In order to determine the available cargo space gained by this method let us assume the following data : Ninety tons of oil used each 24 hr., and at the rate of 30 steaming days, 2700 tons of oil is consumed. The equivalent amount of coal would be, taking the oil at 15 deg. B. or 6.65 bbl. of oil the ton = 17,955 bbl. of oil and four bbl. of oil being equivalent to one ton of coal would make 4489 tons of coal. Figuring coal at 42 cu. ft. to the ton would give a total of 188,538 cu. ft., figuring on ship's measurements, 40 cu. ft. to the ton would give us 4463 tons available for cargo space.
In many instances ship owners could use oil to advantage, providing they use the ballast or water bottoms to store the fuel oil.
Even large oil carrying steamers are using oil fuel on the outward voyage, owing to the difference in the price of the fuel. Fuel oil is carried in bulk in specially constructed tank steamers. The tanks being so designed as to be able to carry oil, or can be cleaned to carry cargo.
U. S. regulations for the instalation of fuel-oil petroleum for the production of motive power on ocean and coastwise steam vessels : On all ocean and coastwise steam vessels burning oil, as fuel for the production of motive power, the fuel oil tanks including settling tanks shall be constructed of iron or steel plates of not less than five-sixteenths inch in thickness, when such tanks are built separate from the hull, and shall withstand a pressure of 15 lb. per sq. in. : Provided, however, that where the oil is carried in water bottoms or deep tanks constructed as part of the hull, the same shall be tested to a 30 ft. head.
In all tanks built separate from the hull, the rivet holes shall be fairly drilled, and in no case punched and reamed ; the rivets shall be spaced four diameters of the rivet from center to center ; the seams shall be double chain riveted ; the edges of the seams shall be calked inside and out, and the burrs shall be removed from the sheets before riveting.
On ocean and coastwise steamers all pipes over 2 in. in diameter shall be flanged where attached to tanks. The filling pipes on tanks shall run through the top of tank and be carried to the bottom with a U bend extending upward at least 12 in. above the bot tom to prevent filling pipe from clogging, to expel gases in the tank through the vent pipes when tanks are being filled. The area of the vent pipes shall be not
less than the area of the filling pipe, and shall be car ried over the upper deck or superstructure to the at mosphere and have non-return U bends properly fitted with wire gauze. Where bends or turns are necessary to carry this pipe, they shall be made with bends or 45 deg. elbows. Where there are a number of vents connected with the vent box, box shall be covered with wire gauze.
No openings shall be cut in the bottom, ends, or sides of tanks, unless for suction, and when such holes are cut in the bottom or sides of tanks an internal gate valve shall be placed inside the tank, connected by a rod leading through the top of the tank with a stuffing box attached thereto, and a wheel or handle for shut ting off same from the top, which shall be accessibly placed so valve may be shut immediately at all times.
The valves on all tanks shall be so arranged as to be accessible at all times, and when placed on tanks in the double bottoms under the cargo hold they shall have rods connected thereto carried to the deck in accessible places.
All pipes and connections between feed pumps and burners on all high pressure systems shall withstand may be made with flanges or screwed fittings.
a pressure of 500 lb., and all connections in pipe lines When heaters are used, the joints shall be made on the outside of the heater. A continuous pipe or pipes shall be carried through the heads or ends of the heater, and all joints shall be made on the outside to prevent oil getting into the boiler : Provided, however, that this construction is not necessary when the steam from the heater does not exhaust into the main con denser.
On ocean or coastwise wooden vessels, where oil tanks are set in the vessel, lead lining shall be placed underneath the tanks, having a weight of not less than 8 lb. per sq. ft., to prevent any oil from getting into the bilges of the vessel. No bulkheads shall be re quired around oil tanks, except the water-tight bulk heads required by law.
The throttle valve on the pumps shall be arranged to be closed from the fireroom, or from some accessible place either outside the room where the pumps are located, the engine rooms or the deck above the boiler rooms, the location of these rods to be designated by the inspector in whose district the installation is made.