Stainless Steel with helium shield gas.

[Pangea]

I have a special assignment coming up and the requirement calls for helium instead of argon for my shielding gas. Now I've used helium for many years to DCEN aluminum and even been lazy enough to not change over bottles to weld some steel with the helium but this new task is something out of the ordinary. I've never seen a welding requirement for helium on stainless. This is at the NASA and you'd hope that they would know what they needed. The engineer claims that argon would introduce a contamination to the system. Must be a helium system I'll be welding on.

[vicegrip]

Oddly I have just been wondering about trying just that.

I use 420 SS filler to build-up broken bolts.
And on tooling of unknown alloy and/or hardness.

I can't allways preheat an entire component.
Focussing an argon arc to heat a region, is a tad too
pointed, Maybe the nice wide hot cone from Helium
would help. But then would it be a good weld?
Or just a brain-fart.
vg

[LittleJohnDeere]

Didn't the term heliarc come from that - helium arc? I think I read somewhere that Airco started it and their welder was called the Heliarc.

The funny thing about a lot of engineers is their ego. They are like doctors and didn't learn how to say "I don't know," in school. However, they are part of the spoke in the wheel. Maybe this guy doesn't have your expertise and knowledge of welding processes and his ego won't let him admit it. Maybe you could coach him a little, not sure of your situation though.

[usmcpop]

Check out the entries for the 1920's and the 1940's here: http://www.weldinginfocenter.com/history/his_01.html

Gas tungsten arc welding (GTAW) had its beginnings from an idea by C.L. Coffin to weld in a nonoxidizing gas atmosphere, which he patented in 1890. The concept was further refined in the late 1920s by H.M.Hobart, who used helium for shielding, and P.K. Devers, who used argon. This process was ideal for welding magnesium and also for welding stainless and aluminum. It was perfected in 1941, patented by Meredith, and named Heliarc® welding. It was later licensed to Linde Air Products, where the water-cooled torch was developed.

Here's a Heliarc setup from 1942 from an old Pop Science magazine:

[taylorkh]

As this thread has morphed in to a walk down memory lane... Here is a video of how welding was done in 1942 http://www.archive.org/details/WeldingO1942

Ken

[usmcpop]

Oh, sorry, that was a recent pic of Vicegrip. I don't know where the old pic went.

[urch55]

Oh, sorry, that was a recent pic of Vicegrip. I don't know where the old pic went.

Pops, I bet you could not keep a straight face while you were typing.

[kcd616]

Pops, I bet you could not keep a straight face while you were typing.

To be serious, even though that was funny. And was probably a pic of someone I know and welded with
Helium is tough to weld with due to it much lighter than air, and to use it for a shielding gas for anything but overhead means you need to run way MORE gas than argon to get a good shield.
The reason why it was heliarc to start with was helium was easier to bottle and get pure.
I think chemistry bears out again.
Sincerely,
Kent

[usmcpop]

Pangea,

Could the Helium requirement be a matter of the available purity of the gas?

[Pangea]

Pangea,

Could the Helium requirement be a matter of the available purity of the gas?

No it seems that the gas issue has to do with the system being welded on. Either it has sensors vulnerable to Argon or the apparatus can't have any argon introduced into it.

[flamin]

Here is a tidbit I found in one of my books, regarding helium shielding gas with GTAW on SS. I've never personally used straight helium with stainless, so I can't personally make any comparisons.

"For equal arc lengths and welding currents, the tungsten arc voltage in helium will be about 50% higher than the tungsten arc voltage in argon. While this permits more uniform joint penetration and higher welding speed, it also limits the use of this combination to thick sections (14ga-.074" or thicker)."

[donald branscom]

Helium gas usually increases penetration on thick sections.
What is the welding process being used?