Classification of Asphalt
Pipeline and Hazardous Materials Safety Administration · Apr 9, 1996 · Reference No. 96-0076
Interprets: 49 CFR § 172.101
Reggie’s quick take
A company asked how to classify emulsion asphalt and blacktop bituminous concrete under federal hazmat rules. PHMSA said the shipper must do the classifying. Asphalt with a flash point of 100 to 200°F that is not heated is a combustible liquid, UN 1999. Asphalt that is intentionally heated and shipped at or above its flash point is a Class 3 flammable liquid, described as "Hot Asphalt, 3, NA 1999, III." Such a cargo tank needs "FLAMMABLE" placards, the number 1999, and "HOT" markings under § 172.325.
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 November 30, 1995, requesting clarification on the proper classification for emulsion asphalt-water based and black top bituminous concrete under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180).
Under 49 CFR 173.22, it is the shipper's responsibility to properly classify a hazardous material. This office does not generally perform this function. A material with a flashpoint at or above 37.8°C (100°F) that is intentionally heated and offered for transportation at or above its flashpoint, meets the defining criteria of a Class 3 (flammable) liquid, as defined in § 173.120 and also meets the definition of an elevated temperature material (see § 171.8). Domestically, this material would be described as "Hot Asphalt, 3, NA 1999, III". Asphalt with a flash point of 100-200°F that is not intentionally heated would be described as "Asphalt, cut back, Combustible liquid, UN 1999, III". A cargo tank containing the Class 3 material must display "FLAMMABLE" placards and the identification number, i.e., "1999", on both sides and both ends, as well as the "HOT" marking on two opposing sides, as specified in § 172.325.
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.