Guidelines for Determining the Probability of Ignition of a Released Flammable Mass

Complemented by an estimating tool spreadsheet based on a fixed set of chemicals to assist in risk estimations, Probability of Ignition of a Released Flammable Mass converts a "best guess" to a calculated value based on available information and current technology. The text documents and explains the science and background of the technology-based approach. The tool, when populated with appropriate data, yields an estimate of the probability that a defined release of a flammable material will ignite if exposed to an ignition source. This information can be used to make risk assessments with a higher degree of confidence than estimates made before and it provides valuable information for use in the development of a facility's Emergency Response Plan.

FORWARD XI
1 INTRODUCTION 1
1. 1 Objectives 1
1. 2 Motivation for this Book 1
1. 2. 1 A Brief History of Fire Protection 2
1. 2. 2 The Development of Risk-Based Approaches to Flammables Management 3
1. 2. 3 Difficulties in Developing Ignition Probability Prediction Methods 4
1. 2. 4 Missing Variables 5
1. 2. 5 Summary of Industry Needs and Path Forward 5
1. 2. 6 Applications for This Book 6
1. 2. 7 Limitations in Applying the Approaches in This Book 7
1. 3 Ignition Probability Overview 8
1. 3. 1 Theoretical Basis for Ignition 8
1. 3. 2 Key Ignition Factors Related to the Properties of the Fuel, and Available Surrogates that can be Used for Developing Probability of Ignition Predictions 13
1. 3. 3 Key Ignition Factors Related to the Release Source 19
1. 3. 4 Key Ignition Factors Related to the External Environment After the Release 27
1. 4 Control of Ignition Sources 30
1. 4. 1 Ignition Source Management 30
1. 4. 2 Minimization of Release 33
1. 5 Vapor Cloud Explosion Probability Overview 33
1. 6 Detonation Overview 35
1. 6. 1 Detonation Using a Strong Ignition Source 35
1. 6. 2 Deflagration-to-Detonation Transition 35
1. 6. 3 Buncefield 35
1. 7 Other Ignition Topics - Hydrogen 36
1. 7. 1 Ignition Mechanisms 36
1. 7. 2 Other Hydrogen Ignition Topics 37
2 ESTIMATION METHODS 39
2. 1 Introduction 39
2. 1. 1 Event Tree 39
2. 1. 2 Failure Frequency Data for Use in Event Trees 41
2. 1. 3 Quantification of the Event Tree 41
2. 2 Factors Influencing the Probability of Immediate Ignition 41
2. 2. 1 Temperature of Release Relative to the Autoignition Temperature 42
2. 2. 2 Minimum Ignition Energy (MIE) of Material Being Released 42
2. 2. 3 Pyrophoricity of Released Material 44
2. 2. 4 Pressure/Velocity of Discharge 44
2. 2. 5 Droplet Size 45
2. 2. 6 Presence of Particulates 46
2. 2. 7 Configuration/Orientation of Equipment Near/At the Point of Release 46
2. 2. 8 Temperature of Release (as it relates to its effect on MIE) 46
2. 2. 9 Phase of Release (API RBI) 47
2. 2. 10 Flash Point and Release Rate (TNO) 47
2. 3 Factors Influencing the Probability of Delayed Ignition 47
2. 3. 1 Strength and Numbers of Ignition Sources 47
2. 3. 2 Duration of Exposure 51
2. 3. 3 Release Rate/Amount 51
2. 3. 4 Material Being Released 53
2. 3. 5 Release Phase/Flash Point/Boiling Point 53
2. 3. 6 Distance from Point of Release to Ignition Source 54
2. 3. 7 Meteorology 54
2. 3. 8 Events Originating Indoors 54
2. 4 Factors Influencing the Probability of Explosion, Given Delayed Ignition 57
2. 5 Potential Interdependence of Variables 57
2. 6 Summary of Variables Used in Each Analysis Level 58
2. 7 Basic (Level 1) Probability of Ignition Algorithms 59
2. 7. 1 Level 1 Algorithm for Probability of Immediate Ignition 59
2. 7. 2 Level 1 Algorithm for Probability of Delayed Ignition 60
2. 8 Level 2 Probability of Ignition Algorithms 61
2. 8. 1 Level 2 Algorithm for Probability of Immediate Ignition 61
2. 8. 2 Level 2 Algorithm for Probability of Delayed Ignition 62
2. 9 Advanced (Level 3) Probability of Ignition Algorithms 67
2. 9. 1 Level 3 Algorithm for Probability of Immediate Ignition 67
2. 9. 2 Level 3 Algorithm for Probability of Delayed Ignition 67
