EVALUATION OF COATING PERFORMANCE FOR CORROSION UNDER INSULATION (CUI) PREVENTION

Corrosion under insulation (CUI) is one of the major problems that that can lead to unexpected downtime to industry. Main corrosion prevention of CUI is by coating applied to the required industrial standard. In reality, the coating quality varies which affects the coating performance under insulation. Hence, the performance of coating is dependent on the physical condition of coating. Thus, this project is carried out to evaluate the coating performance of different coating quality for CUI prevention. The objective of the project is to evaluate the performance of three samples of coating quality under simulated CUI condition. The first coating sample was the good coating sample as per standard, PTS.30.48.00.31. The second coating sample was non-conformance coating condition in terms of coating thickness, and the last sample was physically-damaged coating. The performance of the samples was evaluated using electrochemical impedance spectroscopy method. Based on the impedance distribution data from EIS testing the best coating performance was obtained by the good coating condition sample, followed by thinner off spec coating condition and physical damaged coating condition. The impedance of good coating and thickness off spec decreased slightly with immersion time. However the impedance of damage coating decreases significantly with immersion time. The experiment results concluded that proper coating application is very important to obtain long lasting and high quality coating. Damage on coating and thinner off specification of coating will affect the performance of coating in protecting the metal from corrosion especially in corrosion under insulation environment.