Classification of Hydraulically Pressurized Article that Contains a Non-Flammable Gas
Pipeline and Hazardous Materials Safety Administration · Jul 18, 2006 · Reference No. 06-0140
Interprets: 49 CFR § 180.407
Reggie’s quick take
Someone asked which proper shipping name applies to a hydraulically pressurized article holding a non-flammable gas under identification number UN3164. PHMSA said the name is "Articles, pressurized hydraulic." The HMT entry for UN3164 covers both pneumatic and hydraulic articles, and the user picks the term that fits the material, as cited in § 172.101. So for a hydraulic article, use "Articles, pressurized hydraulic."
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 letter dated June 9, 2006, regarding the correct proper shipping name for a hydraulically pressurized article that contains a non-flammable gas under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171- 180). Specifically, you ask whether the proper shipping name for such an article under identification number UN3164 would be: (1) Articles, pressurized hydraulic; (2) Articles, hydraulic; or (3) Hydraulic.
The entry corresponding to the identification number UN3164 in the § 172.101 Hazardous Materials Table (HMT) is "Articles, pressurized pneumatic or hydraulic containing non-flammable gas. One of the terms, pneumatic or hydraulic is intended to be selected, as appropriate, for the material to be described. The intent of combining multiple proper shipping names under one entry in the HMT is to keep the table as short as possible without impairing its effectiveness.
Therefore, the most appropriate proper shipping name for an article in the scenario you describe would be "Articles, pressurized hydraulic."
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.