Abstract
The stray current from DC subway system in Korea has affected the cathodic protection (CP) design of the buried pipelines adjacent to the railroads. Among various mitigation methods, the drainage bond method either of polarized type or of forced type was widely adopted by the pipeline engineers. However, this method suffers disadvantages about increased interference to other pipelines adjacent to the railroad as well as electrolytic corrosion of the rail components.
In order to overcome this problem, an alternative suitable stray current mitigation method is under design by our group. As a quantitative analysis of the present condition is a prerequisite to this design, we investigated the stray current under drainage bond method. To acquire the drainage current and pipe-to-soil (P/S) potential data, we developed a stand-alone stray current logger and measured both the currents from all of the drainages bonded between gas/water pipelines and rail negatives and the P/S potentials of the pipelines in Seoul for 24 hours at a sampling rate of 4 Hz. Analysis of the drainage current evinces the hazardousness of the present mitigation method and supports the necessity of proper countermeasures.
