Transient Numerical Simulation Study on Corrosion Law of Defective Pipelines Under Disbonded Coating
LI Lei1, SUN Dongxu1,*, CHAI Yuying2, XIE Fei1, WU Ming1
1 College of Petroleum and Natural Gas Engineering, Liaoning Petrochemical University, Fushun 113001, Liaoning, China 2 Shenyang Blower Works(Group) Co., Ltd., Shenyang 110869, China
Abstract: To study the crevice corrosion of metal pipes with defects under disbonded coatings, a two-dimensional mathematical model was established, which fully considered the effects of mass transfer process of solution in the crevice, potential gradient change and the principle of electric neutrality. The influence of cathodic protection on the corrosion behavior of metal pipelines containing defects was studied by numerical simulation, and the evolution of dissolved oxygen concentration, ion concentration and conductivity of solution in defects with time under transient conditions were analyzed. The numerical simulation results show that the cathodic protection potential could not completely protect the defects in the crevice before 35 h, the potential difference at the defects gradually decreased with the increase of the distance from the crevice;in the defect area, due to the influence of electromigration mass transfer and solution concentration gradient on the diffusion of ions, cations move towards the defect interior and anions towards the defect exterior;the reduction reaction causes the conductivity of the solution to increase with time, but to decrease with the increase of the crevice depth. The conductivity at the bottom of the defect is slightly higher than that at the defect mouth.
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2025, Vol. 39 
