Monday, September 25, 2023


Is a rusty propane tank a safety concern?

Dear RV Shrink:
rvshrinkWe just stopped for propane and the guy wouldn’t fill us. He told my husband our attached tank did not look healthy enough.

We have a Class B Sprinter with about 100,000 miles on it. We bought it used and the tank does have some surface rust. This guy poked it a bit and a big chunk of paint came off leaving an ugly rusted area near the fill cap. My husband just tried another propane station and the kid filled us up, no questions asked.

I’m nervous, but my husband says the first guy was just over-cautious. Are we on borrowed time? Please answer quick — the tank seems to be located under my seat. —Overwrought and Under Pressure in Portland

Dear Overwrought:
It sounds like you need a second, professional opinion — and I would do it at the next available propane dealer. I don’t have all the facts here. Is the tank even date stamped for a legal fill? A rig with 100,000 miles could mean old or just well-traveled.

All underbelly tanks get rusted, some more than others, depending on salt conditions. It’s a good idea to wire brush them once a year, shoot some Rustoleum on them, and inspect them for any damage.

Most underbelly tanks are thicker than regular bottles, some up to 1/2 inch. If you are just losing surface paint it could be fine, but a propane dealer would be a better judge of your condition with a hands-on inspection.

Even if your husband is confident you have no issue, it might make you feel better to hear it from a guy that works with equipment like yours everyday. If it is outdated, it can be inspected and re-stamped, it can often be reconditioned or, worst case scenario, it can be replaced with a new tank. —Keep Smilin’, RV Shrink



  1. I wasn´t sure from Overwrought´s description if this ¨attached tank¨ was DOT cylinder or underbelly permanently mounted. Sprinter could be a Class B motorhome or DYI conversion.

    For external cylinders, they are DOT regulated and must be recertified by the date (or sticker) on the tank.

    If tank is mounted permanently (underbelly), that it was built/certified under ASME rules, not DOT. Permanently mounted motorhome tanks need to be maintained, but there is not a stamped date. As suggested, brush and spray paint to keep rust free.

    Having a professional safety check for leaks is a good idea after approx 16 years. Fittings or gauge can be replaced and tank repaired, if needed. At a certain point, the labor for maintenance may outweigh the cost of new Manchester or Worthington underbelly tank.

  2. It’s up to the interpretation of the person filling the tank. I once had a manager at a U-Haul refuse to refill a 20lb BBQ tank because there was rust on the handle! The tank is supposed to be visually inspected prior to filling to include hydro date, and visible damage to include deep gouges, dents, and signs of corrosion. (Technically it starts to corrode the instant the metal leaves the forge but who’s counting right?)

    The presumption is the person filling the tank has a working knowledge of what they’re doing and the associated safety precautions. That’s not always the case.

  3. A few years ago I was Given an older Propane tank, the previous owner had bought new tanks because someone told him it would cost a lot to get the new style valve installed , and it would have to be re-certified, which would also cost a lot . The paint was chipped and there was some surface rust. I replaced the valve , cleaned up and painted the tank a nice blue, and no one has even looked at the date on it since!
    If you have only surface rust,and the tank hasn’t been abused clean and paint it. This is normal maintenance .
    Remember paint is first and fore most protection for the metal . Good looks is just a bonus.
    White corrosion on aluminum is oxidation just like rust on steel and iron. And just as damaging!!

    • Ignorance on the part of the 18 year old, minimum wage, propane filler at the gas station is a shame. I strongly suspect you know there are regulations and your work was not certified. For a government document, this 1 pager is written at a level the any gas station filler or you can probably understand. Wish taxes were this easy.

      If you have a tank that is expired, it needs re-certification. Take it one of the propane exchange locations. Immediately, you’ll have a different filled tank that is certified. When your old tank arrives at their facility, they will clean up, fix-up and appropriately re-certify.

  4. Propane guy was either over cautious, or ill-informed. The type of tank determines the wear out condition of the tank, not any rust appearance. The propane tank that was used in the GMC motorhome (1973 to 1978) is still legal to refill, regardless of appearance. I believe the covering rules were on AGME specification tanks.
    The carry-in portable bottles have a whole different set of rules.
    Find a different shop. A little wire brush and paint would improve this situation. Do not paint over or remove the certification label.

  5. I, too, was refused a refill to my attached propane tank a while back. So, I went right over to my RV repair man, who inspected it and found only surface rust. And then he wire brushed it, sanded it, and painted it with Rustoleum. Apparently it is now a law that propane dealers cannot refill your tank if it has surface rust, as they do not know if it is only on the surface or has compromised the integrity of the tank.

  6. Yes, but even if a tank is in good condition be aware to check tne mounting straps and mount area. We had a tank on a 91 class C fall out while traveling down the road. The mounting was carriage bolts thru the wood floor. In time these bolts had worked their way thru the wood and allowed the tank to drop. I was able to make temporary repair on road. Then installed metal braces out of angle iron. It was a scary time for sure.

  7. That applies to DOT tanks, the ones that are removable. The ASME tanks that are fixed in most motorhomes do not require recertification, but inspection and painting are still a good idea.

  8. Federal law requires a tank recertification of any tank after 10 years. Most propane dealers do not look at tank’s date stamp if tank is well maintained.
    A little spray paint goes a long way!!!

    • inspection required for portable d.o.t. tanks for those found on trailers. fixed tanks (A.S.M.E that are in motorhomes,etc) do not require any inspection or re-certification.

    • Please distinguish between DOT portable bottles used on trailers and grills and ASME attached tanks. The latter, on most CL A motorhomes, are not subject to the 10 year rule and fall in a totally different category than portable bottles. Maintenance and removal of surface rust clearly are appropriate.

    • A “little spray paint” can be like lipstick on a pig.

      If permanently installed on motorhome, preventing damage by arresting rust is appropriate. ASME does not mandate timed recertifications. However any dents or mounting issues needed to be addressed.

      For portable propane cylinders (BBQ grill tanks and the likes), there are very specific DOT certification dates and rules. Lipstick on the pig, it will still be a pig.


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