Section 4 Fuel oil pumps, pipes, fittings, tanks, etc.

4.1.1 The power supply to all independently driven fuel oil transfer and pressure pumps is to be capable of being stopped from a position outside the space which will always be accessible in the event of fire occurring in the compartment in which they are situated, as well as from the compartment itself.

4.2.1 All pumps which are capable of developing a pressure exceeding the design pressure of the system are to be provided with relief valves or approved equivalent means. Each relief valve is to be in closed circuit, i.e. arranged to discharge back to the suction side of the pump and to effectively limit the pump discharge pressure to the design pressure of the system.

4.2.2 Where centrifugal type pumps are fitted, pressure-relief valves will not be required, provided that pipes, valves and fittings are suitable for the greater of the design pressure or pump non-delivery pressure.

4.3.1 Valves or cocks are to be interposed between the pumps and the suction and discharge pipes, in order that any pump may be shut off for opening up and overhauling.

4.4.1 Transfer, suction and other low pressure oil pipes and all pipes passing through oil storage tanks are to be made of steel, having flanged or other approved joints suitable for a working pressure of not less than 7 bar. The flanges are to be machined and the jointing material is to be impervious to oil. Where the pipes are 25 mm bore or less, they may be of seamless copper or copper alloy, except those which pass through oil storage tanks. Oil pipes within the machinery spaces are to be fitted where they can be readily inspected and repaired.

4.4.2 Pipes conveying oil under pressure are to be of seamless steel or other approved material having flanged or welded joints suitable for a working pressure of not less than 16 bar, are to be placed in sight above the platform in well lighted and readily accessible parts of the machinery spaces. The number of flanged joints are to be kept to a minimum.

4.4.3 Where pipes convey heated oil under pressure, the flanges are to be machined, and the jointing material, which is to be impervious to oil heated to 150 °C, is to be the thinnest possible, so that the flanges are practically metal to metal. The scantlings of the pipes and their flanges are to be suitable for a pressure of at least 14 bar or for the design pressure, whichever is the greater.

4.4.4 For requirements regarding bilge pipes in way of double bottom tanks and deep tanks, see Pt 5, Ch 11, 7.7 Bilge pipes in way of double bottom tanks and Pt 5, Ch 11, 7.8 Bilge pipes in way of deep tanks.

4.4.5 For requirements relating to flexible hoses, see Pt 5, Ch 10, 7 Flexible hoses.

4.4.6 Fuel oil tanks in the machinery space situated at Port side and Starboard side may be connected with a crossover. Where fitted, the arrangements are to comply with the requirements of Pt 5, Ch 12, 4.4 Pipes conveying oil 4.4.7.

4.4.7 The crossover is provided with valves of an approved type and ductile material, fitted in a visible and accessible position and secured to the relevant tanks.

4.4.8 The crossover pipe must have a diameter of not less than 3” (88,9 mm) and a wall thickness of not less than 8,8 mm and is to be suitably protected against mechanical damage. The pipe is to be manufactured from seamless steel or other approved material having welded joints of the full penetration type.

4.4.9 Connections on the crossover intended for fuel oil supply to the engines or any boiler may be fitted provided a quick closing valve as per Pt 5, Ch 12, 4.6 Valves on tanks and their control arrangements 4.6.2 is installed at each connection.

4.4.10 Alternatively, when the valves for the crossover fitted to the tanks are quick closing valves, the following conditions are to be complied with;

• The wall thickness of the crossover pipe is to be not less than indicated in Table 10.2.3 Minimum thickness for steel pipes, last column.
• The crossover pipe is to be in compliance with Pt 5, Ch 12, 4.4 Pipes conveying oil 4.4.2.
• The individual connections to the engines and boilers are not required to comply with Pt 5, Ch 12, 4.4 Pipes conveying oil 4.4.9.
• Operating the quick closing valves of the crossover should not lead to shut-off of the fuel supply to main and auxiliary engines causing a dead ship situation.

