Effects of Flow Velocity on Erosion-Corrosion Behavior of N80 Steel in NaCl Aqueous Solution Containing Sand

In order to reveal the affecting mechanism of flow velocity on erosion-corrosion of N80 steel, the erosion-corrosion behavior of N80 steel in NaCl aqueous solution containing sand was studied at different flow velocities using rotary cylinder electrode device combined with electrochemistry method, weight loss method and corrosion morphology observation. The results show that the erosion-corrosion rate of the N80 steel increased slightly first and then increased obviously with the increase of flow velocity. Oxygen diffusion characteristics appeared on the cathode of N80 steel under different conditions of flow velocity. The Tafel slope of the cathodic reaction was greater than that of the anodic reaction for the N80 steel, so the whole reaction process was controlled by the cathodic oxidation-reduction reaction. In the process of oil transportation, the method of controlling the flow velocity of corrosive medium could be applied to reduce erosion-corrosion of tube wall for improving the service life of pipeline.