Need procedure for TIG welding 3/8" tee joint

admin

I have been trying to weld several 3/8" A36 tee joints using the TIG process, but am having trouble getting a good throat thickness. I am using a 1/8" electrode @ 250A and have tried both 3/32" and 1/8" filler rod. In both cases I am pushing a fair amount of filler into each puddle. My welds look reasonably good, and show proper penetration on cross section analysis, but they all tend to be concave with about 2/3 of the necessary throat thickness. When I try to really pile on the filler the toes of the weld look cold. So I am interested in how everyone else would perform this weld. Would most use a single pass, or some method of multi-pass for this configuration? Any specifics are greatly appreciated.
Reply:Polarity:DCEN (straight polarity)Amperage Range:225-300For mild steel, increase amperage 10%.Gas:ArgonGas Flow Rate:13 cfh or 20 psiWelding Speed:5 inches per minuteTorch Cup Orifice Diameter:1/2" (12.7 mm)Use ceramic cup when welding with less than 250 amps. Use water-cooled torch when welding with more than 200 amps. Are you using a watercooled torch?Filler Metal Diameter:3/16" (4.8 mm)That should take care of it. No need to thank me. As the worlds best welder, just doing my part.Last edited by JohnnyWelder; 11-16-2009 at 03:53 PM.
Reply:Originally Posted by JohnnyWelderPolarity:DCEN (straight polarity)Amperage Range:225-300For mild steel, increase amperage 10%.Gas:ArgonGas Flow Rate:13 cfh or 20 psiWelding Speed:5 inches per minuteTorch Cup Orifice Diameter:1/2" (12.7 mm)Use ceramic cup when welding with less than 250 amps. Use water-cooled torch when welding with more than 200 amps. Are you using a watercooled torch?Filler Metal Diameter:3/16" (4.8 mm)That should take care of it. No need to thank me. As the worlds best welder, just doing my part.
Reply:I think if you look at what you have said about this problem the solution is fairly simple.  You say penetration and leg length are good, so lets not do anything to effect that.  Really the only thing left that wont effect either of those two and will help your throat length is the amount of filler.That being said, you need to either find a way to get more filler into the puddle (add more wire, switch to larger dia) or look into making this a multi-pass weld.Have we all gone mad?
Reply:Originally Posted by sdoneckerMy settings:250A, Argon 20 cfm, #7 cup, water cooled torch, 1/8" electrode, 1/8" fillerSo I assume you would be performing this operation in a single pass.According to the procedure handbook the legs should be 3/4T, which implies the root should be 3T/sqrt(32). In the case of T = 3/8" you should have 0.281" legs and 0.198" root.I am getting the correct leg length but my root is 0.125"  to  0.150".I guess my question is what should I do to increase the root? Should I just use more heat and filler?Thanks for the reply.
Reply:That's a big bead to lay in one pass.   I would do it multi-pass.  Put in a root pass with good penetration and about half the leg length you need (3/16 in this case), then put in a second pass along the lower toe line of the root pass, then put in a 3rd pass along the upper toe line of the second pass and that should fill it to size.   Use more passes if you need to.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Originally Posted by sdoneckerI have been trying to weld several 3/8" A36 tee joints using the TIG process,  So I am interested in how everyone else would perform this weld. Would most use a single pass, or some method of multi-pass for this configuration? Any specifics are greatly appreciated.
Reply:you can build it up all day... Attached Images
Reply:Don't forget tungsten geometry plays a part in the formation of the weld. A longer taper will give you less penitration but will widen your weld out more. A blunter end on your tunsten will give you more penitration but wont help the legs of your weld (can't believe the worlds best welder forgot to mention that)
Reply:I was contemplating your problem at work today, comparing it to some of the things I weld. I think you'll find that a christmas tree weave will really help you make a nice large fillet weld.