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

Consequence of Failure Methodology for Storage Tank Bottoms ........................................... 12
Required Properties at Storage Conditions ........................................................................ 12
Hydraulic Conductivity for Storage Tank Bottom .............................................................. 12
Fluid Seepage Velocity for Storage Tank Bottom .............................................................. 13
Calculation of Fluid Seepage Velocity for Storage Tank Bottom ..................................... 13
Release Hole Size Selection ......................................................................................................... 13
Calculation of Release Hole Sizes ....................................................................................... 13
Release Rate Calculation .............................................................................................................. 14
Storage Tank Bottom Release Rate ..................................................................................... 14
Calculation for Storage Tank Bottom Release Hole Size .................................................. 14
Inventory Volume and Mass Available for Release ................................................................... 15
Calculation of Storage Tank Bottom Inventory Mass ........................................................ 15
Type of Release ............................................................................................................................. 15
Impact of Detection and Isolation Systems on Release Magnitude ......................................... 15
Release Rate and Volume for the Consequence of Failure Analysis ...................................... 15
Storage Tank Bottom Release Volume................................................................................ 15
Determine the Financial Consequences ..................................................................................... 16
Calculation of Storage Tank Bottom Financial Consequence .......................................... 16
Nomenclature ................................................................................................................................. 17
Tables ............................................................................................................................................. 21
Figures ............................................................................................................................................ 27
5 HEAT EXCHANGER TUBE BUNDLES ................................................................................................. 28
Overview ......................................................................................................................................... 28
Background .................................................................................................................................... 28
Basis of Model ............................................................................................................................... 28
Required Data ................................................................................................................................ 28
Methodology Overview ......................................................................................................... 28
Probability of Failure ..................................................................................................................... 29
Definition of Bundle Failure .................................................................................................. 29
Probability of Failure Using Weibull Distribution ............................................................... 29
POF Calculation ..................................................................................................................... 30
Consequence of Failure ................................................................................................................ 32
Risk Analysis ................................................................................................................................. 32
Risk Matrix .............................................................................................................................. 32
Inspection Planning Based on Risk Analysis ............................................................................ 33
Use of Risk Target in Inspection Planning ......................................................................... 33
Determine Inspection Recommendation ............................................................................. 33
Calculate Characteristic Life at Plan Date .......................................................................... 34
Calculation of Risk ................................................................................................................ 34
Calculation of Risk ................................................................................................................ 34
Bundle Inspect/Replacement Decisions using Cost Benefit Analysis .................................... 34
Decision to Inspect or Replace at Upcoming Shutdown ................................................... 34
Optimal Bundle Replacement Frequency ........................................................................... 35
Nomenclature ................................................................................................................................. 37
Tables ............................................................................................................................................. 40
Figures ............................................................................................................................................ 44
6 PRESSURE-RELIEF DEVICES (PRDS) ................................................................................................ 45
General ........................................................................................................................................... 45
Overview ................................................................................................................................. 45