Leaking argon cylinder?? Help please

Primetime · Feb 4, 2014

I'm trying to hook up a fresh argon cylinder to my TIG welder, and I feel like pulling my hair out right now. There's a very audible hiss, and you can even feel a slight leak around the threads where the regulator attaches to the cylinder. Pressure only reads about 1800 PSI, and this is a fresh cylinder. I even tried switching out regulators, and I had the same result. Tried cleaning the fittings on both the cylinder and my regulator, same result, it still leaks.

I've never experienced this before, BUT I've only switched cylinders out maybe six times

So if I'm doing something wrong, please enlighten me... Because I'd rather hear it on here than try to return a "defective" cylinder and look like a fool for not knowing how to hook a cylinder up

I just don't remember ever reading about anything like this happening.

Thanks in advance...

papasmirf · Feb 4, 2014

I've had acetylene and hydrogen bottles leak the same way. I think after a bottle has been used dozens of time the threads get distorted (stretched) and same with the flares of the regulators. I've had to really chow down on some of them. I may should have use some sealant but didn't like the idea of screwing up my regulators.

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drujinin · Feb 4, 2014

Teflon tape on the flair, three turns/wraps is usually enough.

vwguy3 · Feb 4, 2014

Tape/paste will do nothing on a CGA 580 fitting.
Take the cyl back to the supplier and have them exchange it for you.

rlitman · Feb 4, 2014

And bring your regulator with you.

Do NOT put anything on the threads. The threads do not make the seal.
On a CGA-580, the seal is between the mating cone shaped flare surfaces. If there is a deep scratch in either one of them, that would make a leak. If the damage is in the cylinder's valve, the supplier should replace it. If the damage is in the stem of your regulator, you can buy a replacement.

With CGA-580, there are two styles of regulator stems.
One has a brass nut that must be tightened with a wrench, and that is what is found on most welding regulators. Those require a lot of force, because they seal metal-to-metal.
The other type has a large plastic hand wheel. Those are meant to be hand tightened, because the face of the regulator's seating surface has an o-ring which forms the seal. These are much less likely to leak when the tank seat is iffy, because the o-ring can conform to the shape. Since these are popular for helium balloon regulator use, I would expect them to seal at least as well as the wrench fit ones (if helium doesn't leak, nothing does).

So, have your LWS look at the valve AND your regulator. If the problem is with the valve, they'll replace the cylinder for you. If it is with your regulator, either they'll have a replacement stem (if you're lucky), or they can order one (and they'll know how to install it). And if you need a stem, I suggest you get the o-ring seated one as a replacement if you can easily (and affordably).

papasmirf · Feb 4, 2014

I know this sounds that it should be a given thought, but try cleaning both fittings.

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RodJ · Feb 4, 2014

Do you crack the valve first to blow out any debris that might be right at the bottom of the fitting? You've already cleaned the fittings and tried other regulators, so if it continues, take the cylinder back along with your regulator(s) and have both inspected.

I have to remind myself that argon can kill. Just fill up a room with it and try to breath.

Meltedmetal · Feb 4, 2014

Take a look at the seat in the valve, where your regulator should seal. It may have been damaged by someone, before you, screwing in and over tightening a damaged regulator/flow meter. If it is damaged it may damage your regulator. And yes check for foreign material in the valve.---Meltedmetal

BD1 · Feb 4, 2014

Return to supplier with tank and regulator for their inspection.

walkerweld · Feb 4, 2014

That is the only realistic solution in this case.
If you did not have a leak with a previous cylinder, and now you do have a leak, even with different regulators, the problem lies with the seating surface of the regulator receiver port on the cylinder valve.
And putting tape or pipe dope on mounting threads is futile, the threads are not part of the sealing/seating surfaces. The threads only serve to provide the compression force that holds the regulator entrance pipe securely against the receiver port seat of the cylinder supply valve assembly. Putting tape or pipe dope on the actual seating surfaces will not accomplish anything as the high pressure of the gas in the cylinder will bludgeon its way right through. Applying tape or dope to the same on an OXYGEN cylinder WILL result in an explosion.

Primetime · Feb 4, 2014

Thanks for the suggestions everyone. I had tried teflon tape, obviously that didn't help. I always crack the valve before hooking the regulator up, and I retried that a couple times once I discovered the leak, no effect. Tried cleaning both sealing surfaces, no effect. This was all before I came on here asking for help.

So it looks like I'll be returning the cylinder after all, thanks for the suggestions to bring a regulator with as I hadn't considered that.

lowcountrydigger · Mar 7, 2014

I have used anti seize (never seize) to stop a leak on damaged valves.
Just paint a modest amount on the valve where it seals (male and female) tighten it down real good and have at it, worked for me.

rlitman · Mar 7, 2014

I would never recommend applying anything to a leaking valve stem. Using such advice on an oxygen cylinder can easily lead to things like death, dismemberment, etc.

Leaking argon cylinder?? Help please

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