Section 4 Bilge pumping and drainage systems

4.1.1 Arrangements are to be made for draining all watertight compartments other than those intended for permanent storage of fluids. Where drainage is not considered necessary, drainage arrangements may be omitted provided the safety of the linkspan is not impaired.

4.1.2 Pumping arrangements are to be provided having suctions and means of drainage so arranged that any water within any watertight compartment of the linkspan or any watertight section of any compartment, can be pumped out through at least one suction under all possible conditions of operation.

4.1.3 The bilge pumping system is to be designed to prevent water flowing from one watertight compartment to another.

4.1.4 Small compartments may be drained by individual hand pump suctions.

4.1.5 Where the safety or operation of the linkspan could be affected by the ingress of water into a space provided with bilge pumping arrangements, the space is to be provided with a bilge level alarm.

4.2.1 The bilge drainage arrangements are to comply with Pt 4, Ch 5, 4.1 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 under all possible design operating and survival conditions.

4.2.2 Where a bilge main is fitted, one of the suctions referred to in Pt 4, Ch 5, 4.2 Bilge drainage of machinery spaces 4.2.1 is to be a branch bilge suction, i.e. a suction connected to the bilge main. The second bilge suction is to be a direct bilge suction.

4.2.3 Where a bilge main is not fitted, the branch bilge suction referred to in Pt 4, Ch 5, 4.2 Bilge drainage of machinery spaces 4.2.2 may be replaced by a suction from a submersible bilge pump.

4.2.4 Additional bilge suctions may be required for the drainage of wells or other recesses.

4.3.1 The sizes of bilge suction pipes are to be suitable for the dimensions of the spaces requiring bilge drainage arrangements.

4.3.2 Where a bilge main is fitted, the internal diameter is to be not less than 50 mm.

4.3.3 The diameter of branch bilge suctions is to be not less than 25 mm.

4.4.1 Not less than one power pump and one manual bilge pump suitable for bilge pumping duties are to be provided. Each pump is to take suction from the bilge main or other bilge system arrangement for draining all spaces as applicable.

4.4.2 The power driven pumps may be used for other services (other than flammable liquid transfer) but they are to be immediately available for bilge duty when required.

4.4.3 Pumps required for essential services are not to be connected to a common suction or discharge chest or pipe unless the arrangements are such that the working of any pumps so connected is unaffected by the other pumps being in operation at the same time.

4.4.4 Each power operated bilge pumping unit is to be capable of giving a speed of water through the bilge suction piping of not less than 2 m/s.

4.5.1 The arrangement of valves, cocks and their connections is to be such as to prevent the possibility of one watertight compartment being placed in communication with another, or machinery spaces or other dry compartments being placed in communication with the sea or with tanks. For this purpose, screw-down non-return valves are to be provided in the following fittings:

1. Bilge valve distribution chests.

2. Direct bilge suctions and bilge pump connections to main bilge line.

4.5.2 Bilge suction pipes are to be entirely separate from sea inlets or from pipes which may be used for filling or emptying spaces where water or oil is carried.