Research on fluctuation characteristics of AC interference parameters and corrosion behavior of buried gas pipelines

With the large-scale construction of high-speed railways in China, pipelines are subject to increasingly severe alternating current (AC) interference. It's been found through detection that the AC interference parameters of pipelines near high-speed railways fluctuate greatly. Based on the field test data, this paper statistically analyses the fluctuation law of parameters on the pipeline. On this basis, an indoor simulation experiment was configured to explore the effect of AC current density and cathodic protection potential on dynamic AC corrosion. The results showed that for the same level of cathodic protection, a higher AC current density indicates a higher dynamic AC corrosion rate. When the AC current density increases to 100 A/m2 or higher, the corrosion rate tends to decrease first and then increase with the negative shift of cathodic protection potential. The corrosion risk assessment diagram under dynamic AC interference was drawn through the experiment of field buried coupon experiment and the laboratory simulation experiment. In addition, the mechanism of AC corrosion is discussed to provide a reference for assessing the corrosion risk under dynamic AC interference.