General Chat
Q:
Hey guys I have a quick welding question..
I'm sick of running my open downpipe, so it's exhuast time..
I have a 3" Stainless Steel downpipe.. and I bought some 3" Mild Steel piping.. I tried to have a shop expand the end so I can slip it over the downpipe, and clamping it down, but the exhuast fell off today after hitting a bump..
SOO... Can I spot weld the Mild Steel piping to the Stainless Steel?!
I have a Lincoln Electric wire-feed MIG welder
F54/P90a w Megasquirt and a Holset Hy35W
3" hand made exhuast, Large NPR intercooler, big injectors, Tokico Illuminas, Arizona Z Springs, BIG sway bars, Innovate Wideband
www.putfile.com/proxlamus
A:
Yes.. You can weld stainless to standard steel. Do it in a open area, with lots of ventilation. Stainless gives off some nasty toxic gas!
B.
76' 280z Modified .......Soon to be SC'd
75' 280z Daily driver (bone stock)........SOLD!
A:
You can Mig to spot weld, but you should TIG it with 309 rod.
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Garrett Turbo Dealer
3.1L TwinTurbo L28
10.62@134.1
A:
Try putting a hanger closer to the down pipe then cutting a couple of slots in the expanded end of the mild steel pipe before you clamp it.
I have heard that welding mild steel to stainless with regular mild rod or wire will contaminate the stainless and cause it to begin rusting in that area.
I'm sure that with the right rod/wire this wouldn't be a problem.
Good Luck!!
I refuse to tip toe through life, only to arrive safely at death.
A:
You can use a mig for exhaust. Every muffler shop I've ever been to used mig for everything. But BURLEIGH is right. Just welding the stainless will cause it to rust because those fumes it creates are caused by the rust treatment burning off. I would go with the above and cut a couple small acute "V" cuts to give the pipe more space to close in around the downpipe. You could also try some of the exhaust sealant from advance or auto zone. It's in a tube similar to RTV, but it's heat resistant. If you run it around the end of the downpipe before sliding the exhaust on it should help seal around the clamped portion.
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77 280Z - TEC3 Engine Management, Coil Packs, 3.1 Stroker, 550CC injectors, tripple throttle body FI intake, MSA Stage II Cam, etc...etc...
79 Fairlady - Rusty
81 280ZX - DD
A:
thanks guys!
F54/P90a w Megasquirt and a Holset Hy35W
3" hand made exhuast, Large NPR intercooler, big injectors, Tokico Illuminas, Arizona Z Springs, BIG sway bars, Innovate Wideband
www.putfile.com/proxlamus
A:
Yes, I thought I responded to this last evening, but I'm with James: 309 is the alloy I was told to use also.
As for "ventilation" and stainless steel giving off "nasty toxic gasses" please reserve comment---that's just bad information all around.
Galvanized, as a function of the zinc burning off at high temperature and changing to cyanide maybe, but not stainless!
(RE)
People Are Idiots, Just look around here and you will see!
Tony D: "Knowledgeable but Caustic"... rationull
My brother from another mother calls himself "Willie D"
Post Edited (Jan 10, 9:17am)
A:
STAINLESS IS AN ALLOY!
YOU GUYS AT CONFUSING ALUMINIZED AND GALVANIZED PIPING WITH STAINLESS STEEL!
AAARRGH!
Stainless steel is used on the stock headpipes of most vehicles because of it's INHERENT UNCOATED RESISTANCE to corrosion. YOu usually can not get a magnet to stick ot it unless it's a magnetic stainless like the 400 Series.
If you can not stick a magnet to it, chances are it's stainless steel, and like James mentioned you should use a 309 rod.
Generally you will use the rod with a higher number than the alloy you are welding. So with 304 stainless you would use 309 for welding to a mild steel.
This is in the archives btw, some time ago, but a welder went into detail on the alloys to choose.
For some simple "won't fall off again" plug welds, you can almost use anything.
And if you get technical, the intergranular makeup of the Heat Affected Zone of any weldment is more prone to corrosion than either of the two base metals. It is where fatigue will occur. That is the area NEXT to the welds, not through the weld itself!
People Are Idiots, Just look around here and you will see!
Tony D: "Knowledgeable but Caustic"... rationull
My brother from another mother calls himself "Willie D"
A:
> Stainless gives off some nasty toxic gas!
Its amazing what gets posted on this site from time-to-time.
http://www.lincolnelectric.com/knowledge/articles/content/migweldss.asp
http://www.lincolnelectric.com/knowledge/articles/content/stainlesssteel.asp
- John
Post Edited (Jan 10, 9:34am)
A:
I agree with you TonyD.
I also knew that he was talking about the stainless steel alloy and not a coated steel.
I have seen stainless steel welded to mild steel and it always rusted at and around the welds. Even the stainless did. I would think, as was stated, that using the proper rod would reduce this effect.
However, a little rust on his exhaust system probably wouldn't hurt anything for some time.
I refuse to tip toe through life, only to arrive safely at death.
A:
Whoo hoo ..
just got out from under the car..
I used numerous spot welds almost all the way around, and I wire brushed it clean, and sprayed a little high temp spray paint to prevent rust from building up.
Now my open downpipe dumping RIGHT underneath me is WAYY out in the back of the car... sounds soo much better and no more vibrating cockpit and my ears being rattled to death...
Thanks guys!
Ohh BTW.. I ran out of gas, so I just used a .035 FLUX core wire to do the spot welds.. no problems
F54/P90a w Megasquirt and a Holset Hy35W
3" hand made exhuast, Large NPR intercooler, big injectors, Tokico Illuminas, Arizona Z Springs, BIG sway bars, Innovate Wideband
www.putfile.com/proxlamus
A:
Even stainless welded to stainless with a stainless filler can develop rust in the heat affected zone on each side of the weld. Its caused by carbide precipitation and can be significantly reduced through the proper selection of base material, filler, and heat control.
http://www.burnsstainless.com/TechArticles/Stainless_article/stainless_article.html
- John