Is It Safe to Buy a Used Propane Tank? Read the Date First

Yes, a used propane tank can be safe to buy, and the everyday 20-pound grill tank is one of the easier secondhand items to judge, because the important facts are stamped right into the metal. Three checks decide it: the date (a tank needs a fresh inspection 12 years after its stamped date before anyone may refill it), the valve (it must have the three-lobed handle of an overfill prevention valve), and the body (no deep dents, heavy rust or fire damage). Pass all three and the tank is as usable as a new one. Fail one and it is either a cheap swap or a trip to the hazardous waste drop-off, not a bargain.

A used propane tank is only a deal if the date, the valve and the metal all pass. Check those three before you pay.

Right now is when these questions come up in the DC area: patio heaters and fire tables come out as nights get cold, holiday cooks drag the grill back out, and plenty of spare tanks get listed online by people clearing garages. Here is how to read one in about two minutes.

Where is the date stamp on a propane tank?

Every refillable tank is marked with the month and year it was made. Anoka County, Minnesota's propane guidance puts it plainly: the tank carries that date, and a tank more than 12 years old must be recertified before it can be refilled.

On a typical grill tank, look at the metal collar (the ring-shaped handle around the valve). You will see a row of letters and numbers: the specification, a serial number, and a date written as month and year, such as 04 19 for April 2019. If the tank has already been inspected again, you will see a second, later date, often with a letter after it.

What do the letters E and S after the date mean?

This is the part most online answers get muddled, so we read the federal rules themselves. The marking rule (49 CFR 180.213) and the requalification rule (49 CFR 180.209) say:

One honest note: many older guides, and some refill counters, still say an S stamp lasts 7 years. The rule text we read on eCFR this week says 10. If a filler tells you otherwise, that is their call at the counter, so a tank close to either line is a tank to price low or skip.

The simple rule for a buyer: find the newest date on the collar, add 12 years if it has no letter, 5 years if it has an E, and treat an S stamp as due 10 years later. If that date has passed, the tank is "out of date". It is not dangerous to hold, but it cannot legally be refilled until a propane dealer requalifies it.

How do I know if a propane tank has the right valve?

Look at the handle you turn. The U.S. Department of Transportation's hazardous materials office (PHMSA) explains that the national propane code, NFPA 58, requires an overfill prevention device on tanks that hold 4 to 40 pounds of propane, which covers the standard grill tank. It applies to any such tank made or requalified after September 30, 1998, and to any refill on or after April 1, 2002.

Anoka County describes how to spot it: the safe valve has a three-lobed handwheel and the letters OPD forged into the brass. A round handle, or one with five or more lobes, is the old kind. That tank cannot be refilled until the valve is replaced, and a propane dealer can retrofit one.

Why it matters: the valve's float stops the fill at a safe level. A tank filled too full leaves no room for the liquid propane to expand, so gas may escape.

What damage means walk away?

The federal inspection rules list what an inspector looks for: leaks, corrosion, gouges, dents or digs in the shell, a broken or damaged foot ring or collar, and fire damage. You can do a rough version of that check yourself:

1. Dents and gouges. A shallow scuff in the paint is normal. A sharp dent, a crease, or a gouge you can catch a fingernail in is a reason to pass.
2. Rust. Light surface rust on the foot ring is common. Flaking, pitted rust on the body, especially on the bottom, is not.
3. Fire or heat. Blistered or scorched paint means the tank has been in a fire. Do not buy it at any price.
4. The foot ring and collar. Both should be whole and straight. A bent foot ring makes a tank tip easily.
5. Smell. If you can smell gas around a tank that is supposed to be full, do not put it in your car.
6. Welds or homemade fixes. Any repair on the body rules it out.

Bring a used tank home upright, in a ventilated spot, and do not leave it sitting in a closed car. When you first connect it, check the fitting for bubbles with soapy water, never with a flame. If you are pairing it with a heater, read our guide on using a patio heater on a covered porch first.

Can you exchange an expired propane tank?

Often, yes. Anoka County notes that some stores that sell propane will swap an empty tank without the safe valve for a filled one with it, sometimes for about the price of a refill. Policies vary by store, so ask before you go. This is why an out-of-date tank should be priced close to nothing: its main value is as a trade-in, not as a tank.

That gives you a quick way to judge an asking price:

• In date, safe valve, clean body: worth a fair price, close to what a new tank would cost you.
• Out of date or old valve, otherwise sound: worth only what a swap or requalification costs you.
• Damaged, scorched or leaking: worth nothing. Do not take it, even free.

How do you get rid of an old propane tank in the DC area?

Never put one in the trash or the recycling bin, empty or not. Anoka County warns that an "empty" tank still holds vapor and can explode in a garbage truck. Fairfax County's waste collection team made the same warning in September 2026, after crews were hurt when a compacted gas container exploded, as FFXnow reported.

• First choice everywhere: return or swap it through a propane dealer or exchange rack.
• Montgomery County, Maryland: the county's recycling team advised in a 2014 post that tanks a supplier cannot take back go to the Shady Grove Processing Facility and Transfer Station (16101 Frederick Road, Derwood), whose household hazardous waste drop-off is listed as open daily. Check the county page before you drive.
• Fairfax County and other nearby counties, and DC: use your local household hazardous waste program, and check its accepted-items list first.

The bottom line

A used propane tank is safe to buy when the newest date on the collar is still current, the valve has the three-lobed OPD handle, and the body has no deep dents, heavy rust or fire marks. Read the collar before you hand over money, and price an out-of-date tank as a trade-in. For anything else secondhand that runs on gas or batteries, our recall check guide shows how to look a model up in a minute. You can browse what is on sale now at Buy Now, and questions about how our shop works are answered on our FAQ page.

If someone you know is about to grab a tank off a marketplace listing, send them this before they pay.