Investigation on Erosion-Corrosion Behavior of Q235 Steel in Liquid-Solid Flow Using Electrochemical Method and Numerical Simulation

With the rapid increase of sand content in crude oil, erosion corrosion has gradually become the key factor of pipeline failure, especially for the elbow. Therefore, in this paper, the corrosion rate, corrosion morphology, electrochemical experiment and numerical simulation were investigated to study the erosion -corrosion behavior of 90 degrees elbow. The results showed that with the increase of experiment time, the corrosion rate of Q235 steel at different angles showed increased linearly, while the max pitting depth basically remained unchanged. In the inlet section of 0=0-45 degrees, Q235 steel was subjected to the joint action of erosion and impact. With the increase of angle, the breakage degree of corrosion product layer on Q235 steel surface became more serious. In the outlet section of 0=45 degrees-90 degrees, Q235 steel was only affected by erosion, and the distribution of corrosion products and holes had obvious directionality. The pure erosion process can be divided into three stages of the formation of erosion morphology, development in the longitudinal direction and general erosion. Under the conditions studied in this paper, the current density of pure erosion was only 42.16% of that of erosion -corrosion. The reason was mainly that the loose FeO(OH) can promote the electrochemical process and also accelerate the diffusion of products.