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

RISK-BASED INSPECTION METHODOLOGY, PART 2—PROBABILITY OF FAILURE METHODOLOGY 2-75
11.10 Figures
STEP 1: Determine the
susceptibility for cracking
Cracks
present?
Yes
High
Susceptibility
Cracks
Removed?
No
Yes
No
Exposed to S
and O 2 and H 2O during
operation?
Yes
FFS
No
Exposed to S
and O 2 and H 2O during
shutdown?
No
Not Susceptible
Alloy
Yes
Thermal
History
Determine Susceptibility
Using Table 11.2.
Op. Temp
Yes
Use downtime
protection according to
NACE RP 0170?
No
Reduce Susceptibility
Determined by 1 Level
High -> Medium
Medium -> Low
Low -> None
STEP 2: Determine the time in-service,
age, since the last inspection.
STEP 3: Determine the number of inspections
and the corresponding inspection
effectiveness category for all past inspections
using Table 2.C.9.5.
STEP 4: Determine the severity index
from Table 11.3.
STEP 5: Determine the base damage
factor for PTA cracking using Table 6.3.
STEP 6: Calculate the escalation in the
damage factor using Equation (2.30).
Figure 11.1—Determination of the PASCC DF