7.1 Tanks for the purposes mentioned above should
be arranged to satisfy the intended service of the ship.
7.2 Sludge tanks may be separate and independent
but may also be combined, as suitable, depending on the size and the
service of the ship.
7.3 The merits of arranging an independent tank
for the collection of separated sludge should be considered, having
regard to the smaller tank volume that needs to have cleaning and
heating arrangements and the reduced space requirement for tank capacity
that should preferably by arranged above the tank top.
7.4 If a bilge-water holding tank is arranged,
it should be separate and independent from other tanks for the collection
of sludge.
7.5 Ships operating with residual fuel oil of
a relative density greater than 0.94 at 15°C should be provided
with a bilge-water holding tank of adequate capacity and fitted with
heating facilities to preheat the oily mixture prior to the discharge
of the tank's contents to the sea through 100 ppm or 15 ppm equipment.