Methods to tig welding SS exhaust
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  1. #1
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    Methods to tig welding SS exhaust

    what is the proper way to TIG a SS exhaust? fusion weld? run a bead with filler? or fusion first then run a bead over?

    yesterday i was trying to make a SS cup (yes, a cup). the cylinder was thin gauge SS and the bottom was a flange cap that came off equipment. i had to get full penetration so bacteria wouldnt grow in there. my stepfather told me to fusion weld it but of course i didnt listen. i tried to do the weld with 3/32 filler while attempting to get full pen and ended up over cooking the weld and ruined the project for me.

    as an example my stepfather walked a fusion bead around the other half as an example. didnt get full pen the whole way because i think he backed off the pedal but it still did a better job than me with a 3/32 trying to melt both the rod and the base metal all the way.

    if this were a car exhaust with a V-band what wouldve been the proper way to weld this? i understand that full pen doesnt matter as much on exhausts than it does on food stuff. would you fusion it first THEN add filler afterwards?

    sorry for the long read

  2. #2
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    Re: Methods to tig welding SS exhaust

    Fusion if you can get a 100% tight fit. You need to back gas or block gas with a backing bar (aluminum or copper). THen you can ad a littlemore heat and not burn the backside, this gets full penetration with ease on thinwall. There are also backing compounds like Solarflux where back gas isn't practical. I've added filler in most cases because full tight fit isn't easy on some shapes, this added material helps gill any gap that forms as the metal heats from welding. Both are good, but no filler fusion requires more skill in setup and execution. It also usually looks better.

  3. #3
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    Re: Methods to tig welding SS exhaust

    I always add filler for these. The only time I wouldn't is for a tack to hold it in place. 1 pass with filler. Backpurge. done
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  4. #4
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    Re: Methods to tig welding SS exhaust

    The way it is done for fittings on tanks is a fit-up that is melted into a weld, if that makes sense. You have two flanges next to each other proud of the joint (sticking out like a "T") and you fuse them down into a weldment. Called an "edge flange," maybe?
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  5. #5
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    Re: Methods to tig welding SS exhaust

    A V-band has a ring to be used for filler when welding. Pipe to pipe joints should have filler as many times an autogenous weld on thin ss material hooked to a vibrating engine will crack.

    I only use autogenous welds for pretty art. Anything that needs to hold together I use filler. Unless the joint is designed with extra material like the V-band to be used as "filler".
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  6. #6
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    Re: Methods to tig welding SS exhaust

    You have to run a back purge on stainless. Put a small bevel on both sides and run a fusion bead, add wire as needed. When your puddle starts swirling, you're getting penetration. Then put a cap on it.

    3 inch schedule 10 stainless pipe welds, fusion root - pipe rolled on positioner:


  7. #7
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by TimmyTIG View Post
    You have to run a back purge on stainless. Put a small bevel on both sides and run a fusion bead, add wire as needed. When your puddle starts swirling, you're getting penetration. Then put a cap on it.

    3 inch schedule 10 stainless pipe welds, fusion root - pipe rolled on positioner:

    would you go back with a bead cap with filler?

    for an exhaust what would be the proper way? would a fusion weld crack on an exhaust because of lack of material?

  8. #8
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    Re: Methods to tig welding SS exhaust

    When I do it like that it comes out below flush, so you have to put a cap on it, to meet code. You probably could get away without it on a car exhaust.

  9. #9
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    Re: Methods to tig welding SS exhaust

    Timmy I think he is on 16 gauge. 1 pass with filler and it's done

  10. #10
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    Re: Methods to tig welding SS exhaust

    I do quite a lot of stainless exhaust work and I still struggle to get nice consistent beads on the thin stuff.

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  11. #11
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by VPT View Post
    I do quite a lot of stainless exhaust work and I still struggle to get nice consistent beads on the thin stuff.

    Where do you get the flared ends to use on the vee band clamp?

  12. #12
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    Re: Methods to tig welding SS exhaust

    You'll want to use smaller filler wire. It's nothing but a headache you try to weld something with filler wire thicker than the actual part.

  13. #13
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    Re: Methods to tig welding SS exhaust

    On thin stainless butt welds 16 gauge and thinner, I run no bevel, slight autonomous tacks, purge 8 times volume. Then when ready to weld, gently build a bead, then drive it into the joint resulting in some melt-thru. Keep moving forward adding filler to the bead not the seam, and keep driving the puddle to maintain melt-thru. It takes some skill and speed to do this but it is how it is done. If you try to add filler to the seam and not the puddle you risk key-holing.

    I do the same on every metal including alum and magnesium. Some metals do not require backpurge, but the welding technique is the same. Care must be taken however to not use too big a filler as when crammed in it will freeze the puddle slightly and upon removing can cause some suck-back.
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  14. #14
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by shovelon View Post
    On thin stainless butt welds 16 gauge and thinner, I run no bevel, slight autonomous tacks, purge 8 times volume. Then when ready to weld, gently build a bead, then drive it into the joint resulting in some melt-thru. Keep moving forward adding filler to the bead not the seam, and keep driving the puddle to maintain melt-thru. It takes some skill and speed to do this but it is how it is done. If you try to add filler to the seam and not the puddle you risk key-holing.

