DC Interference from Communication Lines: Two Pipeline Case Studies

Abstract Direct current (DC) interference from communication lines, including phone lines, has been recognized as a source of interference and possible corrosion risk to pipelines. This paper presents two case studies where such interference was identified and mitigated. The identification process involved various survey techniques, including pipe-to-soil (P/S) potential measurements under different communication line grounding conditions, close interval surveys (CIS), cell-to-cell surveys, measurements taken on the communication lines, and standard P/S potential readings. Each case employed a distinct remediation strategy, one above grade and the other involving excavation. The findings contribute to a broader understanding of DC interference mechanisms and practical mitigation approaches in pipeline integrity management.