Compatibility between Pipeline Anti-corrosion Coating and Thermal Insulator in the Presence of Cathodic Protection

摘要

In this paper the disbondment characteristics of anti-corrosion coating below an intact insulator at 150 °C have been investigated. The anti-corrosion coating in such situation may be susceptible to water accumulation if the insulator deteriorates elsewhere providing entry point for water and the water subsequently migrates laterally along the pipeline. Under this situation, Cathodic protection (CP) may not reach the steel surface to protect it. To simulate this situation, the cathodic disbondment (CD) test was conducted using a specially designed experimental set up in which the pipe sample was titled to simulate the inclination of pipeline and to facilitate the lateral movement of water. During the test no lateral movement of water beneath an intact insulator was observed for over 150 days and the anticorrosion coating (beneath the intact insulator) did not undergo any change. However, the area of disbondment of anticorrosion coating in the adjacent section that was exposed directly to aqueous phase (i.e., outer insulator and polyethylene layers were removed before the test) was higher.