Flux core welding test

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I need help with 6g flux core weld test, this is on 6 inch sch. 80 pipe.  Using a miller pipe worx 400. Mig root down hill then duel shield up hill.  I had worm tracks in the hot pass that carried to the cover pass. I was told to keep the nozzle tight to the pipe, which makes it impossible to see the weld puddle at all.  I was running 23.5 volts 240 wire feed at 50 cfm gas flow, which is 75/25. Any advice on the correct gas flow, wire stick out, wire feed ?
Reply:worm tracks are caused by moisture in the flux. not much you can do about that except get a new roll. I don't do many position welds these days, but I wouldn't generally set the volts below 26.5 if I was, unless it was 2 inch. I would put the wire 10 over the volts to avoid undercut. So 26.5 and 275 as a starting point. Maybe colder on the hot pass to keep from burning thru.How did you like the PipeWorx 400? We have a few of those at work, I love them for wire.You don't have to keep the stickout so close you can't see what you're doing.Last edited by TimmyTIG; 10-01-2014 at 08:05 PM.
Reply:TimmyTig the pipeworx machine is user friendly, do you know the gas flow you run it at? I was told to much gas can also cause worm tracks, and also too high of voltage.
Reply:50 should be fine and that doesn't cause worm tracks in my experience. Too much gas can possibly cause porosity and cool your weld off too fast making it look funky, but not 50. anywhere from 30 to 50 should be fine.Believe me, high voltage is not the cause of the worm tracks either. I did some 6 inch schedule 80 rollouts the other day set on 33 and 320 and they were slicker than snot.worm tracks is wet wire, end of story. Don't let them bull**** you.
Reply:here's you a link to the Lincoln site about worm tracks:http://www.lincolnelectric.com/en-us...ess-welds.aspx
Reply:Ksnyder,A couple months back I ran into a worm track and porosity problem trying to run some flux core on pipe.  It really had me stymied because just the week before I was using the exact same set up to do some structural work and wasn't having any problems.   I soaped all my gas connections and couldn't see any leaks.  But while standing next to the flow meter and having some one else pull the trigger I discovered the flow meter was making a high pitched squel when gas was flowing thru it.  Changed out the flow meter and it solved the problem.   The only thing I can figure is that some thing failed internally in the flow meter and caused it to suck air in. Also once before when trying to help some one else out with a worm track problem they were having with flux core and 100% CO2 shielding I tracked the cause down to that white nylon washer / disc that's used to make the seal when hooking a flow meter to a CO2 bottle.  It had gotten pretty scarred up from people not being careful of it when changing out bottles.  While I don't have any direct experience with the Pipeworx 400 I have run that machines predecessor the PipePro 450 RFC quite a bit the past year.   Looking at some of the parameters I wrote down for various things while trying to figure that machine out I'd recommend that for an .045 wire with 75/25 (out of position) you try 200 on the wfs and 24.5 on the volts.   No guarantee that'll solve your problems but if all else fails you might want to give those numbers a try.
Reply:Too high of voltage/wire speed ratio or excessive stick-out are other common causes of this. Both of these conditions lead to the wire getting too hot before it reaches the puddle, and the flux breaking down prematurely. I think if you increase the wire speed (amperage),  you will shorten the arc, as well as gain more puddle control.  You can also lower your voltage at your current wire speed, effectively lowering the amperage of the weld.  It is important to think of FCAW in that way, voltage=arc length & amperage=wire speed.  Higher voltage is really about allowing more wire speed, not heat. Wire speed forces the machine to generate amps and for a 6g fill pass I would say 185 +or- 20 amps would be the ticket. From the moment the wire leaves the contact tip, the wire is carrying the current, and a little wire+big current=lots of heat. If the stickout is too long the wire will have gotten to hot to function correctly when it reaches the arc, however some stickout is good to preheat the filler so when it reaches the arc it will flow more smoothly into the puddle.  Many wires function very differently, it can be difficult to say certain parameters will work on your machine in your situation, but I think you are very close. Long story short, I think your voltage is too high. I think TimmyTig is doing a spray transfer FCAW , which is allot different than a 6g pipe. Spray transfer does not uphill.Last edited by Davidbrown; 10-02-2014 at 10:08 PM.Constant Current Weldor.
Reply:you think his voltage is too high at 23.5? How much DualShield have you welded?I wasn't suggesting he use 33/320 on a 6G, I was just using that to show that you can go a hell of a lot hotter than 23.5 and NOT get worm tracks.
Reply:33/320. 8 inch standard wall rollout weld---no worm tracks, high voltage. Attached ImagesLast edited by TimmyTIG; 10-03-2014 at 08:51 PM.
Reply:I have not done flux core pipe but when I got those worms marks I was too close.  The idea is that the wire needs a bit more distance to heat up before it reaches the puddle.  Check the literature for your wire and see what the contact tip to work distance is supposed to be.  Sometimes all you need is to extend your nozzle out a bit if you are crowding with the nozzle.
Reply:Its not the voltage per se, but the voltage at that wire speed. It is clear you have limited experience with flux core, you obviously dont run it out of position much. Sure you can run insane voltages, and it works great, but not with what this guy is trying to do.  Do us all a favor when you back to work, turn your voltage up, keep your wire feed speed the same. Then observe the worm tracks. You will then understand what we are all talking about. From Lincolns' FCAW guide:"The presence of surface porosity indicates that the arc voltage is too high and should be lowered"Its there under the subtitle "Setting your voltage"Constant Current Weldor.
