Pipe test with mig...

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OK... First off... I'm a Union Boilermaker and primarily welt tubes TIG root and stick it out on a 2" tube but I have run a lot of mig for structural steel. Recently have been offored a good oportunity to move on to a more stable local job if i can pas this 6" schedule 80 pipe test and was hoping that I can get some pointers from you guys to help me pass this test.There are 4 tests and the first 2 I can probably do in my sleep.Test 1> 6G on 2" schedule 80, TIG root/fill/cap  This isn't a problemTest 2> 2G/3G plate   open root 6010 and 7018 fill/cap with back gouge.  Again... should be gravy Now... for what worries me.Test 3> 6" schedule 80, MIG root downhill ER70s-6 not sure of diamater Test 4>  is filling and capping this pipe uphill with 71T1-1 and again... don't know wire diamaterI have never tested anything other than plate on mig and it was almost always Esab Ultra 7100 which runs really smooth, in 2g/3g/and 4g. But I can honestly say that I haven't run much flux core other that puting down galvanized deck plating on a couple new construction jobs but that was years ago. Any input would be appreciated and if you guys can point me to setup charts for these wires so I can cut down on dial in time while at the bench.Thanx In AdvanceSteve
Reply:Steve,The short arc downhill root should not be a problem.  I'd use 1/16" land and 1/8"-3/32" root opening.  Watch out for the root closing up on you, as short arc mig doesn't have much penetration.  If you could say what wire diameter, I could recommend voltage and Wire Feed Speed settings.  Use a slight drag technique.  I've seen guys drag the nozzle of the gun down the bevel while putting in a root with MIG, almost like walking the cup while TIG welding.  But I don't like using that technique myself.  Pay attention to how much wire stickout you use.  Shorter is better, 3/16" to 3/8", no more.  A long stickout will promote more spatter, and you could see problems with the end of the wire balling up at 6 o'clock.  Too much stickout will give you porosity for sure.  Make sure you have enough gas flow, I like about 40 cfh with 75/25, about 30CFH with 100% CO2.  Bump those up 10 CFH if you're outside and there's any breeze.  Contamination on the pipe can give you problems with the root pass.  If allowed, clean the pipe to bare metal 1/4" to 1/2" back from the bevel inside and out.  If you're using an RMD or STT machine for the root pass, you'll have an easier time of it, but get someone from the company to help you set up the machine.  There's too many bells and whistles on these machines to fool around with during a test if you've never used one before.A side-to-side weave motion can help spread the heat and keep the bead flat, especially at 6 oclock.Standard short arc MIG is prone to cold lapping.  So figure out how fast to travel while getting good fusion without too much metal on the inside of the pipe.  A solid root pass will help you avoid burning through with your first fill using fluxcore also.Your E71T1 fill and cap will run a lot like E7018, in terms of technique.  I'd guess you'll be using 0.045" wire.  Probably 24-26V and 250-350 IPM of wire feed speed.  Hopefully they'll give you a welding procedure that lists what settings to use with their chosen fluxcored wire product.Lower voltage and wire speed will help as you get your sea legs, so to speak.  A Z-weave works just fine.  I find a weave easier than running stringers in 5G.  A combination of weave and stringers works for me in 6G; weave the hot pass and then stringers the rest of the way out.If the weld procedure for your test allows, I'd suggest dropping the voltage and wfs on your cap pass to avoid problems with undercutting the toe lines.  On 6" test coupons you'll also want to allow time for the pipe to cool between passes, especially before capping out.  This will help with getting the beads to freeze in place and stay flat in the middle of the joint.Good luck.Last edited by A_DAB_will_do; 06-16-2011 at 09:13 AM.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Ahhh... now thats the kind of answer I was hoping for with the little info that I could give. That alone will help me a lot. I wish I had the wire size, machine model and more info on the test specs. Kinda going in blind, I wish I had more mig experience then I wouldn't be so lost when setting up these machines.The E71T-1 sounds like it runs pretty nice if you compare it to 7018. I hope they allow a weave as that will let me control my puddle if I'm running a little hot when I get to the overhead. Now I"ve noticed in the past that voltage seems to control my puddle size and wire speed seems to be more heat related. Is this true with all mig/fluxcore welding or was it just my imagination?Also, How do your recommend setting up a scrap piece for dialing in the machine?  Would you setup up vertical, overhead or both to run some test beads?
