Propane Tank Labeling Requirements: Cylinders, ASME, Requalification

Propane tank labeling requirements fall into two tracks depending on the tank. Portable cylinders that you carry to a fill station follow the Department of Transportation’s hazardous materials rules in Title 49 of the Code of Federal Regulations, and they need permanent collar stampings, a Class 2.1 flammable gas hazard label, the proper shipping name with UN identification number, and a current requalification mark. Stationary ASME tanks that sit on your property and get refilled by a delivery truck follow NFPA 58, and they need a stainless steel nameplate carrying thirteen specific pieces of information. If any required marking is missing, corroded, or painted over, federal law bars the supplier from filling the tank.

What Must Appear on a Portable Cylinder

The collar or shoulder of a portable propane cylinder carries a set of stampings pressed permanently into the metal or onto a plate welded to the tank. Federal regulations require these markings to be plainly and permanently applied.1eCFR. 49 CFR 178.35 – General Requirements for Specification Cylinders A typical 20-pound grill cylinder will show:

All of these must remain legible for the life of the cylinder. The regulation states the requirement plainly: markings on a cylinder must be legible and meet the applicable specification.3eCFR. 49 CFR 173.301 – General Requirements for Shipment of Compressed Gases and Other Hazardous Materials in Cylinders, UN Pressure Receptacles, and Spherical Pressure Vessels

Separate from the metal stampings, a portable cylinder in transportation must carry hazard communication markings. The proper shipping name (“Liquefied Petroleum Gas” or equivalent) and the UN identification number UN1075 must be marked on the package in characters at least 6mm high for cylinders with a water capacity of 60 liters or less.4eCFR. 49 CFR 172.301 – Marking Requirements The Class 2.1 Flammable Gas diamond label, red with the flame symbol and hazard class number in black or white, must also appear. On a propane cylinder specifically, the label background may match the cylinder’s own color as long as adequate contrast is kept. The label has to survive at least 30 days of transportation conditions without deteriorating or substantially changing color.5eCFR. 49 CFR Part 172 Subpart E – Labeling

Most consumer cylinders also carry a precautionary warning label describing the flammability of the contents, telling the user to check for leaks by smell (propane is odorized so a leak smells like rotten eggs), and directing anyone who suspects a leak to evacuate and call emergency services. Cylinder exchange programs typically require this label before putting a tank on the rack.

What Must Appear on a Stationary ASME Tank

Large tanks built to the ASME Boiler and Pressure Vessel Code and installed permanently on a property don’t carry collar stampings. They carry a stainless steel nameplate. NFPA 58 requires the nameplate to be attached in a way that resists corrosion and to remain visible after the tank is set in place. If the tank is buried, mounded, or insulated so the nameplate can’t be read, the same information has to be duplicated on adjacent piping or a nearby structure.

The nameplate must include:

  • Service designation (underground, aboveground, or both).
  • Supplier name and address, or trade name.
  • Water capacity in pounds or gallons.
  • Maximum allowable working pressure (MAWP) in psi.
  • A statement reading, “This container shall not contain a product that has a vapor pressure in excess of ___ psig at 100°F.”
  • Outside surface area in square feet.
  • Year of manufacture, shell thickness, head thickness, overall length, outside diameter, head design, serial number, ASME code symbol, minimum design metal temperature, and degree of radiography.6MiSafeCanna. NFPA 58 Liquefied Petroleum Gas Code – 2020 Edition

Delivery drivers check the nameplate before every fill. A missing or unreadable nameplate stops the delivery until a qualified technician verifies the tank’s specifications and installs a replacement plate.

The Requalification Stamp and What Its Letter Codes Mean

Propane cylinders have to be periodically requalified to confirm they can still safely hold pressurized gas. The original test date stamped at the factory starts the clock. A DOT cylinder used for liquefied petroleum gas qualifies for an external visual inspection in place of a full hydrostatic pressure test, and that inspection is valid for five years.7eCFR. 49 CFR 180.209 – Requirements for Requalification of Specification Cylinders

When a cylinder passes, the technician stamps a specific mark into the metal or onto a permanently attached plate. The format is prescribed: the requalifier’s identification number (RIN) is set in a square pattern between the month and year of the test, with a letter code after the date identifying the test performed.8eCFR. 49 CFR 180.213 – Requalification Markings for DOT Specification Cylinders The codes to know:

  • “E” means an external visual inspection, valid for 5 years.9Pipeline and Hazardous Materials Safety Administration. Requalification Guidance for Propane Cylinders
  • “S” means a proof-pressure test, valid for 10 years.9Pipeline and Hazardous Materials Safety Administration. Requalification Guidance for Propane Cylinders
  • No letter, or a star symbol, means a volumetric expansion test; the requalification interval depends on the specific cylinder specification and service.

An external visual inspection can also be performed by a holder of a Visual Identification Number (VIN), which works like a RIN but only covers visual requalification.10GovInfo. Federal Register Vol. 85, No. 248 – Cylinder Requalification Requirements A date stamp followed by “E” and a square of numbers on the collar is the record of the cylinder’s most recent visual inspection.

When a Label Is Damaged, Painted Over, or Missing

Adhesive labels wear differently from stamped metal, and the fix depends on which is affected.

The manufacturing stampings on a portable cylinder’s collar are meant to last for decades, but they can corrode, get painted over during a refurbishment, or wear down with heavy use. Once they become unreadable, the cylinder is effectively retired. That data can’t be recreated without tracing the cylinder’s history back to the manufacturer’s original data report. Some state LP gas programs will authorize a duplicate data plate if enough identifying information, such as manufacturer name and serial number, can still be recovered to verify the records.11NC Agriculture. Standards – Name Plate Information Without that verification, the tank has to be taken out of service.

Adhesive hazard labels and consumer warning stickers give out sooner than metal stampings, especially on cylinders that live outdoors. Replacement label kits are widely available from propane equipment suppliers. Checking your cylinder’s collar stampings, hazard diamond, and requalification date once a year is enough to catch problems before you arrive at a fill station with a tank the operator can’t legally service.

What Non-Compliance Costs You

The immediate consequence of a labeling problem is refill refusal. Federal law bars the filling of a cylinder that can’t be verified as safe, so the supplier has no discretion; they have to turn the cylinder away.

The financial exposure sits on commercial operators, distributors, and filling stations. The Pipeline and Hazardous Materials Safety Administration enforces the hazardous materials rules, and a knowing violation can carry a civil penalty of up to $103,139 per violation. If a violation results in death, serious injury, or substantial property destruction, the maximum climbs to $240,658.12Pipeline and Hazardous Materials Safety Administration. Civil Penalty Summary For a homeowner, the practical stakes are smaller but real: a cold grill, a cold heater, and a trip to have the cylinder inspected, relabeled, or replaced.