Corrsion of Buried Steel Pipeline Caused by Stray Current from Subway Maintenance Base and Protective Countermeasures

In order to study and master the condition of the stray current of natural gas 9 section pipeline in Shanghai and take corresponding measures the impact of stray current on gas pipeline was monitored using remote measurement system. The cathodic protection potential and the magnitude of potential gradient on ground surface were simultaneous measured. The results indicate that the current leakage in the Jinqiu road subway maintenance base was the interference source of stray current upon Shanghai high-pressure natural gas 9 section pipeline. The rail potential, grounding, track to earth insulation and overhead power line were also tested. The causes for the current leakage in the subway maintenance base were analyzed, and protective countermeasures were proposed based on the measured results. The countermeasures inclucle to reinforce the construction and management of the rail insulation, the testing and measurement of the grounding electrode in the transformer substation, and the drained current protection.