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-53
Table 2.B.5.6M—H 2 SO 4 Corrosion—Estimated Corrosion Rates for Alloy C-276 (mm/y)
Acid
Concentration
(wt%)
0.91
m/s
Temperature
52 °C 59 °C 73 °C 86 °C
2.59
m/s
3.05
m/s
0.91
m/s
2.59
m/s
3.05
m/s
0.91
m/s
2.59
m/s
3.05
m/s
0.91
m/s
2.59
m/s
3.05
m/s
98 0.08 0.15 0.23 0.1 0.2 0.3 0.13 0.25 0.38 0.51 1.02 1.52
92.5 0.1 0.2 0.3 0.13 0.25 0.38 0.51 1.02 1.52 1.27 2.54 3.81
85 0.13 0.25 0.38 0.25 0.51 0.76 0.51 1.02 1.52 1.52 3.05 4.57
75 0.13 0.25 0.38 0.25 0.51 0.76 0.51 1.02 1.52 1.27 2.54 3.81
55 0.13 0.25 0.38 0.25 0.51 0.76 0.38 0.76 1.14 1.02 2.03 3.05
20 0.1 0.2 0.3 0.13 0.25 0.38 0.38 0.76 1.14 1.02 2.03 3.05
8 0.1 0.2 0.3 0.13 0.25 0.38 0.25 0.51 0.76 0.76 1.52 2.29
5 0.08 0.15 0.23 0.1 0.2 0.3 0.13 0.25 0.38 0.38 0.76 1.14
Table 2.B.5.7—H 2 SO 4 Corrosion—Estimated Corrosion Rates for Alloy B-2 (mpy)
Acid
Concentration
(wt%)
3
ft/s
Temperature
125 °F 137.5 °F 162.5 °F 187.5 °F
8.5
ft/s
10
ft/s
3
ft/s
8.5
ft/s
10
ft/s
3
ft/s
8.5
ft/s
10
ft/s
3
ft/s
8.5
ft/s
10
ft/s
75 2 4 6 3 6 9 4 8 12 5 10 15
45 3 6 9 4 8 12 4 8 12 5 10 15
32.5 4 8 12 5 10 15 5 10 15 5 10 15
25 5 10 15 10 20 30 10 20 30 10 20 30
NOTE 1
NOTE 2
Oxidants present (even in a few ppm) accelerate corrosion rates and pitting.
Alloy B-2 should not be used in oxidizing conditions.
Table 2.B.5.7M—H 2 SO 4 Corrosion—Estimated Corrosion Rates for Alloy B-2 (mm/y)
Acid
Concentration
(wt%)
0.91
m/s
Temperature
52 °C 59 °C 73 °C 86 °C
2.59
m/s
3.05
m/s
0.91
m/s
2.59
m/s
3.05
m/s
0.91
m/s
2.59
m/s
3.05
m/s
0.91
m/s
2.59
m/s
3.05
m/s
75 0.05 0.1 0.15 0.08 0.15 0.23 0.1 0.2 0.3 0.13 0.25 0.38
45 0.08 0.15 0.23 0.1 0.2 0.3 0.1 0.2 0.3 0.13 0.25 0.38
32.5 0.1 0.2 0.3 0.13 0.25 0.38 0.13 0.25 0.38 0.13 0.25 0.38
25 0.13 0.25 0.38 0.25 0.51 0.76 0.25 0.51 0.76 0.25 0.51 0.76
NOTE 1
NOTE 2
Oxidants present (even in a few ppm) accelerate corrosion rates and pitting.
Alloy B-2 should not be used in oxidizing conditions.