From Corrosion Condition of the Coupons Buried in the Renjing Pipeline to See the Function of Cathodic Protection

Burying coupons near the pipeline is an important method for studying pipeline corrosion and doing quantitative analysis about the effect on pipeline cathodic protection. After inspecting the coupons that have been buried in the Xiongxian pump station section of the Renjing crude oil pipeline for 16 years, the result shows that the surface smoothness of the electrified coupon with corrosion protection coating approaches to the initial condition, the surface of the electrified coupon without corrosion protection coating shows light corrosion, and the surface of the unelectrified coupons without corrosion protection coating shows serious corrosion. According to the calculation of the average corrosion rate, average thickness-loss and weight-loss rate, it is understood that cathodic protection can play a significant part in the long safety operation of pipeline beside the coating.