Classification of Ferrosilicon
Pipeline and Hazardous Materials Safety Administration · Jan 29, 1997 · Reference No. 97-0133
Interprets: 49 CFR § 172.101
Reggie’s quick take
A company asked PHMSA whether its 75 percent ferrosilicon is covered by the Hazardous Materials Regulations. PHMSA said that, based on the test results the company sent, the ferrosilicon does not meet the criteria for Division 4.3 and, if it meets no other hazard class, it is not subject to the HMR. PHMSA also said shippers must classify their own materials under § 173.22, and the agency does not have to verify those decisions.
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 to your letter dated December 17, 1996, regarding the applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to ferrosilicon, with 75 percent silicon.
The Hazardous Materials Regulations govern the transportation of hazardous materials in commerce. Under 49 CFR 173.22, it is the shipper's responsibility to properly classify a hazardous material. Such determinations are not required to be verified by this office.
Based on the test results provided in your letter, it is our opinion that the ferrosilicon manufactured by your Company, does not meet the criteria of a Division 4.3 and provided it does not meet any other hazard class, 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.