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

2-52 API RECOMMENDED PRACTICE 581
e) STEP 5—Determine the base DF for amine cracking,
amine
D fB
, using Table 6.3 based on the number of
inspections and the highest inspection effectiveness determined in STEP 4 and the Severity Index, S VI ,
from STEP 2.
f) STEP 6—Calculate the escalation in the DF based on the time in service since the last inspection using
the age from STEP 3 and Equation (2.24). In this equation, it is assumed that the probability for cracking
will increase with time since the last inspection as a result of increased exposure to upset conditions
and other non-normal conditions.
amine
11 .
( fB ( ) )
amine
D f = min D ⋅ max[ age, 1. 0] , 5000
(2.24)
7.7 Nomenclature
age
is the component in-service time since the last cracking inspection or service start date
amine
D is the DF for amine cracking
f
amine
D fB
is the base value of the DF for amine cracking
S VI
is the Severity Index
7.8 References
See References [23], [24], [25], [26], [27], [28], and [29] in Section 2.2.
7.9 Tables
Table 7.1—Data Required for Determination of the DF—Amine Cracking
Required Data
Susceptibility (Low, Medium, High)
Amine solution composition
Maximum process temperature, °C (°F)
Steam out? (Yes or No)
Age (years)
Inspection effectiveness category
Number of inspections
Comments
The susceptibility is determined by expert advice or using the procedures in this
section.
Determine what amine solution composition is being handled in this component.
Fresh amine has not been exposed to H 2 S or CO 2 . Lean amine contains low
levels of H 2 S or CO 2 . Rich amine contains high levels of H 2 S or CO 2 . For
components exposed to both lean and rich amine solutions (i.e. amine contactors
and regenerators), indicate lean.
Determine the maximum process temperature in this component.
Determine whether the component has been steamed out prior to water flushing
to remove residual amine.
Use inspection history to determine the time since the last SCC inspection.
The effectiveness category that has been performed on the component.
The number of inspections in each effectiveness category that have been
performed.