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

2.B-38 API RECOMMENDED PRACTICE 581
Table 2.B.4.4—High Temperature H 2 S/H 2 Corrosion—Estimated Corrosion
Rates for 7Cr Steel (mpy)
H 2 S
(mole %)
Type of
Hydrocarbon
Temperature (°F)
425 475 525 575 625 675 725 775 825 875 925 975
0.002
0.0035
0.008
0.035
0.08
0.30
0.75
1.0
Naphtha 1 1 1 1 1 2 3 4 6 8 10 13
Gas oil 1 1 1 2 2 4 5 8 11 14 19 25
Naphtha 1 1 1 2 3 4 6 9 12 16 21 28
Gas oil 1 1 2 3 5 8 11 16 23 30 40 52
Naphtha 1 1 1 2 4 5 8 11 16 21 28 37
Gas oil 1 2 3 4 7 10 15 22 30 40 53 69
Naphtha 1 1 2 4 6 10 14 20 28 37 49 64
Gas oil 1 3 5 8 12 18 27 38 52 71 94 120
Naphtha 1 2 3 5 8 12 17 24 34 46 60 78
Gas oil 2 3 6 9 15 22 33 46 64 86 110 150
Naphtha 1 2 4 7 11 17 25 35 49 66 87 110
Gas oil 3 5 8 13 21 32 47 67 93 130 170 220
Naphtha 2 3 5 8 13 19 28 40 55 74 98 130
Gas oil 3 5 9 15 24 36 53 76 100 140 190 240
Naphtha 2 3 6 10 16 24 35 49 68 92 120 160
Gas oil 4 7 11 19 30 45 66 94 130 180 230 300