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

2-116 API RECOMMENDED PRACTICE 581
Table 16.2M—Corrosion Rates for Calculation of the DF—CUI
Operating
Temperature
(°C)
Corrosion Rate as a Function of Driver 1 (mm/y)
Severe Moderate Mild Dry
−12 0 0 0 0
−8 0.076 0.025 0 0
6 0.254 0.127 0.076 0.025
32 0.254 0.127 0.076 0.025
71 0.508 0.254 0.127 0.051
107 0.254 0.127 0.025 0.025
135 0.254 0.051 0.025 0
162 0.127 0.025 0 0
176 0 0 0 0
NOTE 1 Driver is defined as the CUI condition causing the corrosion rate. See Part 2, Section 15.6.2 for
explanation of drivers.
NOTE 2
Interpolation may be used for intermediate values of temperature.
Table 16.3—Corrosion Rate Adjustment Factor for Insulation Type
Insulation Type
Adjustment Factor, F INS
Unknown/unspecified 1.25
Foamglass 0.75
Pearlite 1.0
Fiberglass 1.25
Mineral wool 1.25
Calcium silicate 1.25
Asbestos 1.25