The Impact of AC and High DC Potentials on Buried Pipelines: Coating Degradation, Corrosion, and Emerging Challenges

As global energy demands surge and HVAC transmission capacities increase through reconductoring and other advancements, the integrity of buried metallic pipelines faces significant threats. Induced alternating current (AC) and high direct current (DC) potentials in pipelines—often caused by proximity to high-voltage power lines—pose complex challenges to cathodic protection systems and pipeline coatings. These currents can lead to coating degradation phenomena such as undercutting, shielding, pH changes, and accelerated corrosion, compromising long-term pipeline integrity.

This presentation will address:

• The mechanisms through which AC and high DC potentials interact with pipeline coatings and cathodic protection systems, leading to coating disbondment, accelerated corrosion, and hydrogen embrittlement.

• The detrimental effects of AC-induced corrosion, which can result in rapid localized damage and through-wall failures in as little as six months, and the exacerbating role of modern reconductoring techniques, which double HVAC transmission capacities without the need for new infrastructure or permits.

• The critical need for regulatory and industry collaboration in establishing more comprehensive communication and monitoring practices between HVAC and pipeline operators, particularly in shared rights-of-way corridors. Effective collaboration can mitigate unforeseen risks posed by increased transmission loads that pipeline operators may not have been made aware of.