Corrosion Mechanism of Cathodic Protected Transmission Pipeline Steel with Damaged Enamel Coatings


Internal coatings have been largely used for corrosion protection of pipeline. One of the concerns with internal coating is mechanical damage threat since the flowing solids will generate abrasive forces and impact on the internal coating. Although the coating cannot prevent the exposed substrate steel from corrosion at the damaged sites, cathodic prevention will continue to exert protection effect on the pipeline. In this study, corrosion mechanism of pipeline steel coated with two types of enamel under cathodic protection were investigated in 3.5 wt.% NaCl solution with electrochemical impedance spectroscopy (EIS) tests. Experiment results show that although cathodic protection cannot improve the corrosion resistance, all the damaged coating under cathodic protection do not have corrosion products generated on the damaged sites. Scanning electron microscopy (SEM) images indicate that damaged enamel coatings still have bonding coating left on the substrate steel.

Meeting Name

2017 Materials Science and Technology Conference and Exhibition, MS&T'17 (2017: Oct. 8-12, Pittsburgh, PA)


Materials Science and Engineering

Second Department

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Cathodic protection; Corrosion prevention; Corrosion resistance; Electrochemical corrosion; Electrochemical impedance spectroscopy (EIS); Enameling; Enamels; Internal corrosion; Natural gas transportation; Pipelines; Scanning electron microscopy (SEM); Sodium chloride; Spectroscopy; Steel corrosion; Steel pipe; Cathodic prevention; Corrosion mechanisms; Corrosion products; Internal coatings; Mechanical damages; Protection effect; Scanning electron microscopy image; Transmission pipelines; Corrosion resistant coatings; Pipe steel

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


File Type





© 2017 Association for Iron & Steel Technology (AIST), All rights reserved.

Publication Date

01 Oct 2017