46 CFR 56.50-70 - Gasoline fuel systems.
(1) Fuel supply piping to the engines shall be of seamless drawn annealed copper pipe or tubing, nickel copper, or copper nickel pipe or tubing meeting the requirements of subpart 56.60.
(2) Thicknesses of tubing walls must not be less than the larger of that shown in Table 56.50-70(a) of this section or that required by 46 CFR 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2).
(3) Tubing fittings shall be of nonferrous drawn or forged metal and of the flared type except that the flareless fittings of the nonbite type may be used when the tubing system is of nickel copper or copper nickel. Tubing shall be cut square and flared by suitable tools. Tube ends shall be annealed before flaring. Pipe fittings shall be of nonferrous material. Pipe thread joints shall be made tight with a suitable compound.
(4) Valves for fuel lines shall be of nonferrous material of the union bonnet type with ground seats except that cocks may be used if they are the solid bottom type with tapered plugs and union bonnets.
Table 56.50-70(a) - Tubing Wall Thickness
|Outside diameter of tubing in inches||Thickness|
|1/8, 3/16, 1/4||#21||0.032|
(1) All fuel pipes, pipe connections, and accessories shall be readily accessible. The piping shall run in sight wherever practicable, protected against mechanical injury, and effectively secured against excessive movement and vibration by the use of soft nonferrous metal liners or straps without sharp edges. Where passing through steel decks or bulkheads, fuel lines shall be protected by close fitting ferrules or stuffing boxes. Refer to § 56.30-25 for tubing joint installations.
(2) Either a short length of suitable metallic or nonmetallic flexible tubing or hose or a loop of annealed copper tubing must be installed in the fuel-supply line at or near the engine to prevent damage by vibration.
(i) If nonmetallic flexible hose is used, it must meet the requirements of 46 CFR 56.60-25(b) for fuel service.
(ii) Flexible hose connections should maintain metallic contact between the sections of the fuel-supply lines; however, if they do not, the fuel tank must be grounded.
(3) Valves in fuel lines shall be installed to close against the flow.
(c) Shutoff valves. Shutoff valves of a suitable type shall be installed in the fuel supply lines, one as close to each tank as practicable, and one as close to each carburetor as practicable. Where fuel tanks are installed below the weather deck, arrangements shall be provided for operating all shutoff valves at the tanks from outside the compartments in which they are located, preferably from an accessible position on the weather deck. The operating gear for the shutoff valves at the tanks shall be accessible at all times and shall be suitably marked.
(d) Strainers. A suitable twin strainer shall be fitted in the fuel supply line in the engine compartment. Strainers shall be of the type opening on top for cleaning screens. A drip pan shall be fitted under the strainer.
(e) Outlets and drains. Outlets in fuel lines for drawing gasoline for any purpose are prohibited. Valved openings in the bottom of fuel tanks are prohibited; however, openings fitted with threaded plug or cap can be used for cleaning purposes.
(f) Fuel suction connections. All fuel suction and return lines shall enter the top of the fuel tanks and connections shall be fitted into spuds. Such lines shall extend nearly to the bottom of the tank.
(g) Filling and sounding pipes. Filling and sounding pipes shall be so arranged that vapors or possible overflow when filling cannot escape to the inside of the vessel but will discharge overboard. Such pipes shall terminate on the weather deck clear of any coamings and shall be fitted with suitable shutoff valves or deck plugs. Filling and sounding pipes shall extend to within one-half of their diameter from the bottom of the tank or from the surface of the striking plate in case of a sounding pipe. A flame screen of noncorrodible wire mesh shall be fitted in the throat of the filling pipe. Sounding pipes shall be kept closed at all times except during sounding.
(h) Vent pipes. Each tank shall be fitted with a vent, the cross-sectional area of which shall not be less than that of the filling pipe. The vent pipes shall terminate at least 2 feet above the weather deck and not less than 3 feet from any opening into living quarters or other below deck space. The ends of vent pipes shall terminate with U-bends and shall be fitted with flame screens or flame arresters. The flame screens shall consist of a single screen of corrosion resistant wire of at least 30 by 30 mesh.
(i) Gasoline tanks. For requirements pertaining to independent gasoline fuel tanks see subpart 58.50 of this subchapter.
(j) Fuel pumps. Each fuel pump must be equipped with controls as required by § 58.01-25 of this subchapter.