welding 2'' SCH 80 with stainless filler help

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What are some good tips on tigging all the way out on stainless. i usually had my purge on 20cfh the whole time I'm welding. I'm using 1/8in wire i run between 80/90 amps and 115 amps for cap. and i look at my root and it is sucking in. and I'm not tieing in on my sides. any pointers thanks?Lincoln 140 Pak MIG Everlast powerarc 140 STLincoln Tombstone
Reply:To hot, particulary on the cap, stainless likes low and slow, i run about 70 for the root, and 85-90 for the fill and cap, nice and slow on the root and feather all tie ins.Do you  have a vent in your purge dams? If not once you close the root the pressure build up in the pipe along with the heat from the fill and cap and push the root back out
Reply:You can turn the purge off after the second pass.
Reply:have nice sharp bevels, no land and keep the arc only on the wire, do not wash up on the sides, do not lay the wire in the joint but kind of keep the wire somewhat pointed into the joint. on the second pass lay the wire down and put the pass in quickly, if you are to slow and you wash up on the bevel to much that is the reason you get suck back.
Reply:Turn your purge down - just float the ball in the flowmeter.Tape the end - cut an x in the top so the o2 pushes out.X2 on shutting it off after 2nd pass.
Reply:People who do it all the time may be able to blast a root in but for newbies and people who just want a reliable way the problem is not getting a heavy enough root to take out the risk out of suck back.  On the flat, no worries of suck back, you want to wash up the sides to hold the root, on 3g you need to wash a little more to tie in, on 2g you only gently hit the top (or you'll risk inside undercut) with a larger sweep on the bottom.  Overhead is a different situation.  Push enough wire to appear convex from outside.  At least three to one filler length to distance traveled.  Just touch the edges of your filler to tie in.  Then grind the excess build-up before the hot pass.  My notes say for .200 wall....1/8" gap, 3/32" filler, 80-90 amps.  Pic symbolizes 4g/6g build-up in overhead, note exterior appearance. Attached Images
Reply:rockcrawler97....on rereading my above post, I find that in my effort to explain the need to get a heavier root, I generalized too much towards mild steel.  For the latter, I use a 1/8th filler and the lay wire and constant feed method for the root.  For ss, I make a special effort to slightly keyhole and then fill.  I find this method better for guaranteeing that I break down the inside edges.  Ideal set-up for me would be 1/8th gap for the overhead with hope that the top would eventually close up to a snug 3/32.  Because of comfort and it's basically the same manipulations, suggest practicing on 2g plate.  Loose 3/32-1/8th gap, starting on a feathered tack, slight motion up to soften top bevel, backward 'c' to soften bottom and then back to the top to receive filler, repeat for stack of dimes across gap.  Experiment trying to add too much filler to get an idea of how much filler is actually required.
Reply:I agree with everything that has been said, I think the torch angle is important. How much stick out you use will determine your torch angle if you are resting the cup, and too much angle seems to cause the puddle shape to elongate and cause suck back. If you keep the arc force driving metal into the seam, you can move faster and get more build up. Let the root cool well before the hot pass, that will also help if your hotpass is sucking it in.Constant Current Weldor.
Reply:must add wire contunu .
Reply:http://www.millerwelds.com/resources...-I-do-at-work=Read this if you have the time. I do this stuff for a living and it still amazes me people recommend 1/8" filler for 2"