HELP! SS MIG welding

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. 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. 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.
Reply to
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The last time I looked, kegs were movable. ;) (OK, so that was 30 years ago last July, but...)
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.
Best of luck.
Reply to
Larry Jaques
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
Reply to
I have not tried using stainless backup flux, but it might be what you need. Superior Flux no 9 is one. The other is Solar Flux. Might solve your problem with having adequate shielding.
One problem is that the flux is expensive. The Superior No. 9 is slightly less expensive.
I have considered mixing up my own flux , but have no real need.
Reply to
Could you make a filler piece to go in the space and then weld over that? Or make a hood out of aluminum foil to surround the area on one side, flood that with gas and stick the tungsten way out to reach into the gap. Then put the hood on the other side to finish?
Reply to
Steve W.
Reply to
Larry Jaques
You just need gas in the area you're welding for shielding. It doesn't matter how you get it there. Listen to Steve and make some sort of device to direct/keep shielding gas where you are welding and then use TIG with a long stickout. Just another hose "Y'd" off your flow regulator to some sort of fabbed nozzle should work.
Argon is heavier than air so it tends to sink. When I was MIG welding inside cavity like things I would back way off on shielding gas flow rate to save gas. You just didn't need much added gas once the cavity was "full".
Put your filler rod in place before hand and use "lay wire" method.
Reply to
Leon Fisk

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