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

RISK-BASED INSPECTION METHODOLOGY, PART 2—PROBABILITY OF FAILURE METHODOLOGY 2-27
Thin
p3
Co is the conditional probability of inspection history inspection effectiveness for damage state 3
COV P
COV S f
COV ∆t
D
is the pressure coefficient of variance
is the flow stress coefficient of variance
is the thinning coefficient of variance
is the component inside diameter, mm (mpy)
D S1 is the corrosion rate factor for damage state 1
D S2 is the corrosion rate factor for damage state 2
D S3 is the corrosion rate factor for damage state 3
Thin
D f
is the DF for thinning
Thin
D fB
is the base value of the DF for thinning
E
is the weld joint efficiency or quality code from the original construction code
F AM is the DF adjustment for AST maintenance per API 653
F DL
F IP
F OM
F SM
F WD
FS Thin
is the DF adjustment for dead-legs
is the DF adjustment for injection points
is the DF adjustment for online monitoring
is the DF adjustment for settlement
is the DF adjustment for welded construction
is the flow stress, MPa (psi)
I 1 Thin is the first order inspection effectiveness factor
I 2 Thin is the second order inspection effectiveness factor
I 3 Thin is the third order inspection effectiveness factor
Thin
N A is the number of A level inspections
Thin
N is the number of B level inspections
B
Thin
N is the number of C level inspections
C
Thin
N is the number of D level inspections
D