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

RISK-BASED INSPECTION METHODOLOGY, PART 2—PROBABILITY OF FAILURE METHODOLOGY 2-127
Table 18.2—SCC Susceptibility—CUI ClSCC
Operating Temperature
SCC Susceptibility as a Function of Driver a
°C °F Severe Moderate Mild Dry
<49 <120 None None None None
49 to 93 120 to 200 High High Medium Low
93 to 149 200 to 300 High Medium Low None
>149 >300 None None None None
a
Driver is defined as the atmospheric condition causing the SCC.
18.10 Figures
Operating
Temperature
STEP 1: Determine the susceptibility using
Table 19.2 and the following adjustment
factors.
Driver
Cracks
present?
No
Yes
STEP 2: Determine the Severity Index
using Table 18.3
High
Susceptibility
Cracks
Removed?
Yes
No
FFS
STEP 3: Determine the in-service time,
age, over which CUI ClSCC may have
occurred.
STEP 4: Determine the number of inspections
and the corresponding inspection
effectiveness category for all past inspections
using Table 2.C.10.4.
STEP 5: Determine the base damage
factor for CUI ClSCC using Table 6.3
STEP 6: Calculate the escalation in the
damage factor based on the time inservice
since the last inspection using
Equation (2.85).
Figure 18.1—Determination of the CUI ClSCC DF