Section 3 Drainage of compartments, other than machinery spaces

3.1.1 All ships are to be provided with an 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 11, 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.

3.1.4 Void spaces which are permanently sealed need not be connected to the bilge system, see also Pt 5, Ch 10, 2.2 Wrought steel pipes and bends 2.2.6.

3.1.5 For drainage arrangements of non-self-propelled ships, see Pt 5, Ch 11, 9 Drainage arrangements for ships not fitted with propelling machinery.

3.1.6 For additional drainage arrangements on ferries and Roll on-Roll off ships, see Pt 4, Ch 2 Ferries and Roll on-Roll off Ships.

3.2.1 In ships having only one hold, and this being 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 In ships having flat bottoms with a breadth exceeding 5 m, bilge suctions are to be fitted in the wings.

3.2.3 Where close ceilings 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.

3.2.4 In ships fitted with double bottoms, suitably located bilge wells are to be provided.

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). Such ships shall meet the requirements of Pt 5, Ch 11, 3.2 Cargo holds 3.2.6. See Pt 5, Ch 11, 6.3 Capacity of pumps 6.3.2 for required bilge capacities.

3.2.6 High level bilge alarms are to be provided in cargo holds.

3.2.7 One of the bilge pumps dealing with the hold should be located in such a way that it will not be affected by a fire or other casualty to the space containing the other pump or the space containing the main source of power. This requirement is not applicable for pumps situated aft and forward in the cargo hold.

3.2.8 The above bilge pump should be supplied from a source of power other than the main source.

3.2.9 The bilge pumping system, including the piping system, should incorporate sufficient redundancy features so that the system will be fully operational and capable of dewatering the hold space(s) at the required capacity in the event of failure of one system component.

3.2.10 Drainage arrangements of cargo holds intended for the carriage of flammable or toxic liquids are to be independent of the bilge system(s) in the machinery space(s) and such ships shall meet the requirements of Pt 5, Ch 11, 3.2 Cargo holds 3.2.11.

3.2.11 Arrangements for the carriage of dangerous goods are to be in compliance with (Inter)National requirements and acceptable to the relevant Administration.

3.2.12 Drainage arrangements of cargo holds in double hull ships may be achieved by the installation of fixed submersible pumps fitted in the cargo hold(s) as per Pt 5, Ch 11, 6.6 Submersible bilge pump arrangements, with a capacity as per Pt 5, Ch 11, 6.3 Capacity of pumpsand with d _m calculated as a branch bilge suction in compliance with Pt 5, Ch 11, 5.2 Branch bilge suctions to cargo and machinery spaces 5.2.1. Not less than two pumps are to be fitted crosswise in the cargo hold, i.e. one pump aft SB and one pump forward PS, or the other way around.

3.2.13 The discharge of the bilge pumps is preferably led directly overboard but may be led through the machinery space if the pipe is seamless and the circumferential welds are butt welds of the full penetration type and no other connections will be fitted in way of the machinery space. Flange connections in the piping are only permitted at the hull connection.

3.2.14 The fixed submersible pumps are to be accessible under all conditions of normal service.

3.2.15 The prime mover of the submersible pumps is to be of the intrinsically safe type when carrying flammable cargoes.

3.2.16 An additional emergency means of pumping is to be provided which may be a portable submersible self-priming pump with a capacity of not less than that required by Pt 5, Ch 11, 3.2 Cargo holds 3.2.12. If the required capacity is such that the portability of the pump is no longer practicable, consideration should be given to divide the required capacity equally over two portable pumps. For storage of the portable pump(s), see Pt 5, Ch 11, 4.2 Submersible pump drainage 4.2.3.

3.2.17 Alternatively, drainage arrangements of the hold by means of two ejectors situated in the hold driven by pumps in the engine room(s) will be specially considered.

3.2.18 For single hull ships, the independent bilge system is to comply with the regular requirements as applicable for a cargo hold. Alternatively, a drainage arrangement as per Pt 5, Ch 11, 3.2 Cargo holds 3.2.17 may be installed.

3.3.1 Flooding of the hold may be provided with a (dedicated) pump situated in the engine room(s).

3.3.2 During the carriage of dangerous goods, the connection with the hold is to be blinded off.

3.3.3 The Owners shall be informed that the stability of the vessel with a flooded hold shall be maintained under all conditions of service.

3.4.1 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.

3.4.2 In general, the drainage arrangements are to be in accordance with Pt 5, Ch 11, 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.

3.4.3 The pumping arrangements for tanks that are intended to carry cargo oil having a flash point of 55°C or above, are also to comply with the requirements of Chapter 12, Pt 5, Ch 12, 2 Fuel oil - General requirements, Pt 5, Ch 12, 3 Fuel oil burning arrangements and Pt 5, Ch 12, 4 Fuel oil pumps, pipes, fittings, tanks, etc., so far as they are applicable.

3.5.1 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.

3.5.2 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. Drainage of the after peak, for ships, other than passenger ships, may be effected by means of a self-closing cock fitted in a well lighted and readily accessible position.

3.5.3 Except as permitted by Pt 5, Ch 11, 3.5 Fore and after peaks 3.5.4, the collision bulkhead in passenger ships is not to be pierced below the bulkhead deck by 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, 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.

3.5.4 Where the forepeak in a passenger ship is divided into two compartments, the collision bulkhead may be pierced below the bulkhead deck by two pipes (i.e. one for each compartment) provided there is no practicable alternative to the fitting of a second pipe. Each pipe is to be provided with a screw-down valve, fitted and controlled as in Pt 5, Ch 11, 3.5 Fore and after peaks 3.5.3.

3.5.5 In ships other than passenger ships, pipes piercing the collision bulkhead are to be fitted with suitable valves operable from above the freeboard deck and the valve chests are to be secured to the bulkhead inside the forepeak. The valve may be fitted on the after side of the collision bulkhead, without remote control, provided that the valve is readily accessible under all service conditions and the space in which it is located is not a cargo space.

3.6.1 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 bilge suctions. The chain locker is not to be drained into the fore peak.

3.6.2 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.

3.6.3 Subject to special approval of any applicable subdivision requirements, the compartments referred to in 3.6.2 may be drained by scuppers of not less than 38 mm bore, discharging to the machinery space and fitted with selfclosing cocks situated in well lighted and visible positions.

3.6.4 Accommodation spaces which overhang the machinery space, may also be drained as in Pt 5, Ch 11, 3.6 Spaces above fore peaks, after peaks and machinery spaces 3.6.3.

3.7.1 The intactness of the machinery space bulkheads, required to be of watertight construction, is not to be impaired by the fitting of scuppers discharging to the machinery space from adjacent compartments which are situated below the bulkhead deck.

3.7.2 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.