Essdot

Wassup guys, need to know what you guys use and the steps to get to a good prep. I'm well into my manifold and hit a couple spots where it started spitting and eating the electrode just like there wasn't any gas. 22cfh on the torch, 6cfh on the backpurge. The interior came out without any problems full pen. The outside messed up like there wasn't any gas.
I'm really leaning toward contamination as it was at particular spots on the circumference, sch10 1.25 304. I don't know where I'm introducing contaminates.
I cut on a dry bandsaw. Carbide bit to clean the inside , 120grit to bevel the outside, wipe with a rag soaked in acetone. 120grit belts haven't been used on anything else. Nor have the carbide bits.

weiRtech

i don't use chemicals and try to avoid embedding abrasives where possible. I prefer a dedicated 8" stainless steel wire wheel.

keep in mind you can also introduce contamination with the filler material as well if it is not clean, or brought out of the argon shield and re-introduced during welding.

aaron

NWDyno

On scheduled pipe, my plumber uses teflon tape. Never have used it on a manifold.

On stainless tube manifolds we use stainless wire wheel that only sees stainless tube before welding.

Essdot

so what do you use to bevel the stainless tube for manifolds? Do you use schedule pipe at all or all thinwall??

NWDyno

I don't bevel tube. I have never used schedule pipe for anything automotive.