Why are acid water tanks used for acid water stripping in the petrochemical industry prone to stress corrosion cracking?
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The picture below is a 5000 cubic meter acid water tank commonly used in petrochemicals. The raw water contains H2S and also contains various media such as CO2, CN-, phenol and oil. The pH value is 10±0.5, and the temperature of the raw water is 65~70°C. Under such operating conditions, the surface corrosion of carbon steel tanks is relatively serious. Stress corrosion cracking occurs at the welding joints and bends of the metal base material (such as the bending and deformation of the steel plate under pressure near the bottom of the column in the tank).
Water vapor, the principle of electrochemical cells, crude oil needs cathodic protection
There is no crude oil here. However, you must pay attention to details when doing cathodic protection, mainly because flammable gases will exist in acidic water.
For anti-corrosion, you can use polyaniline to do a hanging test.