Interpreting Coating Stress Voltages on Underground Gas Pipelines Due To Lightning Strikes on Adjacent Power Lines

Abstract

Lightning flashes on power lines may be the source of electrical and mechanical hazards on metallic pipelines that are buried in the nearby vicinity of these lines. This hazard is usually assessed through the coating stress voltage that accumulates on the pipelines. The coating stress voltage is defined as the voltage between the pipeline metal and the earth immediately outside its coating. It mainly depends on the pipeline's coating resistance, on the surrounding soil resistivity as well as on the rooting configuration of the adjacent power lines with respect to the pipelines' routing. The latter entails that the pipelines may be subjected to momentary interference events caused by lightning flashes on adjacent power lines. This interference may be characterized by the concurrent act of inductive and conductive interference. To this end, this paper firstly investigates lightning-interference events on a buried gas pipeline under varying, rooting and collocation configurations of an overhead transmission line network. Secondly, the paper attempts to weight the influence of the conductive and inductive interference on the accumulated coating stress voltage of the gas pipeline.