As industry trends are resulting in more shared right of ways between power lines and pipeline utilities, the need for mitigation of AC interference is expanding, further driving the desire for efficient solutions. Low impedance grounding systems are generally used to mitigate elevated AC potential and current density on buried pipelines. Multiple mitigation grounding techniques are in use across the pipeline industry, with varying materials, configurations, and construction practices. While there are pros and cons to each, determination of a preferred mitigation design for a given site should consider overall system efficiency, component design life, and specific material properties.
Presently, a comprehensive review of primary mitigation materials is not available to industry, as historical work generally covers a specific subset of these concepts or designs. This study presents a comparative assessment reviewing the electrochemical properties of common AC mitigation materials, and assesses common industry claims with respect to AC mitigation grounding. The intent of this work is to provide the corrosion test data and technical information to support an engineering based decision for mitigation material selection.
Key Words: AC Mitigation, zinc ribbon, passivation, Electrochemical impedance spectroscopy