New Cathodic Protection Criteria Based on Probe Measurements of DC and AC Current Density of Buried Steel Pipelines

摘要

Buried steel pipelines can be protected against corrosion by the combined use of high-resistivity coatings and cathodic protection (CP). Pipe-to-soil potential is periodically surveyed to evaluate the CP level. In recent years, problems due to AC corrosion, overprotection, and corrosion inside pipe casings have been increasing because of changes in burial conditions, new construction techniques, and other factors. Risks of this kind can be assessed by using probes to measure DC and AC current density. New CP criteria based on probe measurements of DC and AC current density have been developed.