two inch sch80 6g pipe test???

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Just some general questions on welding 2" pipe.  Yesterday I was informed through my business agent of work at the edison plant.  The boilermakers(I am a sheet metal worker) need welders to man the job.  I was told by someone at the boilermakers hall it was sch. 80 pipe but the guy I know that went and took and passed the test told me it was closer to 3/8 thickness, whatever.  He also told me to bevel with no land and 3/32 gap.  That seems like a big gap to me with no land.  Is this correct?  Its gonna be a 6g test with a tig root and I guess two passes with 7018.  Stringers.  I was told like two or three stringers for the second pass and three or four or so for the cap.  Black iron pipe.  I am going to go to my hall to try to brush up then go practice at the boilermakers hall and test when ready.  This has to be soon and I have never even tig welded out of position before.  I am generally a good welder though and feel I should be able to do this.  Any suggestions are very welcome.  Thanks for any help.Last edited by abraham; 10-10-2008 at 05:40 AM.Reason: changed title.
Reply:No land and 3/32" root opening is correct.  I'll file the root face just enough to remove any burrs and square the root face up.  You should barely see any flat surface on the root face when you're done prepping.  If you use a heavy land, you'll have trouble tieing in the weld.  3 or 4 tacks is customary.  Make sure to tie in solidly when you start and finish each segment of the root.  Use 1/8" filler, and about 80-85 amps for the TIG root. Lay the filler in the opening, and fuse the filler into the bevel.  Keep the arc on the filler and keep the side to side motion small, just enough to tie the puddle into the bevel.  Travel quickly and try not to linger in any one place too long.  If you spread the puddle too wide, you'll undercut the inside of the weld joint.  This is especially likely on the uphill side of the joint, where gravity is pulling the molten puddle down.Make sure to watch out for suckback when you tie into the tacks.  I like to feather the edges of the tacks and weld into them to make certain the tie-ins are good.The hot pass with 7018 should fill the bevel to within 1/16" of flush.  I do this in one pass with a weave bead.  Keep the side-to-side weave parallel to the floor, not the pipe axis.  Step up and make sure you don't pause too long on the bottom.  More time on the uphill side of the joint than the downhill side.  This will keep the fill even.  If you've never welded pipe, don't pause in the middle, your bead will hump up, and you'll trap slag in the toe lines.  Don't overfill the bevel and don't wet into the top edge of the bevel.  If you do, you'll have a difficult time laying on the first pass of the cap.  The lower toe line is your guide to running a straight cover bead.  Leaving that little shelf gives you a nice, flat first bead of the cover pass, and makes the whole cap look better.  The second and third beads of the cover will look straighter and flatter if you get the first bead right.You can run the hot pass and cap with 1/8" or 3/32" 7018 rod.  I like the 3/32" better personally.  You can run it at lower amperage, say 70amps, whereas the 1/8" rod needs 95amps minimum to run good.  The lower amperage keeps the pipe from overheating.  If the base metal gets too hot, it's very easy to undercut the toe-lines of the cap.  In fact, you might want to take a break and let the pipe cool between the hot pass and the cap.  Some welders like to shorten the rods when running 2" pipe.  This makes it easier to maintain the right work and travel angles.  I do depending on how much my hands are shaking on any given day.Use a wire wheel or 1/8" grinding wheeel to clean up the hot pass.  Make absolutely certain that you do not get carried away and grind away the bevel.  This will screw you up every time.That's all the advice I have at the moment.  If you practice and have troubles, come back with specifics and I'll try to help.