Tig with the wrong gas....sigh

He gets his mail sent here! But, we have developed Murphy repellent!

Reply to
Tom Gardner
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It would be rather difficult for the gas to be "too wrong." Different fittings are used for different gasses. Combinations of left and right hand threads, male and female fittings, that goofy flat fitting that needs a gasket that's used with CO2, etc. One style is used for fuel gasses (acetylene, propane, etc.), another for oxygen, another for inert gasses (argon, helium, C25, etc.). So, it would be easy to get the wrong inert gas, but it will be inert. It won't be fuel or oxygen.

Jerry

Reply to
Jerry Foster

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Sadly, it does happen, usually with some 'help' from a person who 'fixes' the incompatible fittings.

Stuart

Reply to
Stuart Wheaton

Reply to
Dave Hinz

According to Leo Lichtman :

And you shouldn't be able to get the regulator into the bottle. (Or the filling shop should not have been able to get the original connections to mate up to be able to fill it with oxygen. To make that kind of misfill -- a whole *lot* of things would have to go wrong at the same time.

Enjoy, DoN.

Reply to
DoN. Nichols

According to Doug Miller :

What about just pure HP oxygen plus a regulator which has been lubricated with a petroleum based oil? That might go off before you ever got things as far as trying to weld. (Of course -- this is assuming that enough things could have gone wrong at the same time to have oxygen in a tank with a valve which would fit an inert gas regulator. :-)

Enjoy, DoN.

Reply to
DoN. Nichols

Note that, in every case cited, someone changed the fitting on a cryogenic vessel. Were someone to attempt to change the valve/fitting on a bottle of, say, compressed argon, the results would have been rather spectacular...

Jerry

Reply to
Jerry Foster

I think it would have been very spectacular, very quickly, and the outcome depends on how fast the welder realized something was going TERRIBLY wrong, and got the torch away from the hot metal (and himself). I could easily envision the whole torch handle going up in a giant white ball of flame, followed by the "shield gas" hose burning back to the regulator. I heard the description of what happened when a guy was refilling a portable O2 bottle from a large tank, and some greasy crud on the outside of the bottle caught fire due to a small O2 leak. He had just enough time to scream "get OUT, oxygen explosion" and people dived out the windows before the building blew up.

If the welder could have gotten the O2 shut off quickly, like hit the off button on the welder, cutting off the shield gas postflow pronto, and assuming the regulator, hoses, solenoid valve somehow were actually oxygen-safe, then it might just be one of those "Geeezz - will you look at that mess!" moments. If a serious O2 fire developed and got into the regulator, the whole shop would have blown up.

Jon

Reply to
Jon Elson

What about the electrode, electrode collet, tig torch head, and the workpiece metal? Do you know what happens when you combine pure oxygen with hot metal? Think of a cutting torch. But, of course, a cutting torch is designed to have a high gas velocity at the tip, so that a jet of O2 blows the fireworks away from the operator and the torch. The TIG torch has a very LOW velocity of gas over a wider area. The metal will almost certainly burn, damn near ANYTHING will, including porcelain, glass, asbestos, concrete, etc. in a pure oxygen environment. Also, the TIG torch and plumbing are not made "Oxygen safe" as they are not supposed to be exposed to anything with a high O2 concentration. You'll get slag, of course, after things cool off, but in the presence of pure O2, you will get showers of sparks flying all over the place, and I am willing to guarantee the TIG torch will catch fire and burn furiously as long as the O2 is flowing.

Jon

Reply to
Jon Elson

"Jon Elson" wrote: (clip) The metal will almost certainly burn, damn near ANYTHING will, including porcelain, glass, asbestos, concrete, etc. in a pure oxygen environment. (clip) ^^^^^^^^^^^^^^^^^ Jon, your poor understanding of chemistry is leading you to make statements so outrageously exaggerated that your credibility is lost. The things you mention in the above quote won't burn in ANY environment. Glass and porcelain, for example, are fused silicon dioxide--already combined with oxygen, and therefore INCOMBUSTIBLE.

Reply to
Leo Lichtman

I think someone has the wrong idea about oxygen here. Oxygen does NOT burn, it oxydizes. It must have FUEL to produce combustion. Therefore, unless the inside of the oxygen hose is a ready fuel, which is highly unlikely, there isn't much chance of an "oxygen explosion". If you WERE to get oxygen out of the shield gas nozzle and combustion took p[lace on the metal that was being welded, simply moving the welding handle away would stop any fire. If you don't believe what I say, ask an instructor at your local fire academy.

Jim Chandler

Reply to
Jim Chandler

And the fittings are specifically designed to be incompatible PRECISELY to get someone's attention that they might be doing something seriously wrong - and there are more than likely dozens more instances of gas mix-ups each year that do not get reported, because nobody died and they weren't forced to...

Note that for most of the reported incidents they had a "maintenance person" (Janitor) changing the cylinders. Sounds like there needs to be a training standard in place - a card from the gas supplier certifying the employee has been shown what to do and what NOT to do, and they have a clue. That you STOP if the fittings don't match, you DO NOT try to make them fit.

Ahh, but when you try to make any system idiot proof, nature develops a better and more resourceful idiot.

If the idiot trying to use the wrong cylinder just happened to watch the right episode of MythBusters and is just smart enough to realize the results of removing the valve on a full high pressure gas cylinder ("For every action there is an equal and opposite reaction...") he'll cobble up an adapter.

Or go get another whip hose with the right connector for the cylinder valve and change it out.

Time for another dose of chlorine in the Gene Pool...

-->--

Reply to
Bruce L. Bergman

And of course the TIG would have pure oxygen in a flammable line.....

And let us not forget the multi second preflow with oxygen and then the HF arc kicks in...BOOM?

TMT

Reply to
Too_Many_Tools

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