    I do the same on every metal including alum and magnesium. Some metals do not require backpurge, but the welding technique is the same. Care must be taken however to not use too big a filler as when crammed in it will freeze the puddle slightly and upon removing can cause some suck-back.
    Shovels,

    So these tacks you're putting on have the right or power of self-governance?

    Auto-correct must have struck again because I'm guessing you meant "autogenous".

  15. #15
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by HT2-4956 View Post
    Shovels,

    So these tacks you're putting on have the right or power of self-governance?

    Auto-correct must have struck again because I'm guessing you meant "autogenous".
    Dang auto-correct!

    Yes, endogenous. $#@*(&^$$^^-------autogenous!
    Weld like a "WELDOR", not a wel-"DERR"
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  16. #16
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by M J D View Post
    Where do you get the flared ends to use on the vee band clamp?
    These V-bands were customer supplied. The V-bands come complete so I normally don't have to look for just the flares. However some cars like the Audi R8 have a weird size V-band so I had to turn up my own on the lathe. When I buy them I honestly normally get them off ebay as they are normally the cheapest. I can also then mix and match so I can go from stainless to aluminum and the like.



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  17. #17
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by VPT View Post
    These V-bands were customer supplied. The V-bands come complete so I normally don't have to look for just the flares. However some cars like the Audi R8 have a weird size V-band so I had to turn up my own on the lathe. When I buy them I honestly normally get them off ebay as they are normally the cheapest. I can also then mix and match so I can go from stainless to aluminum and the like.



    I had Checks make some for me. They can do 3" , but they couldn't get the flare as big as what I had. I used a round gasket, kind of like a metal O ring between pipe and manifold to get a seal.

  18. #18
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by M J D View Post
    I had Checks make some for me. They can do 3" , but they couldn't get the flare as big as what I had. I used a round gasket, kind of like a metal O ring between pipe and manifold to get a seal.


    Ah. Yes the V-bands I use normally don't have any seal as the two halves are machined to fit perfectly with each other. The aluminum ones sometimes comes with an o-ring because they get used on theintake side of boosted cars and need to seal up well.

    I am working on a car now that has some new ball and socket type connection. It is a separate piece machined ball and then each side of the exhaust is a socket. Different than that old style formed ball and socket on the pipe itself. It allows the joint to be off-strait and still seal up. So far I am not much of a fan as it has a few different pieces that have to get put together at one time.
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  19. #19
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    Re: Methods to tig welding SS exhaust

    I have seen that style before, sounds good in theory. Normally the flares with vee bands seal pretty well. Donaldson makes a few of the flare flanges, but no one stocks them and they are $$$.

  20. #20
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    Re: Methods to tig welding SS exhaust

    I also get my V-bands off eBay. If the fitup is good, there aren't problems, but if there is a gap (pipe is undersized) it can get messy fast with thin wall stuff.

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    That's 409 tubing and 304 fittings welded with 309L.

    If you're worried about vibratory cracking, the trick some folks use in high end racing applications for flanges is welding the inside and then running a TIG brazed fillet of silicon bronze on the outside.
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  21. #21
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    Re: Methods to tig welding SS exhaust

    Would you believe no one makes an oval V-band. :/

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  22. #22
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    Re: Methods to tig welding SS exhaust

    Maybe u could buy Cnc mill and sell them. Do you back purge your exuast systems? Had luck with sola flux b?

  23. #23
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    Re: Methods to tig welding SS exhaust

    I may be running oval with my next setup (twin turbos) and I was going to use the oval to round stubs in order to use v-bands. Burns, SPD, etc. all have them. After having v-bands so you can drop the exhaust in five minutes to drop the transmission I'll never go back to slip joints or clamps! With the exception of the double slip expansion joints - those are trick!
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  24. #24
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by motolife313 View Post
    Maybe u could buy Cnc mill and sell them. Do you back purge your exuast systems? Had luck with sola flux b?

    Think I can pull it off on my manual mill?

    I only backpurge headers/manifolds. Also never used any flux, just clean and weld.
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  25. #25
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    Re: Methods to tig welding SS exhaust

    Quote Originally Posted by Rick Finsta View Post
    I may be running oval with my next setup (twin turbos) and I was going to use the oval to round stubs in order to use v-bands. Burns, SPD, etc. all have them. After having v-bands so you can drop the exhaust in five minutes to drop the transmission I'll never go back to slip joints or clamps! With the exception of the double slip expansion joints - those are trick!
    Oval is very unforgiving. Every bend has to be spot on or it looks like crap. On the firebird we used oval for two reasons, ground clearance and over the rear axle clearance because the guy was running a watts link.

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