§173.304. Filling of cylinders with liquefied compressed gases. — Inbound Citations

(3) Filled, marked, and inspected in accordance with 49 CFR 173.301 through 173.308; and

(1) 300 Packaging of Airline Supplies, Revision 19, July 31, 1996, into §§ 172.102, 173.168, 173.302, and 173.304.

(j) The terms Refrigerant gas and Dispersant gas apply to all nonpoisonous refrigerant gases; dispersant gases (fluorocarbons) listed in § 172.101 of this subchapter and §§ 173.304, 173.314(c), 173.315(a), and 173.315(h) and mixtures thereof; and any other compressed gas having a vapor pressure not exceeding 260 psia at 54 °C(130 °F), used only as a refrigerant, dispersant, or blowing agent.

(2) Filling limits for compressed gases and cryogenic liquids are specified in §§ 173.301 through 173.306 for cylinders and §§ 173.314 through 173.319 for bulk packagings.

(i) Except as provided in subpart C of part 171 of this subchapter, packages prepared under § 173.167 of this part, or packages prepared under Packing Instruction Y963 of the ICAO Technical Instructions, packages offered or intended for transportation by aircraft must conform to the general requirements for transportation by aircraft in § 173.27.

(a) Unless otherwise stated, as used in this section, the term “cylinder” includes a UN pressure receptacle. As used in this subpart, filled or charged means an introduction or presence of a hazardous material in a cylinder. A cylinder filled with a Class 2 hazardous material (gas) and offered for transportation must meet the requirements in this section and §§ 173.301a through 173.305, as applicable.

(1) Compressed gases must be in UN pressure receptacles built in accordance with the UN standards or in metal cylinders and containers built in accordance with the DOT and ICC specifications and part 178 of this subchapter in effect at the time of manufacture or CRC, BTC, CTC or TC specification, and requalified and marked as prescribed in subpart C in part 180 of this subchapter, if applicable. The DOT, ICC, CRC, BTC, CTC and TC specifications authorized for use are as follows:

(2) A cylinder must be filled in accordance with this part, except that a “TC” cylinder must be filled in accordance with the Transport Canada TDG Regulations (IBR; see § 171.7 of this subchapter). Before each filling of a cylinder, the person filling the cylinder must visually inspect the outside of the cylinder. A cylinder that has a crack or leak, is bulged, has a defective valve or a leaking or defective pressure relief device, or bears evidence of physical abuse, fire or heat damage, or detrimental rusting or corrosion, may not be filled and offered for transportation. A cylinder may be repaired and requalified only as prescribed in subpart C of part 180 of this subchapter.

(3) Pressure relief devices must be tested for leaks before a filled cylinder is shipped from the cylinder filling plant. It is expressly forbidden to repair a leaking fusible plug device where the leak is through the fusible metal or between the fusible metal and the opening in the plug body, except by removal and replacement of the pressure relief device.

(4) A cylinder that previously contained a Class 8 material must be requalified in accordance with § 180.205(e) of this subchapter.

(5) When a cylinder with a marked pressure limit is prescribed, another cylinder made under the same specification but with a higher marked pressure limit is authorized. For example, a cylinder marked “DOT-4B500” may be used when “DOT-4B300” is specified.

(6) No person may fill a cylinder overdue for periodic requalification with a hazardous material and then offer it for transportation. The prohibition against offering a cylinder for transportation that is overdue for periodic requalification does not apply to a cylinder filled prior to the requalification due date.

(7) A cylinder with an authorized service life may not be offered for transportation in commerce after its authorized service life has expired. However, a cylinder in transportation or a cylinder filled prior to the expiration of its authorized service life may be transported for reprocessing or disposal of the cylinder's contents. After emptying, the cylinder must be condemned in accordance with § 180.205 of this subchapter.

(8) The pressure of the hazardous material at 55 °C (131 °F) may not exceed 5/4 of the service pressure of the cylinder. Sufficient outage must be provided so the cylinder will not be liquid full at 55 °C (131 °F).

(9) Specification 2P, 2Q, 3E, 3HT, spherical 4BA, 4D, 4DA, 4DS, and 39 cylinders must be packed in strong non-bulk outer packagings. The outside of the combination packaging must be marked with an indication that the inner packagings conform to the prescribed specifications.

(10) Any person who installs a valve into an aluminum cylinder in oxygen service must verify the valve and the cylinder have the same thread type.

(11) Cylinder valves manufactured on or after November 7, 2019, used on cylinders to transport compressed gases must conform to the applicable requirements in CGA V-9 (IBR; see § 171.7 of this subchapter). A valve for a UN pressure receptacle must conform to the requirements of § 173.301b(c)(1). Cylinder valves used on cylinders in liquefied petroleum gas (LPG) service are permitted to comply with the requirements of NFPA 58 (IBR; see § 171.7 of this subchapter).

(12) Cylinder valve protection caps manufactured on or after November 7, 2019, must conform to the requirements of CGA V-9.

