Effectiveness of Cathodic Protection under Insulation of Buried Pipelines

In view of the risk of corrosion under insulation (CUI) of a crude oil insulation pipeline in a western oil field, a field test was carried out by burying a full-size insulation pipe close to the pipeline. The cathodic protection and corrosion rate under the thermal insulation layer were monitored by inspection pieces, micro reference Ag/AgCl electrodes, ER (voltage, resistance) corrosion probes. The results showed that the undamaged jacket and insulation had certain protection and corrosion prevention for the pipeline. When the jacket and insulation were peeled or damaged because of aging, the stability of the cathodic protection circuit or test circuit cannot be guaranteed under the action of water containing dissolved oxygen, and the pipeline may be corroded. Therefore, cathodic protection is difficult to become an effective means of corrosion protection under insulation.