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Iso-Corrosion Diagrams

Each of these iso-corrosion diagrams was constructed using numerous corrosion rate values, generated at different acid concentrations and temperatures. The blue line represents those combinations of acid concentration and temperature at which a corrosion rate of 0.1 mm/y (4 mils per year) is expected, based on laboratory tests in reagent grade acids. Below the line, rates under 0.1 mm/y are expected. Similarly, the red line indicates the combinations of acid concentration and temperature at which a corrosion rate of 0.5 mm/y (20 mils per year) is expected. Above the line, rates over 0.5 mm/y are expected. Between the blue and red lines, corrosion rates are expected to fall between 0.1 and 0.5 mm/y.

625Hydrobromic
625Hydrochloric

625Sulfuric

Hydrobromic Acid

Concentration 50°F 75°F 100°F 125°F 150°F 175°F 200°F 225°F Boiling
Wt. % 10°C 24°C 38°C 52°C 66°C 79°C 93°C 107°C
2.5 - - - - <0.01 - <0.01 - <0.01
5 - - - - <0.01 0.13 0.6 - -
7.5 - - - - <0.01 <0.01 0.93 - -
10 - - - - 0.15 0.82 - - -
15 - - <0.01 0.3 0.64 - - - -
20 - 0.1 0.16 0.33 0.65 - - - -
25 - - - - - - - - -
30 - - 0.11 0.21 0.34 0.72 - - -
40 - - 0.08 0.15 0.25 0.42 0.79 - -

All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Job 17-04.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.

Hydrochloric Acid

Concentration 50°F 75°F 100°F 125°F 150°F 175°F 200°F 225°F Boiling
Wt. % 10°C 24°C 38°C 52°C 66°C 79°C 93°C 107°C
1 - - - - - <0.01 <0.01 - 0.23
1.5 - - - - - - - - -
2 - - - - - - - - -
2.5 - - - - - - - - -
3 - - <0.01 <0.01 <0.01 2.07 - - -
3.5 - - - - - - - - -
4 - - - - - - - - -
4.5 - - - - - - - - -
5 - - <0.01 <0.01 - 4.65 - - -
7.5 - - 0.07 0.49 - - - - -
10 <0.01 0.15 0.3 1.16 - - - - -
15 0.06 0.19 0.4 1.06 - - - - -
20 0.06 0.16 0.36 0.82 - - - - -

All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Jobs 56-97 and 3-98.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.

Sulfuric Acid

Concentration 75°F 100°F 125°F 150°F 175°F 200°F 225°F 250°F 275°F 300°F 350°F Boiling
Wt. % 24°C 38°C 52°C 66°C 79°C 93°C 107°C 121°C 135°C 149°C 177°C
1 - - - - - - - - - - - -
2 - - - - - - - - - - - -
3 - - - - - - - - - - - -
4 - - - - - - - - - - - -
5 - - - - <0.01 0.06 - - - - - 0.4
10 - - - - 0.01 0.24 - - - - - 1.05
20 - - - - 0.02 0.58 - - - - - 2.84
30 - - - 0.01 0.03 0.68 - - - - - -
40 - - <0.01 0.02 0.58 - - - - - - -
50 - - - 0.01 0.89 - - - - - - -
60 - - <0.01 0.48 0.92 - - - - - - -
70 - <0.01 0.23 0.63 - - - - - - - -
80 - 0.05 0.31 0.91 2.54 - - - - - - -
90 <0.01 0.17 1.26 - 6.97 - - - - - - -
96 - - - - - - - - - - - -

All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Jobs 57-97 and 4-98.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.

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