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Welding stainless exhaust pipe

montrose818

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Got some flux core stainles wire but it only came in .35, reading people say it will burn through exhaust. I dont have a lot of stainless to practice on to test it. Can I tack it and then oxy acetylene in? Or is tig the only way to do it right?

Thank you
 
montrose818 said:
Got some flux core stainles wire but it only came in .35, reading people say it will burn through exhaust. I dont have a lot of stainless to practice on to test it. Can I tack it and then oxy acetylene in? Or is tig the only way to do it right?

Thank you
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If you TIG it you will want to purge it.

I would think that the only thing that wire is good for is plate welding and the like.

Someone will likely come along and inform you that I am an idiot though:laughing:
 
You will have a lot of difficulty trying to use the 035 on SS without blowing through it. Best to tack with the wire, then tig the rest.
 
TrikeKid said:
Depends on what kind of stainless it is but I've welded plenty of "stainless" mufflers and resonators in with normal wire.
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This.

And I've welded a hell of a lot of exhaust with .035 too. It's a bitch but doable, easier if it's all slip fit connections (and therefore lap joints).
 
Lilyota said:
If you TIG it you will want to purge it.

I would think that the only thing that wire is good for is plate welding and the like.

Someone will likely come along and inform you that I am an idiot though:laughing:
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you sir....are an idiot:laughing:

shape of what is being welded has nothing to do with wire size

a 'normal' auto exhaust has so many corners cut, even the 'pro shops' just melt it together...it is all going to rust out anyway
 
Yea, roll of stainless MIG wire, still run C25 (trimix is ideal), tack tack tack. Just get the bitch to stick together, nobody is going to see it and it will just rust out in the next weakest spot anyway.
 
I do like said above and got some stainless .030 Mig wire and used it on my welder. Like said above I have welded it with regular steel mig wire and then coated the joints to prevent it from rusting BUT even with stainless mig wire if you don't change the liner and use Trimix gas it could still rust and not weld ideal.
 
Lilyota said:
If you TIG it you will want to purge it.

I would think that the only thing that wire is good for is plate welding and the like.

Someone will likely come along and inform you that I am an idiot though:laughing:
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No reason to back purge exhaust unless you have the extra time and money. Hot side to a turbo and intake tubes should always be backpurged.
 
wire size is unimportant if you can slow your feeder down far enough
I've used 045 on 18ga, you aren't running beads mind you, but it'll do fine
I always end up with butt joints and if it is something that can be positioned, running it vertical down will help tremendously

if you're melting the inside of the tube and it is 300 series stainless and not mild or ferritic 409 you'll run into "sugaring" which is where the stainless goes nuts and turns into these huge boogers of slag that are hard to even grind out, this is where you backpurge.
I've had 1.5" wastegate tubing close itself up damn near down to 1" diameter from that shit

stainless welds just like mild, but it does not transfer heat away from the weld, so you need to use a lot less heat and let it cool down often
 
Just wanted to updatem I bought Blue Demon .035 stainless wire https://www.amazon.com/Blue-Demon-308LFC-stainless-gasless/dp/B00G5GHA7E

Had to crank it up to like 85% heat on my MVP 210 (8 setting) and fairly slow speed (25?) and it worked GREAT.

Biggest problem was welding it crunched holding pipe in my hand without much to lean on, after having a strong latte couple hours prior.

But, its legit. Welds are pretty clean and smooth as long as you are steady. I am a happy camper. .035 not an issue because it takes so much more heat.
 
SLOWPOKE693 said:
Tack-tack-tack-tack....
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this

ive welded dozens of exhausts with 035 flux

just took the cat off my jeep last week and butt welded a piece in to replace it, tack tack tack no problemo, that includes welding the top of the pipe blind because it was still installed in the jeep so you couldnt see the top of the pipe. 1/16" gap no problem either :flipoff2:
 
Based on rust I've seen on "custom" exhaust most shops don't even bother with stainless wire. Just ER70 for everything.
 
kf4zht said:
Based on rust I've seen on "custom" exhaust most shops don't even bother with stainless wire. Just ER70 for everything.
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I know nothing of metallurgy but Im surprised it works

in any case, ss flux core wire worked great
 
CaptainBalding said:
No reason to back purge exhaust unless you have the extra time and money. Hot side to a turbo and intake tubes should always be backpurged.
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Can you explain this a bit more? I thought you were always supposed to purge stainless, but then you say only parts of the air system (intake/exhaust) should be purged? Why do those parts need to be but the other parts don't need to be?

I know nothing about welding, but am about to make my second header and the first one I back purged and turned out pretty good, but the extent of learning was watching Finnegan's Garage and Michael Furick's tutorial.
 
kf4zht said:
Stainless is just steel with more chromium. You can weld stainless right to mild, though I doubt that is approved for anything that requires testing.
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If be chromium you mean nickle then yes.
 
snivilous said:
Can you explain this a bit more? I thought you were always supposed to purge stainless, but then you say only parts of the air system (intake/exhaust) should be purged? Why do those parts need to be but the other parts don't need to be?

I know nothing about welding, but am about to make my second header and the first one I back purged and turned out pretty good, but the extent of learning was watching Finnegan's Garage and Michael Furick's tutorial.
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Depends on the type of stainless and its intended use.

If it fucking counts for visual, structual, and food grade absolutely.


Ferritic 409 exhaust? Absolute waste of money an energy.
 
Even 304 or 316 it's a waste. Tight joints fusion welded have so little sugaring on the backside it's not worth the effort.

Now if your Gappy McGaperson throwing a bunch of rod at it then yes, backside gonna look like shit.
 
snivilous said:
I know nothing about welding, but am about to make my second header and the first one I back purged and turned out pretty good, but the extent of learning was watching Finnegan's Garage and Michael Furick's tutorial.
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thats pretty brave man, from no welding to SS header

pics?

how do you guys get the angles right at the bend, measure it somehow? or cut it 10 times until its right?

noob to tube.
 
montrose818 said:
thats pretty brave man, from no welding to SS header

pics?

how do you guys get the angles right at the bend, measure it somehow? or cut it 10 times until its right?

noob to tube.
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I can sort of weld, this was just my first time welding SS and first time doing exhaust. It's all 304 and iirc like .040" since Summit doesn't advertise how thin their shit is :flipoff2:

LnINJXwh.jpg


Sounds like it doesn't hurt to back purge it and will help someone like me who doesn't know what's happening :grinpimp:, and I already have everything to purge so will continue to do that. I just watched this video a bunch and tried to mimic what they did:

 
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