Application of Specialized Assembled Flexible Anode to Stray Current Drainage in Pipelines

Abstract With the rapid development of urban transportation systems, the occurrence of intersections and parallels between urban railway lines and buried gas pipelines became increasingly prevalent. The severe and periodic DC stray current generated during railway line operations accelerates pipeline corrosion, thereby significantly impacting pipeline safety. A natural gas pipeline in Nanjing, China had long been affected by dynamic DC stray interference currents from the subway (with a maximum DC current density reaching 976 A/m2). The existing DC current drainage system with sacrificial anodes failed to address on-site interference issues effectively. Moreover, due to geographical location constraints, construction conditions and power supply limitations, traditional forced drainage systems cannot be properly installed or operated. Therefore, the adoption of a new specialized assembled flexible anode combined with a solar intelligent potentiostatic device for forced drainage purposes was proposed in this paper. Following implementation of this system, under-protection states of the pipeline was successfully suppressed while corrosion was effectively alleviated. Application results demonstrated that the specialized assembled flexible anode combined with solar intelligent potentiostat drainage system could offer remarkable effectiveness in draining excess current while minimizing installation position restrictions and convenient construction processes. Furthermore, it exhibits excellent economic performance and holds significant potential for widespread application.