My Formula's (dual) exhaust is going to consist of SLP shorties, SLP header pipes or header pipes that I fabricate, cats, mufflers, and some pipes after the mufflers (and I may be able to put an H in). Everything except for the 2 1/4" to 2 1/2" transition pipes is stainless steel (of various grades).

I'm planning on using ox/MAPP (or something else?) with whatever rod you tell me I'll need.

Can I weld the pipes (and mufflers and cats) or do I have to braze them?

What rod should I use?

Any help is much appreciated.

 

Is it possible to do stainless with flux core (FCAW) mig'ing? I thought you needed the gas bottle, with pure argon...

 

I've never tried to weld stainless before. (I bought some extra pipe so I can practice before I do the real thing.) Anyway, I read some old posts, and it looks like you're right about the argon, Tom.

I'm going to edit my above post--instead of asking about arc and gas, I'll just asking about gas welding. I figure I can get more answers to the questions that TomP has refined for me if my questions make sense.

 

double post

 

i think you have to use Tungsten-InertGas for stainless steel. from what i remember, MIG usually produces crappy welds, esp with novices, it is easy to make a superficial weld with no real penetration. and as far as oxy/acetylene goes, ive heard that it releases poisonous fumes. (or was that galvanized steel?) either way, i dont think any of them well nearly as good as TIG (aka GTAW),

and brazing? you might as well use bubble gum and an ice cube. brazing has NO penetration, the base metals arent welded or fused together. with brazing, you just combine the two metals with an all-purpose joining metal. real cheap. id rather take my junk to a high-school or cc metalshop and have them do it with TIG then to have some "professional" use MIG or even worse braze.

 

Is it possible to gas weld stainless steel and what do I need to do it?

 

You can MIg stainless, I was just looking through my welder's manual last night and they give parameters for MIGing stainless. I recall that you had to use pure argon, and I'm sure a special wire. I doubt you could flux core wire weld it. For strength, TIG is for sure the best bet, but for exhaust work MIG should be fine as long as you get some practice. I dont think you are supposed to gas weld (as in oxyfuel torch) stainless because of the lack of shield gas, but agian for exhaust you may be able to get it to work with a stainless fill rod.

 

I work in a tube shop for GE. Our main metals are stainless, and inconel. Have it TIG welded using AMS 5680. Argon for backup gas. That is how I'm going to build mine with aircraft quality stainless.

 

bob is right, tig weld would be better

 

you can weld stainless with stick, mig, or tig all you need is the correct filler metal and shielding gas

 

chevyfan stole my avatar thingy......man....everyone wants that damned thing...LOL.. I GOT TO IT FIRST....BACK OFF

 

OK. I can arc weld (somewhat) and my dad can arc weld and he is very good with gas. Neither of us have any experience with MIG. I know that it's supposed to be very easy to learn. I think I'm going to send back the stainless pipes and just have Arlington Motorsports Racing fab the exhaust. They have a good reputation on ls1.com, they're installing my sfc's, and a guy I trust recommended them to me. They'll do duals on a thirdgen or a fourth gen for $450 if you supply the mufflers. Once I get the money back on the stainless pipes, that's $300. It's a lot, but it's not that bad when you compare it with the cost of setting up to do the welding myself. Plus, they use a Dr. Gas X pipe and I was only maybe going to be able to fit an H.

 

Be careful with that "aircraft quality" tag. In the aviation industry there are several types of stainless we use, but the one we don't use is the one you'll most likely want to use for an exhaust system, 409 stainless. The others, which we use ,will rust, eg; 301HH, 301QH and 70-17.

~M~

 

Thanks Morley
I learned something, I thought all stainless wouldnt rust. This is for plumbing parts on GE jet engines. DC10 up to Boeing 777. pretty sure they wouldnt put something that could rust up there.

 

I'm not sure it how technical it was, but there was a post about stainless steel rusting, as it pertains to SLP headers on the exhaust board a little while ago. I'll bet you can find out more information by searching.

 

Cort,

400-series SS has quite a bit of free iron in it, and can still rust. 300-series stainless is alloyed so that all free Fe electrons are taken in covalence with other elements' electrons, and therefore won't liberate and combine with oxygen (rust).

Did I get that right, Ede?

Many SS exhaust systems are using 400 SS instead of 300. You'll pay quite a bit more for 300, and the benefits are negligible. Check with SLP on your particular exhaust parts, since I know they offer both on most of their systems ( except for Impalas - 300 only )

 

One last thought. After you are done cutting and welding your exhaust together, see if you can get it passivated. This process removes all "foregin" metals from the stainless and will help in reducing the chance of it rusting.

~M~

 

Oh well... if it does rust after time I'll make a new one. 2 1/2 inch tubing and the bending are free.

 

It's the only welding I've done so far, and it didn't take me long to catch on. I had one major problem- I was watching the spark as I moved the gun, instead of watching the puddle. As soon as I got it through my head that I should watch the puddle, the quality of my welds improved dramatically! And it was then that I finally heard the "sizzle" of the MIG, which means you've got the wire speed/amperage/puddle correct.

 

as for stainless rusting, i've seen it all. i've done PMI (positive metal idintifaction) so i knew the type or series of metal for sure and if it's put into the wrong enviroment it'll rust, or experience erosion amd pitting especially in the HAZ (heat affected zone) or the area next to the weld. something else to keep in mind welding is about the worse thing you can do to metal, but it's often the most effective way to join two pieces of metal.