49 CFR 172 Special Provision 53 (Numeric Codes)

These provisions are multi-modal and apply to bulk and non-bulk packagings.

Code	53
Description	Packages of these materials must bear the subsidiary risk label, “EXPLOSIVE”, and the subsidiary hazard class/division must be entered in parentheses immediately following the primary hazard class in the shipping description, unless otherwise provided in this subchapter or through an approval issued by the Associate Administrator, or the competent authority of the country of origin. A copy of the approval shall accompany the shipping papers.
HazMat with this Code	UN 3101 - Organic peroxide type B, liquid UN 3111 - Organic peroxide type B, liquid, temperature controlled UN 3102 - Organic peroxide type B, solid UN 3112 - Organic peroxide type B, solid, temperature controlled UN 3221 - Self-reactive liquid type B UN 3231 - Self-reactive liquid type B, temperature controlled UN 3222 - Self-reactive solid type B UN 3232 - Self-reactive solid type B, temperature controlled