Can you tack weld stainless steel tubing with a mig welder?

[atikovi]

I need to replace a 4 inch section of exhaust pipe. I'll cut it out, position the new piece in place and tack weld it. Then remove it from the car and take it someplace to get it tig welded. Will my mig welder do the job with the standard wire it came with?

 

[PCustoms]

No, it will cause the whole care to rust out in 3 months

 

[atikovi]

I expect to sell it before then.

 

[MoonRise]

Short answer- Yes, but ...

Longer answer-Yes you can tack weld with a MIG.

But if you use plain mild steel wire (ER70-Sx) and plain C25 mixed gas, you will introduce plain steel and extra carbon into those tack welds. Which will rust more and faster than the stainless steel tubing or properly prepared stainless steel welds.

You (or the Welder you hire to TIG weld everything with actual stainless steel filler and using 100% argon shielding gas and BACKPURGING the tubular stainless steel exhaust tubing PROPERLY to prevent "Sugaring" of the stainless steel) should probably retack the tubing with the stainless steel filler and proper backpurging and then grind out the mild steel tack welds to minimize corrosion. And then TIG weld the exhaust with the stainless steel filler and argon shielding gas and proper backpurging.

Your call on how right you want the job done.

 

[atikovi]

OK I'll keep that in mind.

 

[welder4956]

I need to replace a 4 inch section of exhaust pipe. I'll cut it out, position the new piece in place and tack weld it. Then remove it from the car and take it someplace to get it tig welded. Will my mig welder do the job with the standard wire it came with?

What grade of stainless steel is the exhaust pipe? A lot of OEM stainless exhaust is type 409, which is a ferritic grade. A few carbon steel tacks on 409 is not a big concern, especially if whoever TIG welds it grinds out the tacks and welds over that area with ER309 wire. Or you could use ER409 mig wire: https://www.weldingsuppliesfromioc....eel-mig-2-lb-spool-ss409-1f?gc_id=20946202281

If the exhaust is type 304 or other 300 series, I would not use carbon steel wire for the tacks. You could pick up a 2 lb. roll of ER308 or ER309 wire and use that with argon or even 75/25 gas for a somewhat acceptable tack weld. The tacks may look a little oxidized, but no big rust concern after you go over it with TIG with the correct wire and gas. https://www.northerntool.com/products/klutch-er308l-stainless-steel-mig-welding-wire-size-0-030in-2-lb-spool-5018066?cm_mmc=Google-LIA&utm_source=Google_LIA&utm_medium=Welding > MIG + Flux Core Welding > MIG + Flux Core Wire&utm_campaign=Klutch&utm_content=5018066&ogmap=SHP|LIA|GOOG|STND|c|SITEWIDE||Welding|{adgroup}||856744471|42214674623

 

[Old Man Roger]

I’ve welded stainless steel to mild steel using my mig and I’ve welded stainless to stainless with the same wire. The weld will rust but no faster than welding mild steel to mild steel.

I had a stainless pipe on a motorcycle that I used regularly wire on, I hit the weld with a wire wheel to pretty it up once in a while.

 

[jack stand]

I expect to sell it before then.

Weld away!

 

[whateg01]

I expect to sell it before then.

Can't wait for somebody from GJ to buy the car then come here to rant about the stainless steel exhaust rusting

 

[LS1-IROC]

Yes, I've done it many times. Typically I would tack with a mig then pull off vehicle and tig weld the joint with stainless filler rod. However I have also use mild steel filler rod in a pinch, it will look like hell in a year of driving however.

 

[PCustoms]

Can't wait for somebody from GJ to buy the car then come here to rant about the stainless steel exhaust rusting

We need a rant thread bingo card, winner gets a defective HF wrench with a Snap-On handle.

Also, for anyone who didn't get it, my first post was sarcasm.

 

[danielbuck]

are you just cutting out and replacing a 4" straight section? You probably don't need to tack weld it on the vehicle. Just mark a center line on all pieces, remove the exhaust pieces, bring it to however you are going to have Tig weld it, and have them weld the pieces together with the new 4" section in the middle. so long as the center lines are lined up, it should be fine. I've welded my own exhaust like this before.

 

[atikovi]

Rusted bellows,



I want to replace with,



Plan is to remove exhaust from car,



Cut out the bellows section with a cutoff wheel, mount the two exhaust sections back on the car so everything is aligned, put the new flex pipe in place and tack weld it, then take it back off and get it tig welded someplace.

 

[PCustoms]

I wouldn't waste money having that tig welded.

 

[atikovi]

I wouldn't waste money having that tig welded.

Well Mr. Money Bags, I rather waste $100 repairing something instead of spending $1,000 replacing it.

 

[manwithtools]

I wouldn't waste money having that tig welded.

Well Mr. Money Bags, I rather waste $100 repairing something instead of spending $1,000 replacing it.

I think he's saying he would just MIG it with ER70 since you plan to flip it anyhow...

 

[atikovi]

I think he's saying he would just MIG it with ER70 since you plan to flip it anyhow...

Just because I'm flipping it doesn't mean I'm not going to do it right.

