Dynamic DC Stray Current Interference Investigation and Mitigation Design for a Sacrificial Anode Protection Pipeline

摘要

In order to control corrosion of sub-high-pressure natural gas pipeline which is caused by dynamic DC stray current interference, a series of cathodic protection related parameters were tested, including pipe-to-soil potential, soil resistivity, sacrificial anode performance and stray current parameters. The test results show that dynamic DC stray current, which is always flowing in or out of anode, is one of the main interference sources for the pipeline. A pre-feasibility study using a forced current drainage method and a polarity drainage method were carried out on a 4 km pipeline segment. According to the results of the experimental test section, the polarity drainage method can improve the cathodic protection effect and therefore was applied to the whole pipeline.. Also, some pipeline segments, which originally failed to meet the CP criteria, were thereafter shown to meet the criteria.