###### Editorial Note on [Part 173](/current/title-49/part-173?toc=1)

#### Editorial Note:

Nomenclature changes to part 173 appear at [70 FR 56098](https://www.federalregister.gov/citation/70-FR-56098), Sept. 23, 2005.

#### § 173.21 Forbidden materials and packages.

Unless otherwise provided in this subchapter, the offering for transportation or transportation of the following is forbidden:

(a) Materials that are designated “Forbidden” in Column 3 of the [§ 172.101](/on/2024-09-24/title-49/section-172.101) table.

(b) Forbidden explosives as defined in [§ 173.54 of this part](/on/2024-09-24/title-49/part-173/section-173.54).

(c) Electrical devices, such as batteries and battery-powered devices, which are likely to create sparks or generate a dangerous evolution of heat, unless packaged in a manner which precludes such an occurrence.

(d) For carriage by aircraft, any package which has a magnetic field of more than 0.00525 gauss measured at 4.5 m (15 feet) from any surface of the package.

(e) A material in the same packaging, freight container, or overpack with another material, the mixing of which is likely to cause a dangerous evolution of heat, or flammable or poisonous gases or vapors, or to produce corrosive materials.

(f) A package containing a material which is likely to decompose with a self-accelerated decomposition temperature (SADT) or polymerize with a self-accelerated polymerization temperature (SAPT) of 50 °C (122 °F) or less, or 45 °C (113 °F) or less when offered for transportation in portable tanks, with an evolution of a dangerous quantity of heat or gas when decomposing or polymerizing, unless the material is stabilized or inhibited in a manner to preclude such evolution. For organic peroxides, see [paragraph (f)(2)](/on/2024-09-24/title-49/section-173.21#p-173.21(f)(2)) of this section. The SADT and SAPT may be determined by any of the test methods described in Part II of the UN Manual of Tests and Criteria (IBR, *see* [§ 171.7 of this subchapter](/on/2024-09-24/title-49/section-171.7)).

(1) A package meeting the criteria of [paragraph (f)](/on/2024-09-24/title-49/section-173.21#p-173.21(f)) of this section may be required to be shipped under controlled temperature conditions. The control temperature and emergency temperature for a package shall be as specified in Table 1 in this paragraph based upon the SADT or SAPT of the material. The control temperature is the temperature above which a package of the material may not be offered for transportation or transported. The emergency temperature is the temperature at which, due to imminent danger, emergency measures must be initiated.

Table 1 to Paragraph (f)(1)—Derivation of Control and Emergency Temperature

| Type of receptacle | SADT/SAPT1 | Control temperatures | Emergency temperature |
| --- | --- | --- | --- |
| Single packagings and IBCs | SADT/SAPT ≤20 °C (68 °F) | 20 °C (36 °F) below SADT/SAPT | 10 °C (18 °F) below SADT/SAPT. |
| Single packagings and IBCs | 20 °C (68 °F) <SADT/SAPT ≤35 °C (95 °F) | 15 °C (27 °F) below SADT/SAPT | 10 °C (18 °F) below SADT/SAPT. |
| Single packagings and IBCs | 35 °C (95 °F) <SADT/SAPT ≤50 °C (122 °F) | 10 °C (18 °F) below SADT/SAPT | 5 °C (9 °F) below SADT/SAPT. |
| Single packagings and IBCs | 50 °C (122 °F) <SADT/SAPT | (2) | (2) |
| Portable tanks | SADT/SAPT ≤45 °C (113 °F) | 10 °C (18 °F) below SADT/SAPT | 5 °C (9 °F) below SADT/SAPT. |
| Portable tanks | 45 °C (113 °F) <SADT/SAPT | (2) | (2) |
| | | | |
| --- | --- | --- | --- |
| 1 Self-accelerating decomposition temperature or self-accelerating polymerization temperature. | | | |
| 2 Temperature control not required. | | | |

(2) For hazardous materials listed in the Self-Reactive Materials Table in [§ 173.224(b)](/on/2024-09-24/title-49/section-173.224#p-173.224(b)), control and emergency temperatures, where required, are shown in Columns 5 and 6, respectively. For hazardous materials listed in the Organic Peroxide Table in [§ 173.225](/on/2024-09-24/title-49/section-173.225), control and emergency temperatures, where required, are shown in Columns 7a and 7b of the table, respectively. In addition, the following organic peroxides shall be subjected to temperature control during transport:

(i) Organic peroxides type B and C with a SADT ≤50 °C;

(ii) Organic peroxides type D showing a medium effect when heated under confinement, as determined by test series E in Part II of the UN Manual of Tests and Criteria (IBR, *see* [§ 171.7 of this subchapter](/on/2024-09-24/title-49/section-171.7)), with a SADT ≤50 °C or showing a low or no effect when heated under confinement with a SADT ≤45 °C; and

(iii) Organic peroxides types E and F with a SADT ≤45 °C.