Reply:I know just how you feel.  If you can get the person handling the test to give a datasheet for the T-1 fluxcore, or if they have a WPS for you to follow;  You'll be in the best shape.  Each manufacturer's fluxcored wires use slightly different settings.  The numbers I gave you are ballpark figures.  Start there if you have nothing else to go on.E71T-1s are very nice to weld with.  Imagine a 7018 rod that stays the same length and never runs out.  It's the same technique. Pause on the toe lines and move fast through the middle of the joint.  Your beads may be thicker, so you might get away with fewer passes to fill a joint.  But don't go crazy filling the bevel in 1 pass unless it's sch 40 or thinner pipe.Small adjustments in voltage are key.  Once you find a WFS that seems to put down the right amount of metal for a good looking bead, make small adjustments up or down in voltage until you find the sweet spot.  0.5 volts is a med-large adjustment to make with a T-1 wire.  Voltage controls arc length, which in turn controls how flat or crowned the puddle is.  Voltage is like pressure on the weld puddle.  Wire feed speed controls amperage, puddle size.  Travel speed and angle control puddle shape, size, and also affects how crowned or flat the beads are.Voltage and WFS are related to one another.  Adjusting one up often means you have to turn the other up too.  If you don't stay inside the operating window for the wire, you'll see problems.  Too low a voltage, for a given WFS and you'll have the wire stubbing into the puddle.  Too high a voltage(for the WFS setting) and you'll see wormtrack porosity on the surface of the beads.  Porosity that looks like swiss cheese is almost always due to a loss of shielding gas coverage.To set up the machine weld some flat, vertical up and overhead fillets if you have the time and material.  If you're limited, I'd dial the machine in for a vertical up fillet weld on some scrap angle iron or some flat plates tacked in a T joint.  A good setting for vertical up with get you through the welding at 6 and 12 o'clock, with minimal problems.  It won't get you max productivity, but who cares so long as the weld looks good and you don't fail the bend tests.My experience has been that more guys have trouble with the top of pipe or flat welds with fluxcore.  It's easy to trap slag by not moving fast enough.  Nobody welds slowly overhead, and on the vertical portion of a joint, gravity is helping you keep the slag out of the way. Originally Posted by rab986Ahhh... now thats the kind of answer I was hoping for with the little info that I could give. That alone will help me a lot. I wish I had the wire size, machine model and more info on the test specs. Kinda going in blind, I wish I had more mig experience then I wouldn't be so lost when setting up these machines.The E71T-1 sounds like it runs pretty nice if you compare it to 7018. I hope they allow a weave as that will let me control my puddle if I'm running a little hot when I get to the overhead. Now I"ve noticed in the past that voltage seems to control my puddle size and wire speed seems to be more heat related. Is this true with all mig/fluxcore welding or was it just my imagination?Also, How do your recommend setting up a scrap piece for dialing in the machine?  Would you setup up vertical, overhead or both to run some test beads?
Reply:Yeah... it sounds like it runs a lot like the Ultra 7100, which made some beautiful welds as long as you found the sweet spot. Laying under a 10' diamater steam header that is 30" off the ground had a tendancy to get you to find that sweet spot pretty damn quick. LOL It was 045 and seemed to run pretty good around 26-28 V with about a wire speed somewhere betwee 240-280 depending on how cold it was outside in upstate NY. On the root, Im not sure of the wire size but would you suggest a weave from land to land or will it fill itself, assuming that I have the welder set up correctly.Also... if they throw an LN25 at my feet, I'm assuming that both wires are reverse polarity (DCEP)Last edited by rab986; 06-17-2011 at 01:29 AM.
Reply:If its a UA based test, its open root with an RMD process (like on Miller PipeWorx Pro) which is very easy to use, no weave just a drag with the RMD, careful not to get to far ahead of the puddle or else you'll get porcupines.  also itf its a UA based test its a Bend test, not an xray.  I've hade a few friends pass a mig xray but subsequently failed the bend.  when you run your fill/hot make sure you are grabbing the walls of the bevelPipefitter/Welder- Pipefitters Local 537 BostonAmerican by Birth, Union by Choice4th Generation member Local 537
Reply:26-28V and 240-280 IPM is smokin hot for a short circuit MIG root pass with 0.045" solid wire.  Sounds more like settings for spray transfer, but exact settings will depend on shielding gas mix, With 0.045"  and 75/25, I'd be setup more along the lines of 18-20V and 140-160 WFS for short circuit MIG.  Heavy pipe with a heavy land and higher settings might be better for root pass and fill & cap passes.You should be able to put the root in without weaving for most of the joint.  A slight weave at the top can help with avoiding burning through, but it's easy to wind up with lack of fusion too.  A slight weave on the bottom can help flatten out the bead so there's little or no grinding needed before putting the next pass in.Yes, your solid wire root pass and t-1 fluxcore wires will both run reverse(DCEP) polarity. Originally Posted by rab986Yeah... it sounds like it runs a lot like the Ultra 7100, which made some beautiful welds as long as you found the sweet spot. Laying under a 10' diamater steam header that is 30" off the ground had a tendancy to get you to find that sweet spot pretty damn quick. LOL It was 045 and seemed to run pretty good around 26-28 V with about a wire speed somewhere betwee 240-280 depending on how cold it was outside in upstate NY. On the root, Im not sure of the wire size but would you suggest a weave from land to land or will it fill itself, assuming that I have the welder set up correctly.Also... if they throw an LN25 at my feet, I'm assuming that both wires are reverse polarity (DCEP)