Abstract
AC Interference effects on pipelines are significantly impacted by electric transmission line design and proximity to the pipelines. Transmission line routing, phase conductor arrangement, vertical and horizontal phase conductor separation, tower construction, and tower grounding systems all have a strong impact on the resulting electromagnetic fields around the transmission lines, and thus the resultant induced voltage on nearby pipelines.
Pipeline AC Corrosion is a function of the induced AC pipeline voltage and is further influenced by pipeline material, pipeline coating systems, and soil characteristics local to the pipeline. When considering modern pipelines, more conductive soils result in greater AC current density at coating defects (holidays). Soil stratification can further significantly influence both the resultant induced AC pipeline voltage and possible pipeline AC corrosion. This paper explores the effects that soil resistivity, layer stratification, and pipeline coating quality have on AC interference, including impacts from induced AC voltage, holiday current densities, and conductive coupling hazards.
