[ronin8002]

Hey guys, having some trouble with putting a good tig root in pipe and looking for some help.

Machine: Miller CST 280 with scratch start tig rig, gas lens, #8 cup, 3/32 2% lanthanated tungsten.

Gas: 10 cfh

Amps: 85

Filler metal: 1/8" er-70 s2

Metal: Carbon steel pipe, 3" Schedule 40, 37* bevel, no land, gap tacked at 1/8" (shrinks a little after tacking)

Position: 1G

I've watched Jody's videos on pipe root passes with TIG but I'm having trouble with excessive reinforcement when I do the lay wire technique. Basically the metal drips into the inside of the pipe. If I go faster it looks better inside but the bead is humped up on the outside and looks cold/not completely fused with the bevels. If I oscillate over the wire I get better fusion on the outside of the pipe but I get ugly grapes on the inside. I have cleaned 1" back from the joint both inside and outside the pipe. Smaller filler metal doesn't seem to help. Any tips?

[Otto Nobedder]

Welcome!

Since you're doing lay-wire,

Try it with 3/32 rod and report back.

Steve S

[ronin8002]

Thanks for the quick reply Steve. I've tried 3/32 filler with the same gap and 75 amps, same results. I'm wondering if it's a torch angle issue...I'm freehanding the root with a finger propped on the pipe and the torch leaned back maybe 35* from the direction of travel. Too much?

[Otto Nobedder]

Maybe.

No two of us do it quite alike. For a 6010 stick root, I do "bury rod", where many prefer "whip and pause".

I do my TIG roots as a "move and dab" freehand, rather than lay-wire. A fellow I work with actually freehands working wall-to-wall, with a dab each step, and he passes his code tests, too.

When you find what works for you, you'll wonder why it was so hard before.

Steve S

[plain ol Bill]

Sounds like your parameters are close to me. I would kick the gas up to 15-16 myself. Gap tight enough you cannot get 1/8 to go through it, weld straight up the gap with no oscillation and tungsten right in the middle. Just watch the edge for fusion and keep moving. Practice this if you can and adjust you amperage if needed. When putting the coupon into place in the 6G I always put the bottom tack so one the edge of the tack was dead bottom with the remainder of the tack running up the weak hand side. Never had an inspector call me out for doing that and it gave me a little advantage. Had to test for each different contractor (likely over 100 test's), made most of them busted a few.
Any welder tells you he never busted a test either is a liar or never took many!
Root pass 1/8" dia. filler
Hot pass 3/32" dia,
No, I did not confuse which size.

If you are getting hangy downy things on the inside you are too hot or not moving fast enough.

[plain ol Bill]

Oops, never mind I just noticed this was 1G and I was thinking 6G. I don't ever remember taking a 1G.

[Braehill]

Ronin,
Torch angle seems a bit too much for me, I try to always aim for the center of the pipe, this keeps me consistent with my torch angle the whole way around. I run maybe a 10-15* torch angle. I try to keep a small keyhole and keep the filler to the leading edge of the puddle where it will only take what it needs. I try to get as little reinforcment as possible, but still be present. Too little reinforcment on the root and you have suck back on your fill passes, but no grapes.

I've used both 1/8 and 3/32 and haven't seen much difference if you're only feeding the leading edge without forcing the rod in there. Like Steve said, find what works for you, everyone is different and there's only one way to find out what works for you, try different methods.

Len

[ronin8002]

Thanks for the tips guys. I'll try messing with torch angle and amperage today and see if I can figure this out.

[DylanWelds]

Thoriated tungsten 1/8
3/32 filler - 1/8 gap
1/8 filler - 5/32 gap
either way 100-120 amps. On a 6G I like to stick my wire on the inside of the pipe and melt it that way on the bottom, then keyhole dab the sides and top. Anyway, try both lay wire and dabbing. I walk my root in. If you walk your root , rest your cup in the bevel pointig straigh5 in and find where the tip of your tungsten is level with the knife edge of the pipes to determine your tungsten stick out. whether your walking it or free handing you don't want to weld too much outside of the root zone. You want to keep your tungsten focused on the gap and filling the gap only. Too much side to side will give you underfilled root. And I use 35cfh gas always. Just what we used in school and I've never had to pay for gas so I never changed it when I got out to the field. #8cup as well.

[DylanWelds]

Also if youre welding in the 1g position and getting excessive reinforcement, keep what you're doing, just don't put much emphasis on actually shoving the wire in there and see if that helps. when your welding a pipe from the bottom to the top there's a halfway point where you go from shoving it in there to the arc doing the work for you. Sorry I missed that the first time you read it. Hopefully some of this helps ya

[Coldman]

My preferred method for 3" Shed 40 is:
3/32" gap no land, 30-35 degree prep
3/32" wire ER70S-4 (I avoid S-2)
3/32" electrode.
Root pass - laywire, 105 amps.
Second pass - 110 amps (fill the joint up)
Cap - 125 amps (single weave pass)

I use this method all the time and gives a little reinforcement inside with smooth appealing finish.
Cheers!

[ronin8002]

Hey guys, just wanted to give an update. I shortened my tungsten stickout to help me hold about a 15-20 degree torch angle and rest the cup on the bevels without dipping the tungsten, and also turned the amps up much higher...110-115. I think part of the issue is I was running too cold which meant I was going too slow. With the higher amps I could get a nice puddle and faster fusing of the wire which allows me to move faster. Still have some trouble spots but I think that has more to do with my torch manipulation at this point. I'll get hung up too long on one spot or the cup will slip forward in the joint....mostly when I'm transitioning around the pipe from 2 o'clock to 12 o'clock. Probably would be good for me to do some dry runs on the torch movement, or work on my freehand some more. Thanks for all the help and I'll keep practicing.

[Rick_H]

Are you scooting forward and back or walking the cup? If your slipping forward you may be gripping too hard, just lighten up the grip a little, breathe and take your time. I'd practice using both hands a well, makes 6g much easier.....dry runs help;)

[ronin8002]

Lately I've been trying the scoot forward and back movement for the root using a freehand technique. For the hot pass I'll walk the cup that that's where I would get the slippage....tried lightening up my grip and that has helped. Thanks!!!!