Investigating the accelerated test condition to produce cracking failure of water ballast tank coatings

The shipping industry and its stakeholders have raised concerns of coating degradation leading to corrosion in water ballast tanks (WBTs) of in-service Double Hull (DH) tankers and bulk carriers. It is extremely challenging to maintain, inspect and repair WBT coatings due to their size and complex structural geometry. Hence there is an increasing demand from the shipping industry for better WBT coating quality and performance to increase the life span of the DH tankers and bulk carriers. Prior to their application WBT coatings are subjected to the Performance Standard for Protective Coatings for Dedicated Sea Water ballast tanks (PSPC) test protocols to assess their performance. When in-service WBT coatings are subjected to hygrothermal cycling which is due to their working condition i.e. change in temperature as a result of the day/night cycle and the ballasted/de-ballasted cycle. Cargo temperature can also add to this cyclical burden. Stresses that are induced in the coating via hygrothermal cycling may contribute to the initiation of cracks in the coating. Therefore there is both academic and industrial interest to better understand and identify the factors that contribute to the cracking phenomena of these coatings. This investigation examined the effectiveness of the accelerated tests consisting of defined environmental factors to produce coating cracking failure at the welded joints under laboratory conditions.