compressor tank failure mode

My compressor use is limited to using a carry tank for filling tires and very small brad-nailing jobs. The tank used to scare me, thinking of the energy contained in 125 lb of compressed air. And now I see that my tank has an "expiration date" (already passed) embossed on it. And I'll get rid of it if it is a danger. But I was thinking--what does happen if the tank fails? It's not like a bomb, where there is a near-instantaneous increase in pressure that tears the tank apart. It seems to me that what is likely to happen is rust will create a thin spot that will eventually fail, releasing rather unspectacularly all the air in the tank.

Is there any safety risk in using an "expired" tank?

Reply to
alexy
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Depends on the condition of the tank. If it is solid, no internal rust, it can last for many more years. I can't see it from here, nor do I know the condition and past use so I'm not going to give my OK. I'd tap it with a hammer at the very least to feel for rust spots. Proper testing is either using ultrasonic equipment or pressure testing.

Reply to
Edwin Pawlowski

I have never heard of an expiration date on a tank. Sounds more like a tactic to generate sales down the road. Typically a tank will eventually rust inside and a pin hole will developed. The hole will leak and it will get bigger.

Reply to
Leon

All three of my 12 gallon storage tanks have expiration dates stamped near the valve. 20 lb. Propane tanks have had them even longer.

Possibly...

More likely, someone sued and stupidity ensued.

Reply to
B A R R Y

Yeah, I am not sure what the OP has. The title talks about "compressor tank failure". Then he mentions carrying around a tank for tires and small nail jobs. I have carried a small tank compressor to a location with no electricity and used it to nail a few pieces of trim. IIRC I have seen dates on the stand alone tanks.

Reply to
Leon

If you are involved with SCUBA or hp gasses you would have heard of them. They show when the tank needs to be inspected (anually) and pressure tested (around every 5 years) if it is a steel tank the falure mode is usually not explosive.

Both ally and steel tanks have been known to last well over 30 years. However as the usual working pressure is around 200 bar they have much stronger walls than most compressor tanks, and the fill is (should be)

0% water so less (0) rust.
Reply to
Jerome Meekings

No doubt, but I was refering to the Compressor tank failure mentioned in the title of the OP thread.

Reply to
Leon

Leon wrote: ...

Virtually positive he's using an old propane tank as a "bubble"...

--

Reply to
dpb

"Jerome Meekings" wrote

Same goes for my box of Wheaties ... and, strangely enough, it has about as much to do with the question posed.

Reply to
Swingman

My compressor, a dual tank Emglo, was purchased in 1987. About 8 years ago it developed leakage around the bottom supports (the rails that hold it off the ground). A friend tried to repair it using a MIG welder, to no avail. Then I posted the problem to some newsgroup or another and someone posted his fix: use epoxy. I did so and am still using that compressor (though I think I'm beginning to hear another leakage hiss).

Reply to
Lee K

That's what my intuition was telling me, but I wanted to test that with the folks here. Thanks.

Reply to
alexy

Sorry for the confusion. I have a small "carry tank" similar to this:

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made the title more general, since I suspect the same issues apply if you mount a compressor on top of the tank or fill it from a gas station's air hose (except that air from the filling station is very wet in my experience).

Reply to
alexy

See link in my reply to Leon.

Reply to
alexy

Thanks, Lee. The important part for me is that it was a "leaking hiss", not a catastrophic failure. My carry tank is cheap enough that I will just replace rather than try to fix it when the time comes. But I am cheap enough not to want to replace it just because of some date stamp, as long as I am not creating a safety hazard.

Reply to
alexy

I used to manufacture tanks to ASME codes. Can't remember an expiration date ever being part of the process. Also did due diligence on a manufacturer of air compressors and then worked in a tool group that included a compressor manufacturer (not the same one). To my knowledge, no expiration dates there.

Hgh pressure dive tanks have an expiration date, that is they have to be visually inspected periodically and then hydrostatically tested periodically or their certification "expires". If they don't pass either one, they are not returned to you. They are dangerous when worn, but normally take 2000 psi or greater.

As far as failure mode on a 125-150 psi working pressure tank, if rust occurs internally then it may cause a slow leak that will get worse until the tank won't hold any more, but not catasrophic. I have seen a poorly seated drain coupling blow out with force but towards the floor.

Frank

Reply to
Frank Boettcher

If you use it in a business with other folks around, you might consider replacing to limit your liability regardless of how well you believe the repairs have been done. The ASME code certification is invalidated by repair to the tank without opening a new code certification which can be done, but not worth the cost on that type of tank. Very small chance of any injury, but it could blow a fitting or a glob of rust/epoxy.

if you use it for personal use then it doesn't really matter that much if you are confident of the repairs.

Frank

Reply to
Frank Boettcher

Uh, wrong, certain small sizes are exempt but larger tanks (depending on capacity and dimensions) have expiration dates including scuba tanks, airgun tanks and so on. Metal tanks are usually good for five years between hydro recerts, fiber-wrapped tanks from three to five years depending on the design. Fiber-wrapped tanks can only be recertified three times and then have to be destroyed, but all-metal tanks are good so long as they pass inspection and testing, I've seen fifty-pound CO2 tanks with the earliest markings being WWII-era. In the U.S. this is federal DOT law BTW, although you'll also find additional local requirements, e.g. there are states where you can't get a scuba tank refilled if it doesn't have an annual interior visual inspection sticker even if it has a current hydro-test certificate.

Tanks generally don't develop pinhole leaks that eventually get larger, when they fail they fail suddenly and usually catastrophically. If you don't believe any of that get down to your local scuba shop and ask them, they get bulletins on tank failures and can show you photos.

Reply to
DGDevin

You are talking HIGH PRESSURE tanks. Normal compressor tanks run 150psi max and I've never had one hydrotested. My current tank has a hydrotest date on it because it held propane for over 20 years, then sat for several years before being put into service as an air compressor tank. We had a 30 year old truck fuel tank (round saddle tank)that we used as an air tank for over 10 years that did rust through at the bottom. It was brazed twice before we stopped using it (I think one of the guys took it home to use - was at our car club at the time) In the ten years I was service manager at the Toyota dealership the 80 gallon tank was never recertified, and it was the same tank that had been hanging on the wall10 years earlier when I worked in the same shop as a mechanic.

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Reply to
clare at snyder dot ontario do

Find me a typical shop compressor tank that gets anywhere near 2000PSI and I'll worry about it. At 125PSI, there will be no catastrophic failure.

scott

Reply to
Scott Lurndal

What is up with the friggin scuba tanks????????????? We are talking low pressure compressor air tanks. And yes those get pin hole leaks and leak, been there done that.

Reply to
Leon

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