4 Bilge drainage of machinery spaces
bilge drainage arrangements in the machinery space are to comply with Pt 5, Ch 13, 3.1 General, except that the arrangements
are to be such that any water which may enter this compartment can
be pumped out through at least two bilge suctions when the ship is
on an even keel, and is either upright or has a list of not more than
5°. One of these suctions is to be a branch bilge suction, i.e.
a suction connected to the main bilge line, and the other is to be
a direct bilge suction, i.e. a suction led direct to an independent
power pump. Examples of the necessary arrangements are detailed in Pt 5, Ch 13, 4.2 Machinery space with double bottom and Pt 5, Ch 13, 4.3 Machinery space without double bottom.
passenger ships, the drainage arrangements are to be such that machinery
spaces can be pumped out under all practical conditions after a casualty,
whether the ship is upright or listed.
4.2 Machinery space with double bottom
the double bottom extends the full length of the machinery space and
forms bilges at the wings, it will be necessary to provide one branch
and one direct bilge suction at each side.
the double bottom plating extends the full length and breadth of the
compartment, one branch bilge suction and one direct bilge suction
are to be led to each of two bilge wells, situated one at each side.
4.3 Machinery space without double bottom
there is no double bottom and the rise of floor is not less than 5°,
one branch and one direct bilge suction are to be led to accessible
positions as near the centreline as practicable.
ships where the rise of floor is less than 5°, and in all passenger
ships, additional bilge suctions are to be provided at the wings.
4.4 Additional bilge suctions
bilge suctions may be required for the drainage of depressions in
the tank top formed by crankpits, or other recesses, by tank tops
having inverse camber or by discontinuity of the double bottom.
ships in which the propelling machinery is situated at the after end
of the ship, it will generally be necessary for bilge suctions to
be fitted in the forward wings as well as in the after end of the
machinery space, but each case will be dealt with according to the
size and structural arrangements of the compartment.
ships propelled by electrical machinery, special means are to be provided
to prevent the accumulation of bilge water under the main propulsion
generators and motors.
4.5 Separate machinery spaces
the machinery space is divided by watertight bulkheads to separate
the boiler room(s), or auxiliary engine room(s) from the main engine
room, the number and position of the branch bilge suctions in the
boiler room(s) or auxiliary engine room(s) are to be the same as for
addition to the branch bilge suctions, required by Pt 5, Ch 13, 4.5 Separate machinery spaces 4.5.1, at least one independent
power pump direct bilge suction is to be fitted in each compartment.
Similar provision is to be made in separate motor rooms of electrically
passenger ships, each independent bilge pump is to have a direct bilge
suction from the space in which it is situated, but not more than
two such suctions are required in any one space. Where two or more
such suctions are provided, there is to be at least one suction on
each side of the space.
4.6 Machinery space – Emergency bilge drainage
addition to the bilge suctions detailed in Pt 5, Ch 13, 4.1 General, an emergency bilge suction
is to be provided in each main machinery space. This suction is to
be led to the main cooling water pump from a suitable low level in
the machinery space and is to be fitted with a screw-down non-return
valve having the spindle so extended that the hand wheel is not less
than 460 mm above the bottom platform.
two or more cooling water pumps are provided, each capable of supplying
cooling water for normal power, only one pump need be fitted with
an emergency bilge suction.
ships with steam propelling machinery, the suction is to have a diameter
of at least two-thirds that of the pump suction. In other ships, the
suction is to be the same size as the suction branch of the pump.
main cooling water pumps are not suitable for bilge pumping duties,
the emergency bilge suction is to be led to the largest available
power pump, which is not a bilge pump detailed in Pt 5, Ch 13, 6.1 Number of pumps and Pt 5, Ch 13, 6.2 General service pumps. This pump is to have a capacity not less than that required
for a bilge pump and the bilge suction is to be the same size as that
of the pump suction branch.
the pump to which the emergency bilge suction is connected is of the
self-priming type, the direct bilge suction on the same side of the
ship as the emergency suction may be omitted, except in passenger
bilge suction valve nameplates are to be marked `For emergency use
4.6.7 Where UMS (Unattended Machinery Space) notation is to be assigned,
the requirements of Pt 6, Ch 1, 4.7 Bilge level detection 4.7.2 are
not applicable for valves serving an emergency bilge system, provided
bilge valve is normally maintained in a closed position;
device is installed in the emergency bilge piping; and
bilge suction piping is located inboard of a shell valve that is fitted
with the control arrangements complying with Pt 6, Ch 1, 4.7 Bilge level detection 4.7.2.
4.7 Tunnel drainage
tunnel well is to be drained by a suction from the main bilge line.
In all ships, including passenger ships, this well may extend to the
the tank top in the tunnel slopes down from aft to forward, a bilge
suction is to be provided at the forward end of the tunnel, in addition
to the tunnel well suction required by Pt 5, Ch 13, 4.7 Tunnel drainage 4.7.1.
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