 

[manwithtools]

Okay...

 

[michaelf]

You are way over thinking this.

 

[PCustoms]

Okay...

Yep.

 

[aka Larry]

Just MIG weld it. The flex portion will fail long before the welds do. I know because this is the setup I have on my race car.

 

[sqznby]

Just because I'm flipping it doesn't mean I'm not going to do it right.

What's the right way?

 

[stinkity stoink]

Is that a Subaru? If so, you might not have to bother because it could be a warranty issue.

 

[atikovi]

What's the right way?

Probably tig welded, but I defer to the experts here on things I'm less knowledgeable about.

 

[atikovi]

Is that a Subaru? If so, you might not have to bother because it could be a warranty issue.

Yes. Out of warranty at 220,000 miles.

 

[atikovi]

I want to replace with,

Would the original bellows style be better?

 

[sqznby]

Probably tig welded, but I defer to the experts here on things I'm less knowledgeable about.

Whatever method you have at your fingertips is correct
Either Mig or Tig are both the preferred way. Using the appropriate consumables (gas & wire) for each makes them both the preferrable method. BUT if you don't have them, use what you have.
You are putting way too much thought into something of this scale. It's a replacement part for a daily driver, not a show car or the like.
I'd use the bellow like the original one and gitter dun.
A properly set Mig machine will run nicely (using ER70) on clean material and still get plenty of penetration and last a lot longer than you'd expect or think it would. And it'll look factory if you're good

 

[atikovi]

I'd use the bellow like the original one and gitter dun.
A properly set Mig machine will run nicely (using ER70) on clean material and still get plenty of penetration and last a lot longer than you'd expect or think it would. And it'll look factory if you're good

Ok I ordered the bellows style. I don't mind buying the stainless wire for the mig if I can still use the regular gas I currently have.

 

[whateg01]

Ok I ordered the bellows style. I don't mind buying the stainless wire for the mig if I can still use the regular gas I currently have.

What is "regular gas"? Leaded?

 

[sqznby]

Ok I ordered the bellows style. I don't mind buying the stainless wire for the mig if I can still use the regular gas I currently have.

If you're referring to regular gas as 75/25 no, Tri mix is the proper gas for stainless.
That is why I was saying use what you have. It will be more than enough for what you are trying to accomplish.

 

[atikovi]

If you're referring to regular gas as 75/25 no, Tri mix is the proper gas for stainless.
That is why I was saying use what you have. It will be more than enough for what you are trying to accomplish.

So SS wire with 75/25 gas wouldn't be better than with the wire I have now?

 

[sqznby]

So SS wire with 75/25 gas wouldn't be better than with the wire I have now?

You can but the end results will not be desirable. It'll look different and may not wet in as well and you'll more than likely get a lot of spatter.

What wire do you have now? ER70?

 

[atikovi]

What wire do you have now? ER70?

Whatever came with it 15 years ago when I bought it.

 

[sqznby]

Whatever came with it 15 years ago when I bought it.

Haha gotcha. I'd probably want to check it out beforehand just in case. Could be flux cored wire haha

 

[Aaron_W]

Haha gotcha. I'd probably want to check it out beforehand just in case. Could be flux cored wire haha

On that note is there a flux core option? In case I ever need to weld some stainless and don't want to TIG?

 

[BigMike782]

By tri mix they don’t mean argon/CO2/oxygen. They mean helium/argon/CO2, commonly called A-1025 and pricey as all get out because of the helium.
Linde makes a non helium stainless mix called Stargon SS.

 

[sqznby]

On that note is there a flux core option? In case I ever need to weld some stainless and don't want to TIG?

There is. I don't have any experience with it nor have ever had the need for it. So, I personally can't really say much about it.

By tri mix they don’t mean argon/CO2/oxygen. They mean helium/argon/CO2, commonly called A-1025 and pricey as all get out because of the helium.
Linde makes a non helium stainless mix called Stargon SS.

Correct. Tri mix is very expensive (Helium/Argon CO2) and another reason it is used on rare occasions unless it is called for.
Can't speak of that, sounds cool but don't have any experience with it either.

 

[cannuck]

If you want to tack with mig mix and steel wire, just go ahead and do it. Your Tig guy (or gal) can just tack in between with stainless then grind out your steel tacks and weld over them.

 

[gregs]

I have seen numerous posts on different forums where guys weld ss exhaust tubing with a mig and steel wire. Besides the weld area rusting what are the other issues that may happen. You can find a lot of inexpensive SS exhaust tubing kits and parts. If your not looking to polish it and use it for a show vehicle wouldn't it be better than typical aluminized tubing?

 

[danielbuck]

I have seen numerous posts on different forums where guys weld ss exhaust tubing with a mig and steel wire. Besides the weld area rusting what are the other issues that may happen. You can find a lot of inexpensive SS exhaust tubing kits and parts. If your not looking to polish it and use it for a show vehicle wouldn't it be better than typical aluminized tubing?

it'll just rust, that's it. Same with welding aluminized tubing, it'll rust where you weld.