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

RISK-BASED INSPECTION METHODOLOGY, PART 2—PROBABILITY OF FAILURE METHODOLOGY 2-117
16.10 Figures
Operating
Temperature
STEP 1: Determine the base corrosion rate.
Driver
STEP 2: Compute the final corrosion rate
• Determine adjustment factors:
• Insulation
• Complexity
• Insulation Condition
• Pipe Supports
• Interface
STEPS 3 - 6: Determine the in-service time, age,
over which CUI may have occurred.
STEP 7: Determine S, E and t min
using the original construction code
or API 579-1/ASME FFS-1
STEP 8: Calculate the A rt
using Equation (2.60).
STEP 9: Calculate the Flow Stress
using Equation (2.61).
STEPS 10: Calculate the Strength
Ratio parameter using Equation
(2.62) or (2.63).
STEP 11 - 13: Determine the number and
effectiveness category for inspections using
the Tables provided in Annex 2.C and
calculate Posterior Probabilities for inspection
using Equations (2.64) and (2.65).
STEPS 14 - 15: Determine final
damage factor for external corrosion
using Equations (2.66) and (2.67).
Figure 16.1—Determination of the CUI DF