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jlc904 12-24-2011 12:20 PM

welding stainless question
 
I have a Lincoln Electric 140 wire feed welder. I have some welding to do on a couple Sanke kegs. I am trying to figure out what kind of wire to use and what process will work best (do I need to use shielding gas or just wire). Does anyone know what kind of stainless steel they make kegs out of? Thanks

kevink 12-24-2011 01:34 PM

They're 304SS. TIG is really better suited for welding kegs. Maybe someone with a LOT of experience in MIG welding thin stainless could do an OK job, but even he would rather use TIG than MIG. Have you ever welded stainless before? Do you have a practice keg?

dmfa200 12-24-2011 01:46 PM

This is a good reference

Miller - Welding Calculators

I could be wrong but kegs are probably 304 stainless.
Keg wall thickness is about .050" so that's around 18ga
You will need 308L wire for 304 stainless, and yes on shielding gas.
The calculator says to use a Tri-mix gas.
On thin material a short circuiting arc is used. On thicker material a spray arc is used.

During a short circuiting arc the wire actually comes in contact with the metal being welded an arc is created melts a small droplet of filler and it is deposited on the base metal. Because we use electricity in the US @ 60Hz this happens 60 times a second.

During a spray arc the wire is being melted before it even reaches the base metal. As the wire is being burned, very fine droplets are formed, and they transfer across the arc and onto the metal being welded. Spray arc will produce a smoother weld appearance than a short circuiting arc.
This process is suited for thicker materials in the flat position

Tig welding would be the best process, but if Mig is your choice than I suggest practicing on the tops of the kegs after you've cut them out to get a feel for how stainless wire welds. It's not the same as carbon steel.

outside92129 12-24-2011 03:19 PM

I have a lincoln 140c and used 308L .023 wire with C25/75 gas. Mig with C25/75 is not ideal, stainless is totally different than mild, but the welds are holding up and aren't rusting. Expect lots of spatter and welds that will look like crap. Definitely practice first, SS really surprised the heck out of me when i first worked on it. With the 140C i think i cranked the voltage to max(j) and used wirespeed 5-6. You need to have gas, otherwise your welds will look like a sponge.

I got this from a welding forum and a guy referenced lincoln's website:

"The shielding gas recommended for short-circuiting welding of stainless-steel contains 90% helium, 7.5% argon, and 2.5% carbon dioxide. The gas gives the most desirable bead contour while keeping the CO2 level low enough so that it does not influence the corrosion resistance of the metal. High inductance in the output is beneficial when using this gas mixture.

Single-pass welds may also be made by using argon-CO2 gas. The CO2 in the shielding gas will affect the corrosion resistance of multipass welds made with short-circuiting transfer."
"Gases for pulsed arc welding are argon plus 1% oxygen, the same as used for spray arc welding."

jlc904 12-24-2011 05:00 PM

Quote:

Originally Posted by kevink (Post 3598136)
They're 304SS. TIG is really better suited for welding kegs. Maybe someone with a LOT of experience in MIG welding thin stainless could do an OK job, but even he would rather use TIG than MIG. Have you ever welded stainless before? Do you have a practice keg?

I am somewhat experienced mig welder but have never welded s.s. I do have a practice keg.

Flomaster 12-24-2011 05:24 PM

I wouldn't even think about using a MIG on SS keg and couplers. TIG is really the way to go with this type of thing.

maybe if you were welding 1/2" plates of SS together it would be alright.

-=Jason=-

jlc904 12-24-2011 05:35 PM

Quote:

Originally Posted by Flomaster (Post 3598570)
I wouldn't even think about using a MIG on SS keg and couplers. TIG is really the way to go with this type of thing.

maybe if you were welding 1/2" plates of SS together it would be alright.

-=Jason=-

I have two kegs that I am trying to fix. One has about a 1/2 hole in the very bottom I want to patch. The other had a hole as well. It has been welded but the weld cracked. It might be pretty easy to fix it.

dmfa200 12-24-2011 06:12 PM

How about welding in a half coupling where the hole is and making it a bottom drain.
I think that would be a better fix than trying to plug the hole with weld.

Kyled93 12-24-2011 07:21 PM

I agree to that. Trying to fix a broken weld can be difficult due to it being stainless and it's location. Why not find another keg?


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