Relative Risk of Alternating Current Power Line Faults Affecting Nearby Pipelines

The co-location of pipelines and alternating current (AC) transmission lines can lead to electrical hazards on a pipeline. One example is a transient voltage that electrifies a nearby pipeline during a power line to ground fault. A power line fault, typically caused by a lightning strike, cut power line, or windstorm, results in electrical potential being transferred to ground. A buried pipeline near a fault acts as a grounding conductor, carrying energy to an area of lower potential than the incident location. Current carried through a pipe is a hazard to people and equipment. A current travelling to an above ground structure could lead to an individual becoming part of an electrical circuit if they touch the structure and the possibility of a high electrical current flowing through an individual’s entire body. While current literature describes how to mitigate the effects of power line faults, there are limited sources that describe a process to quantify the probability of power line faults affecting pipelines. In this paper, a method to assess the frequency of AC powerline faults and their potential impact to pipeline infrastructure is described. The model incorporates spatial and historical factors to evaluate the exposure of individual assets to AC power line faults. It estimates the powerline fault frequency and the area of ground potential rise that could lead to safety consequences for workers or members of the public. The collection of fault frequency data, the calculation of fault current from transient voltage hazards, and the estimated area of potential harm from transient voltage hazards are discussed. The model was developed to rank the risk of power line fault incidents across a company’s pipeline system. The results of the assessment help prioritize locations to perform more detailed site-specific analysis for the design and installation of mitigation systems.