Can Hazmat Change Classes During Transportation?

Posted on 7/31/2025 by Lion Technology Inc.

Materials, hazardous and otherwise, can change states. At different temperatures, water becomes gas, and sand becomes glass.

At room temperature, phosphoric acid is a crystalline solid with a melting point of around 100° F. During transportation, ambient temperatures can range from -40° F to over 200° F. So, it is reasonable that solid phosphoric acid could liquefy, and liquid phosphoric acid can corrode metal packagings and vehicles.

So, hazmat can change classes during transportation, right? Wrong.

Hazmat Changes Characteristics, Not Classes

For some materials, we do not wait until they exhibit the characteristics of a hazardous material to classify them. Solid phosphoric acid powder is a Class 8 corrosive hazardous material because of its potential to liquefy and become corrosive. Believe it or not, the Hazardous Materials Regulations (HMR) already cover this specific issue.

“A liquid, or a solid which may become liquid during transportation, that has a severe corrosion rate on steel or aluminum based on the criteria in 173.137(c)(2) is also a corrosive material.”
[49 CFR 173.136(a)]

Put simply, it is the shipper’s responsibility to classify, name, and package a material as if it will exhibit the most hazardous characteristics possible during transportation.

How to Pack Shapeshifting Hazmat

Learn all the DOT’s rules for classifying, packaging, marking, labeling, and documenting your hazmat shipments in full compliance with the Hazardous Materials Regulations at Lion’s Hazmat Ground Shipper Certification (DOT) Workshop.

Or browse all Lion’s hazmat shipper training at Lion.com/Hazmat.

Tags: hazardous materials, hazmat shipping

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