In the natural gas sweetening process, amine aqueous solutions are used to absorb CO2 and H2S acid gases. The resultant solution, that is the mixture of acid gases and amines, causes severe corrosion
problems in process equipment such as the amine regenerating tower. In the present work the effects of concentration and residence time of diethanolamine were studied in the corrosion of 1010 steel.
Electrochemical noise measurements (ENM) was used and correlated with weight loss and surface attack inspection. Tests were performed in a closed loop flow system simulating hydrodynamic conditions, with diethanolamine concentrations in the 30 to 60 % by weight range at 100 °C and a pressure of 15 or 30 lb/in 2 . The results obtained showed accelerated corrosion followed by passive film formation. These effects are related to the increase in amine concentration. That is, the corrosion attack increases but the time of passive film formation decreases as the amine concentration is greater.