The Energy–Barrier Concept 111

Uses of the ETBA 112

Performing the ETBA 112

The ETBA Worksheet 113

ETBA Example 114

System Description 114

The ETBA 114

Summary 118

10 Failure Mode and Effect Analysis 119

Introduction 119

Types of FMEAs 119

Performing an FMEA 120

The FMEA Report 121

FMEA Example 124

System Component Subassembly Description 124

System Operation 128

Failure Mode(s) and Effect(s) 128

Evaluation of Potential Subsystem or Component Failures 129

Summary 132

11 Fault or Functional Hazard Analysis 135

Introduction 135

The FHA Process 136

FHA Example 137

System Description 137

The FHA Process 139

The FHA 141

Summary 143

12 Fault Tree Analysis 145

Introduction 145

Qualitative and Quantitative Reasoning 146

Constructing a Fault Tree 146

Fault Tree Symbols 147

FTA Examples 150

Probability Values and the Fault Tree 153

Summary 156

13 Management Oversight and Risk Tree 157

Introduction 157

The MORT Analytical Chart 158

MORT Use 159

The MORT Event Tree 160

Symbols 160

MORT Analysis Example 161

MORT Color Coding 163

Procedure for MORT Analysis 165

Summary 165

14 HAZOP and What-If Analyses 167

Introduction 167

Background 168

Definitions 168

Objectives 169

Team Members 169

Reference Data Requirements 169

The Concept of “Nodes” 170

Conducting the What-If Analysis 171

What-If Analysis Steps 171

The What-If Analysis Worksheet 173

Conducting The HAZOP Study 175

The HAZOP Worksheet 175

The Analysis Report 176

Summary 177

15 Special Use Analysis Techniques 179

Introduction 179

Sneak Circuit Analysis 180

Types and Causes of Sneaks 180

SCA Input Requirements 181

Advantages and Disadvantages of the SCA 181

Software Hazard Analysis 183

Types of SWHA Techniques 183

Summary 185

Epilogue 187

Appendix A Sources of Additional InformationTraining 189

Appendix B Acronyms and Abbreviations 195

GLOSSARY OF TERMS 199

BIBLIOGRAPHY 223

INDEX 225

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