Problems in the cathodic protection system of gas pipelines and solutions

As a mature cathodic protection technology in China, anti-corrosion coating with impressed-current cathodic protection is often used for external anti-corrosion of long-distance gas pipelines. In this paper, the status of impressedcurrent cathodic protection on 8 gas pipelines in a certain gas transportation zone in Sichuan was analyzed to find out the reasons for the problems of cathodic protection system. First, electric power supply is not independent. Second, partial pipelines are incompetent for off potential testing. Third, off potential doesn't meet the protection criterion. Fourth, some insulating joints suffer serious current leakage. Fifth, partial pipeline anti-corrosion coating is subject to serious defects. And sixth, cathodic protection facilities are not complete. In order to ensure the good state of cathodic protection of gas pipelines, based on actual operation, several solutions were put forward as follows. First, replace the single power supply at the cathodic protection station with the independently regulated cathodic protection power with multi-output function. Second, install a complete set of automatic acquisition system on cathodic protection potential of pipelines. Third, replace the insulating joints with serious current leakage and change the installation positions. Fourth, repair the anti-corrosion coating. And fifth, complete cathodic protection facilities. These methods ensure that the gas pipelines are in a good state of cathodic protection.