USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

PHMSA Explanation of Classification of Thermite Mixtures

Friday, September 22, 2023

This notice is being published to inform the regulated community of how PHMSA has previously reviewed and classified certain thermite formulations and how it has temporarily reclassified certain thermite formulations as Division 4.1 flammable solids instead of Class 1 explosives while PHMSA completes its ongoing research project on thermite formulation classification. The notice also explains how PHMSA is instructing its approved test labs to evaluate thermite formulations submitted for classification testing.  See the notice for full details.