Header/exhaust pipe - tack welding stainless to mild

[myredracer]

Will be building a new exhaust setup and plan to use a stainless steel muffler and mild steel pipe (and ceramic coating the whole thing). Can I tack weld stainless to mild steel pipe with a few dots of regular MIG wire around each piece and then get a certified/pro welder to finish it all off? Or should the tack welds be with stainless wire? I don't want to get into back purging and have never welded stainless before. Google doesn't seem to have an answer for tack welds like this.

 

[motofool33]

Good Luck

 

[myredracer]

The overall length of the exhaust tip, muffler and pipe ahead of the muffler (a 90 degree bend upwards) is really really tight and wouldn't have room for clamps. This is on a vintage car that would only get used on sunny days in the summer and was thinking moisture sitting inside the muffler for extended periods wouldn't be good? The muffler that I had narrowed it down to a Flowmaster HP-2 only comes in s/s. I was thinking of adding some stiffener webs either end of the muffler similar to the photo. The muffler gets bolted to the side of the engine and is rigid but I would expect an overhanging exh. tip would def. be subject to fatigue cracking and is where I thought the stiffeners would be a good idea.

 

[michaelf]

you can tack and weld your muffler and pipe with carbon steel wire with no problem

 

[APEowner]

No problem, I do it all the time. In fact, I welded a mild steel bracket to a stainless muffler as a "temporary" repair on a friends race car a few years ago and we've never gotten around to replacing it.

 

[575cat]

Not like its quality stainless , OE or any others , unless its marine 316 , daily event for me , overthinking again just weld it up and be done .

 

[Stinger]

It's not even a little bit of a problem. You can weld the whole thing with mild steel wire if you want. Depending on the gas used it may cause a little more spatter than normal but the joint will be just fine.

 

[dogdog]

It's fine, works for me, not show car quality welds but been holding for past 5 years no issue related to the weld..... with stainless, you do needed to back purge though.... I used solarflux pasted instead of argon .... too cheap on the gas. For non sanitary weld it is fine.


basically I fit, apply paste, tack with flux core, mark few reference line with high temp marker just in case, wire brush, then tig with 309L.

 

[myredracer]

I used solarflux pasted instead of argon .... too cheap on the gas. For non sanitary weld it is fine.

Did not know about a paste instead of argon. Does it work for MIG tho? The Solar Flux stuff isn't exactly available all over. Is there an equivalent product?

 

[bbcc]

Do you have the 409 or 304 version HP2? 409 stainless can be welded with plane jane steel mig wire with no backpurging or solar flux required. If it's 304 you will need to weld with a 309L filler and back purge/solar flux. Now, for just tacking together I wouldn't have an issue with using regular ol mig wire on either 409 or 304 because it will likely get ground out anyways.

 

[sqznby]

If all you are doing is tacking it, you should be fine. Just use small tacks.
If you are going to an experienced weldor go over everything with him before to make sure you're both on the same page.

 

[kkroger]

I sure hope so, the Stainless Tails are welded to my aluminized mufflers for about 20 years now with regular old ER70S6 MIG Wire....

 

[myredracer]

Do you have the 409 or 304 version HP2? 409 stainless can be welded with plane jane steel mig wire with no backpurging or solar flux required. If it's 304 you will need to weld with a 309L filler and back purge/solar flux. Now, for just tacking together I wouldn't have an issue with using regular ol mig wire on either 409 or 304 because it will likely get ground out anyways.

It's the 409 version. If ordinary mig wire is okay with 409, that is great!

 

[bbcc]

It's the 409 version. If ordinary mig wire is okay with 409, that is great!

Yup, it actually welds quite nice!