Numerical Simulation of Effects of Influence Factors on Cathodic Protection of Pipeline in Casing

The effects of influence factors of cathodic protection in casing on pipe potential and pipe-to-soil potential were studied using numerical simulation. The results show that the coating quality of casing and pipe had a great influence on pipe potential. The better the coating quality was, the more negative the pipe potential was, and the longer the anode service life was. The sacrificial anode installed in the inside of casing had positive effect on the cathodic protection of the pipe in casing. In addition, the electric conductivity of the electrolyte in casing had a certain effect on the pipe potential, and pipe potential shifted negatively with the increase of electrical conductivity. In the casing section, whatever the coating quality was, whether the anode was stalled in casing and whether the electrolyte conductivity change had few effects on the pipe-to-soil potential. It cannot be determined whether the pipe potential reaches the cathodic protection standard or how the internal corrosion environment is, according to pipe-to-soil potential.