Section
3 Drainage of compartments, other than machinery spaces
3.1 General
3.1.1 All
ships are to be provided with efficient pumping plant having the suctions
and means for drainage so arranged that any water within any compartment
of the ship, or any watertight section of any compartment, can be
pumped out through at least one suction when the ship is on an even
keel and is either upright or has a list of not more than 5°.
For this purpose, wing suctions will generally be necessary, except
in short, narrow compartments where one suction can provide effective
drainage under the above conditions.
3.1.2 In
passenger ships, the pumping plant is to be capable of draining any
watertight compartment under all practicable conditions after a casualty,
whether the ship is upright or listed.
3.1.3 In
the case of dry compartments, the suctions required by Pt 5, Ch 13, 3.1 General 3.1.1 are, except where otherwise
stated, to be branch bilge suctions, i.e. suctions connected to a
main bilge line.
3.1.6 For
a normally inaccessible small void compartment such as an echo sounding
compartment, which is accessed from within a normally inaccessible
space such as a forepeak tank, alternative drainage arrangements to
those required by Pt 5, Ch 13, 3.1 General 3.1.1 may
be considered. For such arrangements, a warning notice is to be located
in a prominent position specifying the precautions to be taken prior
opening the manhole of the small void compartment. Means are to be
provided to indicate flooding of the compartment without opening,
such as fitting indicator plugs to the manhole. Drainage arrangements
are to be submitted to LR for approval.
3.2 Cargo holds
3.2.1 In
ships having only one hold, and this over 30 m in length, bilge suctions
are to be fitted in suitable positions in the fore and after sections
of the hold.
3.2.2 Where
close ceiling or continuous gusset plates are fitted over the bilges,
arrangements are to be made whereby water in a hold compartment may
find its way to the suction pipes.
3.2.3 Where
the inner bottom plating extends to the ship's side, the bilge suctions
are to be led to wells placed at the wings. If the tank top plating
has inverse camber, a well is also to be fitted at the centreline,
but in the case of trawlers and fishing vessels, a single well fitted
at the centre may be accepted. For capacity and construction of bilge
wells, see
Pt 5, Ch 13, 7.6 Bilge wells.
3.2.5 For
cargo holds having non-weathertight hatch covers or where hatch covers
have been omitted, drainage arrangements are to take into account
the effects of additional water ingress into the hold(s). High level
bilge alarms are to be provided in cargo holds having non-weathertight
hatch covers or where hatch covers have been omitted, see also
Pt 4, Ch 8, 11 Hatch covers.
3.2.6 Drainage
arrangements of cargo holds intended for the carriage of flammable
or toxic liquids are to be designed to prevent inadvertent drainage
of such products through machinery space piping systems.
3.3 Holds and deep tanks for alternative carriage of liquid or dry
cargo
3.3.1 Where
holds and deep tanks are intended for the alternative carriage of
liquid or dry cargo, the drainage arrangements are to be in accordance
with the following:
-
For dry cargoes, Pt 5, Ch 13, 3.1 General and Pt 5, Ch 13, 3.2 Cargo holds.
-
For water ballast,
fuel oil or cargo oil having a flash point of 60°C or above, Pt 5, Ch 13, 3.5 Tanks and cofferdams.
-
For cargo oil
having a flash point below 60°C, Pt 5, Ch 15 Piping Systems for Oil Tankers.
3.4 Ships where hatch covers are omitted
3.4.1 The requirements of this section apply to ships which have been assigned
the class notation Hatch Covers omitted in Hold (No(s) ...).
3.4.2 The bilge pumping system is to have a required capacity to pump:
- the maximum hourly rate of green water shipped in
seagoing conditions as established by the comprehensive model testing
specified, see
Pt 3, Ch 9, 10.2 Loading due to water ingress
- an amount equal to rainfall of 100 mm/h regardless of
the installation of rain covers;
- the amount of shipped green water measured during the
seakeeping model tests, see
Pt 3, Ch 9, 10.2 Loading due to water ingress, for
the dead ship condition in beam seas, multiplied by a safety factor of
2;
- four-thirds of the amount of water required for
fire-fighting purposes in the largest hold;
- an amount equal to the capacity required for ships with
closed cargo holds, see
Pt 5, Ch 13, 3.2 Cargo holds;
whichever is the greater.
3.4.3 At least three bilge pumps are to be capable of pumping hold bilges.
3.4.6 The bilge pumping system, including the piping system, is to incorporate
sufficient redundancy features such that the system will be fully operational and
capable of dewatering the hold spaces at the required capacity, see
Pt 5, Ch 13, 3.4 Ships where hatch covers are omitted 3.4.2 in the event of failure of any one system component.
3.4.8 All open cargo holds are to be fitted with high bilge level alarms to alert the
ship’s crew when there is any accumulation of water.
3.4.11 If the loss of suction prevents the proper functioning of the bilge system, special
measures to prevent this are to be considered, e.g. the installation of level
indicators.
3.4.12 Open cargo hold drain wells are to be designed to ensure unobstructed discharge of
water and easy access for cleaning under all conditions.
