Design of CP System for Newly Constructed Pipelines with Respect to Cathodic Protection Criteria Based on DC and AC Current Densities Measured Using Probes

摘要

Recently, the risks such as AC corrosion, overprotection and corrosion inside casing pipes are increasing on cathodically protected pipelines due to the changes in burial situations, application of new construction techniques and so on. Authors have proposed new cathodic protection (CP) criteria based on DC and AC current densities measured using probes that provide an appropriate assessment of those risks together with effective measures to eliminate those risks. The design of CP systems for newly constructed pipelines, on which those risks were likely to occur, was then successfully performed based on the new CP criteria. In this paper, actual procedures to design CP systems with respect to the new CP criteria are demonstrated. In addition, the methodology to eliminate the risk of AC corrosion is presented.