Re: s'less TIG welding - "tank" vs. back-purge

In article <[EMAIL PROTECTED]>,
Richard Smith <[EMAIL PROTECTED]> wrote:

> s'less welding in a "box" filled with Argon - fanciful or practical?
> 


I just got through building one for myself.
I built it for stainless fittings I weld up for breweries, and for
students of mine to use at school for welding Stainless and titanium.


> My intention is to start a TIG welding business doing stainless steel as 
> my regular work.
> 

Best of luck.
Better make sure there is a need in your area.
Don't just asume that you are the only guy to think this up.
I say this because it has taken me 7 years to get a decent client list
to stay afloat.


> "Penetration" stainless welds with just the torch argon supply look 
> horrible underneath (fillet welds are fine with no other protection? - 
> they look so if you don't melt through the thickness of the sheets being 
> joined).
> 

You can use a foil backing tape or SolarFlux to reduce the scorching.


> There is back-purge.  You would certainly do that for a long butt or 
> corner-joint.
> 
> For more complex shapes which are not long, such as s'less kitchen and 
> household objects, back-purge is less easy to apply (?) while OTOH the 
> entire object could be welded in a "box" full of Argon.
> 

I have a pile of purging widgets, from long purge backers for straight
weld (3", 6", 9", 12") and a bunch of large jets made from #3 series
wide mouth gas lenses.
Always coming up with new ones as well.


> That "crozzle" which you get on the top bead even when correctly using 
> torch shielding -- how is that affected by working in a tank?  Do you 
> have less cleaning to do if you weld in Argon?
> 

"crozzle"?
I have never heard that term used.

No matter what, if you weld inside an argon filled glove-box you will
get no oxidation of either side of the weld.




> Do people have arrangements where they have an air-lock and pass sheet 
> metal in and finished objects out, thereby limiting the amount of 
> shielding gas used?
> 

Mine is a simple acrylic box hinged at the back to a heavy aluminum
base plate.
To use you lift the box and place your parts inside, hit the argon flow
and wait about 5 minutes for the argon to purge the air.
Then just weld.

To get ebnough argon flow to purge the box, I swapped the tank
connector from a flow-gauge to a oxygen regulator so I can run the
argon at 40 psi.


> There is Ar/H gas mixes for s'less.  If find the market's there, could 
> imagine having two types of gas (pure Ar for all other purposes).  Have 
> never seen these, but if Hydrogen does for s'less TIG penetration and 
> heat what it does for "stick" (SMA) it must be useful (?).  Are there 
> any issues to using Ar/5%H with a "box"/"tank"?
> 

Argon/Helium mixes are common for TIG.
I prefer to have a tank of each and simply add helium in when I need it

Hydrogen is never used for TIG welding.

> 
> (there's an adddition advantage to welding in a "box"/"tank" - I don't 
> have a dedicated workshop at present and it would be useful to make the 
> welding unintrusive to those around)
> 
> 
> Richard Smith
> 

The arc shines through mine in all directions, but you could make one
from sheet metal with a window on one side.