Field Studies on the Prediction Method of Induced AC Level on Buried Pipelines Using Magnetic Field Sensors

There is a risk of alternating current (AC) corrosion on pipelines that are buried in proximity to overhead AC power transmission lines due to induced AC caused by magnetic fields around the power transmission lines. Grounding of the line pipes is generally applied for the mitigation of induced AC. In the present paper, studies were conducted to predict the induced AC level through the measurement of magnetic flux density using magnetic field sensors. The relationship between magnetic flux density and induced AC level was then obtained through theoretical studies. In addition, as a result of field tests conducted on an existing pipeline buried in proximity to power transmission lines, induced AC level could be predicted through the measurement of magnetic flux density using magnetic field sensors above the pipeline route. Magnetic flux density can be measured regardless of the number and location of power transmission lines as well as other metallic structures, and therefore it is expected that the AC prediction method using magnetic field sensors can be applied on the pipelines buried in proximity to multiple power transmission lines and/or to other metallic structures with complicated configuration.