Understanding the influences of pre-corrosion on the erosion-corrosion performance of pipeline steel

Abstract The initiation and the dynamic progression of erosion-corrosion on a pre-corroded X65 pipeline steel surface was investigated using coupon electrodes and wire beam electrode (WBE). Results show that a concentrated erosion-corrosion region would appear on the steel surface after pre-corrosion which is significantly different from the scatter distributed impingement craters on a fine polished steel coupon. The initiation of localized erosion-corrosion on a pre-corroded steel surface is most probably induced by the instant interfacial chemical and electrochemical heterogeneity, and the instantaneous inhomogeneous sand impingements rather than the surface roughness increasing and the porous rust layer. The pre-corroded area having an initial intense sand impingements would propagate to a concentrated low-lying erosion-corrosion area and small cathodic regions would propagate to isolated islands in the low-lying area.