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

Since 1985, the Center for Chemical Process Safety (CCPS) has been the world leader in developing and disseminating information on process safety management and technology. CCPS, an industry technology alliance of the American Institute of Chemical Engineers (AIChE), has published over 90 books in its process safety guidelines and process safety concepts series, and over 100 training modules through its Safety in Chemical Engineering Education (SACHE) series.

• FORWARD XI1 INTRODUCTION 11.1 Objectives 11.2 Motivation for this Book 11.2.1 A Brief History of Fire Protection 21.2.2 The Development of Risk-Based Approaches to Flammables Management 31.2.3 Difficulties in Developing Ignition Probability Prediction Methods 41.2.4 Missing Variables 51.2.5 Summary of Industry Needs and Path Forward 51.2.6 Applications for This Book 61.2.7 Limitations in Applying the Approaches in This Book 71.3 Ignition Probability Overview 81.3.1 Theoretical Basis for Ignition 81.3.2 Key Ignition Factors Related to the Properties of the Fuel, and Available Surrogates that can be Used for Developing Probability of Ignition Predictions 131.3.3 Key Ignition Factors Related to the Release Source 191.3.4 Key Ignition Factors Related to the External Environment After the Release 271.4 Control of Ignition Sources 301.4.1 Ignition Source Management 301.4.2 Minimization of Release 331.5 Vapor Cloud Explosion Probability Overview 331.6 Detonation Overview 351.6.1 Detonation Using a Strong Ignition Source 351.6.2 Deflagration-to-Detonation Transition 351.6.3 Buncefield 351.7 Other Ignition Topics - Hydrogen 361.7.1 Ignition Mechanisms 361.7.2 Other Hydrogen Ignition Topics 372 ESTIMATION METHODS 392.1 Introduction 392.1.1 Event Tree 392.1.2 Failure Frequency Data for Use in Event Trees 412.1.3 Quantification of the Event Tree 412.2 Factors Influencing the Probability of Immediate Ignition 412.2.1 Temperature of Release Relative to the Autoignition Temperature 422.2.2 Minimum Ignition Energy (MIE) of Material Being Released 422.2.3 Pyrophoricity of Released Material 442.2.4 Pressure/Velocity of Discharge 442.2.5 Droplet Size 452.2.6 Presence of Particulates 462.2.7 Configuration/Orientation of Equipment Near/At the Point of Release 462.2.8 Temperature of Release (as it relates to its effect on MIE) 462.2.9 Phase of Release (API RBI) 472.2.10 Flash Point and Release Rate (TNO) 472.3 Factors Influencing the Probability of Delayed Ignition 472.3.1 Strength and Numbers of Ignition Sources 472.3.2 Duration of Exposure 512.3.3 Release Rate/Amount 512.3.4 Material Being Released 532.3.5 Release Phase/Flash Point/Boiling Point 532.3.6 Distance from Point of Release to Ignition Source 542.3.7 Meteorology 542.3.8 Events Originating Indoors 542.4 Factors Influencing the Probability of Explosion, Given Delayed Ignition 572.5 Potential Interdependence of Variables 572.6 Summary of Variables Used in Each Analysis Level 582.7 Basic (Level 1) Probability of Ignition Algorithms 592.7.1 Level 1 Algorithm for Probability of Immediate Ignition 592.7.2 Level 1 Algorithm for Probability of Delayed Ignition 602.8 Level 2 Probability of Ignition Algorithms 612.8.1 Level 2 Algorithm for Probability of Immediate Ignition 612.8.2 Level 2 Algorithm for Probability of Delayed Ignition 622.9 Advanced (Level 3) Probability of Ignition Algorithms 672.9.1 Level 3 Algorithm for Probability of Immediate Ignition 672.9.2 Level 3 Algorithm for Probability of Delayed Ignition 672.10 Developing Inputs When Chemical Properties Are Not Available 692.10.1 Estimating Input Properties of