46 CFR § 119.440 - Independent fuel tanks.
(a) Materials and construction. Independent fuel tanks must be designed and constructed of materials in compliance with the requirements of this paragraph.
(1) The material used and the minimum thickness allowed must be as indicated in Table 119.440(a)(1), except that other materials which provide equivalent safety may be approved for use under paragraph (a)(3) of this section. Tanks having a capacity of more than 570 liters (150 gallons) must be designed to withstand the maximum head to which they may be subjected in service, but in no case may the thickness be less than that specified in Table 119.440(a)(1).
|Material||ASTM Specification (latest edition) [see also § 114.600 of this chapter]||Thickness in millimeters (inches) & [gage number] 1 vs. tank capacities for:|
|4 to 300 liter (1 to 80 gal) tanks||More than 300 liter (80 gal) and not more than 570 liter (150 gal) tanks||Over 570 liter (150 gal) 2 tanks|
|Nickel-copper||B127, hot rolled sheet or plate||0.94 (0.037) [USSG 20] 3||1.27 (0.050) [USSG 18]||2.72 (0.107) [USSG 12]|
|Copper-nickel 4||B122, UNS alloy C71500||1.14 (0.045) [AWG 17]||1.45 (0.057) [AWG 15]||3.25 (0.128) [AWG 8]|
|Copper 4||B152, UNS alloy C11000||1.45 (0.057) [AWG 15]||2.06 (0.081) [AWG 12]||4.62 (0.182) [AWG 5]|
|Copper-silicon 4||B 96, alloys C65100 and C65500||1.29 (0.051) [AWG 16]||1.63 (0.064) [AWG 14]||3.66 (0.144) [AWG 7]|
|Steel or iron 5 6||1.90 (0.0747) [MSG 14]||2.66 (0.1046) [MSG 12]||4.55 (0.1793) [MSG 7]|
|Aluminum 7||B209, alloy 5052, 5083, 5086||6.35 (0.250) [USSG 3]||6.35 (0.250) [USSG 3]||6.35 (0.250) [USSG 3]|
|Fiber reinforced plastic||as required 8||as required 8||as required 8|
1 The gage numbers used in this table may be found in many standard engineering reference books. The letters “USSG” stand for “U.S. Standard Gage,” which was established by the act of March 3, 1892 (15 U.S.C. 206), for sheet and plate iron and steel. The letters “AWG” stand for “American Wire Gage” (or Brown and Sharpe Gage) for nonferrous sheet thicknesses. The letters “MSG” stand for “Manufacturers' Standard Gage” for sheet steel thickness.
2 Tanks over 1514 liters (400 gallons) shall be designed with a factor of safety of four on the ultimate strength of the material used with a design held of not less than 1220 millimeters (4 feet) of liquid above the top of the tank.
3 Nickel-copper not less than 0.79 millimeter (0.031 inch) [USSG 22] may be used for tanks up to 114- liter (30-gallon) capacity.
4 Acceptable only for gasoline service.
5 Gasoline fuel tanks constructed of iron or steel, which are less than 5 millimeter (0.1875 inch) thick, shall be galvanized inside and outside by the hot dip process. Tanks intended for use with diesel oil shall not be internally galvanized.
6 Stainless steel tanks are not included in this category.
7 Anodic to most common metals. Avoid dissimilar metal contact with tank body.
8 The requirements of § 119.440(a)(2) apply.
(2) Fiber reinforced plastic may be used for diesel fuel tanks under the following provisions:
(i) The materials must be fire retardant. Flammability of the material must be determined by the standard test methods in American Society for Testing and Materials (ASTM) D635, “Rate of Burning and/or Extent and Time of Burning of Self-Supporting Plastics in a Horizontal Position,” and ASTM D2863, “Measuring the Minimum Oxygen Concentration to Support Candle-like Combustion of Plastics (Oxygen Index),” or other standard specified by the Commandant. The results of these tests must show that the average extent of burning is less than 10 millimeters (0.394 inches), the average time of burning is less than 50 seconds, and the limiting oxygen index is greater than 21.
(ii) Tanks must meet UL 1102, “Non-integral Marine Fuel Tanks,” or other standard specified by the Commandant. Testing may be accomplished by an independent laboratory or by the fabricator to the satisfaction of the cognizant OCMI.
