stainless steel exhaust

[kramXmark]

Im not sure if I messed up my stainless steel exhaust. I did the tack welds to hold everything together but I forgot to run a back purge. There's some sugaring but if I do a proper purge on the full weld pass, can I still fix that? Or should I redo those tacks? I dont want to start over!

 

[IamMckenzy]

You can probably fix it without starting over. If you run a proper back purge on the full weld pass, it should help clean up the sugaring. If the tacks are holding everything together well, there's no need to redo them. Just be cautious and take your time with the back purge to avoid further issues

 

[careerMan#01]

Im not sure if I messed up my stainless steel exhaust. I did the tack welds to hold everything together but I forgot to run a back purge. There's some sugaring but if I do a proper purge on the full weld pass, can I still fix that? Or should I redo those tacks? I dont want to start over!

Yeah... sugaring's not ideal cos it weakens the stainless and can lead to cracking, especially on an exhaust where temps fluctuate. If the tacks are small and you can fully fuse over them during a proper back purged final pass, you might be okay, but if they're crusty or deep, it's probably best to grind them out and redo.

 

[StillAlive]

Im not sure if I messed up my stainless steel exhaust. I did the tack welds to hold everything together but I forgot to run a back purge. There's some sugaring but if I do a proper purge on the full weld pass, can I still fix that? Or should I redo those tacks? I dont want to start over!

Sugaring's a no go for stainless exhaust. A full purge won't fix the already sugared tacks. I agree that OP is better to redo those tacks with a proper back purge for a strong, corrosion resistant weld. Better safe than sorry, right!

 

[Wyo.welder]

You're probably fine. If the tacks have some sugaring but the material is still good, you could just grind them out and do your final welds with a proper back purge. No need to start over, just make sure you clean up the oxidized areas so you don't trap any junk in the weld. I agree with them all

 

[mavel weng]

The short answer is, yes, you should redo those tack welds. Don't try to salvage the job by welding over them.

 

[red widow]

You absolutely have to back purge your tacks and the entire root pass on stainless pipe and tube. The tack welds are a part of the root pass so they need the same protection. When you don't back purge, the backside of the weld gets that grainy, crystalline texture which is a direct sign of a bad weld. That sugaring is a defect and it introduces porosity which makes the entire weld weak.