# Evaluation of the Effects and Consequences of Major Accidents in Industrial Plants

The book analyzes the different major accidents which can occur in process plants and during the transportation of hazardous materials. The main features of fires, explosions and toxic releases are discussed, and a set of mathematical models allowing the prediction of their effects and consequences are explained. With a practical approach, the models are applied to simple illustrative examples, as well as to more complex real cases. The use of these calculations in the frame of Quantitative Risk Analysis is also treated.Evaluation of the effects of major accidents in industrial installations covers the following topics: general introduction, source term, fire accidents, vapour cloud explosions, BLEVEs and vessel explosions, atmospheric dispersion of toxic or flammable clouds, vulnerability, and quantitative risk analysis.This book is a useful tool for engineering professionals, as well as an interesting reference for teaching at graduate and post-graduate levels.

Audience
Engineers from the industry, consultants Engineers from the administration University students and professors

Included in series
Industrial Safety Series

Hardbound, 378 Pages

Published: October 2007

Imprint: Elsevier

ISBN: 978-0-444-53081-3

## Contents

• Preface v1. Introduction 11. Risk 12. Risk analysis 23. Major accidents 53.1 Types 53.2 Damage 94. Domino effect 124.1 Classification of domino effects4.2 An example case5. Mathematical modelling of accidents 14Nomenclature 16References 162. Source term 191. Introduction 192. Liquid release 212.1 Flow of liquid through a hole in a tank 212.2 Flow of liquid through a pipe 242.2.1 Liquid flow rate 242.2.2 Friction factor 273. Gas/vapour release 303.1 Flow of gas/vapour through a hole 303.1.1 Critical velocity 303.1.2 Mass flow rate 333.1.3 Discharge coefficient 333.2 Flow of gas/vapour through a pipe 353.3 Time-dependent gas release 404. Two-phase flow 424.1 Flashing liquids 424.2 Two-phase discharge 435. Safety relief valves 445.1 Discharge from a safety relief valve 456. Relief discharges 476.1 Relief flow rate for vessels subject to external fire 486.2 Relief flow rate for vessels undergoing a runaway reaction 497. Evaporation of a liquid from a pool 537.1 Evaporation of liquids 537.2 Pool size 537.2.1 Pool on ground 537.2.2 Pool on water 537.3 Evaporation of boiling liquids 537.4 Evaporation of non-boiling liquids 548. General outflow guidelines for quantitative risk analysis 558.1 Loss-of-containment events in pressurized tanks and vessels 568.2 Loss-of-containment events in atmospheric tanks 568.3 Loss-of-containment events in pipes 568.4 Loss-of-containment events in pumps 568.5 Loss-of-containment events in relief devices 568.6 Loss-of-containment events for storage in warehouses 578.7 Loss-of-containment events in transport units in an establishment 578.8 Pool evaporation 578.9 Outfllow and atmospheric dispersion 58Nomenclature 58References 593. Fire accidents 611. Introduction 612. Combustion 612.1 Combustion reaction and combustion heat 622.2 Premixed flames and diffusion flames 633. Types of fire 633.1 Pool fires 643.2 Jet fires 653.3 Flash fires 653.4 Fireballs 664. Flammability 664.1 Flammability limits 664.1.1 Estimation of flammability limits 674.1.2 Flammability limits of gas mixtures 694.1.3 Flammability limits as a function of pressure 704.1.4 Flammability limits as a function of temperature 704.1.5 Inerting and flammability diagrams 714.2 Flash point temperature 724.3 Autoignition temperature 735. Estimation of thermal radiation from fires 745.1 Point source model 745.2 Solid flame model 775.2.1 View factor 785.2.2 Emissive power 806. Flame size 836.1 Pool fire size 846.1.1 Pool diameter 846.1.2 Burning rate 866.1.3 Height and length of the flames 876.1.4 Influence of wind 876.2 Size of a jet fire 906.2.1 Jet flow 906.2.2 Shape and size of the jet fire 926.2.3 Influence of wind 946.3 Flash fire 997. Boilover 1007.1 Tendency of hydrocarbons to boilover 1027.2 Boilover effects 1038. Fireball 1048.1 Fireball geometry 1048.1.1 Ground diameter 1048.1.2 Fireball duration and diameter 1048.1.3 Height reached by the centre of the fireball 1058.2 Thermal features 1068.2.1 Radiant heat fraction 1068.2.2 Emissive power 1078.2.3 View factor 1088.3 Constant or variable D, H and E 1089. Example case 109Nomenclature 113References 1154. Vapour cloud explosions 1191. Introduction 1192. Vapour clouds 1203. Blast and blast wave 1213.1 Blast wave 1213.2 Detonations 1223.3 Deflagrations 1233.4 Blast scaling 1233.5 Free-air and ground explosions 1244. Estimation of blast: TNT equivalency method 1255. Estimation of blast: multi-energy method 1276. Estimation of blast: Baker-Strehlow-Tang method 1337. Comparison of the three methods 1368. A statistical approach to the estimation of the probable number of fatalities in accidental explosions 1389. Example case 140Nomenclature 144References 1445. BLEVEs and vessel explosions 1471. Introduction 1472. Mechanism of BLEVE 1492.1 Liquid superheating 1512.2 Superheat limit temperature 1532.3 Superheat limit temperature from energy balance 1562.4 When is an explosion a BLEVE? 