welding stainless exhaust tubing

[HotRod4PaPa]

I am new to tig welding, and have questions about welding 304 stainless exhaust tubing for a street rod exhaust system. What tungsten and filler rod should I use? I believe the tubing will be 14 or 16 gauge. I will be using a Miller 180SD. Can someone suggest an amperage setting? Is the stainless more difficult to weld than mild steel? If it is more difficult to weld, should I just go with mild steel and have it coated? I understand the stainless will run about double the coated mild steel exhaust system. Thanks

[myclone]

Pretty informative posts about this here....\/
https://www.pro-touring.com/forum/showthread.php?t=10007&highlight=weld
https://www.pro-touring.com/forum/showthread.php?t=7677&highlight=weld
Lots of info to be picked up here too (Ive learned a LOT just by reading/searching this site)...\/
http://www.weldingweb.com/index.php

[Matt@RFR]

https://www.pro-touring.com/forum/showthread.php?t=10526&highlight=stainless+tig

https://www.pro-touring.com/forum/showthread.php?t=9333

https://www.pro-touring.com/forum/showthread.php?t=3117

https://www.pro-touring.com/forum/showthread.php?t=986

https://www.pro-touring.com/forum/showthread.php?t=4412

https://www.pro-touring.com/forum/showthread.php?t=3797

https://www.pro-touring.com/forum/showthread.php?t=3285

[HotRod4PaPa]

Matt. Is "back purge" the process of filling the tubing with shielding gas while welding? Is this something you strongly recommend doing on stainless?

[Matt@RFR]

Yessir. And remember that once the tube fills with argon, it still needs flow. Around 5cfh is fine.

With stainless, Ti, Inconel, any of the Chrome Moly steels, aluminum...basically anything other than mild steel requires a back purge if the root will penetrate the backside of the joint.

Also, remember that argon is heavier than air, so fill the tube from the bottom up, and also try to seal the inlet as best you can. The far end of the tube only needs an 1/8" hole in it.

[HotRod4PaPa]

Thanks for the help. I appreciated each reply. Great information!

[FCRacing]

I just finished a set of SS headers in anouther guys shop using this exact welder (Shop Owner's)my setting for SS 18g was 18amps with purge, butt to butt no-rod on the 2.375 upper primarys and 2.500 lower primary (step header) with a 030 wire at the transition welds using 25amps............should work sweet for you.......Rhys FCRacing