API RP 581 - 3rd Ed.2016 - Add.2-2020 - Risk-Based Inspection Methodology

4.14 Tables ............................................................................................................................................. 46
4.15 Figures ............................................................................................................................................ 71
5 COF—LEVEL 2 ....................................................................................................................................... 73
5.1 Determine the Fluid Composition and Associated Properties ................................................. 73
5.1.1 General ................................................................................................................................... 73
5.1.2 Required Properties at Storage Conditions ........................................................................ 73
5.1.3 Required Properties at Flashed Conditions ....................................................................... 74
5.1.4 Calculation of Fluid Properties ............................................................................................ 75
5.2 Release Hole Size Selection ......................................................................................................... 75
5.2.1 General ................................................................................................................................... 75
5.2.2 Calculation of Release Hole Sizes ....................................................................................... 75
5.3 Release Rate Calculation .............................................................................................................. 76
5.3.1 Source Term Modeling .......................................................................................................... 76
5.3.2 Determining the Release Phase ........................................................................................... 76
5.3.3 Vapor Release Source ........................................................................................................... 76
5.3.4 Two-phase Release Source .................................................................................................. 76
5.3.5 Liquid Release Source .......................................................................................................... 77
5.3.6 Calculation of Release Rates ............................................................................................... 77
5.4 Estimate the Fluid Inventory Available for Release ................................................................... 77
5.4.1 General ................................................................................................................................... 77
5.4.2 Calculation of Inventory Mass .............................................................................................. 77
5.5 Determine Release Type ............................................................................................................... 77
5.5.1 General ................................................................................................................................... 77
5.5.2 Calculation of Release Type ................................................................................................. 77
5.6 Estimate the Impact of Detection and Isolation Systems on Release Magnitude .................. 78
5.6.1 General ................................................................................................................................... 78
5.6.2 Calculation for Detection and Isolation Systems ............................................................... 78
5.7 Determine the Release Rate and Mass for COF ......................................................................... 78
5.7.1 General ................................................................................................................................... 78
5.7.2 Aerosol and Rainout Modeling ............................................................................................. 78
5.7.3 Calculation of Jet Release Rate and Pool Release Rate ................................................... 78
5.7.4 Vapor Sources from Boiling or Non-boiling Pools ............................................................ 79
5.7.5 Cloud Dispersion Modeling .................................................................................................. 80
5.7.6 Cloud Dispersion Calculation .............................................................................................. 80
5.8 Determine Flammable and Explosive Consequences ............................................................... 81
5.8.1 Event Tree Calculations ........................................................................................................ 81
5.8.2 Pool Fires ............................................................................................................................... 86
5.8.3 Jet Fires .................................................................................................................................. 90
5.8.4 Fireballs .................................................................................................................................. 91
5.8.5 VCEs ....................................................................................................................................... 93
5.8.6 Flash Fires .............................................................................................................................. 96
5.8.7 Determination of Flammable Consequence for Each Release Case (Hole Size) ............ 96
5.8.8 Determination of Final Flammable Consequence Areas ................................................... 96
5.8.9 Calculation of Flammable Consequence Areas ................................................................. 97
5.9 Determine Toxic Consequences .................................................................................................. 103
5.9.1 General ................................................................................................................................... 103
5.9.2 Toxic Impact Criteria ............................................................................................................. 103
5.9.3 Release Duration ................................................................................................................... 105
5.9.4 Toxic Event Probabilities ...................................................................................................... 105
5.9.5 Consequences of Releases Containing Multiple Toxic Chemicals .................................. 105
5.9.6 Toxic Consequence Area ...................................................................................................... 105