1593. Vessel failure 1633.1 Mechanism 1633.2 Pressure required for vessel failure 1644. Estimation of explosion effects 1654.1 Thermal radiation 1654.2 Mechanical energy released by the explosions 1654.2.1 Ideal gas behaviour and isentropic expansion 1664.2.2 Real gas behaviour and irreversible expansion 1684.3 Pressure wave 1694.4 Using liquid superheating energy for a quick estimation of ÆÂ´P 1734.5 Estimation of ÆÂ´P from characteristic curves 1764.6 Missiles 1784.6.1 Range 1814.6.2 Velocity 1825. Preventive measures 1836. Example cases 186Nomenclature 190References 1926. Atmospheric dispersion of toxic or flammable clouds 1951. Introduction 1952. Atmospheric variables 1952.1 Wind 1962.2 Lapse rates 1992.3 Atmospheric stability 2002.4 Relative humidity 2042.5 Units of measurement 2043. Dispersion models 2053.1 Continuous and instantaneous releases 2053.2 Effective height of emission 2074. Dispersion models for neutral gases (Gaussian models) 2084.1 Continuous emission 2094.2 Instantaneous emission 2154.3 Short-term releases 2185. Dispersion models for heavier-than-air gases 2195.1 Britter and McQuaid model 2215.1.1 Continuous release 2215.1.2 Instantaneous release 2235.1.3 Finite duration release 2256. Calculating concentration contour coordinates 2276.1 The Ooms integral plume model 2276.2 determining concentration contour coordinates 2277. Dispersion of dust 2308. Atmospheric dispersion of infectious agents 2318.1 Emission source 2318.2 Dispersion of airborne pathogenic agents 2328.3 Epidemics: dispersion of airborne viruses 2329. Escaping 23610. Sheltering 23610.1 Concentration indoors 23610.1.1 Continuous release 23610.1.2 Temporary release 23710.1.3 Instantaneous release 23910.1.4 A simplified approach 24111. Example case 242Nomenclature 244Annex 6-1 246References 2477. Vulnerability 2491. Introduction 2492. Population response to an accident 2493. Probit analysis 2504. Vulnerability to thermal radiation 2544.1 Damage to people 2544.1.1 Probit equations 2574.1.2 Clothing 2584.1.3 Escape 2584.1.4 Effect of hot air 2614.2 Material damages 2615. Vulnerability to explosions 2635.1 Damage to human beings 2635.1.1 Direct consequences 2635.1.2 Indirect consequences 2655.1.3 Collapse of buildings 2685.2 Consequences of an explosion for buildings and structures 2696. Vulnerability to toxic substances 2716.1 Dose and probit equations 2736.2 Substances released from a fire 2757. Inert gases 2778. Influence of sheltering 2798.1 Thermal radiation 2798.2 Blast8.3 Toxic exposure9. Relationship between the number of people killed and the number of people injured in major accidents 28010. Zoning according to vulnerability 28111. Example case 283Nomenclature 288Annex 7-1 287References 2888. Quantitative risk analysis 2911. Introduction 2912. Quantitative risk analysis steps 2923. Individual and societal risks 2943.1 Individual and societal risks definition 2944 Risk mapping 2964.1 Individual risk contours 2964.2 Procedure 2964.3 Societal risk 2985. Introductory examples of risk calculation 2996. Frequencies and probabilities 3066.1 Frequencies of most common loss-of-containment events 3066.2 Failure of repression systems 3066.3 Human error 3066.4 Probabilities for ignition and explosion of flammable spills 3066.5 Meteorological data 3097. Example case 3097.1 Estimation of the frequencies of initiating events 3117.2 Event trees of the diverse initiating events 3127.3 Effects of the different accidental scenarios 3197.4 Calculation of the individual risk 327Nomenclature 329References 331Annex 1 Constants in the Antoine equation 333Annex 2 Flammability levels, flash temperature and heat of combustion (higher value) for different substances 335Annex 3 Acute Exposure Guideline Levels (AEGLs) 337Annex 4 Immediately Dangerous to Life and Health concentrations (IDLH) 345Annex 5 Determining the damage to humans from explosions using characteristic curves 347Index 353