Segregated ballast tanks. These are tanks which must be provided on board crude oil tankers after the MARPOL 1973/1978 Convention entered into force in 1983.
Cargo oil and ballast must be segregated to prevent pollution. Segregated ballast is ballast water that is introduced into a tank which is completely separated from the cargo oil and oil fuel system and which is permanently allocated to the carriage of ballast or to the carriage of ballast or cargoes other than oil or noxious liquid substances.