CARGO TANK WASHING After discharge of cargoes oil tanker cargo
tanks can be cleaned by either hot or cold water, fresh or seawater, or by
crude oil washing. Water cleaning machines can be fixed in a tank or may
be portable, the portable machine being connected by hose to a deck watermain
before being introduced through a tank cleaning hatch into the tank.
Crude oil carriers can have fixed washing equipment in the tanks connected
to the cargo pumps via cross-connections at the ships manifold to the cleaning
main and can use crude oil instead of water as the washing medium.
This is usually done while the tanker is discharging cargo and it enables
re-dissolving of oil fractions adhering to the tank surfaces to take place so
that these residues can be discharged with the cargo. There may then be no
need to water wash tanks for the removal of residues unless clean water
ballast is to be carried in the tank.
Further Reading
‘MARPOL 73/78 Consolidated Edition 2002’, IMO publication (IMO-1B
520E) (see Annex 1 – Chapter I – Regulation 18 – Pumping, piping and
discharge arrangements for oil tankers).
‘MARPOL 2005 Amendments 2005’, IMO publication (IMO-1525E)
‘SOLAS Consolidated Edition 2004’ IMO publication (IMO-1D 110E) (see
Chapter II-2 – Part D – Fire safety measures for tankers).
‘Code for the Construction and Equipment of Ships Carrying Dangerous
Chemicals in Bulk (BCH Code)’, IMO publication (IMO-772E)
‘International Code for the Construction and Equipment of Ships Carrying
Dangerous Chemicals in Bulk (IBC Code)’, IMO publication (IMO-100E)
Some Useful Web Sites
www.victorpyrate.com see ‘Tank washing machines’ and ‘Gas freeing fans’.