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  1. #1

    Default underfill prevention on root pass

    What's up fellas , I recently started an apprenticeship for UA plumbers and pipefitters and am preparing for my 6g welding test tig root and hot pass 7018 out on a 2 inch super coupon. The stick portion of the test I can run good and the hotpass is fused in nicely (i will provide pictures I'm better with a stinger than a computer lol) and I thought I had the root pretty good but they burst my bubble on that say flush on the inside of the pipe wasn't good enough I needed a visible 1/16 after the test was done . I wanna get this down before my next class just so I can get my name on the test list , I'm running 80 amps 1/8in gap knife edge 1/8in filler on the root on a miller tb 302 I'm having trouble getting that extra reinforcement on the inside it just turns out flush

  2. #2
    Join Date
    Apr 2009
    Location
    KANSAS
    Posts
    511

    Default

    Can your wire fit thru the gap? The easiest way to get some but not to much penetration is to set your gap just a hair wider than your wire. Using a 5/32 space on the first tack will usually leave you just about right after you put the rest of your tacks in.

    The trick is to hold half of your wire in the inside of the knife edge, this will give you roughly 1/16 fill on the inside but you can't "wash" up on your walls or it will pull it back to flush. run slightly colder and a hair faster. You need to melt it in, but thats all, if you lally gag around it will suck back.

    Another trick is to weld, weld, weld. Root it, hot it, then go to sticking don't stop and smoke a cig and see how everyone else is doing. You can take a break before you cap to decrease the chance of undercut, but other than that weld, weld, weld. The heat will pull your coupons together and swish out your bead. I've taken a lot of test were the bottom of the bead was just about flat but the QC sayed to run it on out. When they would come back to look at the cap, they usually liked the bead a lot better. Because it had stud up some. I know it sounds a little crazy but I've ended up pushing a lot of them threw, especially on Tig tube tests were you only stop if your out of wire.

    Them 2'' XXS ain't much fun are they. The ID's about the size of a quarter. LOL
    Good Luck
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  3. #3

    Default

    I'll give that a try RH , after I read your post I realized I was trying to set my gap so I could rest my filler wire inside my gap as opposed to sitting it inside the knife edge , and as far as them test coupons go I'm glad I don't have to weld them in the field 30 ft in the air or 9 in from the ground in the booth is just fine for me . When I do run one of them coupons out I stay right on it as you suggested until the cap, them things do suck until you get the groove lol. I'll try another one using your advice n post pics , thank you for your help

  4. #4
    Join Date
    Jan 2009
    Location
    Whitehorse, Yukon
    Posts
    279

    Default

    That's right-- hot, close and fast for the root. Push as much wire in as the joint will take. Sounds like you already have the right idea-- good luck on test day!!

    WH
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  5. #5

    Default

    Well that's about enough for the day I figured I should try a root pass using these new techniques on a 6 in piece of sched 40 and well its embarrassing its going to take some practice , I know its going work cuz the parts that ran fine were exactly what I need to do and as for the pics I dropped my camera in the garage before I could take any and ran outta argon and gasoline for my welder thanks for the help guys but I think its time to jump in the bottle and find a crazy woman tonight lol. Oh and on the bottom of the pipe the filler metal kept jumping on to my tungsten is this an easy fix or no thanks again

  6. #6
    Join Date
    Feb 2011
    Posts
    26

    Default figure 8's

    I was alway's taught to roll the tig in a figure 8 , cupping as i push the rod in the gap to get proper penetration on both sides and fill.

  7. #7
    Join Date
    Jan 2009
    Location
    Whitehorse, Yukon
    Posts
    279

    Default

    Ya that'll happen fng656. Learning to mess with the pedal on the overhead portion can be a difficult and sometimes humbling experience. Keep the wire laid right in your grove and walk the torch a little back and forth over the puddle. Lots of filler and a LITTLE weave will help keep the puddle from boiling and jumpin onto your tungsten.
    Big Blue 400D
    Trailblazer 302
    Miller S-32 suitcase
    12VS suitcase
    Lincoln LN-7 (BIG suitcase)
    Victor torches
    Lincoln 350MP with 35' push-pull gun
    Lincoln PrecisionTIG 375
    Spectrum 1000 plasma cutter

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