The Effect of Chlorinated Seawater on Coating Performance of Epoxy for a Ship's Water Ballast Tank

摘要

Many kinds of organic coatings have been applied to protect ships in various corrosive environments. Mainly epoxy coating systems have been used to protect water ballast tanks of ships from corrosion. Since aquatic nuisance species via a ship's ballast water have induced detrimental ecological issues, numerous water ballast treatment systems designed to block inflow of aquatic species are presently being studied. However, by using these treatment technologies, there have been concerns that they may have some adverse effects on the performance of coating systems for ships' ballast tanks. Because coating performance in water ballast tanks is an especially important factor in determining a ship's lifetime, it is essential to evaluate coating performance in the seawater treated by water ballast treatment systems. Therefore, this study was performed to verify the effect of chlorinated seawater by electrochemical process on epoxy coating performance for ships' water ballast tanks. Two different representative epoxy systems for water ballast tank lining were selected, and coating performance testing was carried out in accordance with IMO PSPC Regulations by using the simulated wave ballast tank with natural seawater and chlorinated seawater environment for 6 months. Aspects of coating performance such as adhesion strength, anti-corrosion resistance, and cathodic disbondment resistance were evaluated and FT-IR analysis was conducted to confirm the chemical molecular structure change caused by coating degradation. It could be concluded from this study that the electrochemically chlorinated seawater with the chlorine level up to 10 ppm would have no or little influence on epoxy coating performance nor the chemical molecular structure of the coating film.