Estudo da corrosão-erosão do aço API 5L em meios contendo CO2 : aplicação de inibidor de corrosão e influência do filme de FeCO3

Abstract

Carbon steel pipeline degradation occurs as a result of erosion-corrosion during oil and gas production. Sand particles contribute to this effect when they are present in conjunction with a high flow velocity. In carbon dioxide (CO2) environments, and under certain conditions, the corrosion rate of the steel can be reduced by the formation of a protective iron carbonate (FeCO3) layer or using corrosion inhibitors. This work assesses the ability of FeCO3 to protect the underlying steel in flow-induced corrosion and erosion-corrosion environments. Autoclave tests are performed at 60°C and 30 bar in a 1.5wt.%NaCl CO2-saturated solution for a duration of 48h to develop 60μm average thick FeCO3 films. Flow induced corrosion and erosion-corrosion tests were performed in a submerged impinging jet (SIJ) apparatus at 25 and 60°C and a flow velocity of 15 m/s (both with and without 1000 mg/L sand). Tests were also conducted in the presence of a commercially available corrosion inhibitor to evaluate the interaction. Results indicate that the sole presence of FeCO3 layer is not able to considerably suppress corrosion of the carbon steel substrate in erosion-corrosion environments. Experiments in the presence of both the FeCO3 film and corrosion inhibitor demonstrated that there is a notable synergistic effect between these two components in providing resistance to erosion-corrosion.