Kinetic study of the effect of a mixture of two corrosion inhibitors in reducing the corrosion rate of 1018 carbon steel petroleum pipelines in sea water

In oil and gas production industry, internal corrosion is a well-known phenomenon and has a serious problem. Carbon steel is the most widely used engineering material in petroleum production, refining, pipelines, and chemical processing industries. Amines are one of the groups of compounds that have improved inhibition efficiency against corrosion in carbon steel. Two amine-based inhibitors (Inhibitors A and B), which are widely used by Saudi Aramco, the largest oil producing and manufacturing company, have been evaluated. However, optimizing the concentration of those inhibitors according to the operating conditions is required to minimize the operating cost. The corrosion inhibitors in seawater are desirable to increase the metal lifetime. The aim of this paper is to study the effect of each inhibitor (Inhibitors A and B) and the combination/mixture of them on the corrosion behavior of 1018 carbon steel pipelines in sea water at 55°C, 1000 rpm, and pH 8.2 using a circulating flow loop system inside an autoclave. Results confirmed that a mixture of inhibitors A and B reduced the corrosion rate more than each one acting alone. Results confirmed that a mixture of 5 ppm of Inhibitor A and 5 ppm of Inhibitor B is the optimum with inhibition efficiency of 71.3%.