AC corrosion behavior and the effect of stone-hard-soil on corrosion process in the earth alkaline rich environment
By Liang, Yi; Du, Yanxia; Chen, Le; Tian, Nianpei; Zhang, Lei; Qiao, Lijie
Published in Engineering Failure Analysis
2022
Abstract
Many oil and gas pipelines are parallel with high voltage transmission lines in a long distance. Corrosion failures in such situation have been reported and typical corrosion morphology (stone-hard-soil) have found in these failures. In this paper, AC corrosion behavior and the effects on corrosion process after the formation of typical corrosion morphology are investigated in earth alkaline rich environment through laboratory simulated tests. This study produce a corrosion rate map where high CP AC corrosion and local corrosion are observed. In domain of high CP AC corrosion, local environment, including typical morphology of stone-hard-soil and corrosive electrolyte at interface, are analyzed. After the formation of stone-hard-soil, the electric field and its effects on migration of Cl-, are discussed. These results, combining the changes in instantaneous potential and pH at local regions, provide a guide to understand the occurrence and development of local corrosion under high CP level and AC interference.