November 4, 2026 · 4 min
RV propane tank inspection: cylinders on a trailer, a fixed tank on a motorhome
Recreational vehicles carry propane in two very different containers. Which one you have decides what gets inspected, by whom, and what a filler will refuse.
An RV owner who asks about a propane tank inspection usually wants to know one of three things: why a filler refused to fill, whether the tank is still legal to use, or what to check before a trip. The answer depends first on the kind of container on the vehicle. Travel trailers and fifth wheels generally carry removable cylinders. Motorhomes generally carry a tank mounted permanently to the chassis. They are built to different codes and handled differently.
Removable cylinders on trailers
The upright cylinders on a trailer tongue or in a side compartment are portable cylinders built to Department of Transportation specifications. They are the same family as a grill cylinder, larger in some cases, and they follow the same rule: a manufacture date stamped on the collar, and a requalification due a set period later. The marks and how to read them are explained in reading the marks on a cylinder collar. A cylinder past its date is refused at the filling station until it has been requalified or exchanged.
Permanently mounted tanks on motorhomes
A motorhome tank is usually an ASME tank, built to the pressure vessel code and bolted to the frame. It is filled in place, through a fill valve on the side of the vehicle, and it does not carry a requalification date. Instead it carries a nameplate with the code stamp, the working pressure and the capacity. What decides whether it can be filled is its condition: the mounting, the valves, the gauge, the absence of damage and of serious corrosion.
What a filler looks at
Whatever the container, the person filling it is expected to check it. On a cylinder, the date, the overfill prevention device on the valve, the collar and foot ring, dents and rust. On a motorhome tank, the nameplate, the brackets and bolts, road damage underneath, the fill valve and the fixed liquid level gauge used to stop filling at the right level. A refusal on any of these is not personal. It is the filler declining to put liquefied gas under pressure into a container it cannot vouch for.
Road damage and corrosion underneath
Motorhome tanks live under the vehicle, in road spray, salt and grit. The mounting brackets corrode, stones chip the coating, and a tank that has been scraped on a curb or a ramp may carry a dent nobody has seen. Looking underneath with a light before each season, and after any contact with the ground, is the most useful check an owner can make. Deep pitting, a gouge or a dent in the shell are reasons to have the tank looked at before it is filled again.
The rest of the propane system
Most RV propane problems are not the tank. They are the regulator, the hoses, the pigtails between cylinder and regulator, and the fittings at each appliance. Construction of RV propane systems is governed by NFPA 1192, the standard on recreational vehicles, and a leak test of the system is the check that service centers perform. RVs also carry a propane leak detector near the floor. It should be tested as its manufacturer describes, and replaced when it reaches the end of its stated life.
Who does what
The owner looks and reports. The filler checks before filling. An RV service center tests the system for leaks and replaces regulators and hoses. Requalification of a portable cylinder is done only by a firm authorized for it, and repairs on an ASME tank are not done at all outside the code: a damaged tank is replaced. The general logic of who inspects which kind of tank is set out in who inspects what, and the three families of propane containers are compared in the overview of propane tank inspection.
Before buying a used RV
Read the dates on any cylinders, find the nameplate on a motorhome tank and make sure it is legible, look at the brackets underneath, and ask when the system was last leak tested and when the regulator was replaced. A seller who cannot answer is not necessarily hiding anything, but the answers belong in the price, and a leak test before the first trip costs far less than a surprise at the first campground.
Not sure which rules apply to your tank?
Describe the tank, what it holds and why the question came up. Four questions, then a call.
Free and with no obligation: we call you back to confirm the details, then, with your OK, your request goes to one certified inspector who covers your area and follows up with a quote.