Effect of Monoethanolamine on Corrosion of A283 Carbon Steel in Propionic Acid Solution

Abstract

This research studied the effect of monoethanolamine or MEA on corrosion of A283 carbon steels both in water and 5 vol.% propionic acid solution at boiling point temperature of solution. MEA concentrations ranging from 30 to 90 wt.% in water was used. The 5 vol.% propionic acid containing around 45 and 75 wt.% MEA additions (100:1 and 100:5) by volume in the test solution was studied. The carbon steel coupons were tested in a liquid phase, liquid and vapor phase and vapor phase. The weight losses of coupons were evaluated to calculate corrosion rate. A scanning electron microscope and X-ray diffraction were used to characterize the corrosion surface of coupons. The results showed that the corrosion rate order was in the liquid phase > in the liquid and vapor phase > in the vapor phase. MEA decreased the corrosion rate of A283 carbon steel both in water and 5 vol.% propionic acid solution containing around 45 and 75 wt.% MEA additions (100:1 and 100:5) by volume. MEA can be considered as corrosion inhibitor of carbon steel both in water and propionic acid solution. The formed layers of FeO(OH), Fe₂O₃ and Fe₃O₄ on the surface were detected to prevent a corrosion attack. The formed layer of Fe₃C was also found and discussed. The more severe corrosion was in ferrite.