Effect of Cavitation on Carbon Dioxide Corrosion and the Development of a Test for Evaluating Inhibitors

Abstract

Development of an ultrasound-based, bench-top test to measure the effectiveness of corrosion inhibitors when subjected to cavitating bubbles is outlined in this paper. It is proposed that the cavities produced by an ultrasonic probe have some similarities to the collapsing bubbles that are found in the mixing region of slug flow, a type of flow that is common in multiphase pipelines. Therefore, the test is potentially a rapid and economical way of evaluating inhibitors under the regime of slug flow. Linear polarization resistance measurements were made to determine the effect of ultrasound on the corrosion rate of carbon steel electrodes in a 1-M sodium chloride (NaCl) solution saturated with carbon dioxide (CO2). Inhibitors that performed well in the bubble test, including two commercial inhibitors that inhibited to virtually identical corrosion rates making inhibitor selection difficult, were subjected to the new test. In the ultrasound-based test, the inhibitors were clearly distinguishable.