46 CFR 56.50-75 - Diesel fuel systems.
(a) Vessels greater than 100 gross tons.
(1) The diesel fuel system shall comply with §§ 56.50-60, 56.50-85, and 56.50-90. The fuel supply piping to engines shall be of seamless steel, annealed seamless copper or brass pipe or tubing, or of nickel copper or copper nickel alloy meeting the requirements of subpart 56.60 for materials and § 56.50-70(a)(2) for thickness. Fuel oil service or unit pumps shall be equipped with controls to comply with § 58.01-25 of this subchapter.
(2) The installation shall comply with § 56.50-70(b).
(3) Tubing connections and fittings shall be drawn or forged metal of the flared type except that flareless fittings of the nonbite type may be used when the tubing system is steel, nickel-copper, or copper-nickel. When making flared tube connections the tubing shall be cut square and flared by suitable tools. Tube ends shall be annealed before flaring.
(b) Vessels of 100 gross tons and less and tank barges -
(1) Materials. Fuel supply piping shall be of copper, nickel copper or copper nickel having a minimum wall thickness of 0.035 inch except that piping of other materials such as seamless steel pipe or tubing which provides equivalent safety may be used.
(2) Tubing connections and fittings. Tubing connections shall comply with the provisions of § 56.50-75(a)(3).
(3) Installation. The installation of diesel fuel piping shall comply with the requirements of § 56.50-70(b).
(4) Shutoff valves. Shutoff valves shall be installed in the fuel supply lines, one as close to each tank as practicable, and one as close to each fuel pump as practicable. Valves shall be accessible at all times.
(5) Outlets and drains. Valves for removing water or impurities from fuel oil systems will be permitted in the machinery space provided such valves are fitted with caps or plugs to prevent leakage.
(6) Filling pipe. Tank filling pipes on motorboats and motor vessels of less than 100 gross tons and tank barges shall terminate on an open deck and shall be fitted with suitable shutoff valves, deck plugs, or caps.
(7) Vent pipes. Each tank shall be fitted with a vent pipe complying with § 56.50-85.
(8) Independent diesel fuel tanks. See subpart 58.50 of this subchapter for specific requirements.