The Influence of Flow Rate and Inhibitor on the Protective Layer Under Erosion-Corrosion Conditions Using Rotating Cylinder Electrodes

This paper will report findings for an investigation into the influence of organic inhibitor concentration on the hardness of protective scales covering X65 carbon steel surface using rotating cylinder electrode (RCE). The experiments were conducted at a temperature of 70 °C, pH of 5.9 and 0.3 m/s velocity with different concentrations of CRW9150 inhibitor using a Forties brine saturated with carbon dioxide (CO₂) and 0.1% HST60 PSA sand. Weight gain/loss was measured for: fresh X65 specimens and specimens before and after removing iron carbonate scale in both uninhibited and inhibited systems. In addition, the hardness of the surface specimens and scales were measured using the nano-indenter. This was supported by post-test analysis of samples using scanning electron microscopy (SEM) to assess both the nature and the thickness of these protective films. It was found that the weight loss was reduced by more than 25, 50 and 55% when 25, 50 and 150 ppm of CRW9150 inhibitor were introduced respectively. Nevertheless, inhibitor concentration was found not be effective to reduce the weight loss of the scaled surfaces.

Keywords: inhibitor, hardness, iron carbonate, CO₂ and sand.