Anomalous Depletion Reasons of Sacrificial Anodes on Deepwater Submarine Pipelines

In recent years, there has been an accelerated consumption of sacrificial anodes in the eastern waters of the South China Sea, posing a risk of failure for deepwater cathodic protection systems. In order to investigate the reasons for abnormal consumption of sacrificial anodes in submarine pipelines, design data research and indoor evaluation tests were carried out. The indoor evaluation tests included the demand test for protective current density of pipeline steel, the electrochemical performance evaluation test of anodes, and the indoor scaling test of the electrical connection between submarine pipelines and underwater systems. The focus was on exploring the influence of temperature and the electrical connection between submarine pipelines and underwater structures on sacrificial anode consumption. The results indicate that temperature was not the main factor causing abnormal anode consumption in submarine pipelines, but when the pipeline was electrically connected to underwater structures with poor cathodic protection, the output current of the sacrificial anode near the underwater structure increased, and the service life of the anode would be significantly reduced. This was the main reason for the accelerated consumption of sacrificial anodes.