Fusion (fillerless) welding 304L tubing

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I've done a little fillerless welding, but mostly mild steel tubing and it was for mock-up purposes.  I recently had a buddy show me that he welds up full exhaust systems without filler.  He's using 304 tubing with about a .065" wall thickness and he fits his connections very tight.I don't know alot about fillerless welding, but I was always under the impression that sacrafices penetration and strength.  Is this true?  If so, how do you determine whether fillerless is OK for an application?  And would you deem it OK for an automotive exhaust system?Any information on fillerless welding would be greatly appreciated."There are two types of people in America - those who try to classify everyone into two types and those who don't."
Reply:Originally Posted by SuedePflowI've done a little fillerless welding, but mostly mild steel tubing and it was for mock-up purposes.  I recently had a buddy show me that he welds up full exhaust systems without filler.  He's using 304 tubing with about a .065" wall thickness and he fits his connections very tight.I don't know alot about fillerless welding, but I was always under the impression that sacrafices penetration and strength.  Is this true?  If so, how do you determine whether fillerless is OK for an application?  And would you deem it OK for an automotive exhaust system?Any information on fillerless welding would be greatly appreciated.
Reply:304 stainless will let you get away with fusion welding without a cracking issue....316 isn't so kind and you need filler and even then you must pay attn. I had an account with a company called Deadenbear  Products (Drag race application)  where I pulsed the stainless (304)  throttle shafts together and didn't use filler.......Must have made hundreds of them in 8 years.......just be careful and check for cracks....  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Exhaust tubing is a whole nuther animal compared to sanitary tube welds, component welds shown by B.C.....it sees very high temps, heat cycling, oxidation.Apples aren't Oranges.Blackbird
Reply:Exactly, and fit is everything, so take that extra time and make the weld joint fit good  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Ahh, autogenous...  I knew there was a proper term for this. B_C - That's pretty cool that you did those for Dedenbear.  I've been a dealer of theirs for many years and I'm sure I've sold a few of those throttle kits over the years. I appreciate the info, guys."There are two types of people in America - those who try to classify everyone into two types and those who don't."