PHMSA letter of interpretation

Placement of hazard warning labels on propane cylinders

Pipeline and Hazardous Materials Safety Administration · Dec 22, 2008 · Reference No. 08-0243

PHMSA says to use caution with this letter. On January 21st, 2016, PHMSA published Final Rule, HM-233F, which incorporated Special Permit 13544 by adding Special Provision N95 to allow for the transportation of UN1075 and UN1978 without marks and labels under certain conditions. HM-233F also incorporated Special Permit 14251 by revising § 172.400a to indicate that overpacked cylinders may be marked in accordance with CGA Pamphlet C-7, provided the overpack is properly labeled.

Interprets: 49 CFR § 172.400, 49 CFR § 172.406

Reggie’s quick take

A propane marketer that refills 20-pound cylinders asked whether a Flammable Gas label must be permanently affixed to the neck of each cylinder, rather than placed on a removable plastic sleeve around the body. PHMSA said a sleeve is acceptable. Under § 172.406, a label may be affixed by other suitable means to a cylinder, so a removable sleeve showing the label can meet the rule. The agency also noted that a neck ring marking can replace the label on certain cylinders (§ 172.400a). It said empty, cleaned and purged cylinders should follow the empty packaging rules in § 173.29.

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 September 19, 2008, regarding requirements under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) that apply to the placement of hazard warning labels on propane cylinders.

You state that as a propane marketer and refiller of 20 pound cylinders, your company has placed over 900 "Flammable Gas" labels on propane cylinders. The cylinders at issue have never had the Flammable Gas label affixed to the cylinder (neck) for transportation, although they had contained Propane prior to customers bringing them in for refilling. You ask if your understanding is correct that a cylinder containing Propane should have a Flammable Gas label permanently affixed to the cylinder (neck), rather than on a removable "plastic sleeve" placed around the body of the cylinder that displays the Flammable gas label among advertisements.

It is unclear whether you are addressing the placement of the Flammable Gas label on the neck of a cylinder that contains propane or cylinders that have been emptied and no longer represent a flammable gas hazard in transportation, but are brought to your company for refilling. Generally, a hazard warning label must be printed on or affixed to a surface (other than the bottom) of the package or containment device containing the hazardous material, and located on the same surface of the package and near the proper shipping name marking, if the package dimensions are adequate.

As prescribed in § 172.400a(a)(i) and (ii) of the HMR, a hazard warning label is not required on a cylinder containing a Division 2.1, 2.2 or 2.3 material that is not overpacked and durably and legibly marked in accordance with CGA Pamphlet C-7, Appendix A; that is, a neck ring label may be used on a cylinder in place of a hazard warning label.

A hazard warning label may be printed on or placed on a securely affixed tag, or may be affixed by other suitable means to a: 1) package that contains no radioactive material and that has dimensions less than those of the required label; 2) cylinder; and 3) package with such an irregular surface that a label cannot be satisfactorily affixed. Therefore, a removable "plastic sleeve" affixed to, or placed around the body of the cylinder that displays the Flammable Gas label for Propane is acceptable (See § 172.406).

Cylinders that are emptied and cleaned and purged of residue and that no longer pose a hazard in transportation must be shipped in accordance with the empty packagings requirements prescribed in §173.29.

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.