techniques for 2" stainless(duplex) tig torch angle & warping.. help?

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Hey i was wondering if anyone could share any techniques to prevent 2" stainless piping from warping or bowing out of shape, like a banana i guess.... would it be all about heat control? also i was curious how you would go about fixing a pipe that has already bowed like a banana... heating up the opposite side of the pipe so when it cools it comes back into shape? if so, how would you do that without ruining the cap?but my main question would be if anyone has any techniques to maintain correct torch angle on a small bore pipe from 6-12 in position cap welding... i find i can go from 6-9 or 6-3 but then i lose my torch angle and the puddle elongates like an oval, so my bead isn't consistent from 6-12, have to stop at 9 or 3 and re-position.. i need more practice of course but was just curious if anyone knew any tips to tryi usually hold the torch down far on the handle and brace with with a finger on the pipe and i switch it up right hand/left hand in the 6G position but both side right hand in 5g... forced myself to learn with my left hand instead of reaching around the pipeanyway, i appreciate any information anyone can pass along and hope the post could help more people then just myselfthanks in advance
Reply:Originally Posted by then3wguyHey i was wondering if anyone could share any techniques to prevent 2" stainless piping from warping or bowing out of shape, like a banana i guess.... would it be all about heat control? also i was curious how you would go about fixing a pipe that has already bowed like a banana... heating up the opposite side of the pipe so when it cools it comes back into shape? if so, how would you do that without ruining the cap?but my main question would be if anyone has any techniques to maintain correct torch angle on a small bore pipe from 6-12 in position cap welding... i find i can go from 6-9 or 6-3 but then i lose my torch angle and the puddle elongates like an oval, so my bead isn't consistent from 6-12, have to stop at 9 or 3 and re-position.. i need more practice of course but was just curious if anyone knew any tips to tryi usually hold the torch down far on the handle and brace with with a finger on the pipe and i switch it up right hand/left hand in the 6G position but both side right hand in 5g... forced myself to learn with my left hand instead of reaching around the pipeanyway, i appreciate any information anyone can pass along and hope the post could help more people then just myselfthanks in advance
Reply:thanks for your quick reply... im not sure the exact type of duplex but its not super duplex, using 3/32 zeron 100 filler wire for the root (i think zeron or zerox, ill check after) and different type of 1/8 for fill cap, cant remember off handand its not a mig process im using... im using tig from root to cap (F6), no mig gunperhaps ill have to try using my body to brace my arm with instead of fingers on the pipe,,, just curious of other possible ideas to trythanks for your quick replyLast edited by then3wguy; 01-19-2014 at 02:20 PM.
Reply:as far as positioning, you might try walking the cup instead of fingering.you have the right idea on straightening. If you need to move it a lot you can grind some out and re-weld on the side that needs to pull.If I'm doing a 5G position weld I always weld the top half first on one side, then drop down and get the bottom, then do the same thing on the other side. That way you aren't carrying so much heat all the way to the top.
Reply:Originally Posted by TimmyTIGIf I'm doing a 5G position weld I always weld the top half first on one side, then drop down and get the bottom, then do the same thing on the other side. That way you aren't carrying so much heat all the way to the top.
Reply:I usually do every pass like that. But you're right about the root tie ins, and they aren't much fun on duplex, are they?
Reply:Duplex is sensitive to heating and you can easily ruin the corrosion resistance by re-heating or re-welding to straighten a warped joint.  IF you're working to a strict welding procedure this will never fly with the welding inspector.  If the joint is warping in a predictable manner, you're best bet is to fit it in a way that it shrinks or pulls into alignment.  Without some more detail on what you're welding and why you think it's pulling/warping, I'm out of suggestions.... Originally Posted by TimmyTIGyou have the right idea on straightening. If you need to move it a lot you can grind some out and re-weld on the side that needs to pull.