The Laws of Fiji
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9.23
Seawater and bilge systems shall be designed and constructed to maintain the watertight integrity of the hull in normal and abnormal conditions. Any reference to “sea” or “seawater” in this part also applies to ships operating in freshwater.
Seawater and bilge systems essential to the safety of the ship shall provide a reliable means for fulfilling their specific functions.
Discharges, inlets and seawater piping within a ship shall be deemed to have satisfied the Required Outcomes in subparagraphs 9.23.1 and 9.23.2 if they comply with subparagraphs 9.23.4 to 9.23.6.
- 9.23.4.1Seagoing ships of 24m and more in measured length
All discharges, inlets and scuppers on seagoing ships that are required to be marked with a load line, shall comply with the load line conditions of assignment for discharges, inlets and scuppers.
- 9.23.4.2Inlet and discharge valves
All sea inlet and overboard discharge pipes (including sanitary discharges) shall be fitted with valves or cocks unless required otherwise by subparagraphs 9.23.4.3 or 9.23.4.4.
- 9.23.4.3Small discharges
A small discharge may not be fitted with a valve provided that—
- (a)the internal diameter of the discharge does not exceed 50mm; and
- (b)the lowest point of the discharge is not less than 225mm above the deepest loaded water line.
- 9.23.4.4Scupper discharges
A scupper discharge which passes through the ship’s side from a space above the bulkhead deck may be fitted with a non-return valve in lieu of a screw-down valve or cock.
- 9.23.4.5Valves and cocks
Valves and cocks shall be manufactured from bronze, ductile cast steel or equivalent material. Where a valve with a screwed bonnet is a sea injection valve or a valve controlled by an extended spindle, the bonnet shall be secured so that it cannot slacken when the valve is operated.
- 9.23.4.5.1Fitting
Valves and cocks shall be fitted such that they are readily accessible at all times. They shall be mounted on pads or flanges and secured to one of the following—
- (a)The hull of the ship.
- (b)Water boxes.
- (c)Standpipes.
Where secured to standpipes, the standpipes shall be as short as practicable.
- 9.23.4.5.2Types
Valves and cocks with a bore greater than 50mm shall be of the flanged type. Those with bores 50mm or less shall either be of the flanged type or the screwed type (see subparagraph 9.23.4.5.3).
- 9.23.4.5.3Skin fittings and standpipes
Valves and cocks shall be secured to the hull of the ship by means of a metallic skin fitting or standpipe. The finished wall thickness of any such stand pipe shall be a minimum 1.25 times the calculated thickness for a hull of the same material as the standpipe.
- 9.23.4.5.4Gratings
Gratings shall be fitted on the outside of the hull to all seawater inlets. The clear area through the grating shall be at least twice the area of the connected valve. Gratings should be removable to permit access.
- 9.23.5.1General characteristics
Material for seawater piping shall be suitable for its intended service taking into account the nature of fluid carried and the demands imposed by its location in the ship. All piping that may come into contact with seawater shall be corrosion-resistant.
NOTE:
Other characteristics that are relevant for pipes used for seawater applications include resistance to internal pressure, vacuum and external pressure, axial strength, operating temperature limitations, impact resistance, resistance to fatigue, ageing and erosion, fluid absorption, material compatibility, fire endurance and smoke generation upon combustion.
- 9.23.5.2Metallic piping
- 9.23.5.2.1Material
Metallic piping shall be copper, stainless steel, aluminium alloy of a grade suitable for long-term exposure to seawater or carbon steel which has been protected against corrosion (eg galvanising).
- 9.23.5.2.2Thickness
The thickness of metallic piping shall be sufficient to withstand the likely maximum pressure with due allowance for corrosion and erosion that may occur. In any case, the thickness of metallic piping shall not be less than the following—
tp = 0.012di + t0
Where—
- t p = minimum pipe thickness, in millimetres;
- d i = internal diameter, in millimetres; and
- t 0 = 1.8mm for carbon steel or aluminium;
- 1.1mm for copper, or
- 0.8mm for stainless steel or copper alloy.
- 9.23.5.3Rigid plastic piping
- 9.23.5.3.1Application
Rigid plastic piping shall meet the requirements contained in IMO Resolution A 753(18) as amended by Resolution MSC 313(88), or the requirements of a Classification Society.
IMO Resolution A 753(18) as amended by Resolution MSC 313(88), places limits on the extent to which rigid plastic piping can be used for essential services on board ship. In particular, fire endurance, reliability and the consequences of failure are important considerations.
- 9.23.5.3.2Installation
- 9.23.5.3.2.1Rigid plastic piping shall be arranged so that it is readily accessible for inspection and protected against mechanical damage and contact with hot surfaces.
- 9.23.5.3.2.2Where acrylonitrile butadiene styrene (ABS) piping is used in pressure applications, it shall comply with AS 3518.1. Fittings for ABS piping shall comply with AS 3518.2.
Plastic piping has a coefficient of linear expansion that is 8 to 10 times that of steel. Where plastic piping is used, design requirements over the range of service temperatures will have to be considered.
- 9.23.5.4Flexible piping
- 9.23.5.4.1General characteristics
Flexible piping shall be reinforced synthetic rubber. It shall comply with a relevant national or international standard and shall have the following performance characteristics—
- (a)Resistance to water, petroleum products, heat and vibration.
- (b)Capable of operation under suction without collapse and resultant reduction in effective cross-sectional area.
- (c)Capable of withstanding internal pressure present within the system.
- 9.23.5.4.2Application
Flexible piping shall be readily visible and located so as to prevent mechanical damage and contact with hot surfaces. Subject to paragraph 9.24.4.4, flexible piping shall only be used in the following applications—
- (a)In short lengths of no more than 760mm for vibration damping or to accommodate relative movement of machinery.
- (b)In ships less than 12.5m in length, provided that—
- (i)the length of piping does not exceed half the beam of the ship;
- (ii)the run of the piping is as direct as practicable; and
- (iii)it is adequately supported.
- 9.23.5.4.3Method of securing
- 9.23.5.4.3.1The method of securing flexible piping to a rigid pipe or fitting shall be appropriate for the nature of fluid carried and the risks associated with leakage of that fluid.
- 9.23.5.4.3.2Where clips are used to secure flexible piping of 25mm internal diameter and above, at least 2 such clips shall be fitted at each end of the flexible pipe and the clips shall be of corrosion-resistant material.
- 9.23.5.5Pipe fittings — material
Pipe fittings shall not be made of malleable iron.
- 9.23.6.1Piping for filling or discharging fish cargo tanks
Non-metallic piping may be used for filling or discharging fish cargo tanks provided that—
- (a)the piping complies with subparagraph 9.23.5.3;
- (b)bilge alarms are fitted in each compartment in which the piping is installed; and
- (c)any penetration by the piping of a high fire risk space bulkhead, including the bulkhead of a machinery space, is via a valve.
- 9.23.6.2Valves for fish tank pumping systems
A valve shall be provided at each connection to a fish tank. The valves shall either be readily accessible, or where not readily accessible the valves shall either be capable of being readily closed from a position above the bulkhead deck, or shall be non-return valves.
Valves need not be provided on the pipe connections to a fish tank if a rupture of the pipe would not reduce the safety of the ship. Factors to be considered include the effect of discharging the tank contents into the bilge of the ship and the effect of the ruptured pipe on the ship’s weather tight integrity.