(3) Refrigeration may be used as a means of stabilization only when approved by the Associate Administrator. Approvals issued by the Bureau of Explosives are no longer valid (see [§ 171.19 of this subchapter](/on/2024-09-24/title-49/section-171.19)). Methods of stabilization approved by the Associate Administrator are as follows:

(i) For highway transportation:

(A) A material meeting the criteria of this [paragraph (f)](/on/2024-09-24/title-49/section-173.21#p-173.21(f)) may be transported only in a transport vehicle, freight container, or motor vehicle equipped with a mechanical refrigeration unit, or loaded with a consumable refrigerant, capable of maintaining the inside temperature of the hazardous material at or below the control temperature required for the material during transportation.

(B) Each package containing a material meeting the criteria of this [paragraph (f)](/on/2024-09-24/title-49/section-173.21#p-173.21(f)) must be loaded and maintained at or below the control temperature required for the material. The temperature of the material must be determined by appropriate means and entered on a written record at the time the packaging is loaded.

(C) The vehicle operator shall monitor the inside temperature of the transport vehicle, freight container, or motor vehicle and enter that temperature on a written record at the time the package is loaded and thereafter at intervals not exceeding two hours. Alternatively, a transport vehicle, freight container, or motor vehicle may be equipped with a visible or audible warning device that activates when the inside temperature of the transport vehicle, freight container, or motor vehicle exceeds the control temperature required for the material. The warning device must be readily visible or audible, as appropriate, from the vehicle operator's seat in the vehicle.

(D) The carrier shall advise the vehicle operator of the emergency temperature for the material, and provide the vehicle operator with written procedures that must be followed to assure maintenance of the control temperature inside the transport vehicle, freight container, or motor vehicle. The written procedures must include instructions for the vehicle operator on actions to take if the inside temperature exceeds the control temperature and approaches or reaches the emergency temperature for the material. In addition, the written temperature-control procedures must identify enroute points where the consumable refrigerant may be procured, or where repairs to, or replacement of, the mechanical refrigeration unit may be accomplished.

(E) The vehicle operator shall maintain the written temperature-control procedures, and the written record of temperature measurements specified in [paragraph (f)(3)(i)(C)](/on/2024-09-24/title-49/section-173.21#p-173.21(f)(3)(i)(C)) of this section, if applicable, in the same manner as specified in [§ 177.817 of this subchapter](/on/2024-09-24/title-49/section-177.817) for shipping papers.

(F) If the control temperature is maintained by use of a consumable refrigerant (e.g., dry ice or liquid nitrogen), the quantity of consumable refrigerant must be sufficient to maintain the control temperature for twice the average transit time under normal conditions of transportation.

(G) A material that has a control temperature of 40 °C (104 °F) or higher may be transported by common carrier. A material that has a control temperature below 40 °C (104 °F) must be transported by a private or contract carrier.

(ii) For transportation by vessel, shipments are authorized in accordance with the control temperature requirements in 7.3.7 of the IMDG Code (IBR, see [§ 171.7 of this subchapter](/on/2024-09-24/title-49/section-171.7)).

(g) Packages which give off a flammable gas or vapor, released from a material not otherwise subject to this subchapter, likely to create a flammable mixture with air in a transport vehicle.

(h) Packages containing materials (other than those classed as explosive) which will detonate in a fire.

(1) For purposes of this paragraph, “detonate” means an explosion in which the shock wave travels through the material at a speed greater than the speed of sound.

(2) When tests are required to evaluate the performance of a package under the provisions of this paragraph, the testing must be done or approved by one of the agencies specified in [§ 173.56](/on/2024-09-24/title-49/section-173.56).

(i) Except for a package containing a lighter design sample that meets the requirements of [§ 173.308(b)(2)](/on/2024-09-24/title-49/section-173.308#p-173.308(b)(2)), a package containing a lighter (see [§ 171.8 of this subchapter](/on/2024-09-24/title-49/section-171.8)) containing a Division 2.1 material, of a design that has not been examined and successfully tested by an authorized person under the criteria specified in [§ 173.308(a)(4)](/on/2024-09-24/title-49/section-173.308#p-173.308(a)(4)) or, a lighter design containing a Class 3 material, that has not been approved by the Associate Administrator.

(j) An organic peroxide of the “ketone peroxide” category which contains more than 9 percent available oxygen as calculated using the equation in [§ 173.128(a)(4)(ii)](/on/2024-09-24/title-49/section-173.128#p-173.128(a)(4)(ii)). The category, ketone peroxide, includes, but is not limited to:

Acetyl acetone peroxide

Cyclohexanone peroxide(s)

Diacetone alcohol peroxides

Methylcyclohexanone peroxide(s)

Methyl ethyl ketone peroxide(s)

Methyl isobutyl ketone peroxide(s)

(k) Notwithstanding any other provision of this subchapter, including subpart C of part 171 and 175.10(a)(2) of this subchapter, an oxygen generator (chemical) as cargo on a passenger-carrying aircraft. This prohibition does not apply to an oxygen generator for medical or personal use of a passenger that meets the requirements of [§ 175.10(a)(7) of this subchapter](/on/2024-09-24/title-49/section-175.10#p-175.10(a)(7)).

[Amdt. 173-224, [55 FR 52609](https://www.federalregister.gov/citation/55-FR-52609), Dec. 21, 1990]

###### Editorial Note

#### Editorial Note:

For Federal Register citations affecting [§ 173.21](/on/2024-09-24/title-49/section-173.21), see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at *[www.govinfo.gov](http://www.govinfo.gov).*