2008 Volume 57 Issue 11 Pages 493-499
There is a risk of AC stray current corrosion on pipelines that are buried in proximity to overhead AC power transmission lines or AC-powered rail transit systems due to electromagnetic induction caused by magnetic fields around the loading currents. Grounding of the line pipes is generally applied for the mitigation of the 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 in order to provide appropriate assessment of AC stray current corrosion risk as well as the optimum design of grounding systems. The relationship between magnetic flux density around power transmission lines and induced AC level on buried steel pipelines 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, and thus the relationship obtained in the present study was proven to be appropriate. It is then expected that the AC prediction method using magnetic field sensors can be applied on the pipelines buried in proximity to multiple power transmission lines with complicated configuration.