stainless tig root problems
Hi, i'm welding stainless pipe and i'm having trouble making the root pass stand out. i'm getting alot of suck back and every once in a while i have a pin hole at my tie-ins. i dont know what i'm doing wrong. I went to Tulsa Welding School and i remember one of my instructors made a root pass and it looked like he ran a bead on the inside of the pipe. could you please refresh my memory on how to do this? i know that making the root pass look like this took quite some time, and that there is a faster way to put in a root pass but i'm just having trouble all around with this. thanks for your help
Hi, Jody here from weldingtipsandtricks
first of all, the inside of the pipe needs to be purged with argon. some aluminum tape like used for hvac comes in handy for taping ends as well as taping the whole joint while it purges.
make sure to have a vent hole in the uppermost place of the tape.
argon is heavier than air and will fill a pipe like water...keep that in mind as far as where you put the hose in and where the vent hole is.
you need a 37.5 deg bevel and a 1/8 gap with no land.
use a 1/8 rod and lay it in the gap.
aim the tungsten right on the tip of rod where it impinges on the root gap,
use just enough amps to fuse and dont wiggle much side to side.
if you walk the cup, keep the wiggle motion to a minimum. and keep the torch angle as close to 90 deg as you can while still flowing the puddle.
I like to free hand stainless root passes because i can move as quickly as i need to .
walking the cup is great but is not the be all end all for tig welding pipe.
as far as your tie-ins go...i use to feather them with a grinder but learned a better way.
i just light up on the tack, fuse the filler rod to the end, and then back up about 1/4 inch and go with it fusing everything together.
hard to explain without a video,
coming soon..videos on tig welding pipe
this is all for now, hope it helps.