Studies of Inhibition and Monitoring of Metal Loss in Gas Systems Containing Solids

Abstract Carbon and low alloy steels can suffer metal loss via a synergistic erosion-corrosion mechanism in corrosive solids-containing environments. Corrosion inhibiting chemicals are frequently used to mitigate the corrosion component in hydrocarbon systems. Achieving effective corrosion inhibition in high velocity systems suffering from erosion-corrosion has historically been considered difficult. Furthermore, synergistic erosion-corrosion has been observed in lesser CRA grades(1). This has led to some companies issuing internal guidance that limits the operating conditions for process systems. Examples are as follows: -Maximum fluid velocity for corrosion inhibited carbon steel systems capped to prevent excessive shear reducing inhibitor efficiency.Maximum erosion rate capped in both carbon steel and 13% chromium containing stainless steel systems to mitigate synergistic erosion-corrosion. This paper describes a recent study carried out to explore the potential to increase fluid velocities above the currently adopted limits and thus optimise production rates. The study aimed to both validate the efficacy of erosion-corrosion inhibitors in high velocity corrosive gas systems and explore the maximum allowable erosion rate before the onset of synergistic erosion-corrosion for three materials.