Reply:Been running it for 14 years, in all positions, bub. From South Texas to the top of Alaska. You're the one that's in over his head here. You sound like one of those classroom welders.Oh, I'm sorry. I see you're one of those 'weldors'.
Reply:We put a brand new roll of wire on Friday, I ran the hot pass around a 6 inch pipe and had 7 different worm tracks about one inch long. I went and got the instructor, he ran 10 stringers keeping the nozzle pretty tight, they were fine. I did two more and had a worm track in one.  Wire stick out seems to be the problem I'm to far away, guess I need practice, thanks for the help.
Reply:Timmy,Nice looking work in the picture in post #9.Here's a similar joint done all the way with .045 hard wire.  RMD mode for the root and pulsed spray mode for the fill and cap.   Starting with it already fit and tacked just under 12 minutes to weld it out. Last edited by HT2-4956; 10-06-2014 at 10:33 AM.
Reply:This picture shows what I was refering to in my first paragraph in post #6.   It was .045 dual shield with 75/25.   IIRC what I was trying for was a 1 pass (fill and cap) over an RMD hard wire root.   As you can see it started off going good but some where in the middle of the pass some thing went horribly side ways on me.  Man, talk about being unpleastantly surprised when I chipped the slag.  All though it wasn't my first suspicion I now know that it must have been an internal failure in the flow meter.  Changing out the flow meter solved the problem.  Unfortunetly I spent several hours scrathing my head looking at all kinds of other things trying to figure out what was causing it before it clicked for me that it was the flow meter.Another really disconcerting thing about it was that I really wasn't able to tell from any visual change in how it was welding that I was getting that level of gross porosity while I was actually doing the welding.  Last edited by HT2-4956; 10-06-2014 at 12:50 PM.
Reply:12 minutes!!??? I'm impressed. I timed an 8 inch yesterday, short arc/dualshield. took me 30. 15 just for the root, but I like to cut the tacks all the way out, so that takes time. QC is extremely anal at our shop.I really like that RMD, but we only have a few machines that run it, I don't get to use them often enough.I've seen that last weld before in my bay. Weird how  you can't even see it happening, ain't it?That pulse cap looks really nice. IDK why we don't do that.Last edited by TimmyTIG; 10-06-2014 at 02:42 PM.
Reply:Give you an example of our QC's. I had a 1 inch stainless slip on flange weld, TIG. Had one speck of undercut, maybe an eighth long, less than a 32nd deep. It was on the flat part of the flange, not even on the pipe. I couldn't even see it in the shop, took it in the office to show the foreman and in there under the fluorescent lights I could just make it out. Made me fix it.The other welder couldn't believe it either, he took a picture to show his buddies how goofy our shop is.
Reply:Ran another practice pipe today, set the machine at 22.5 volts and tried the wire speed at 225, 235 and 240. Seems to work well for me at that voltage, don't see a lot of difference changing the wire speed. A guy was using the machine to take a test before I got there and that's where he had it set 22.5 / 240.
Reply:Originally Posted by TimmyTIG12 minutes!!??? I'm impressed. I timed an 8 inch yesterday, short arc/dualshield. took me 30. 15 just for the root, but I like to cut the tacks all the way out, so that takes time. QC is extremely anal at our shop.I really like that RMD, but we only have a few machines that run it, I don't get to use them often enough.I've seen that last weld before in my bay. Weird how  you can't even see it happening, ain't it?That pulse cap looks really nice. IDK why we don't do that.
Reply:Here's an RMD root on 8" sch 40 in the 6G position.  Notice how full the groove is.  That's just the root pass as welded.Some ID pictures of how the roots look.Across the top.Bottom section.Welded out with pulsed sprayed hard wire.
Reply:This is our training / practice / testing set up.  The guy welding is a young hand that was already an accomplished pipe stick welder.  This is his first go at wire welding pipe.  I ran a few demo beads on the set up on left for him to watch and then he ran a few practice beads on it before starting the one he's on.  He did that one start to finish on his own and got good straps to bend out of it.   Needless to say we were both pretty tickled over that out come.
Reply:That looks like a Team positioner in the background. I work for Team in Port Arthur. Those positioners are pretty awesome.
Reply:At what arc length and wire speed are you putting the root in at in the 6 g position, also what root gap?  I did mine 1.5/150 with a 3/16 gap no land.
Reply:Depends on wire diameter and slightly on gas mix.  For 0.045" solid wire RMD and C25 I like 0.0 and 140-150; with about 1/16" land.  For 0.035" wire about 170-80 wire and 1/16" land.  Some guys like a knife edge, but I find it easier at the top of the pipe with a slight land to take some of the heat.  1/8" root opening minimum.  I like 5/32" opening, and have welded them as large as 1/4".  But really wide root opening means much lower WFS and much slower travel speed.  Suckback can be an issue as well. Originally Posted by KsnyderAt what arc length and wire speed are you putting the root in at in the 6 g position, also what root gap?  I did mine 1.5/150 with a 3/16 gap no land.
Reply:Originally Posted by TimmyTIGThat looks like a Team positioner in the background. I work for Team in Port Arthur. Those positioners are pretty awesome.Originally Posted by KsnyderAt what arc length and wire speed are you putting the root in at in the 6 g position, also what root gap?  I did mine 1.5/150 with a 3/16 gap no land.