Department of Transportation (DOT) portable propane cylinders (types 4B, 4BA, 4BW, and 4E), which are normally used in your travel trailer or fifth wheel, need to be recertified 12 years after the manufacture date. (Some other propane cylinders may have a 10 year recertification date) After the initial recertification, they will need to be recertified every 5 years, if requalified by visual inspection, which is how most RV DOT cylinders are recertified.1
The type of cylinder and the date of manufacture is stamped into the collar of the propane cylinder or a propane dealer can tell you if you are approaching your recertification date at your next fill up. Don’t be caught by surprise – it is illegal to refill a DOT cylinder that is beyond its certification date. You don’t want to be left out in the cold!
To find a recertification location near you, go to this DOT portal or download the RIN Locator App to your smart phone (Android and iOS)
What about propane tanks in motorhomes? American Society of Mechanical Engineers (ASME) propane tanks in Motor homes are made with a heavier thicker metal wall and are permanently mounted. They do not need this recertification, but should be visually inspected regularly for corrosion/rust or other damage.
You can find more information below:
1 If a proof pressure test requalification method is used, then the following recertification is 10 years according to Code of Federal Regulation for DOT Requalification of Propane Cylinders 49 CFR 180.209(e). NFPA 58 (2020) Annex C.126.96.36.199 currently says 7 years before the next recertification, but updates are done less frequently. The proof pressure test can be identifed by an "S" after the last date of recertification. If a Volumetric expansion test with the water jacket method is used, then the following recertification is 12 years.