Erosion–corrosion of engineering steels—Can it be managed by use of chemicals?

One significant contributory factor in the degradation of both pipelines and downhole tubulars in the oil and gas industry is erosion–corrosion. An erosion–corrosion investigation was carried out with three different steels—carbon steel, martensitic stainless steel and superduplex stainless steel. The materials were chosen to represent “active” and “passive” corrosion materials and are the same materials used in completions. Tests were carried out under three different regimes spanning a range of fluid velocities to simulate the severity of the mechanical erosion effect. A commercial corrosion inhibitor was used to investigate the inhibitor ability to reduce damage due to erosion–corrosion. In each of the conditions, pure corrosion and combined erosion–corrosion were studied by electrochemical and gravimetric techniques. The experiments were conducted using a jet impingement rig capable of producing jet velocities up to 20 m/s in a CO2-saturated environment with sand. Erosion–corrosion mechanisms were determined from microstructural studies by SEM and inhibitor adsorption tests. The paper shows that the inhibitor effectively reduced erosion–corrosion damage for carbon steel; it was only in severe erosion–corrosion conditions that inhibitor has any noticeable effect for martensitic stainless steel and there were no conditions where the inhibitor offered a benefit for the superduplex stainless steel.