Effect of Temperature and Pressure on Corrosion and Hydrogenation of Steel in Chloride-Acetate Environment with Different Concentrations of Hydrogen Sulfide and Carbon Dioxide

Low-carbon pipe steel’s corrosion rate and hydrogenation in a chloride-acetate solution with CO₂/H₂S mixtures at different temperatures and pressures were investigated. The rate of corrosion and hydrogenation depend on the H₂S concentration and the properties of corrosion films. In a solution with a pressure ratio of \({P}_{{\text{CO}}_{2}}:{P}_{{\text{H}}_{2}\text{S}}=30:1\) and at the beginning of exposure at a pressure ratio of 3:1 corrosion slows down due to the formation of Fe_1+xS mackinawite film. Over time, mackinawite transforms into hexagonal FeS troilite with an acicular structure, and the corrosion rate increases in approx. 2 times. The corrosion rate of steel at 60°C and 5 MPa in a solution with a pressure ratio of \({P}_{{\text{CO}}_{2}}:{P}_{{\text{H}}_{2}\text{S}}=30:1\) was twice as low as at 20°C and 0.1 MPa. A dense layer of cubic iron sulfide FeS crystals was formed on the surface, which reduces corrosion. The adsorption of hydrogen by the steel reduced in approx. 15 times as the temperature increases.