(a)
(1) Desensitized explosives that—
(i) When dry are Explosives of Class 1 other than those of compatibility group A, which are wetted with sufficient water, alcohol, or plasticizer to suppress explosive properties; and
(ii) Are specifically authorized by name either in the Hazardous Materials Table in § 172.101 of this subchapter or have been assigned a shipping name and hazard class by the Associate Administrator under the provisions of—
(A) A special permit issued under subchapter A of this chapter; or
(B) An approval issued under § 173.56(i).
(2)(i) Self-reactive materials that are thermally unstable and can undergo an exothermic decomposition even without participation of oxygen (air). A material is excluded from this definition if any of the following applies:
(A) The material meets the definition of an explosive as prescribed in subpart C of this part, in which case it must be classed as an explosive;
(B) The material is forbidden from being offered for transportation according to § 172.101 of this subchapter or § 173.21;
(C) The material meets the definition of an oxidizer or organic peroxide as prescribed in this subpart, in which case it must be so classed;
(D) The material meets one of the following conditions:
(
(
(
(E) The Associate Administrator has determined that the material does not present a hazard which is associated with a Division 4.1 material.
(ii)
(A)
(B)
(C)
(D)
(
(
(
(E)
(F)
(G)
(iii)
(A) Its physical state (
(B) A determination as to its control temperature and emergency temperature, if any, under the provisions of § 173.21(f);
(C) Performance of the self-reactive material under the test procedures specified in the UN Manual of Tests and Criteria (IBR, see § 171.7 of this subchapter) and the provisions of paragraph (a)(2)(iii) of this section; and
(D) Except for a self-reactive material which is identified by technical name in the Self-Reactive Materials Table in § 173.224(b) or a self-reactive material which may be shipped as a sample under the provisions of § 173.224, the self-reactive material is approved in writing by the Associate Administrator. The person requesting approval shall submit to the Associate Administrator the tentative shipping description and generic type and—
(
(
(iv)
(3) Readily combustible solids are materials that—
(i) Are solids which may cause a fire through friction, such as matches;
(ii) Show a burning rate faster than 2.2 mm (0.087 inches) per second when tested in accordance with the UN Manual of Tests and Criteria (IBR, see § 171.7 of this subchapter); or
(iii) Any metal powders that can be ignited and react over the whole length of a sample in 10 minutes or less, when tested in accordance with the UN Manual of Tests and Criteria.
(4) Polymerizing materials are materials which, without stabilization, are liable to undergo an exothermic reaction resulting in the formation of larger molecules or resulting in the formation of polymers under conditions normally encountered in transport. Such materials are considered to be polymerizing substances of Division 4.1 when:
(i) Their self-accelerating polymerization temperature (SAPT) is 75 °C (167 °F) or less under the conditions (with or without chemical stabilization) as offered for transport in the packaging, IBC or portable tank in which the material or mixture is to be transported. An appropriate IBC or portable tank for a polymerizing material must be determined using the heating under confinement testing protocol from boxes 7, 8, 9, and 13 of Figure 20.1 (a) and (b) (Flow Chart Scheme for Self-Reactive Substances and Organic Peroxides) from the UN Manual of Tests and Criteria (IBR, see § 171.7 of this subchapter) by successfully passing the UN Test Series E at the “None” or “Low” level, or by an equivalent test method with the approval of the Associate Administrator;
(ii) They exhibit a heat of reaction of more than 300 J/g; and
(iii) Do not meet the definition of hazard classes 1–8 (including combustible liquids).
(iv) The provisions concerning polymerizing substances in paragraph (a)(4) will be effective until January 2, 2023.
(b)
(1)
(2)
(c)