Cailiao Baohu (Dec 2022)

Analysis on Application of Impressed Current Cathodic Protection for Buried Pipelines under AC Interference

  • GUO Yong, DING Jifeng, GAO Zhixian, YIN An, ZHANG Bo, YANG Chaohui, LI Xiangyang

DOI
https://doi.org/10.16577/j.issn.1001-1560.2022.0360
Journal volume & issue
Vol. 55, no. 12
pp. 208 – 212

Abstract

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In order to study the effectiveness of pipeline cathodic protection system in preventing AC interference corrosion under AC interference， the testing device for stray current interference of buried steel pipelines was established， and the influence of cathodic protection current on the AC corrosion behavior of test coupons was studied. With the change of the applied DC voltage，the changes of parameters such as the cathodic protection power-off potential， the AC current density and the DC current density of the coupons over time were monitored by data recorders. Results showed that the influence of the increase and decrease of the applied DC current on the test coupons was irreversible； With the increase of applied DC current， the AC current density decreased and the diffusion resistance increased； When the DC current increased， the cathodic protection potential would no longer shift negatively after polarization to -1.10 V (vs CSE)， and the polarization process was changed from electrochemical control to concentration polarization control. The ratio of AC to DC current density revealed that，the AC interference could not be reduced simply by increasing the cathodic protection current， and it was necessary to adopt the AC drain method to reduce the impact of AC interference.

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