[Beardo]

Hi guys! Here's the deal. I recently got a job as a TIG welder. I'm a beginner with 3 months welding time under the mask. It's all peachy so far, but for the last few days I was suppose to weld some 2" thinner walled pipes. When I say thinner, I mean 3 mm. That's the thinnest I came across until now.
So, I got 2" pipes, 3 mm wall thickness, 2 mm wire, 2.5 mm distance between two pipes, 75 amps for the root pass. Now, I can put a decent root pass, but the problems arise when I'm suppose to put the cover pass. I wait until the root is cold and I thoroughly clean the welding area and the heat affected zone. But whatever I do, I can't put a decent cover pass. I tried using 80-85 amps, 2 and 2.4 mm wire.
With less amps I can't get the puddle to flow and I'm too slow so the pipe gets too hot and I melt the root pass. With more amps I can be faster and the puddle is flowing, but then I get the obscene amount of undercut and again, I melt the root. I add more wire and keep the torch a moment longer on sides to fill the undercut, but with more wire puddle is cooled and won't flow as freely. And I melt the root.
Is there some middle ground I haven't found? Some crucial details I'm unaware of?
I would appreciate any help.

[Coldman]

Hi Beardo,
I weld 2" sched 40 (3.9mm wall) at 95 amps root and cap. Your pipe is only slightly thinner at 3.0mm, I wouldn't go below 85 amps personally.
Some pics would help, but make sure you are filling the bevel completely with the root and that you are getting some reinforcement.
Keep your electrode sharp, use 2.4mm wire, use laywire technique on the cap and weave keeping the wire in the puddle, this way you can control puddle temperature. Keep moving or you will overheat or suckback that is the key.

[wheresmejumper]

To keep the puddle nice and flowing,with less amps,i use 1.6 wire adding very little at a time.
Too much wire,or too big a wire chills the pool and it loses momentum

or walking the cup can have the same benefits