Clarification of Subsidiary Labeling Requirements
Pipeline and Hazardous Materials Safety Administration · Apr 2, 2014 · Reference No. 13-0239
Interprets: 49 CFR § 172.402, 49 CFR § 172.419
Reggie’s quick take
A company asked whether it can keep using the shipping name "UN2920, Corrosive liquid, flammable, n.o.s., 8 (3), PG II" for a liquid that is corrosive and also flammable, with a flash point of 107 to 125 °F. The company wants to use the subsidiary label exception in § 172.402(a)(2) for shipments by highway or rail. PHMSA said yes. No subsidiary label is required for domestic highway or rail shipments. A flammable liquid label under § 172.419 is still required when the package goes by air or vessel.
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 responds to your e-mail requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR 171-180) applicable to exceptions from labeling a package with a subsidiary label as prescribed in § 172.402(a)(2). In your letter, you request regulatory guidance for a substance that meets the defining criteria for a Packing Group II corrosive liquid and has a flash point that ranges from 107 °F - 125 °F (Packing Group III, flammable liquid). You ask whether you may continue to use the description “UN2920, Corrosive liquid, flammable, n.o.s., 8 (3), PG II” for the substance while taking advantage of the labeling exception provided in § 172.402(a)(2) for transportation by highway or rail.
The answer is yes. A subsidiary label is not required for domestic transportation by highway or rail. However, permissive labeling is allowed, provided the label represents a hazard presented by the material. A “FLAMMABLE LIQUID” label conforming to § 172.419 is required on such a package when it is offered for transportation by air or vessel, and the substance would be appropriately described as “UN2920, Corrosive liquid, flammable, n.o.s. (Technical Name), 8 (3), PG II.”
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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.