2.23 CLEAN BALLAST TANK SHIP PREPARATIONS

Ships operating with clean ballast tank systems require a final flushing of the ballast discharge system prior to arriving at the loading port. While the ship is still outside prohibited waters the ballast discharge system must be aligned according to the ballast discharge procedures for the loading port and a quantity of ballast discharged. It is only necessary to discharge enough to ensure that the piping system and pumps contain no hidden pockets of oil which could result in a pollution incident in the loading port.

The procedure to be followed using the example vessel from the IMO Dedicated clean ballast tanks booklet (section 2.2.3) is:
1 Verify that the slop tank valves are closed.
     • Port slop tank valves nos. 61, 64, 133 and 111.
     • Starboard slop tank valves nos. 54, 63, 108, 132.
2 Open valves for discharging ballast.
    • No.1 cargo main valves nos. 40, 41, 59, 60, 104, 144 and 123.
    • No.1 discharge main valves nos. 155, 156 and 127.
    • No.2 dedicated clean ballast tank nos. 36, 37.
    • Starboard sea suction valve No.115.
3 Start the No.l pump and flush overboard for five minutes. Stop the No.l pump.
4 Close No.2 clean ballast tank valves nos. 36 and 37.
5 Open No.4 dedicated clean ballast tank valves nos. 58 and 67.
6 Start the No.l pump and flush overboard for five minutes.
7 Stop the No.l pump and close all valves.

The ballast system is now ready for discharge of clean ballast in port, provided no other operations are conducted using the flushed lines or pump. If another ballast handling operation is conducted, the lines must be flushed again as above before the chief officer can be certain of their being properly prepared for the loading port.