Electrochemical corrosion behavior of X-65 steel in the simulated oil sand slurry. I: Effects of hydrodynamic condition

Abstract

Oil sand slurry hydrotransport pipelines are experiencing serious corrosion and erosion. In this work, rotating disk electrode technique was used to study the effects of fluid hydrodynamics on corrosion of X-65 steel in the simulated oil sand slurry by potentiodynamic polarization curve and electrochemical impedance spectroscopy measurements. In the absence of sands, the cathodic polarization current increases with the increasing electrode rotating speed due to the accelerated oxygen diffusion and reduction. However, the anodic polarization current decreases because of the improved oxidation of the steel. Although the oxygen diffusivity increases with temperature, the resultant oxidation of steel by oxygen is not sufficient to offset the enhanced reactivity of steel at an elevated temperature. The presence of oils is believed to form a layer of oily phase on the steel surface, facilitating the cathodic reduction of oxygen and inhibiting dissolution of the steel. With the increasing sand content and size in the solution, the corrosion of steel is enhanced.