Study on corrosion inhibitor in large pipelines under multiphase flow using EIS

An imidazoline based inhibitor behavior in carbon dioxide environment has been studied in large pipelines under different slug flow conditions by electrochemical impedance method. It is found that, for each of the slug flow condition, charge transfer resistance, R-t, and Warburg impedance coefficient. sigma. increase with increasing exposure time. It is suggested that the performance of the corrosion inhibitor is dependent on exposure time. The corrosion inhibitor has a good performance of corrosion protection by forming more compact inhibitor films on the metal surface at longer exposure time. Experimental results also show that. at a given time, both R-t and sigma decrease with increasing the Froude number of slug flow. This fact implies that the inhibitor film is damaged and washed away from the metal surface by high turbulence and the higher frequency of bubble pulse in high Froude number of slug flow, thus leading to low corrosion resistance. (C) 2001 Elsevier Science Ltd. All rights reserved.