When you shop for a propane tank, you’ll see two certification types: ASME and DOT. Both are safe, both are legal, and both hold propane — but they’re designed for completely different applications. Choosing the wrong one can mean a failed inspection or a tank that doesn’t fit your needs.
What Is an ASME Propane Tank?
ASME stands for the American Society of Mechanical Engineers. ASME tanks are stationary storage vessels built to the ASME Boiler and Pressure Vessel Code. They are permanently installed at a fixed location — your home, farm, or business — and are not designed to be transported once filled.
ASME tanks are identified by:
- A nameplate stamped with “ASME” and the vessel’s specs
- Larger sizes (typically 120 gallons and up)
- Fixed legs or saddles for stationary mounting
- No DOT requalification requirement
What Is a DOT Propane Tank?
DOT stands for the U.S. Department of Transportation. DOT cylinders are portable, refillable pressure vessels built to DOT standards for transportation. Forklift cylinders, BBQ grill tanks, and RV tanks are all DOT cylinders.
DOT tanks are identified by:
- A collar stamped with “DOT” spec markings
- A 12-year requalification requirement (must be recertified every 12 years)
- Portable design — can be legally transported when filled
- Smaller sizes (20 lbs, 33.5 lbs, 100 lbs, 120 gallon)
Key Differences at a Glance
| ASME | DOT | |
|---|---|---|
| Use | Stationary (permanent) | Portable (transportable) |
| Common sizes | 120 gal – 30,000+ gal | 20 lb – 420 lb (120 gal) |
| Requalification | Not required | Every 12 years |
| Transport when filled | Not permitted | Permitted |
| Installation | Fixed, by licensed installer | Can be self-installed (small sizes) |
Which One Do You Need?
Choose ASME if: You’re heating a home, powering a whole-house generator, fueling agricultural equipment, or installing any permanent propane system. Your propane supplier will come to you to refill it.
Choose DOT if: You need a portable cylinder — for a forklift, RV, food truck, or a backup cylinder you’ll exchange or transport yourself.
Can They Be Used Interchangeably?
No. A DOT cylinder cannot legally be used as a permanent stationary tank, and an ASME tank cannot be transported filled. Local codes and your insurance provider will require the correct type for your application.
Shop ASME and DOT Tanks
Propane Tank Traders carries both ASME and DOT certified tanks in every size, new and used. All tanks are certified before shipment and delivered nationwide for a $350 flat freight rate.