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Author Topic: Welding Stainless Exhaust Coupling. Advise Needed  (Read 8537 times)

clytle374

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Welding Stainless Exhaust Coupling. Advise Needed
« on: December 31, 2007, 05:56:39 PM »
So here are the pieces, All pieces are 304SS.  Made out of SS so I can weld to the SS flex coupling. 



I need to fill the inside of the tube with argon and weld as usual? any other advise to avoid warping?  How hot do I dare get SS? 

NOTE: I know the hole in the exhaust flange is not round, but it matches the engine's port.   
 

dieseldave

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #1 on: December 31, 2007, 06:16:56 PM »

   Phone up or take it to an exhaust shop and ask them how they weld it. Probably MIG with stainless wire is what they would use.

   I know that some cars have a stainless steel exhaust system. Or part of it is stainless,like the catalytic converter.

clytle374

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #2 on: December 31, 2007, 06:35:16 PM »
OOPS forgot some info in there.  I will be TIG welding it, with 309 filler.

I haven't found anyone in my area that does SS exhaust.

My big concern is warping and overheating.  ie Should I be trying to sink the heat away while welding it?   
I welded a small scrap piece and found it turned to a orangeish-pinkish-brownish color real easy, the coloring is only on the skin as it files off easily.  Too hot?



biobill

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #3 on: December 31, 2007, 10:16:45 PM »
   Hotater would know.    In my very limited experience trying to TIG stainless, I'd get a beautiful looking weld with a line of blued metal next to it that would crack when stressed. Never did figure it out.
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4x4_Welder

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #4 on: January 01, 2008, 04:27:24 AM »
No need to purge the tube, this isn't a seawater line or high pressure air system.  Around 65-80 amps, tack on four sides, then link the tacks.  309 filler would be fine, and it will discolor.  You can try something like sta-brite, or just wire brush it while hot.  If you want it really shiny, scrub it with a scotch-brite pad after.
I TIG decorative stainless all day at work, used to do heavy structural stuff in stick, MIG, dual-shield, and TIG.
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Tom

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #5 on: January 01, 2008, 04:33:54 AM »
Using silver solder to braze it works well to and will leave a pretty finish. Just use a good flux and dip it after you are done to crack the flux off.
Tom
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clytle374

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #6 on: January 01, 2008, 06:24:23 AM »
Thanks for the advise, here it is.



Still warped up a bit, small leak around the exhaust port.  I'm still using stock gasket, I think a better one will fix it.


rcavictim

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #7 on: January 01, 2008, 08:49:27 PM »
Thanks for the advise, here it is.



Still warped up a bit, small leak around the exhaust port.  I'm still using stock gasket, I think a better one will fix it.



Permatex copper RTV gasket maker sealant will handle 700F.  I would use it to act as a gasket to mount the pipe to the head. It will likely survive there.  You can remove the factory type exhaust gasket completely and save it in the parts box.

You could use a new wheel on a 7 inch angle grinder as a mill to flatten the warped surface of your pipe flange.  Need to put the object in a sturdy vice to do this.
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clytle374

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #8 on: January 01, 2008, 11:02:25 PM »
Looking good !
I like the mounting method of your starter - is this a factory setup ?

Jens

Yep thats the stock GM-90 setup, it is a really really close fit.  Makes the coolant connection and the access door a real pain.


Permatex copper RTV gasket maker sealant will handle 700F.  I would use it to act as a gasket to mount the pipe to the head. It will likely survive there.  You can remove the factory type exhaust gasket completely and save it in the parts box.

You could use a new wheel on a 7 inch angle grinder as a mill to flatten the warped surface of your pipe flange.  Need to put the object in a sturdy vice to do this.

I'll try the Permatex, I didn't know it would take that much heat. 

Doug

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #9 on: January 01, 2008, 11:36:31 PM »
If you search Smokstak.com there is thread about making high temp gaskets.
There is also a NAPA part number posted for exhaust gasket/head material.
AS I understand asking a NAPA parts counter clerk for a sheet of head gasket/exhaust gasket material will get you nothing but blank stares with a part number.

Kind of like going to Aklands and saking for whitworth sockets " We don't sell that brand " DUH....
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jtodd

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #10 on: January 02, 2008, 06:13:40 AM »
So here are the pieces, All pieces are 304SS.  Made out of SS so I can weld to the SS flex coupling. 

I need to fill the inside of the tube with argon and weld as usual? any other advise to avoid warping?  How hot do I dare get SS? 

NOTE: I know the hole in the exhaust flange is not round, but it matches the engine's port.   
 

This looks very much like the rig I set up for mine!  I just used the stainless steel vibration attachments for a truck exhaust.  Everything on the upper part of my rig is stainless.  It discolors a bit when TIG welding thinner stuff, but a bit of polishing solves that quickly enough.  3m pads work well.  It's also possible to make quick work of it with a die grinder and the 3M "twist-on" pads that are slightly more aggressive than the green pads but at 13k RPM they polish stuff quickly.

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I'm not certain why you made a new flange - could you have just welded a BST male pipe thread end to the flex coupling and used the existing threaded flange that came with the engine?  That's what I did. 

As for gaskets: check out McMaster-Carr  (http://www.mcmaster.com/ around page 3347 in the current website catalog) - they have lots of selections and will tell you exactly what the specs are.  Just get a sheet of it, a pencil, a box opener, and some time.  There is Permetex non-hardening sealer to seal up the smallest of fissures in the final assembly and tightening, but you should be relying on mechanical force to keep exhaust gasses from leaking, and not a spreadable gasket material. 

JT
« Last Edit: January 03, 2008, 04:54:45 PM by jtodd »

Firebrick

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #11 on: January 03, 2008, 04:38:38 PM »
A large mill file will flatten your warped flange very nicely and easily. 

cujet

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Re: Welding Stainless Exhaust Coupling. Advise Needed
« Reply #12 on: January 10, 2008, 03:40:11 AM »
Sorry I did not see this thread earlier. I build equal length 321 ss headers for turbo race cars. Same things apply.

Find a 6 inch belt sander (the shop floor models) and sand your flange flat. It is the best and fastest way for exhaust systems. Flat "bastard" files take forever and do not produce good results unless you are quite skilled.

Your job looks great and will likely last a lifetime.

Chris
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