§ 58.50-5 - Gasoline fuel tanks.

§ 58.50-5 Gasoline fuel tanks.

(a) Construction —

(1) Shape. Tanks may be of either cylindrical or rectangular form, except that tanks for emergency electrical systems shall must be of cylindrical form.

(4) Openings. Openings for fill, vent and fuel pipes, and openings for fuel level gages where used, shall be on the topmost surface of tanks. Tanks shall have no openings in bottoms, sides, or ends, except that an opening fitted with threaded plug or cap may be used for tank cleaning purposes.

(2) Materials and construction. The material used and the minimum thickness allowed shall must be as indicated in Table table 1 to § 58.50-5(a)(2) except that consideration will be given to other materials which provide equivalent safety as indicated in § 58.50-15.

(3) Prohibited types. Tanks with flanged-up top edges that may trap and hold moisture shall not be used.

Table 1 to § 58.50-5(a)(2)

Material	ASTM specification (all incorporated by reference; see

46 CFR

§ 58.03-1)	Thickness in inches and gage numbers1 vs. tank capacities for—
	1- through 80-gallon tanks	More than 80- and not more than 150-gallon tanks	Over 150-gallon tanks2
Aluminum5

B 209

B209, Alloy 50866	0.250 (USSG 3)	0.250 (USSG 3)	0.250 (USSG 3).
Nickel-copper

B 127

B127, Hot rolled sheet or plate	0.037 (USSG 20)3	0.050 (USSG 18)	0.107 (USSG 12).
Copper-nickel

B 122

B122, Alloy No. 5	0.045 (AWG 17)	0.057 (AWG 15)	0.128 (AWG 8).
Copper

B 152

B152, Type ETP	0.057 (AWG 15)	0.080 (AWG 12)	0.182 (AWG 5).
Copper-silicon

B 96

B96, alloys C65100 and C65500	0.050 (AWG 16)	0.064 (AWG 14)	0.144 (AWG 7).
Steel or iron4		0.0747 (MfgStd 14)	0.1046 (MfgStd 12)	0.179 (MfgStd 7).

Notes:

¹ Gauges used are U.S. standard “USSG” for aluminum and nickel-copper; “AWG” for copper, copper-nickel, and copper-silicon; and “MfgStd” for steel.

² Tanks over 400 gallons will be designed with a factor of safety of four on the ultimate strength of the material used with a design head of not less than 4 feet of liquid above the top of the tank.

³ Nickel-copper not less than 0.031 inch (USSG 22) may be used for tanks up to a 30-gallon capacity.

⁴ Fuel tanks constructed of iron or steel, which is less than 3/16-inch thick must be galvanized inside and outside by the hot dip process.

⁵ Anodic to most common metals. Avoid dissimilar metal contact with tank body.

⁶ And other alloys acceptable to the Commandant.

(3) Prohibited types. Tanks with flanged-up top edges that may trap and hold moisture must not be used.

(4) Openings. Openings for fill, vent and fuel pipes, and openings for fuel level gages where used, must be on the topmost surface of tanks. Tanks must have no openings in bottoms, sides, or ends, except that an opening fitted with threaded plug or cap may be used for tank cleaning purposes.

(5) Joints. All metallic tank joints shall must be welded or brazed.

(6) Fittings. Nozzles, flanges, or other fittings for pipe connections shall must be welded or brazed to the tank. The tank openings in way of pipe connections shall must be properly reinforced where necessary. Where fuel level gages are used, the flange to which gage fittings are attached shall must be welded or brazed to the tank. No tubular Tubular gage glasses or trycocks shall try cocks must not be fitted to the tanks.

(7) Baffle plates. All tanks exceeding 30 inches in any horizontal dimension shall must be fitted with vertical baffle plates where necessary for strength or for control of excessive surge. In general, baffle plates installed at intervals not exceeding 30 inches will be considered as meeting this requirement.

(8) Baffle plate details. Baffle plates, where required, shall must be of the same material and not less than the minimum thickness required in the tank walls and shall 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 shall must be provided.

(b) Installation.

(1) Gasoline fuel tanks used for propulsion shall must be located in water-tight compartments separate from, but adjacent to the engineroom engine room or machinery space. Fuel tanks for auxiliaries shall must be located on or above the weather deck outside of the engine housing or compartment and as close to the engine as practicable. All tanks shall must be so installed as to provide a free circulation of air around the tanks.

(2) Cylindrical tanks with longitudinal seams shall must be arranged horizontally where practicable so that such seams are located as near the top as possible.

(3) Fuel tanks shall must be so installed as to permit examination, testing, or removal for cleaning.

(4) Fuel tanks shall must be adequately supported and braced to prevent movement. Portable fuel tanks are not permitted.

(5) All fuel tanks shall must be electrically bonded to the common ground.

(c) Testing.

(1) Prior to installation, tanks vented to atmosphere shall must be tested to, and must withstand, a pressure of 5 pounds per square inch psig or 11⁄2 .5 times the maximum head to which they may be subjected in service, whichever is greater. A standpipe of 111⁄2 .5 feet in height attached to the tank may be filled with water to accomplish the 5 pounds per square inch -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 shall must be tested in the presence of a marine inspector to a head not less than that to which the tank may be subjected in service. Fuel may be used as a testing medium.

(3) All tanks not vented to atmosphere shall must be constructed and tested in accordance with part 54 of this subchapter.

[CGFR 68-82, 33 FR 18878, Dec. 18, 1968, as amended by CGFR 72-59R, 37 FR 6190, Mar. 25, 1972; USCG-1999-5151, 64 FR 67180, Dec. 1, 1999; USCG-2003-16630, 73 FR 65187, Oct. 31, 2008; USCG-2016-0498, 82 FR 35089, July 28, 2017]