During the operation of cathodic protection, the main causes of pipeline leakage are as follows:
① Improper construction, cross pipeline is not standard. When a protected pipeline crosses a non-protected pipeline, the spacing between the two pipelines does not meet the requirements due to improper construction. After being buried for a period of time, the backfill soil layer changes, and the two pipelines are overlapped together to break the anti-corrosion layer. The metal contact of the two pipelines forms a leakage point.
② Insulation flange failure or leakage. For the convenience of management, the cathodic protection station is usually built together with the station, and the protection pipeline is equipped with insulated flanges in and out of the station. When the pipeline conveying medium contains conductive impurities, leakage into the station and the unprotected pipeline. If the insulating flange quality is not good, after the insulation parts are damaged during use, the protection pipe and the non-protection pipe will be connected electrically, resulting in leakage fault.
③ Leakage at the damage point of the anticorrosive layer. In the later stage of pipeline operation, the increase of damage point will also cause the pipeline leakage.