(iii) Tanks must be designed to withstand the maximum head to which they may be subjected to in service.
(iv) Installation of nozzles, flanges or other fittings for pipe connections to the tanks must be acceptable to the cognizant OCMI.
(v) Baffle plates, if installed, must be of the same material and not less than the minimum thickness of the tank walls. Limber holes at the bottom and air holes at the top of all baffles must be provided. Baffle plates must be installed at the time the tests required by UL 1102, or other standard specified by the Commandant, are conducted.
(3) Materials other than those listed in Table 119.440(a)(1) must be approved by the Commandant. An independent tank using material approved by the Commandant under this paragraph must meet the testing requirements of UL 1102, or other standard specified by the Commandant. Testing may be accomplished by an independent laboratory or by the fabricator to the satisfaction of the OCMI.
(4) Tanks with flanged-up top edges that may trap and hold moisture are prohibited.
(5) Openings for fill pipes, vent pipes, and machinery fuel supply pipes, and openings for fuel level gauges, where used, must be on the topmost surfaces of tanks. Tanks may not have any openings in bottoms, sides, or ends, except for:
(i) An opening fitted with a threaded plug or cap installed for tank cleaning purposes; and
(ii) In a diesel fuel tank, openings for supply piping and tubular gauge glasses.
(6) All tank joints must be welded or brazed. Lap joints may not be used.
(7) Nozzles, flanges, or other fittings for pipe connections to a metal tank must be welded or brazed to the tank. Tank openings in way of pipe connections must be properly reinforced where necessary. Where fuel level gauges are used on a metal tank, the flanges to which gauge fittings are attached must be welded or brazed to the tank. Tubular gauge glasses, if fitted to diesel fuel tanks, must be of heat resistant materials, adequately protected from mechanical damage, and provided at the tank connections with devices that will automatically close in the event of rupture of the gauge or gauge lines.
(8) A metal tank exceeding 760 millimeters (30 inches) in any horizontal dimension must:
(i) Be fitted with vertical baffle plates, which meet paragraph (a)(9) of this section, at intervals not exceeding 760 millimeters (30 inches) to provide strength and to control the excessive surge of fuel; or
(ii) The owner shall submit calculations to the Commanding Officer, Marine Safety Center demonstrating the structural adequacy of the tank in a fully loaded static condition and in a worst case dynamic (sloshing) condition.
(9) Baffle plates, where required in metal tanks, must be of the same material and not less than the minimum thickness required in the tank walls and must be connected to the tank walls by welding or brazing. Limber holes at the bottom and air holes at the top of all baffles must be provided.
(10) Iron or steel diesel fuel tanks must not be galvanized on the interior. Galvanizing, paint, or other suitable coating must be used to protect the outside of iron and steel diesel fuel tanks.
(b) Location and installation. Independent fuel tanks must be located and installed in compliance with the requirements of this paragraph.
(1) Fuel tanks must be located in, or as close as practicable to, machinery spaces.
(2) Fuel tanks and fittings must be so installed as to permit examination, testing, or removal for cleaning with minimum disturbance to the hull structure.
(3) Fuel tanks must be adequately supported and braced to prevent movement. The supports and braces must be insulated from contact with the tank surfaces with a nonabrasive and nonabsorbent material.
(4) All fuel tanks must be electrically bonded to a common ground.
(c) Tests. Independent fuel tanks must be tested in compliance with the requirements of this part prior to being used to carry fuel.
(1) Prior to installation, tanks vented to the atmosphere must be hydrostatically tested to, and must withstand, a pressure of 35 kPa (5 psig) or 1.5 times the maximum pressure head to which they may be subjected in service, whichever is greater. A standpipe of 3.5 meters (11.5 feet) in height attached to the tank may be filled with water to accomplish the 35 kPa (5 psig) test. Permanent deformation of the tank will not be cause for rejection unless accompanied by leakage.
(2) After installation of the fuel tank on a vessel, the complete installation must be tested in the presence of a marine inspector, or an individual specified by the cognizant OCMI, to a head not less than that to which the tank may be subjected in service. Fuel may be used as the testing medium.
(3) All tanks not vented to the atmosphere must be constructed and tested in accordance with § 119.330 of this part.