46 CFR § 182.455 - Fuel piping.
(a) Materials and workmanship. The materials and construction of fuel lines, including pipe, tube, and hose, must comply with the requirements of this paragraph.
(1) Fuel lines must be annealed tubing of copper, nickel-copper, or copper-nickel having a minimum wall thickness of 0.9 millimeters (0.035 inch) except that:
(i) Diesel fuel piping of other materials, such as seamless steel pipe or tubing, which provide equivalent safety may be used;
(ii) Diesel fuel piping of aluminum is acceptable on aluminum hull vessels provided it is a minimum of Schedule 80 wall thickness; and
(iii) when used, flexible hose must meet the requirements of § 182.720(e) of this part.
(2) Tubing connections and fittings must be of nonferrous drawn or forged metal of the flared type except that flareless fittings of the non-bite type may be used when the tubing system is of nickel-copper or copper-nickel. When making tube connections, the tubing must be cut square and flared by suitable tools. Tube ends must be annealed before flaring.
(3) Cocks are prohibited except for the solid bottom type with tapered plugs and union bonnets.
(4) Valves for gasoline fuel must be of a suitable nonferrous type.
(b) Installation. The installation of fuel lines, including pipe, tube, and hose, must comply with the requirements of this paragraph.
(1) Gasoline fuel lines must be connected at the top of the fuel tank and run at or above the level of the tank top to a point as close to the engine connection as practicable, except that lines below the level of the tank top are permitted if equipped with anti-siphon protection.
(2) Diesel fuel lines may be connected to the fuel tank at or near the bottom of the tank.
(3) Fuel lines must be accessible, protected from mechanical injury, and effectively secured against excessive movement and vibration by the use of soft nonferrous metal straps which have no sharp edges and are insulated to protect against corrosion. Where passing through bulkheads, fuel lines must be protected by close fitting ferrules or stuffing boxes. All fuel lines and fittings must be accessible for inspection.
(4) Shutoff valves, installed so as to close against the fuel flow, must be fitted in the fuel supply lines, one at the tank connection and one at the engine end of the fuel line to stop fuel flow when servicing accessories. The shutoff valve at the tank must be manually operable from outside the compartment in which the valve is located, preferably from an accessible position on the weather deck. If the handle to the shutoff valve at the tank is located inside the machinery space, it must be located so that the operator does not have to reach more than 300 millimeters (12 inches) into the machinery space and the valve handle must be shielded from flames by the same material the hull is constructed of, or some noncombustible material. Electric solenoid valves must not be used, unless used in addition to the manual valve.
(5) A loop of copper tubing or a short length of flexible hose must be installed in the fuel supply line at or near the engines. The flexible hose must meet the requirements of § 182.720(e).
(6) A suitable metal marine type strainer, meeting the requirements of the engine manufacturer, must be fitted in the fuel supply line in the engine compartment. Strainers must be leak free. Strainers must be the type of opening on top for cleaning screens. A drip pan fitted with flame screen must be installed under gasoline strainers. Fuel filter and strainer bowls must be highly resistant to shattering due to mechanical impact and resistant to failure due to thermal shock. Fuel filters fitted with bowls of other than steel construction must be approved by the Commandant and be protected from mechanical damage. Approval of bowls of other than steel construction will specify if a flame shield is required.
(7) All accessories installed in the fuel line must be independently supported.
(8) Outlets in gasoline fuel lines that would permit drawing fuel below deck, for any purpose, are prohibited.
(9) Valves for removing water or impurities from diesel fuel in water traps or strainers are permitted. These valves must be provided with caps or plugs to prevent fuel leakage.
(c) Alternative procedures. A vessel of not more than 19.8 meters (65 feet), carrying no more than 12 passengers, with machinery powered by gasoline and a fuel system built in accordance with ABYC H–24 (incorporated by reference; see 46 CFR 175.600), or 33 CFR 183, subpart J, or with machinery powered by diesel fuel and a fuel system built in accordance with ABYC H–33 (incorporated by reference; see 46 CFR 175.600), will be considered as meeting the requirements of this section.