Definition(s)
Ballast Tank
A ballast tank is a tank which is used solely for salt-water ballast. A space which is used for both the storage of liquids and salt-water ballast will be treated as a salt-water ballast tank when substantial corrosion has been found in that space.
Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 1, Regulations, June 2013, Lloyd’s Register, Global Standards