CORROSION AND MATERIALS SELECTION FOR AMINE SERVICE

Amines are used in refineries and gas plants around the world to remove both H2S and CO2 from feed gas. The corrosion in amine plants is not caused by the amine itself, but is caused by the hydrogen sulphide, CO2 and by amine degradation products. Amines are compounds formed by replacing hydrogen atoms of ammonia, NH3 by organic radicals. Problems with amine units can be corrosion or by cracking (sulphide stress cracking, hydrogen induced cracking associated with hydrogen blistering, stress-orientated hydrogen induced cracking, and alkaline stress corrosion cracking). Areas to have a close look at is where impingement erosion could occur, where there is elevated temperatures, where flashing off of CO2 could occur, and where heat stable salts could cause scaling. Carbon steel and stainless steel are suitable for most applications, with the choice of material being determined by the susceptibility to the damage modes in each location. Careful consideration should also be given to the repair of plant (controlling weldment hardness