-DaveBenson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:The land and gap are often up to whoever fits the joint. There are limits, in that world often being as much as 1/8 and 1/8, but 3/32 and 3/32 is common. I agree that a narrower land can be easier to work.Often, pre-prepped coupons are supplied for the tests, 2"NPS, Sch160 is common, as is 2-5/8OD mechanical tube with a 5/8" wall (small enough dia to go down to 1"OD, heavy enough wall for a root and >1/2 fill and cover for the unlimited thickness).bring a flashlight and small mirror. They are usually ok. You may not be permitted a grinder, but a file is usually ok, chipping hammer and brush definately. A steel rule (one of those 6" long, skinny, thin jobs with a pocket clip) is handy, as well, especially with a mirror, as it is a lot easier to check the root with a visual reference. Check the root BEFORE closing up.. . shine the light in the end and look through the gap. You can, to a point, fix some issues, like a spot with incomplete burn-in, before covering.I also recommend feathering the tacks, but check to see if the number matters. I have seen a few that insist on 4 tacks, others are happy with three or 4. Originally Posted by abrahamJust some general questions on welding 2" pipe.  Yesterday I was informed through my business agent of work at the edison plant.  The boilermakers(I am a sheet metal worker) need welders to man the job.  I was told by someone at the boilermakers hall it was sch. 80 pipe but the guy I know that went and took and passed the test told me it was closer to 3/8 thickness, whatever.  He also told me to bevel with no land and 3/32 gap.  That seems like a big gap to me with no land.  Is this correct?  Its gonna be a 6g test with a tig root and I guess two passes with 7018.  Stringers.  I was told like two or three stringers for the second pass and three or four or so for the cap.  Black iron pipe.  I am going to go to my hall to try to brush up then go practice at the boilermakers hall and test when ready.  This has to be soon and I have never even tig welded out of position before.  I am generally a good welder though and feel I should be able to do this.  Any suggestions are very welcome.  Thanks for any help.
Reply:Due to lack of material ( we are a sheet metal local) and a little confusion on the test(the guy I talked to at the boilermakers local told me it was sch 80.  the guy I talked to in my local who took the test and is currently working there told me it was closer to 3/8) and we(the training center) have a aledged sample of the test and it is clearly heavier than sch 80 I have been practicing on various materials.  My instructor started us on running horizontal beads on 3/8 plate with 7018.  Ofcourse that was no problem.  Then we started welding t-joints in the flat.  Then we started tiging 3/8 plate horizontally.  All of which was no problem for me.  Then I started practicing on the shc 80 pipe (which is 2" id and the code is 2" od, did'nt know at the time) and did pretty well the first day, but am having a hell of a time as of today.   How do you hold the torch?  Do you go right handed on one side and left handed on the other or  no?  Just had a frustrating day.  Can weld the stuff up, down, and sideways literally, but put me on that 2" tube and I can hardly do a thing.  At least today anyway.  Any more input welcome.
Reply:Oh yea, one other thing I forgot to mention is that I have been using a eighth inch gap and I should be going 3/32.  That might be a big help right there.
Reply:No offense, but if you have to ask this many questions, you're not likely to be able to do the job.  Even IF you get lucky enough to pass the test, a few xray's later, you may wind up fired.I don't mean this in a bad way, but consider that lives will be at risk with your welding.  OTJ weld training on boiler tubes is not a good idea.  It could not only lead you to the unemployment lines, but may also land you in prison or in the courtroom...or both.
