Induced Currents and Voltages in Underground Metallic Pipelines due to nearby Power Lines

During the last decades, environmental and economic reasons impose that gas or water pipelines share the same distribution paths with high voltage or medium voltage power lines, to restrain the financial and the ecological costs. Therefore, the cases where underground metallic pipelines and power lines share proximal rights-of way for considerable lengths are a common practice. The electromagnetic interference of power lines upon the metallic buried pipelines is an issue of priority, to avoid the development of induced voltages that could jeopardize the safety of the personnel and the integrity of the pipelines structure. Indeed, the developed voltages and currents can be dangerous for people who touch metallic structures connected with the pipelines or just stand nearby. Moreover, the induced voltages can result in the corrosion of a pipeline due to electrochemical effect, leading to repair or/and replacement costs and environmental repercussions. It is worth mentioning that the interference comprises an inductive, a conductive and a capacitive part. The capacitive part can be safely ignored in the case of buried pipelines, since the conductive component is considered only under fault conditions and affects the part of the pipeline near the faulted structure. The inductive component is present both during faults and normal operating conditions and is the dominant one. Due to the inductive interference, voltages and currents are induced in a buried metallic pipeline.