Performance Testing of Some Marine Coatings Under Simulated Ballast Tank Conditions

Ballast tanks on ships are used in various modes – completely filled with seawater, partially filled, or sometimes completely empty.  It is the normal practice to coat the interior of the tanks with a suitable coating and also apply cathodic protection (CP).  During service, the interiors of the ballast tanks are exposed to complete immersion in seawater when they are full.  When half full, the top half of the tank interior is exposed to moist, salt-laden air while the bottom half is completely immersed.  When completely empty, the tank interior only has moist salt-laden air. 

A project was undertaken to study the performance of some marine coatings under simulated ballast tank conditions by utilizing a large (2000-gallon) mock-up ballast tank.  The methodologies used for coating performance evaluation are discussed.  The impact of the type of surface preparation, in particular abrasive blasting (AB) and ultra high pressure waterjetting (UHP-WJ), on coating performance was investigated and the results are reported in the paper.

 Key words:  Ballast tank, surface preparation, coating performance, abrasive blasting (AB), ultra high pressure waterjetting (UHP-WJ);