Reply:I have to agree with Enlpck.  Sounds like you're working with XX hvy wall, not schedule 80.  That's no big deal.  He's also right in that out in the field you're not likely to get perfect root opening and lands.  But there's no sense in trying to learn with one hand tied behind your back.  Start with the ideal setup and get comfortable welding under good conditions.  Then worry about what to do when things are FUBAR.Ask 10 TIG welders how they hold the torch and you'll get at least 12 answers.  I tend to grip it like a pencil, up close to the cup.  Then a standard back cap lays in the webbing between my thumb and index finger.  If I need more rotation on the cup while walking it, I move my hand down to the bottom of the handle and slip the hose inbetween my pinky and ring fingers.  This gives me better leverage against the pull of the hose and more range of motion to roll or walk the cup from side to side.I've seen some guys wrap the torch handle in foam and tape to make it larger in diameter.  This seems to make them more comfortable.  Yes, when TIG welding pipe in the 6G position, I swap hands holding the torch and go with whatever is most comfortable.  For 2G I'll also swap hands, and free-hand the weld rather than walking the cup.  For 5G position, it's the same hands and walking the cup all the way.  I'll also invert the torch handle when starting at the bottom of the joint.  Some guys can walk the cup with the torch handle pointing down, but I find it tough to do this and get consistent motion, arc length, and consequently bead appearance.Has your instructor shown you how to walk the cup?  If not, you've got a long way to go before you're ready to weld boiler tube.  Get your root spacing and land right, or you're just pissing into the wind.  If your setup and prep aren't right, you're making it tough to learn how the other process steps affect the final result.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:I have been walking the cup but not doing to well.  Talked to someone at the boilermakers hall and they told me not to walk the cup.  To all the naysayers.  I am just trying to learn.  I'm sure you had alot of questions when you were learning also.  If not you probably did'nt learn much.  I am a good welder in many other areas.  Have a d9.1 and a stick and mig 1.1 cert Have been welding everyday for the last 18 or so years.  This is not THAT difficult, and I wont start the job untill I know what I am doing .  If I dont land this job I will be ready for the next.  Thanks for the replies and keep the conversation going, thats what the forum is for after all.
Reply:When welding boiler tubes, you will rarely be able to walk the cup.  That's probably why they don't want you to do it on the test.  I'm not knocking you for asking questions, so don't take it that way.  I'm just playing devils advocate, so you don't go into something without considering all sides of it.
Reply:Cool.  3/32 gap and no cup walking and I've got it down finaly.  Took about 20-30 hours or so.  Still going to go in and get all the free practice I can.  The one job is more than half over so I am no longer worried about it.  Come Dec.  I will be more than ready.  Thanks for all the help.
Reply:Just got back from another 4 hours worth of practice.  Hard for me to believe but I need more work with the stick than anything else.  Got the root pretty much down.  Went back to a eighth gap now that I have my technique down a little better.  How long between beads do you wait while testing?  I am just practicing so I am not realy letting it cool between welds and am getting undercut.  Do you guys let it cool for 15-20 minutes between welds or just go at it?  Any other pointers on sticking the cap welcome.
Reply:Your WPS should specify interpass temps.  Find out what they're going to be, get a tempil stick, and use that to gauge when you should resume welding.
Reply:If it's a critical weld or for a test, or you've just got it too hot to put an acceptable bead on it, let it cool.For example, on a 6g test, I MIGHT not let it cool at all until I put my last stringer pass on (the top one).  Especially if a job depends on it, I may let it cool down till I can almost touch it.  .
Reply:When taking the 6G test , let it cool as much as you can between passes if you have time . (In the tig)It may look like a banana when you are done . But that is o.k. (If you have a High Freq turn you r heat up when tie in tacks then bring back down quickly to aviod suckback. It does'nt matter if you just weld one inch at a time as long as it is a good one inch at a time . If you your have trouble with stick , try using a pipe stand to support one of  your elbows and make sure you use both hands at all times to maintain as steady as possible. BTW Walking the cup is the only way to go !!!SantinisLast edited by Santinis; 10-23-2008 at 01:53 PM.Reason: fogot to add
Reply:Originally Posted by SantinisWhen taking the 6G test , let it cool as much as you can between passes if you have time .
Reply:No land and 3/32" root opening is correct. I'll file the root face just enough to remove any burrs and square the root face up. You should barely see any flat surface on the root face when you're done prepping. If you use a heavy land, you'll have trouble tieing in the weld. otherwise good advice but the only question i got is how you going to lay a 1/8 wire in a 3/32 gap?
Reply:Originally Posted by ian_sotherwise good advice but the only question i got is how you going to lay a 1/8 wire in a 3/32 gap?