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

RISK-BASED INSPECTION METHODOLOGY, PART 2, ANNEX 2.B—DETERMINATION OF CORROSION RATES 2.B-7
pH
Table 2.B.2.4—HCl Corrosion—Estimated Corrosion Rates for Type 304, 316,
321, 347 Series Stainless Steels (mpy)
Temperature (°F)
100 125 175 200
0.5 900 999 999 999
0.80 500 999 999 999
1.25 300 500 700 999
1.75 150 260 400 500
2.25 80 140 200 250
2.75 50 70 100 120
3.25 30 40 50 65
3.75 20 25 30 35
4.25 10 15 20 25
4.75 5 7 10 12
5.25 4 5 6 7
5.75 3 4 5 6
6.25 2 3 4 5
6.80 1 2 3 4
NOTE These rates are 10 times the general corrosion rates to account for localized pitting corrosion.
Table 2.B.2.4M—HCl Corrosion—Estimated Corrosion Rates for Type 304, 316, 321,
347 Series Stainless Steels (mm/y)
Temperature (°C)
pH
38 52 79 93
0.5 22.86 25.37 25.37 25.37
0.80 12.70 25.37 25.37 25.37
1.25 7.62 12.70 17.78 25.37
1.75 3.81 6.60 10.16 12.70
2.25 2.03 3.56 5.08 6.35
2.75 1.27 1.78 2.54 3.05
3.25 0.76 1.02 1.27 1.65
3.75 0.51 0.64 0.76 0.89
4.25 0.25 0.38 0.51 0.64
4.75 0.13 0.18 0.25 0.30
5.25 0.10 0.13 0.15 0.18
5.75 0.08 0.10 0.13 0.15
6.25 0.05 0.08 0.10 0.13
6.80 0.03 0.05 0.08 0.10
NOTE These rates are 10 times the general corrosion rates to account for localized pitting corrosion.