Applicability of HMR to Ferrosilicon
Pipeline and Hazardous Materials Safety Administration · Dec 14, 1999 · Reference No. 99-0237
Interprets: 49 CFR § 173.22
Reggie’s quick take
A company asked whether the ferrosilicon it buys and resells falls under the Hazardous Materials Regulations. The company said its product was tested under the Appendix E method to Part 173 and found not to meet the Division 4.3 (dangerous when wet) definition. PHMSA's answer is that the product is not subject to the HMR, but only if it is the same material that was tested and found not to meet Division 4.3. The letter also notes that under § 173.22 the shipper is responsible for classifying its hazardous materials.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response your letter requesting confirmation that the ferrosilicon you purchase and resell is not subject to the Hazardous Materials Regulations (HMR: 49 CFR Parts 171-180). You state that your product was tested in accordance with the test method described in Appendix E to Part 173, and found it does not meet the definition of a Division 4.3 (Dangerous When Wet) material.
As provided in § 173.22 it is the shipper's responsibility to properly classify a hazardous materials. However, if the ferrosilicon sold by your company is the same material that was tested and determined not to meet the Division 4.3 criteria, it is not subject to the HMR.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.