Section 56.50-70 - Gasoline fuel systems(a)Material.(1) Fuel supply piping to the engines must 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 1 to § 56.50-70(a) or that required by § 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see § 56.01-2 ).(3) Tubing fittings must 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 must be cut square and flared by suitable tools. Tube ends must be annealed before flaring. Pipe fittings must be of nonferrous material. Pipe thread joints must be made tight with a suitable compound.(4) Valves for fuel lines must 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 1 to § 56.50-70(a) -Tubing Wall Thickness
| Outside diameter of tubing in inches | Thickness |
| B.W.G. | Inch |
| 1/8, 3/16, 1/4 | #21 | 0.032 |
| 5/16, 3/8 | #20 | .035 |
| 7/16, 1/2 | #19 | .042 |
(b)Installation.(1) All fuel pipes, pipe connections, and accessories must be readily accessible, protected against mechanical injury, and effectively secured against excessive movement and vibration by the use of soft nonferrous metal liners or straps. Where passing through steel decks or bulkheads, fuel lines must be protected by close fitting ferrules or stuffing boxes. Refer to § 56.30-25 for tubing joint installations.(2) 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 § 56.60-25(b) for fuel service.(ii) Flexible hose connections should maintain metallic contact (continuity) between the sections of the fuel-supply lines; however, if they do not, the fuel tank must be grounded.(c)Shutoff valves. Shutoff valves of a suitable type must be installed in the fuel supply lines, one as close to the tank as practicable. Where fuel tanks are installed below the weather deck, arrangements must be provided for operating all shutoff valves at the tanks from outside the compartments in which they are located. The operating gear for the shutoff valves at the tanks must be accessible and suitably marked.(d)Strainers. A suitable twin strainer must be fitted in the fuel supply line in the engine compartment. A drip pan must be fitted under the strainer.(e)Outlets and drains. Outlets in fuel lines for drawing gasoline for any purpose are prohibited. However, fuel tank openings fitted with a threaded plug or cap can be used for cleaning purposes.(f)Fuel suction connections. All fuel suction and return lines must enter the top of the fuel tanks and connections must be fitted into spuds. Such lines must extend nearly to the bottom of the tank.(g)Filling and sounding pipes. Filling and sounding pipes must be so arranged that vapors or overflow when filling cannot escape to the inside of the vessel and will discharge overboard. Such pipes must terminate on the weather deck clear of any coamings and must be fitted with suitable shutoff valves. A corrosion-resistant flame screen of must be fitted in the throat of the filling pipe. Sounding pipes must be kept closed at all times except during sounding.(h)Vent pipes. Each tank must be fitted with a vent, the cross-sectional area of which must not be less than that of the filling pipe. The vent pipes must 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 must terminate with U-bends and be fitted with flame screens or flame arresters. The flame screens must 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 pump shutdown. Each fuel pump must comply with § 58.01-25 of this subchapter.CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGFR 69-127, 35 FR 9978, June 17, 1970; CGFR 72-59R, 37 FR 6189, Mar. 25, 1972; CGD 83-043, 60 FR 24774, May 10, 1995; USCG-2002-13058, 67 FR 61278 , Sept. 30, 2002; USCG-2003-16630, 73 FR 65178 , Oct. 31, 2008