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How Long Are Propane Tanks Good For on an RV?

How Long Are Propane Tanks Good For on an RV?

How long are propane tanks good for? It’s a very important question, and if you own an RV with any type of propane tank, you need to know the answer.

We recently posted an article covering the question “Does propane go bad?” The topic of that post refers to the LP gas itself, that is, the liquid propane inside the tanks.

In today’s post, we’re talking about the tanks that hold the propane.

How long do they last? Do they require inspection? And how do you know when it’s time for propane tank recertification or replacement?

The answers may be critical to your safety and the safety of anyone in the vicinity of your propane tank.

ASME vs DOT Propane Tanks

Not all propane tanks are the same. There are two different types of tanks that are essentially based on their usage and tank size.

DOT Propane Tanks

DOT (Department of Transportation) tanks are small propane tanks that are designed to be portable. These propane cylinders are usually 20-pound tanks (though they can be larger) and are widely available and used on some types of RVs and campers.

A 20-pound propane cylinder holds 4.6 gallons of LP gas.

Portable propane tanks are also used by homeowners and RVers to fuel gas grills, portable propane fire pits, and portable propane heaters.

A DOT portable propane cylinder

This is a portable DOT propane cylinder. DOT cylinders have a similar appearance to this one, though they may be a bit larger. The most popular size for RV and home use is 20 pounds.

ASME Propane Tanks

ASME (American Society of Mechanical Engineers) propane tanks are larger tanks and are not intended to be portable. 

Many RVs have built-in ASME tanks. Some RVs have built-in ASME tanks that are as small as 30 or 40 pounds. However, some Class A motorhomes carry 80-100 pound ASME tanks. 

ASME tanks are available from propane retailers. They vary in size depending on the RV or building they’re fueling.

In stationary locations, ASME tanks are delivered empty and then regularly refilled by a propane dealer at that stationary location.

Two ASME propane tanks - one vertical and one horizontal.

An ASME propane tank is permanently installed either on an RV or at a stationary location such as a home or business. ASME tanks may be vertical (as on the left) or horizontal.

How Long Are Propane Tanks Good For on an RV?

The best way to answer this question is to consider it in terms of expiration dates and inspections.

Depending on whether you have a DOT cylinder or an ASME tank, the expiry date (both literal and figurative) of a propane tank will be different. 

DOT Tank

Portable DOT cylinders have a date stamped into the collar of the tank indicating when the gas tank was manufactured. By U.S. federal law, the expiration date of a DOT propane tank is 12 years from the date of manufacture of the tank (10 years in Canada).

When a DOT propane cylinder reaches (or nears) 12 years from the date stamped on its collar, the tank must be replaced or recertified. 

If your DOT cylinder is in very good condition, it may be recertified (or “requalified”) for another five years. Only a certified propane dealer can recertify a propane tank (call your local dealer to ask). 

The manufacture date on a DOT cylinder is expressed in a month-year format. For example, “10-22” would represent October 2022.

When a DOT cylinder is recertified/requalified, the recertification date will have an “E” or an “H” placed after the date.


ASME tanks are approved by the regulatory body we mentioned earlier (the American Society of Mechanical Engineers). 

Again, these are the tanks you see built into the frame of a motorhome. They’re not removed for refilling – they’re refilled with the tank in place.

ASME tanks don’t have expiration dates nor is any certification period stated or required. However, (and this is VERY important), ASME tanks do require periodic visual inspections.

When a propane retailer fills an ASME tank on a motorhome, they should be visually inspecting the tank. And in states that require motor vehicle inspections, the ASME tank on a motorhome should also be inspected at that time.

A rusted ASME propane tank

A rusted propane tank – whether ASME or DOT – should not be used and should be disposed of properly. If there is excessive rust on your RV’s propane tank, have it replaced.

With all of that said, however, you can’t always count on others to perform a good visual inspection for you. For this reason, it’s wise to visually inspect your ASME tank regularly yourself if possible, AND periodically have it professionally inspected by a certified propane dealer, especially if the tank has rust or if any leaking or other damage is apparent.

A seriously rusted or otherwise damaged propane tank, whether DOT or ASME, should be replaced for your safety and the safety of everyone in the vicinity of that tank.

How Can I Tell How Much Propane is Left in My RV Propane Tank?

Some RVs have monitors inside the rig that show various levels such as contents of the fresh water, gray water, and black water tanks and propane tanks. These indicators sometimes don’t work particularly well on some RVs. But if you have a working wall monitor, you can check the level of propane remaining in your tank there.

Many ASME tanks have a gauge on the tank itself that indicates the level of propane remaining in the tank.

However, if you don’t have a gauge and want to know how much propane is inside a portable cylinder or built-in tank, there’s a simple way to find out. We’ll let Peter explain:

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Tuesday 31st of January 2023

We have a 2015 Thor Majestic 28A. The ASME propane tank struggles to accept propane. Do you think that the tank is too old and needs to be replaced, or does it sound like just the inlet valve needs replacing.


Tuesday 31st of January 2023

Hi John. Sounds like something we'd take to a propane professional to have checked out. Depending on where your tank is mounted (on some RVs it's between the frame rails near the front of the coach), it could be piping/plumbing from the inlet valve to the tank that's causing the trouble. Or it could be the inlet valve. 2015 shouldn't be so old that the tank itself is too old, unless it's been in some harsh environments (salted wintry or parked on a sandy beach in a humid environment) that aged it prematurely.

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