Corrosion Behavior of Pipelines Influenced by Dynamic Stray Currents Derived from Underground Rail Infrastructure

Under the long-term dynamic stray current interference of the subway, the buried pipelines suffered from intensified corrosion due to the dynamic stray current. Cathodic protection technology is one of the key technologies for effectively reducing the corrosion of buried pipelines. Therefore, based on the field-measured dynamic stray current results of the buried pipelines near the subway, we studied the protective effectiveness of cathodic protection on the corrosion of pipelines under dynamic stray current conditions. The results showed that the applied dynamic stray current exacerbated the nonuniformity of the sample surface, leading to local corrosion characteristics, with a relatively small impact on the general corrosion rate. The cathodic protection effect reduced the potential difference on the sample surface. When the cathodic protection potential was -1.2 V (vs SCE), there were no obvious pit characteristics on the sample surface. With the increase in the stray current and the transition to the dynamic stray current conditions, the corrosion potential shifted positively, the corrosion current density increased, the anode reaction control process increased, the capacitance reached a maximum, and the resistance was the smallest. After cathodic protection was applied, the cathodic process was strengthened, the corrosion potential shifted significantly in the negative direction, and the corrosion current density also decreased, showing a significant protective effect.