6g Tig-out Pipe Test

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First of all hello everybody, I'm new to the forum.I've been practicing a 6" pipe 1/2" wall thickness (don't know the sched.) 6g pipe test Tig all the way out, carbon steel, and I'm having trouble on the cover pass on the underside of the pipe (4G section) and some of the sides of the pipe (2g section). I'm doing well on the root and fill passes but when I go to cover the pipe I end up with a lot of undercut on the top side of the weld, I am using a lay-wire technique and am using scratch start/ lift arc so I can't pedal pulse or anything like that. if some of you tig pipe guys could give me some tips it would be much appreciated.
Reply:You mean undercutting the previous bead or undercutting on the toes of your weld? It's hard to tell without knowing your amperage, filler wire size, or if your camping out on it bead after bead without letting it cool. I find that filling my pipe hot is fine, but when it comes to capping I usually let it cool down till I can touch it but still feel warm. I use 1/8" wire all the way out, and I use lift arc. You could just not be holding your sides long enough. Need info and pics if possible.Miller Maxstar 200 SDPiperliner #10 Gold
Reply:Undercutting the top toe of the cap pass. The bottom toe doesn't have undercut. I use 1/8"  wire as well. The couple times I have done it I haven't let it cool for very long, I'll have to try that next time. And do you recommend capping it with one weave or two weaves stacked/ overlapped next to eachother
Reply:hold your wire at the top of the bead, not in the middle. Feed wire until the undercut fills up. At least 2 bead cap on something that thick, most likely 3 would work better. How wide is the bevel flushed out? How wide are your beads?
Reply:From toe to toe the bevel is anywhere from 5/8" to 7/8" I would guess. I never measured it so I'm just guessing off the top of my head
Reply:Yeah, you need at least two beads on that. Especially on a 6G. You could do a one bead cap on 5G with no problem.
Reply:Thanks for the input guys, looking forward to trying it again, once I do another one I'll post up more questions if I have them
Reply:Not sure if this will help but it's worked for me. I'm on a boiler tube job right now same position but 2.5" heavy wall tubing. 80s b2 wire on t-11 material welding new to old. I have noticed when capping on the old side when wetting in on cap thst will undercut  I'm jist doing a single pass cap but I introduce wire at both sides of bevel when progressing my cap this will help eliminate and wash or undercutting. If you still get it you need to introduce more wire if using this process just my experience. I'm using a miller xmt 304 on scratch start 105 amps 3/32 tungsten. Have a good day.  Jeremy