2. 10 Developing Inputs When Chemical Properties Are Not Available 69
2. 10. 1 Estimating Input Properties of Chemicals Not in the Pick List 69
2. 10. 2 Estimating the Properties of Flammable Mixtures 71
2. 11 Worked Example 73
2. 11. 1 Problem Statement 73
2. 11. 2 Level 1 Analysis 74
2. 11. 3 Level 2 Analysis 75
2. 11. 4 Level 3 Analysis 76
2. 12 Application of the Models to a Study with Multiple Ignition Sources 77
3 TECHNICAL BACKGROUND AND DATA SOURCES 78
3. 1 Introduction and Summary 78
3. 2 Government-driven studies 82
3. 2. 1 Rew et al. 82
3. 2. 2 Bevi Risk Assessment Manual (TNO Purple Book) 91
3. 2. 3 HSE / Crossthwaite, et al. 95
3. 2. 4 HSE/Thyer 95
3. 2. 5 HSE/Gummer and Hawksworth - Hydrogen 97
3. 2. 6 Cawley/U. S. Bureau of Mines 98
3. 2. 7 Canvey 99
3. 2. 8 Witcofski (NASA) Liquid Hydrogen 100
3. 3 Information Developed by Industry Groups 100
3. 3. 1 Cox/Lees/Ang 100
3. 3. 2 E&P Forum 103
3. 3. 3 API RBI 103
3. 3. 4 API RP 2216 108
3. 3. 5 IEEE 109
3. 3. 6 UK Energy Institute 110
3. 4 Information Developed in Academia 113
3. 4. 1 Ronza, et al. 113
3. 4. 2 Offshore Explosions (Loughborough) 116
3. 4. 3 Srekl and Golob 116
3. 4. 4 Duarte et al. 117
3. 4. 5 Swain - Ignition of Hydrogen 118
3. 4. 6 Dryer et al. - Hydrogen and Light Hydrocarbons 118
3. 4. 7 Britton - Silanes and Chlorosilanes 119
3. 4. 8 Pesce et al. 120
3. 5 Information Developed by Individual Companies 121
3. 5. 1 Spouge 121
3. 5. 2 Moosemiller 122
3. 5. 3 Johnson - Humans as Electrostatic Ignition Sources 123
3. 5. 4 Jallais - Hydrogen 125
3. 5. 5 Zalosh - Hydrogen 125
3. 5. 6 Smith - Pipelines 127
3. 6 Studies Specific to Ignition of Sprays 128
3. 6. 1 Lee et al. 128
3. 6. 2 Babrauskas 130
3. 7 Case Histories 131
3. 7. 1 Britton - External Ignition Events 131
3. 7. 2 Pratt - Gas Well and Pipeline Blowouts 132
3. 7. 3 Gummer and Hawksworth - Hydrogen Events 133
4 ADDITIONAL EXAMPLES 136
4. 1 Introduction to Examples, and Potential "Lessons Learned" 136
4. 1. 1 "Reality" vs. Predictions 136
4. 1. 2 "Conservatism" - Does it Exist? 137
4. 1. 3 Cases where the Model may not be Appropriate or the Results Misinterpreted 138
4. 1. 4 Summary of Worked Examples 139
4. 2 Worked Examples (based on other CCPS books) 140
4. 2. 1 "Vapor Cloud Explosion Hazard Assessment of a Storage Site" 140
4. 2. 2 "Open Field Release of Propane" 145
4. 2. 3 "Release from Pipeline" 149
4. 3 Worked Examples (chemical and petrochemical plants) 152
4. 3. 1 "Ethylene Tubing Failure" 152
4. 3. 2 "Benzene Pipe Rupture" 154
4. 3. 3 "Spill from Methyl Ethyl Ketone Tank" 155
4. 3. 4 "Indoor Puncture of MEK Tote" 158
4. 3. 5 "Elevated Release" 161
4. 4 Worked Examples (oil refineries) 164
4. 4. 1 "Gasoline Release from a Sight Glass" 164
4. 4. 2 "Overfilling a Gasoline Storage Tank" 168
4. 4. 3 "Overfilling a Propane Bullet" 170
4. 4. 4 "Hydrogen Release from a Sight Glass" 172
4. 5 Worked Examples (Unusual Cases) 174
4. 5. 1 "Indoor Acid Spill - Ventilation Model" 174
4. 5. 2 "Release of Ammonia" 179
4. 6 Worked Examples ('Out of Scope' Cases) 180
4. 6. 1 "Release of Gas from an Offshore Platform Separator" 180
4. 6. 2 "Dust Ignition" 183
4. 7 Worked Examples of the Benefits of Plant Modifications and Design Changes 186
4. 7. 1 "Ignition by Hot Surfaces" 186
4. 7. 2 Release Prevention 189
4. 7. 3 Duration of Exposure 189
4. 7. 4 Benefit of Improved Ventilation of Indoor Releases - Continuation of "Indoor Acid Spill" Example 192
5 SOFTWARE ILLUSTRATION 194
5. 1 Explanation and Instructions for Software Tool 194
5. 2 Opening the Software Tool 194
5. 3 General Inputs and Outputs 195
5. 4 Level 1 Inputs 196
5. 5 Level 2 Analyses 198
5. 6 Level 3 Analyses 200
5. 7 Explosion Probability 200
5. 8 Illustrations of Software Use 201
5. 8. 1 "Vapor Cloud Explosion Hazard Assessment of a Storage Site" (example from Section 4. 2. 1) 201
5. 8. 2 "Open Field Release of Propane" (example from Section 4. 2. 2) 204
APPENDIX A. CHEMICAL PROPERTY DATA 207
APPENDIX B. OTHER MODELS FOR CONSIDERATION 213