On Sat, 12 Sep 2015 17:29:26 -0700, wrote:

On Sat, 12 Sep 2015 16:18:17 -0700, Larry Jaques
wrote:

On Sat, 12 Sep 2015 15:07:39 -0700, wrote:

I need to MIG weld a stainless part. I have a Lincoln SP125+ welder,
C25 , CO2, and argon gasses. I have 308L wire. I can't tig this
because I cannot get the tig torch into the tight space. The welding
is being done on a beer keg.

The last time I looked, kegs were movable.
(OK, so that was 30 years ago last July, but...)


At the top of the keg is a valve that has
had the innards removed so now it is just a sleeve poking out of the
keg top. Into the side of this sleeve I put a hole to accept the OD of
a 3/4 pipe nipple. This nipple needs to be welded into the sleeve. I
welded all the way around the nipple on the inside of the sleeve but
the customer also wants the sleeve welded on the outside. The problem
is that the pipe nipple is practically tangent to the domed top of the
keg. I tried TIGging the nipple all the way around but can't get the
tungsten into the really tight space where the nipple side practically
touches the keg. I could do this with MIG though.

If you can get a MIG tip in there, why wouldn't a TIG gas lens with
extended electrode work, Eric? You know, a short electrode with the
tiny back cover? It seems like that might even be a smaller footprint
than MIG. Or is it a difference in angles which causes the bad fit?
Just curious.
I can get wire in the space but with the tungsten hanging out that
far, even with a gas lens, there is not good enough shielding. But
wire takes up much less space so there is room. Remember, with TIG you
need to get the tungsten and the filler wire at the same spot but
coming from different directions. I may need to fab up a custom cup
for the mig, just a copper collar to go around the stock one, in order
to get the proper ESO, but I don't think so. I cannot fab up a custon
ceramic TIG cup though.
Eric

Reading online at
the Lincoln website I should be using no more than 3 % CO2 mixed with
argon to do the weld. Pure argon is advised against. Will C25 really
not work? This weld is really cosmetic because the internal weld is a
good weld. The finished product will be part of a still for a new
micro distillery and so it must look good. This is why the customer
wants the outside weld and the customer is always right. Since the
still will be used as part of a legal operation it will be showed off
and may lead to other work. I am going to try to convince the customer
to change the plumbing in the future but right now this one needs to
be done the way the customer is asking.

Best of luck.

https://www.youtube.com/watch?v=KVBnkAI3VCc

https://www.youtube.com/watch?v=q0pCir2hmhk

http://www.weldingtipsandtricks.com/...ig-torches.jpg