I have some stainless steel flex couplers, which I want to weld into my exhaust system (also stainless steel). The exhaust pipes are .060" wall thickness, while the metal on the flex couplers is much thinner. It looks to me that as soon as I start trying to TIG these together, I will just blow away the metal on the coupler.
I have included some pics below, with some numbers (like a little numbering system, for reference sake), so maybe someone can tell me where to focus the heat? Should I be mainly heating on #4 (the pipe) with the goal of attaching to #3 only? Or should I be trying to get all four numbers fused together? It seems like a daunting task and I am a relative noob at TIG.
No practice part available + relative TIG newb + unsuitable actual part + crappy fit-up/gaps = disaster waiting to happen.
Sorry, but while it can be done, I would avoid the headache if I were you. All of those little wires will melt away regardless of where you focus the heat if you don't move them out of the way.
But naturally I've been there too, so here goes. Pull the wire braid back at least 1" (meaning you should also pull up/off that slip ring over it). You will have to get creative for this so it doesn't unravel. Build up the outer circumference of the plain exhaust tube ~1/16" to take up the slack from that grand canyon sized gap (Good luck with this if you don't have a pulser). Then weld the inner flex tube to the exhaust tube as a lap joint. Once that is taken care of, then let the wire braid slip over back in place, along with the slip ring. I can't "feel" the tolerances so hopefully they allow for it.
Oscar wrote:....No practice part available + relative TIG newb + unsuitable actual part + crappy fit-up/gaps = disaster waiting to happen.
Sorry, but while it can be done, I would avoid the headache if I were you. All of those little wires will melt away regardless of where you focus the heat if you don't move them out of the way......
Hahahaha, yeah man, I was thinking all the same thoughts, which is why I posted this thread. I will probably end up buying couplers with pipe stubs already attached.
You don't need the braided cover for your application, so you could take it off. I'm not sure that helps in this case because the fit is still poor. The braid is only needed to allow the bellows to meet a pressure rating, but you're not applying any pressure.
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One thing I've had success with when welding SS thick-to-thin is a fusion weld, but WITH a back purge. I appreciate the woven SS coupler will bleed argon, but you could tape it/cover it with aluminum foil to help. This would allow you to fuse #3 to #4, then #2 to #3, then #1 to #4. It may make controlling the heat required for 1/16" filler easier to manage. A large cup, a generous pre-flow, and a generous post flow will help.
Whatever amps you set, make sure its hot enough to puddle instantly so you don't cook the SS.
Mojo88 wrote:Or should I be trying to get all four numbers fused together? It seems like a daunting task and I am a relative noob at TIG.
These are not that difficult... The pipe should slip inside the flex joint a little distance.
You then just use enough filler to basically weld the whole 'stack' together and create a nice bead that locks it all together. 2.4mm filler tends to be a nice size for this to wet it all out and fill the spaces.
You probably won't be able to get into the 'root' of the connection completely as the gap remains too big there, but in the end you should aim to have the weld bead fully attached to the outer 'ring' in the end.
Just put about 4 to 8 tacks around the join to keep it all in place, get comfortable, purge the back and start welding in sections. Let it cool after each 1/8 section so you don't overheat the part.
I’m with Poland308 on this one. Expand the pipes so they slide over the retaining rings and butt up to the ring collar. Simple fusion weld then that won’t overheat the ring causing it to lose grip on the braid.
