Propane Cylinder Requalification Explained

We all need to check in at specific points in our lifespan to see if we need a tune-up. We go to a professional. They assess our well-being and safety and make suggestions from there. Propane cylinder requalification, also known as propane tank recertification, is a checkup on the safety of your propane container.


After a certain amount of time, all portable propane cylinders — most commonly, picture the 20-pound propane tank sizes widely used for BBQs, generators, patio heaters, etc. — need to be checked to ensure they’re effective for continued use. This process is known as propane tank requalification.


This is performed because any propane container small enough to travel by roads and highways (most often tanks from 5 pounds to 420 pounds) falls under the Department of Transportation’s purview. Since they can travel, the DOT needs to ensure they’re safe.


If your tank collar has “DOT” stamped on it, it must be requalified at some point(s) in its potentially long life span.


Propane containers have a manufacture date stamped onto their collar (the metal piece that comes out of the main tank, often used as a handle). Depending on the original manufacture date, the container must be recertified by a professional again 12 years from the date to ensure its continued use.


Paraco Propane Tank Recertification Methods


At Paraco, we requalify propane cylinders using the External Visual Method.


Your professional will inspect the cylinder for dents, gouges, bulges, heat/fire damage, damage to welds, rust, and corrosion that could pose a risk of problems, like a leak.


They will ensure that the ring on the bottom of the container, called a foot ring, is in good enough shape to hold the container properly upright and that all the labels and markings that need to be present are in place.


The cylinder must also have a collar to protect the valve.


They’ll also ensure that the container relief valve is not showing damage. If there’s anything wrong with the valve, it can be replaced for a reasonable fee.


Once requalified, a new date is marked for the container, and it’s good to go until the next External Visual Method requalification interval is up in five years!


Other Requalification Methods


Volumetric Expansion Test


The most intensive method of requalification is the Volumetric Expansion test, a pressure test to determine a cylinder’s total and permanent expansion at a given pressure.


The volumetric expansion test is conducted using the water jacket or direct expansion methods:

(1) Water jacket method is a volumetric expansion test to determine a cylinder’s total and permanent expansion by measuring the difference between the volume of water the cylinder externally displaces at test pressure, and the volume of water the cylinder externally displaces at ambient pressure.

(2) Direct expansion method means a volumetric expansion test to calculate a cylinder’s total and permanent expansion by measuring the amount of water forced into a cylinder at test pressure, adjusted for the compressibility of water, as a means of determining the expansion.


Recertification done by Volumetric Expansion is good for 12 years.


Proof-Pressure Method


Proof pressure test means a pressure test by interior pressurization without determining a cylinder’s expansion.


Requalification by the Proof-Pressure Test is good for ten years.


How do I get an External Visual Inspection done?


Contact us! We’ll be happy to examine your tank to ensure that you can safely continue using it and enjoy propane’s benefits for years to come.


  1. Warren Davis on November 6, 2023 at 2:06 pm

    You don’t say here how one would know if the tank has been recertified. A label or sticker with a specific format. The stamped into the collar date of manufacture can be more than 12 years old if the tank is recertified. If a recertification is done and a date with the correct format is applied, is the tank good until the date shown or 5 years after that date or something else. Is the date followed by an E?

    • Ines on November 7, 2023 at 11:50 am

      Hi Warren! Indeed, a date stamp or a sticker, displaying the month and date, followed by an ‘E,’ signifies that the cylinder underwent visual requalification by an authorized vendor. The cylinder is considered safe for use for a period of 5 years from the date shown.

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