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

2.B-18 API RECOMMENDED PRACTICE 581
Table 2.B.3.4—High Temperature Sulfidic and Naphthenic Acid Corrosion—Estimated Corrosion
Rates for 5Cr-0.5Mo (mpy)
Sulfur
(wt%)
TAN
(mg/g)
Temperature (°F)
≤450 500 550 600 650 700 750 >750
0.7 1 1 2 4 6 8 10 15
1.1 2 3 4 6 10 10 15 20
0.2
1.75 7 10 15 20 25 35 45 50
3.0 10 15 20 30 40 45 50 60
4.0 15 20 30 40 50 60 70 80
0.7 1 2 3 5 8 10 15 20
1.1 2 3 4 6 10 15 20 25
0.4
1.75 2 4 6 8 15 20 25 30
3.0 4 6 8 10 15 20 30 35
4.0 6 8 10 10 20 25 35 40
0.7 1 2 4 6 10 15 23 25
1.1 2 4 6 8 15 20 25 30
0.75
1.75 4 6 8 10 15 20 30 35
3.0 6 8 10 10 20 25 35 40
4.0 8 10 10 15 20 30 40 50
0.7 1 2 5 8 15 20 30 35
1.1 3 5 10 15 20 30 35 40
1.5
1.75 5 10 15 20 30 35 40 45
3.0 10 15 20 30 35 40 45 50
4.0 15 20 30 35 40 50 60 70
0.7 1 3 6 9 15 20 35 40
1.1 5 7 10 15 20 25 40 45
2.5
1.75 7 10 15 20 25 35 45 50
3.0 10 15 20 30 40 45 50 60
4.0 15 20 30 40 50 60 70 80
0.7 2 3 6 10 15 25 35 40
1.1 5 7 10 15 20 30 40 45
3.0
1.75 7 10 15 20 25 35 45 50
3.0 10 15 20 30 40 45 50 60
4.0 15 20 30 40 50 60 70 80