Abstract
This paper highlights the coordinated AC mitigation and cathodic protection strategy for a 167 mile (269 km) long high-pressure interstate natural gas pipeline. Ninety-five percent of the pipeline is located adjacent and parallel to high voltage AC power transmission lines ranging to 500 kV. Analyses and computer simulations during the front-end engineering design predicted that, without suitable mitigation, steady-state AC potentials (referenced to local earth) on the pipeline would easily exceed 100 V; AC coating stress and touch potentials approaching 12,000 V were predicted during a power line to ground fault. The AC mitigation and cathodic protection designs were closely coordinated with operations personnel to assure systems that were maintenance-friendly. Corrosion control commissioning included a multi-channel AC and DC close interval potential survey protocol. The baseline data document the success of the AC mitigation and cathodic protection in safely and cost effectively controlling soil corrosion and AC interference. Long-term surveillance includes state-of-the-art remote monitoring and the use of coupon technology.
