Corrosion-Mechanical Properties and Susceptibility to Hydrogenetaion of Pipe Steel in the Presence of Carbon Dioxide Gas and Hydrogen Sulphide in Environment

Abstract

The effect of different concentrations of CO₂ and H₂S in a chloride-acetate solution on corrosion-mechanical properties of 17G1S-U steel was studied. In a solution saturated with CO₂, the corrosion rate of steel was lower than in the presence of H₂S, but increased over time due to the absence of protective carbonate films on the surface, plasticity parameters were 2–2.7 times lower than in air due to dimple surface damage. The corrosion rate and hydrogenation of steel was determined primarily by the hydrogen sulfide concentration in the environment. At a concentration of 100 mg/dm³, dense films of the troilite-mackinavite composition were formed, which inhibit corrosion. At higher concentrations, the corrosion rate increased due to the sulfides transformation and the formation of surface layers with defects. With an increase in the H₂S concentration from 100 mg/dm³, the strength characteristics of steel decreased in three times, and plasticity decreased in 3–5 times.