4.5.1 Valves, cocks and their pipe connections are to be so arranged that oil cannot be admitted into tanks which are not structurally suitable for the carriage of oil or into tanks which can be used for the carriage of fresh water.

4.5.2 All valves and cocks forming part of the fuel oil installation are to be capable of being controlled from readily accessible positions which, in the machinery spaces, are to be above the working platform. See also Pt 5, Ch 11, 2.3 Valves - Installation and control.

4.5.3 Every fuel oil suction pipe from a double bottom tank is to be fitted with a valve or cock.

4.6.1 Every fuel oil suction pipe from a storage, settling and daily service tank and every fuel oil levelling pipe within the machinery spaces is to be fitted with a valve or cock secured to the tank.

4.6.2 The valves and cocks mentioned in Pt 5, Ch 12, 4.6 Valves on tanks and their control arrangements 4.6.1 are to be capable of being closed locally and from positions outside the space in which the tank is located. The remote controls are to be accessible in the event of fire occurring in these spaces. Instructions for closing the valves or cocks are to be indicated at the valves and cocks and at the remote control positions.

4.6.3 In the case of tanks of less than 500 litres capacity, consideration will be given to the omission of remote controls.

4.6.4 Where the filling pipes to oil tanks are not connected to the tanks near the top, they are to be provided with non-return valves at the tanks or with valves or cocks fitted and controlled as in Pt 5, Ch 12, 4.6 Valves on tanks and their control arrangements 4.6.2.

4.7.1 Settling tanks are to be provided with means of draining water from the bottom of the tanks.

4.7.2 If settling tanks are not provided, the fuel oil bunkers or daily service tanks are to be fitted with water drains.

4.7.3 Open drains for removing water from oil tanks are to be fitted with valves or cocks of self-closing type, and suitable provision is to be made for collecting the oily discharge.

4.8.1 Pipes conveying vegetable oils, edible oils or similar cargo oils are not to be led through fuel oil tanks, nor are fuel oil pipes to be led through tanks containing these cargo oils. For requirements regarding provision of cofferdams between oil and water tanks, see Pt 3, Ch 3 Structural Design.

4.9.1 Pipes in connection with compartments used for storing fresh water are to be separate and distinct from any pipes which may be used for other liquids, and are not to be led through tanks which contain other liquids nor are pipes containing other liquids to be led through fresh water tanks.

4.9.2 Potable fresh water tanks are to be fitted into a cofferdam, see Pt 3, Ch 7, 1.6 Protection of tanks carrying fuel oil, lubricating oil, vegetable or similar oils.

4.10.1 For rectangular steel tanks of welded construction, the plate thicknesses are to be not less than those indicated in Table 12.4.1 Plate thickness of seperate fuel oil tanks, and not less than 3 mm. The stiffeners are to be of approved dimensions.

4.10.2 The dimension given in Table 12.4.1 Plate thickness of seperate fuel oil tanks for the breadth of the panel is the maximum distance allowable between continuous lines of support, which may be stiffeners, washplates or the boundary of the tank.

4.10.3 On completion, the tanks are to be tested by a head of water equal to the maximum to which the tanks may be subjected, but not less than 2,5 m above the crown of the tank.

4.10.4 The dimension given in Table 12.4.1 Plate thickness of seperate fuel oil tanks for the breadth of the panel is the maximum distance allowable between continuous lines of support, which may be stiffeners, washplates or the boundary of the tank.

4.10.5 Valves are to be attached direct to the tank plating. These fittings are to be secured by studs screwed into heavy steel pads welded to the plating. Alternatively, a short rigid pipe stub, welded into the shell plating and provided with a flange, may be used.

4.10.6 Threaded connections below the oil level may be used up to and including NB 25, provided tapered threads will be used. Alternatively, threaded connections with parallel threads, intended for instrumentation connections, are to be provided with a collar and a facing around the hole in order to provide a joint face.