AC Corrosion Influencing Factors for X70 Pipeline Steel

The effects of AC current density, defect area and defect shape of corrosion protection layer on alternating current (AC) corrosion of X70 pipeline steel were studied by AC corrosion simulation experiments. The results show that the corrosion rate of X70 pipeline steel increased with the increase of AC current density. At the same AC interference voltage, the smaller the defect area, the greater the AC current density through the X70 pipeline steel, and the greater the corrosion rate. Among the shapes of circle and rectangles with different length-width ratios,the corrosion rate was the largest at the strip defect with a length-width ratio of 10:1. The AC corrosion rate at rectangular defects slightly increased with the increase of the length-width ratio of defects.