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DEKRA Process Safety Alert: You Could Be Classifying Class 1, Class 4 Materials Incorrectly

Understanding UN/DOT Classifications

Class 1 vs Class 4 Materials

Safety and transportation (shipping and receiving) managers must understand that energetic products that are not intended to provide an explosive or pyrotechnic effect may still have sufficient energy such that they can self-react and potentially explode.

This means they must be properly tested and classified prior to being transported.

Tests are required to determine whether these products must be classified as Class 1 (explosives) or Class 4 (flammable solids).

An example: Even though some Thermite-related substances or products may be classified as a 4.1 flammable solid, these materials produce copious amounts of heat and may produce smoke, flame, blast or other explosive and pyrotechnic effects as well. Therefore, all thermite and related mixtures must be provisionally considered as Class 1 (explosives) and examined accordingly by a US DOT-approved Explosives Test Lab.

The United Nations/Department of Transportation (UN/DOT) system is designed to protect employees, the transportation system and the general public. It doesn’t protect any one if you classify your hazardous materials incorrectly.

Testing Class 1 Products

UN/DOT Class 1 represents explosives, such as high explosives, propellants, pyrotechnic devices and even some articles that self-contain all of the explosive effects. All new or modified Class 1 explosive articles and substances must be submitted to a DOT-approved Explosives Test Lab and examined per the UN and DOT requirements. New products that are potentially explosive must also be examined.

The manufacturer submits the lab’s Test and Recommendation report to the US DOT for final determination of the UN number, Description, Classification, Division and Compatibility Group. An EX number is then issued by the US DOT and the applicant is approved to ship their product. Even if the article or substance is listed in the Hazardous Materials Table, an examination by a DOT-approved lab and final determination by the DOT is required.

Testing Class 4 Products

UN/DOT Class 4.1 represents highly flammable solids, which includes desensitized explosives, thermally unstable self-reactive materials, readily combustible solids, and certain polymerizing materials.

If a company’s product is identical to other Class 4 materials listed in the DOT’s Hazardous Materials Table, they can then use the listing to determine the proper UN number, packaging requirements, and labeling requirements.

However, if the product is a new or modified product that is not listed in the Hazardous Materials Table, then it must be examined for explosive properties by a DOT-approved Explosives Test Lab. Typically, these tests and analyses must also be submitted to the DOT for their approval prior to shipping any products.

Test Before You Ship

Testing to determine UN/DOT classification is required prior to shipping materials such as explosives, flammable solids, or peroxides. In many cases, the regulations do not allow you to test and classify the material yourself.

If you fail to follow the proper UN/DOT classification system, there is the potential risk that a fire or explosion could occur that will pose a threat to human lives, facilities and equipment, as well as create a financial catastrophe for you. With energetic materials, there may be no second chances. That’s why you need to understand how to classify your product and which classification serves which material.

Protection Comes From Testing

Protect your workers and your community, and also reduce financial risk to your company by taking time to understand how the UN/DOT classification works. Here are resources that can help:

Hazardous Materials, Classes and Divisions (49 CFR 173.2)

US DOT Definition of a "New Explosive"

UN/DOT Hazardous Materials Testing

DOT/UN Energetics and Explosives

US DOT Hazardous Materials Table

Explosives Characterization and Testing

PHMSA May 2020 Interpretation Letter on Thermites

How DEKRA Can Help

DEKRA’s DOT-approved Explosives Test Lab and team of experienced examiners and technicians stands ready to help companies navigate the rules, tests, analyses and has the resources needed to have full confidence in and compliance with the Hazardous Materials Regulations (HMR). DEKRA also has the ability to assist in determining the proper name, UN number, hazard class and division, for most other hazardous materials as well.

DEKRA is offering a complimentary 15-minute discussion to help companies navigate the storage and transport of hazardous materials in the effort to protect workers and the community. Please call (609) 799-4449 extension 321 or contact us referencing this offer.