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Propane Tank Recertification Services


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Why does a Propane Tank need to be recertified?

Portable propane tanks like the 20 and 30 lb tanks on the front of travel trailers or connected to your grill are known as DOT cylinders, or Department of Transportation cylinders – because they are meant to be transported and carried around. Because propane is a highly flammable liquid and gas that’s stored at a high pressure the Department of Transportation requires all portable propane tanks to be recertified periodically to make sure tanks used out on the road are safe. So while it might seem like a simple process to take your tank to a local retailer to have it refilled when it runs dry, the process is actually monitored by the United States Department of Transportation. If you try to refill a tank that is due for recertification, you will be turned away until that tank is recertified.

How often does a Propane Tank need to be recertified?

Propane tanks are good for 12 years from the date of manufacture. After that, tanks typically need inspecting and recertification every five years. To check your tank’s status, look at the collar at the top of the tank. You’ll find the date of manufacture stamped into the collar using the typical month and year code. A tank stamped 08 18, for example, was manufactured in August 2018.

When the tank is recertified, the company certifying it will either add a sticker to the tank with the inspection date on it or stamp its own mark into the top of the cylinder. A recertified date code consists of the letter A, B, C, or D as well as a two-digit number. The letter in the code indicates the quarter, and the number signals the year that the tank was recertified. A stamp that reads B 20 indicates certification during the second quarter (April, May, or June) of the year 2020.

There are a few more things to note about the dates/tags listed on your propane tank, and how it indicates the propane inspection type performed on your tank:

Date Only: 

If your propane tank shows only a date, with no letter following it – this is typically the manufacturing date and indicates you will need to have your propane tank recertified within 12 years of the date on the tank.

Date followed by a Letter:

An “S” on the tank after the date indicates an internal hydrostatic method was used for inspection. This means you have 7 years before needing your DOT propane tank checked again.

An “E” following the date listed on your tank means the tank was inspected only visually and externally. This means you will need your propane tank inspected within five years of that date.

The codes are meant to let you and any future technicians who examine the tank know when it was last checked and in which way.

Propane cylinders have identifying marks on the cylinder neck ring (collar), or cylinder shoulder depending on the cylinder type. Requalification Guidance for Propane Cylinders Requalification/Retesting (49 CFR § 180.205)


The “requalification” date, also known as the “retest” date , is an important marking for fillers and/or consumers. Propane cylinders must be requalified or replaced every 5 or10 years depending on the cylinder type, condition, and previous requalification method. (Ref. 49 CFR § 180.205(d) and 180.209(e).)


The original manufacture/test date and any requalification/ retest date(s) must be presented in a specific manner, reviewed, and determined to be within test prior to filling.


Visual Cylinder Inspection:


In accordance with 49 CFR § 173.301(a)(2), cylinders must undergo a visual inspection prior to being filled. If any of the defects noted in items 1 through 4 below are present, the cylinder must not be filled and may only be repaired, requalified, or rebuilt by an authorized U.S. DOT facility (see authorized RIN and VIN holders below):


1. Damage to the cylinder’s exterior including dents; bulges; cuts; or cracks on the cylinder’s surface, or to welds; and any evidence of physical abuse; fire; or heat damage.


2. Detrimental rust, corrosion, or pitting on the cylinder, particularly on the bottom.


3. Absence of/damage to a cylinder foot ring, cylinder neck ring (collar), or valve cover.


4. A leaking or defective valve or leaking or defective pressure relief device.


A cylinder conforming to the Visual Inspection criteria also must be examined for the most recent repair, requalification, or rebuild date prior to filling. Cylinders that are overdue for requalification must NOT be refilled.

  • DOT 4-series propane cylinders must be requalified following their manufacture date every 5 or 10 years.

  •  If no requalification date is present, 10-years from the date of manufacture.

  •  If requalification was completed by the “Volumetric Expansion” method, as indicated by a valid RIN holder’s requalification mark, 10-years after that date.

  • If requalification was completed by the “Proof-Pressure” method, as indicated by a valid RIN holder’s requalification mark followed by an “S” 10-years after that date.

  • If requalification was completed by the “External Visual” method, as indicated by a valid RIN or VIN holder’s requalification mark followed by an “E” 5-years after that date.

Volumetric Expansion Method

The Volumetric Expansion test is the most rigorous test a portable propane tank can go through. The test is done using a “water jacket” for “hydrostatic testing.” A hydrostatic test will test the strength of the propane tank as well as check for any leaks or weak points. The test is done by filling the propane tank with water that is pressurized 2x the normal amount. The tank is then put in a water tank to displace the pressure and make it easier to see if there are any leaks.

If a volumetric test is done when recertifying a propane tank the certification will last for 10 years.

Proof-Pressure Method

The proof-pressure test is similar to the volumetric expansion test but instead of water, air is being used to pressurize the tank to check for any weak points or leaks. During this test the propane tank will be filled with air to a level that is 2X the normal pressure amount. If the cylinder can handle the double pressure and there are no leaks the recertification will be good for 10 years.

Getting A New Valve On A Propane Tank

A big part of propane tank recertification is checking the valve, and these valves aren’t as simple as they might seem.

In addition to the knob you turn to turn on or off the propane there is also a pressure relief valve on the back.

It’s there to release pressure in case the tank is overfilled and the gas inside expands past safe pressure levels.

There’s also an emergency shut off inside the valve that will stop the flow of propane from the tank if it detects an unregulated pressure release. This safety feature is the reason you can’t just open a propane tank to release the gas without a regulator or hose attached. If this ever happens to you the emergency valve can be reset by turning off the main valve and waiting for a few minutes. The emergency shut off can sometimes be accidentally engaged if the propane tank is opened too quickly. That’s why it’s recommended to open a propane tank slowly even when it’s connected to something like a grill or RV.

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