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

2.B-20 API RECOMMENDED PRACTICE 581
Table 2.B.3.5—High Temperature Sulfidic and Naphthenic Acid Corrosion—Estimated Corrosion
Rates for 7Cr-1Mo (mpy)
Sulfur
(wt%)
TAN
(mg/g)
Temperature (°F)
≤450 500 550 600 650 700 750 >750
0.7 1 1 1 2 4 6 7 8
1.1 1 2 3 5 7 8 10 15
0.2
1.75 4 7 10 15 20 25 30 35
3.0 7 10 15 20 25 30 35 45
4.0 10 15 20 25 30 35 45 60
0.7 1 1 2 4 5 8 10 15
1.1 1 2 4 5 8 10 15 15
0.4
1.75 2 4 5 6 10 15 15 20
3.0 3 5 6 9 12 15 20 20
4.0 4 6 9 10 15 20 20 25
0.7 1 1 3 4 6 10 15 15
1.1 2 3 4 6 10 15 15 20
0.8
1.75 3 4 6 10 12 15 20 25
3.0 4 6 10 12 15 20 25 30
4.0 5 10 12 15 20 25 30 35
0.7 1 2 3 6 8 15 15 20
1.1 2 3 6 10 15 15 20 25
1.5
1.75 3 6 10 15 20 20 25 30
3.0 6 10 15 20 20 25 30 35
4.0 10 15 20 20 25 30 35 45
0.7 1 2 4 6 9 15 20 25
1.1 6 7 9 10 15 20 25 30
2.5
1.75 7 9 10 15 20 25 30 35
3.0 9 10 15 20 30 35 35 40
4.0 10 15 20 30 35 40 50 55
0.7 1 2 4 7 10 15 20 25
1.1 2 4 7 10 15 20 25 30
3.0
1.75 4 7 10 15 20 25 30 35
3.0 7 10 15 20 25 30 35 45
4.0 10 15 20 25 30 35 45 60