Originally posted by fastcougar:
I forgot to add or take pictures (will tomorrow) of the inside. Since it was butt welded, there was a seam that needed to be sealed up. so, I ran a bead all the way around the inside seam and then ground it down.

This was my second flange/pipe combo. My first setup, the flange was slightly larger (mild steel as well) and I was able to fit the tubing inside the flange. I then welded it up just like you see in the headers ... full seam weld around the inside of the flange and full external weld as well. Inside was then ground down.

I wanted to do that with this flange, but couldn't because the opening was just too small. If I wanted to, I would have to slit one side and notch it and then crush the pipe down and close the notch and then seam weld that notch ... too much hassle. I'm very confident that this butt weld will hold just fine.



When you are done welding the up and down pipes onto your flanges, just take them down to the machine shop and get them surfaced so they are flat. ESPECIALLY on the down pipe because there is no gasket on it. I used the steel gasket on the up-pipe and no issues.

Also, you can prevent the warpage by not letting the stainless heat up so much. It also welds better. If it gets hot then let it cool down a bit. Preheating a little is fine and may help if the two metals are at different temps, but in No way should you be making it rosy red hot IMHO. Everytime I let my 304 stainless piping get that hot I either blew a hole in it during the weld or it would pop and warp.
Also, you can hammer your pipes when just warm to fit the shape of your flanges as it makes it easier to work with. Work hardening from hammering will make the metal a bit tougher, but when you weld it the stress will relax anyway as it cools in ambient air temps. Saves some time.

BTW, butt welds are fine, I did that on all my flanges so I wouldn't be reducing the cross sectional area or having any weld beads in the way. They hold great too.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black