(a) Liquefied gases (except gas in solution) must be offered for transportation, subject to the requirements in this section and §§ 173.301 and 173.304, in specification cylinders, as follows:

(1) DOT 3, 3A, 3AA, 3AL, 3B, 3BN, 3E, 4B, 4BA, 4B240ET, 4BW, 4E, 39, except that no DOT 4E or 39 packaging may be filled and shipped with a mixture containing a pyrophoric liquid, carbon bisulfide (disulfide), ethyl chloride, ethylene oxide, nickel carbonyl, spirits of nitroglycerin, or toxic material (Division 6.1 or 2.3), unless specifically authorized in this part.

(2) For the gases named, the requirements in table 1 to paragraph (a)(2) apply (for cryogenic liquids, see § 173.316):

(3) A DOT 39 cylinder shall be equipped with a pressure relief device as defined by the commodity in CGA S-1.1, excluding paragraph 9.1.1 (IBR; see § 171.7 of this subchapter). If the commodity is not listed in CGA S-1.1, a CG-7 pressure relief valve must be used.

(a) Liquefied gases and gas mixtures must be offered for transportation in UN pressure receptacles subject to the requirements in this section and § 173.304. In addition, the general requirements applicable to UN pressure receptacles in §§ 173.301 and 173.301b must be met.

(viii) The amount of refrigerant, if liquefied, may not exceed the filling density prescribed in § 173.304.

(c) Mixtures containing compressed gas or gases including insecticides, which mixtures are nonpoisonous and nonflammable under this part must be shipped in cylinders as prescribed in § 173.304(a) or as follows:

(1) Specification 2P (§ 178.33 of this subchapter). Inside metal containers equipped with safety relief devices of a type examined by the Bureau of Explosives and approved by the Associate Administrator, and packed in strong wooden or fiber boxes of such design as to protect valves from damage or accidental functioning under conditions incident to transportation. Pressure in the container may not exceed 85 psia at 70 °F. Each completed metal container filled for shipment must be heated until content reaches a minimum temperature of 130 °F., without evidence of leakage, distortion or other defect. Each outside shipping container must be plainly marked “INSIDE CONTAINERS COMPLY WITH PRESCRIBED SPECIFICATIONS.”

(2) [Reserved]

(3) For a specification 3, 3A, 3AA, 3AL, 3AX, 3AAX, 3B, 3BN, or 3T cylinder filled with gases in other than Division 2.2 (except oxygen and oxidizing gases transported by aircraft, see §§ 173.302(f) and 173.304(f)), the burst pressure of a CG-1, CG-4, or CG-5 pressure relief device must be at test pressure with a tolerance of plus zero to minus 10 percent. An additional 5 percent tolerance is allowed when a combined rupture disk is placed inside a holder. This requirement does not apply if a CG-2, CG-3, or CG-9 thermally activated relief device or a CG-7 reclosing pressure valve is used on the cylinder.

(i) Sections 173.302(f) and 173.304(f) of this subchapter, subpart C of part 172 of this subchapter, and, for passengers only, subpart H of part 172 of this subchapter;

(iv) A pressure relief device for oxidizing gases transported by air in a DOT 39 cylinder must meet the requirements of § 173.302(f)(2)(iii) of this subpart for permanent gases and § 173.304(f)(2)(iii) for liquefied compressed gases.

(a) When transported in the State of Alaska, cylinders of compressed oxygen or other oxidizing gases aboard aircraft are excepted from all the requirements of §§ 173.302(f)(3) through (5) and 173.304(f)(3) through (5) of this subchapter subject to the following conditions:

(1) Transportation of the cylinders by a ground-based or water-based mode of transportation is unavailable and transportation by aircraft is the only practical means for transporting the cylinders to their destination;

(2) Each cylinder is fully covered with a fire or flame resistant blanket that is secured in place; and

(3) The operator of the aircraft complies with the applicable notification procedures under § 175.33.

(a) When transported in the State of Alaska, cylinders of compressed oxygen or other oxidizing gases aboard aircraft are excepted from all the requirements of §§ 173.302(f)(3) through (5) and 173.304(f)(3) through (5) of this subchapter subject to the following conditions:

(1) Transportation of the cylinders by a ground-based or water-based mode of transportation is unavailable and transportation by aircraft is the only practical means for transporting the cylinders to their destination;

(2) Each cylinder is fully covered with a fire or flame resistant blanket that is secured in place; and

(3) The operator of the aircraft complies with the applicable notification procedures under § 175.33.

(a) When transported in the State of Alaska, cylinders of compressed oxygen or other oxidizing gases aboard aircraft are excepted from all the requirements of §§ 173.302(f)(3) through (5) and 173.304(f)(3) through (5) of this subchapter subject to the following conditions:

(1) Transportation of the cylinders by a ground-based or water-based mode of transportation is unavailable and transportation by aircraft is the only practical means for transporting the cylinders to their destination;

(2) Each cylinder is fully covered with a fire or flame resistant blanket that is secured in place; and

(3) The operator of the aircraft complies with the applicable notification procedures under § 175.33.