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

CONTENTS
1 SCOPE .................................................................................................................................................... 1
2 REFERENCES ........................................................................................................................................ 1
2.1 Normative ....................................................................................................................................... 1
2.2 Informative ..................................................................................................................................... 1
3 GENERAL ............................................................................................................................................... 3
3.1 Overview ......................................................................................................................................... 3
3.2 Consequence Categories ............................................................................................................. 3
3.3 Collateral Damage ......................................................................................................................... 4
3.4 Overview of COF Methodology .................................................................................................... 4
3.4.1 General ................................................................................................................................... 4
3.4.2 Level 1 Consequence Analysis ............................................................................................ 4
3.4.3 Level 2 Consequence Analysis ............................................................................................ 4
3.5 COF Methodology for AST Bottoms and Shell Courses ........................................................... 5
3.6 COF Methodology .......................................................................................................................... 5
3.7 Area- and Financial-based COF ................................................................................................... 5
3.8 Use of Atmospheric Dispersion Modeling .................................................................................. 5
3.9 Tables ............................................................................................................................................. 6
3.10 Figures ............................................................................................................................................ 8
4 COF—LEVEL 1 ....................................................................................................................................... 9
4.1 Determine the Representative Fluid and Associated Properties ............................................. 9
4.1.1 Representative Fluids ........................................................................................................... 9
4.1.2 Fluid Properties ..................................................................................................................... 9
4.1.3 Choice of Representative Fluids for Acids and Caustic Fluids ........................................ 9
4.1.4 Estimation of Ideal Gas Specific Heat Capacity Ratio ....................................................... 10
4.1.5 Flammable Fluid Types ......................................................................................................... 10
4.1.6 Release Phase ........................................................................................................................ 10
4.1.7 Calculation of Release Phase ............................................................................................... 10
4.2 Release Hole Size Selection ......................................................................................................... 11
4.2.1 General ................................................................................................................................... 11
4.2.2 Calculation of Release Hole Sizes ....................................................................................... 11
4.3 Release Rate Calculation .............................................................................................................. 11
4.3.1 Overview ................................................................................................................................. 11
4.3.2 Liquid Release Rate Calculation .......................................................................................... 12
4.3.3 Vapor Release Rate Equations ............................................................................................. 12
4.3.4 Calculation of Release Rate ................................................................................................. 13
4.4 Estimate the Fluid Inventory Available for Release ................................................................... 13
4.4.1 Overview ................................................................................................................................. 13
4.4.2 Maximum Mass Available for Release (Available Mass) ................................................... 13
4.4.3 Calculation of Inventory Mass .............................................................................................. 14
4.5 Determine the Release Type (Continuous or Instantaneous) ................................................... 15
4.5.1 Release Type—Instantaneous or Continuous .................................................................... 15
4.5.2 Calculation of Release Type ................................................................................................. 15
4.6 Estimate the Impact of Detection and Isolation Systems on Release Magnitude .................. 15
4.6.1 Overview ................................................................................................................................. 15
4.6.2 Assessing Detection and Isolation Systems ...................................................................... 15
4.6.3 Impact on Release Magnitude .............................................................................................. 16
4.6.4 Impact on Release Duration ................................................................................................. 16