3.5 Tanks and cofferdams
3.5.1 All
tanks (including double bottom tanks), whether used for water ballast,
fuel oil or liquid cargoes, are to be provided with suction pipes,
led to suitable power pumps, from the after end of each tank.
3.5.2 In
general, the drainage arrangements are to be in accordance with Pt 5, Ch 13, 3.1 General. However, where the tanks are
divided by longitudinal watertight bulkheads or girders into two or
more tanks, a single suction pipe, led to the after end of each tank,
will normally be acceptable.
3.5.3 Similar
drainage arrangements are to be provided for cofferdams, except that
the suctions may be led to the main bilge line.
3.5.4 The
pumping arrangements for tanks that are intended to carry cargo oil
having a flash point of 60°C or above, are also to comply with
the requirements of Pt 5, Ch 14, 2 Fuel oil - General requirements, Pt 5, Ch 14, 3 Fuel oil burning arrangements and Pt 5, Ch 14, 4 Fuel oil pumps, pipes, fittings, tanks, etc., as far as they are applicable.
3.6 Fore and after peaks
3.6.1 Fuel
oil, lubrication oil and other flammable liquids are not to be carried
in forepeak tanks.
3.6.2 Where
the peaks are used as tanks, a power pump suction is to be led to
each tank, except in the case of small tanks used for the carriage
of domestic fresh water, where hand pumps may be used.
3.6.3 Where
the peaks are not used as tanks, and main bilge line suctions are
not fitted, drainage of both peaks may be effected by hand pump suctions,
provided that the suction lift is well within the capacity of the
pumps and in no case exceeds 7,3 m. In the case of trawlers and fishing
vessels, drainage of the after peak may be effected by means of a
self-closing cock fitted in a well lighted and readily accessible
position.
3.6.4 Except as permitted by Pt 5, Ch 13, 3.6 Fore and after peaks 3.6.5, the collision bulkhead may be pierced below the
bulkhead deck of passenger ships and the freeboard deck of cargo ships by not more than
one pipe for dealing with the contents of the fore peak. The pipe is to be provided with
a screw-down valve capable of being operated from an accessible position above the
bulkhead deck of passenger ships and the freeboard deck of cargo ships, the chest being
secured to the bulkhead inside the fore peak. An indicator is to be provided to show
whether the valve is open or closed. The valves may be fitted on the after side of the
collision bulkhead, provided that the valve is readily accessible under all service
conditions and the space in which it is located is not a cargo space. Alternatively, for
cargo ships, the pipe may be fitted with a butterfly valve suitably supported by a seat
or flanges and capable of being operated from above the freeboard deck.
3.6.5 Where the fore peak is divided into two compartments, the collision bulkhead
may be pierced below the bulkhead deck of passenger ships and the freeboard deck of
cargo ships by two pipes (i.e. one for each compartment) provided there is no practical
alternative to the fitting of a second pipe. Each pipe is to be fitted and controlled as
in Pt 5, Ch 13, 3.6 Fore and after peaks 3.6.4.
3.7 Spaces above fore peaks, after peaks and machinery spaces
3.7.1 Provision
is to be made for the drainage of the chain locker and watertight
compartments above the fore peak tank by hand or power pump suctions.
3.7.2 Steering
gear compartments or other small enclosed spaces situated above the
after peak tank are to be provided with suitable means of drainage,
either by hand or power pump bilge suctions.
3.7.3 Subject
to special approval of any applicable subdivision requirements, compartments
referred to in Pt 5, Ch 13, 3.7 Spaces above fore peaks, after peaks and machinery spaces 3.7.2 that
are adequately isolated from the adjacent 'tween decks, may be drained
by scuppers of not less than 38 mm bore, discharging to the tunnel
(or machinery space in the case of ships with machinery aft) and fitted
with self-closing cocks situated in well lighted and visible positions.
3.8 Maintenance of integrity of bulkheads
3.8.1 The
intactness of the machinery space bulkheads, and of tunnel plating
required to be of watertight construction, is not to be impaired by
the fitting of scuppers discharging to machinery space or tunnels
from adjacent compartments which are situated below the bulkhead deck.
These scuppers may, however, be led into a strongly constructed scupper
drain tank situated in the machinery space or tunnel, but closed to
these spaces and drained by means of a suction of appropriate size
led from the main bilge line through a screw-down non-return valve.
3.8.2 The
scupper tank air pipe is to be led to above the bulkhead deck, and
provision is to be made for ascertaining the level of water in the
tank.
3.8.3 Where
one tank is used for the drainage of several watertight compartments,
the scupper pipes are to be provided with screw-down non-return valves.
3.8.4 No
drain valve or cock is to be fitted to the collision bulkhead. Drain
valves or cocks are not to be fitted to other watertight bulkheads
if alternative means of drainage are practicable.
3.8.5 Where
drain valves or cocks are fitted to bulkheads other than the collision
bulkhead, as permitted by Pt 5, Ch 13, 3.8 Maintenance of integrity of bulkheads 3.8.4,
the drain valves or cocks are to be at all times readily accessible
and are to be capable of being shut off from positions above the bulkhead
deck. Indicators are to be provided to show whether the drains are
open or shut. These arrangements are not permissible in passenger
ships.
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