Chemicals Not in the Pick List 692.10.2 Estimating the Properties of Flammable Mixtures 712.11 Worked Example 732.11.1 Problem Statement 732.11.2 Level 1 Analysis 742.11.3 Level 2 Analysis 752.11.4 Level 3 Analysis 762.12 Application of the Models to a Study with Multiple Ignition Sources 773 TECHNICAL BACKGROUND AND DATA SOURCES 783.1 Introduction and Summary 783.2 Government-driven studies 823.2.1 Rew et al. 823.2.2 Bevi Risk Assessment Manual (TNO Purple Book) 913.2.3 HSE / Crossthwaite, et al. 953.2.4 HSE/Thyer 953.2.5 HSE/Gummer and Hawksworth - Hydrogen 973.2.6 Cawley/U.S. Bureau of Mines 983.2.7 Canvey 993.2.8 Witcofski (NASA) Liquid Hydrogen 1003.3 Information Developed by Industry Groups 1003.3.1 Cox/Lees/Ang 1003.3.2 E&P Forum 1033.3.3 API RBI 1033.3.4 API RP 2216 1083.3.5 IEEE 1093.3.6 UK Energy Institute 1103.4 Information Developed in Academia 1133.4.1 Ronza, et al. 1133.4.2 Offshore Explosions (Loughborough) 1163.4.3 Srekl and Golob 1163.4.4 Duarte et al. 1173.4.5 Swain - Ignition of Hydrogen 1183.4.6 Dryer et al. – Hydrogen and Light Hydrocarbons 1183.4.7 Britton – Silanes and Chlorosilanes 1193.4.8 Pesce et al. 1203.5 Information Developed by Individual Companies 1213.5.1 Spouge 1213.5.2 Moosemiller 1223.5.3 Johnson – Humans as Electrostatic Ignition Sources 1233.5.4 Jallais – Hydrogen 1253.5.5 Zalosh – Hydrogen 1253.5.6 Smith - Pipelines 1273.6 Studies Specific to Ignition of Sprays 1283.6.1 Lee et al. 1283.6.2 Babrauskas 1303.7 Case Histories 1313.7.1 Britton - External Ignition Events 1313.7.2 Pratt - Gas Well and Pipeline Blowouts 1323.7.3 Gummer and Hawksworth – Hydrogen Events 1334 ADDITIONAL EXAMPLES 1364.1 Introduction to Examples, and Potential “Lessons Learned” 1364.1.1 “Reality” vs. Predictions 1364.1.2 “Conservatism” – Does it Exist? 1374.1.3 Cases where the Model may not be Appropriate or the Results Misinterpreted 1384.1.4 Summary of Worked Examples 1394.2 Worked Examples (based on other CCPS books) 1404.2.1 “Vapor Cloud Explosion Hazard Assessment of a Storage Site” 1404.2.2 “Open Field Release of Propane” 1454.2.3 “Release from Pipeline” 1494.3 Worked Examples (chemical and petrochemical plants) 1524.3.1 “Ethylene Tubing Failure” 1524.3.2 “Benzene Pipe Rupture” 1544.3.3 “Spill from Methyl Ethyl Ketone Tank” 1554.3.4 “Indoor Puncture of MEK Tote” 1584.3.5 “Elevated Release” 1614.4 Worked Examples (oil refineries) 1644.4.1 “Gasoline Release from a Sight Glass” 1644.4.2 “Overfilling a Gasoline Storage Tank” 1684.4.3 “Overfilling a Propane Bullet” 1704.4.4 “Hydrogen Release from a Sight Glass” 1724.5 Worked Examples (Unusual Cases) 1744.5.1 “Indoor Acid Spill - Ventilation Model” 1744.5.2 “Release of Ammonia” 1794.6 Worked Examples (‘Out of Scope’ Cases) 1804.6.1 “Release of Gas from an Offshore Platform Separator” 1804.6.2 “Dust Ignition” 1834.7 Worked Examples of the Benefits of Plant Modifications and Design Changes 1864.7.1 “Ignition by Hot Surfaces” 1864.7.2 Release Prevention 1894.7.3 Duration of Exposure 1894.7.4 Benefit of Improved Ventilation of Indoor Releases – Continuation of “Indoor Acid Spill” Example 1925 SOFTWARE ILLUSTRATION 1945.1 Explanation and Instructions for Software Tool 1945.2 Opening the Software Tool 1945.3 General Inputs and Outputs 1955.4 Level 1 Inputs 1965.5 Level 2 Analyses 1985.6 Level 3 Analyses 2005.7 Explosion Probability 2005.8 Illustrations of Software Use 2015.8.1 “Vapor Cloud Explosion Hazard Assessment of a Storage Site” (example from Section 4.2.1) 2015.8.2 “Open Field Release of Propane” (example from Section 4.2.2) 204APPENDIX A. CHEMICAL PROPERTY DATA 207APPENDIX B. OTHER MODELS FOR CONSIDERATION 213