Welding schedule 10 stainless pipe?

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Can any one help me with a suggested weld procedure for butt welding some 1.5 inch schedule 10 316 stainless elbows?Dimensions of the pipe are 48.26 mm OD with 2.77 mm wall thickness.It would be great if you could suggest:Tungsten diameter? 2.4 or 3.2?? Should your tungsten diameter match material thickeness? Or is that rubbish? Filler rod diameter? 1.6 or bigger??Amps?Any edge prep? I belive they come with a slight bevel?Its only a hobby project and no one is going to die if they fail but i would really appreciate some constructive help from the more experienced (than me) TIG welders on this board.PS. Sorry its all in metric!
Reply:i would use the small tungsten.get some acetone clean thembutt them tight and fuse emChuckASME Pressure Vessel welder
Reply:You probably know your stuff being a pressure vessel welder but just out of interest what amps would you use to fuse them?They are quite thick. 2.77 mm is just a little bit smaller than 1/8th of an inch.Thanks,Doug.
Reply:Are you going to finish (smooth) the welds after? If so, I would bevel both tubes roughly 45 deg. a little over half of the wall thickness, 2.4 tungsten, 1.6 filler, around 60 amps. That way you'll still have weld if you grind it off. ---------- john
Reply:Doug,check out some of articles written on this subject at the Arc Machines web site.  http://www.arcmachines.com/Pages/apps01.htmlThis type of tubing, in this thickness, is commonly welded autogenousely (no filler) with a pulsed GTA, mechanized tube welder.   Pulse is great for this because the puddle is kept small by making overlapping spot welds, preventing too much weld sag, or burn though.  For fixed position welding, like where the tube is horizontal, pulse is essential to allow welding with one setting, in the flat, vertical down, overhead, and vertical up positions.I'm sure it will be much more difficult to weld this manually, unless you can rotate the joint at a fixed speed in a turntable and manually hold the torch.  Since manual control is difficult, you may need to dab in small additions of 1/16 or smaller filler to compensate for weld drop through.I would suggest trying the weld with no bevel, just straight square edges, butted tightly, tack welded, with no gap.  If you can practice on some pieces, start at a low current, weld a short section, look at the penetration on the inside, and adjust the current from there.  The current will depend on your travel speed, so you'll have to try to be very consistent.  You can practice weld on the surface of the tubing, without a joint, it is not much different than a tight fit joint.You will need to temporarily close the ends of the tube, purge with argon from one end, and vent through a small hole (1/16-1/8") out the other, to prevent oxidation of the weld backside.
Reply:I agree with pulser Fit up tight no bevel, the amperage up to the point where it just wants to start keyhole.Fuse the first pass if you want a cover add 1.6mm (1/16th) filler on second pass. Argon purge pipe, 2.4mm (3/32) tungsten should be fine 1.6mm is too easy to over heat.
Reply:Thanks guys. Some good info there.