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Up Topic Welding Industry / General Welding Discussion / welding 2" pipe
- - By abrahamx (*) Date 10-10-2008 09:12
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.
Parent - - By jon20013 (*****) Date 10-10-2008 09:28
Not wanting to freak you, but if you've never done tig welding and you're doing it in the 6G you'd better get cracking on that practice!  The bevel, root opening and zero land sounds about right (the root opening should be "approximately" as wide as the diameter of filler metal you're using.  The difficulty will be getting used to having to feed the rod with opposite hands, relative to which side you're working and learning to feed the right amount.  I can't over-emphasize the need to practice as much as possible because they'll probably be looking for a "wedding ring" root on the inside.  Good luck!
Parent - - By abrahamx (*) Date 10-10-2008 10:09
They will be looking for the wedding ring.  I have tig welded plenty before.  Just on sheet metal though and not out of positiion.  If I had never tig welded before I would not stand a chance.  I pretty much have to test today(its 6 in the morning here), or maybe mon.  Thanks for the input.  I was told to just lay the electrode on the pipe and keep the arc on the filler?
Parent - - By jon20013 (*****) Date 10-10-2008 10:35
Sorry, I misread your post earlier.  Well, I wish you the best, good luck!  As for laying the electrode on the pipe and keeping the arc on the filler, I'd just say watch that puddle, keep your fill adding slow enough to keep the bell hole going but fast enough to control collapse.
Parent - - By abrahamx (*) Date 10-10-2008 11:09
not familiar with the term bellhole
Parent - - By Ringo (***) Date 10-10-2008 11:25
Not to discourage you,but speaking from experience,it takes alot of practice to make it slick.The set-up the guy told you sounds about right.
Parent - - By abrahamx (*) Date 10-10-2008 12:16
I know.  I am not terribly confident in doing this on such short notice.  It will be a good learning experience though and next time I will be ready.  What should I work on to become certifiable for the pipe welding trade?  With Fermi comming around I am told they will be taking qualified welders from my hall(sheet metal) to man some jobs.  What am I best off practicing to be prepared when the call comes?  Any certain dia pipe?  Tig root I assume?  Any general cert?  My training center is not equiped to train for pipe welding so I may pay to go to another school, just not sure what I should enroll in.
Parent - By Ringo (***) Date 10-10-2008 13:02
Its industry dependent.If you plan on working on some papermills or powerplants,I would practice on carbon steel pipe 2" to 6" Sch.40-80, Tig root and hot pass,then 7018.Also,2'' Stainless Steel Sch.10,Tig all the way out.Cut your pipe good and square,so you'll have the same gap all the way around,and you want the tig wire to not fall thru your gap,so you won't have to fight it the whole time.I would practice alot before I took the test if I way you,because if you get looked-out,or bust on the bend test,you'll probably have to wait 30 days before you can test again.And you don't want to be looked at as a no-welding f***.

Good luck man,
Regards,Ringo   
Parent - - By pipewelder_1999 (****) Date 10-10-2008 13:39
A standard test with the Boilermakers is usually a "Super Coupon" or other heavy wall pipe less than 2 7/8" OD. The "commonarc" test are welded with a tig root and 7018 fill and cap. No 2nd pass of tig over the root. There are no grinders allowed but you are given a file. Though I used the termn "standard test" understand that it can vary as needed.

When I weld one I tack 3 of the 4 sides unless the proctor says otherwise. I weld the side without the tack 1st and weld all the way from the bottom to the top.  I try to locate the coupon low enough in the jig where I can easily get over the top but high enough that I can get the bottom by just widening my stance. This allows me to weld the entore coupon with no starts and stops on the sides which decreases how much time I have to spend welding it and also minimizes and discontinuities from the starts and stops.

If you have not welded any pipe or a open root in any materials with GTAW then look at the test as an chance to learn. I would be straightforward with them in the fact that you have no experience. Maybe try running a bead around the outside of a pipe without fitting up a joint.

I think you will have a difficult time but should give it a try if they will let you. Maybe someone there will be willing to help you on the side.

If you can stick weld plate you may be able to get in as a plate welder. 3 Tests, Vert, Horiz, and Ovhd on 1/2" or 3/8" plate with backing.
Parent - - By abrahamx (*) Date 10-15-2008 22:28
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.  Forgot to mention that I have been using a 1/8" gap with the sch80 and I probably should use a 3/32.  That might help the problem right there.  Just realized that at the end of the day.  Ohwell back tommorow for 3 or 4 hours.
Parent - - By pipewelder_1999 (****) Date 10-16-2008 03:23
I would suggest forgetting about putting a root on until you can get comfortable going around the pipe. Maybe take a section of pipe and ring a groove in it all the way around with a grinder and then just practice running a bead in that groove. After that groove is welded t hen start stacking beads on 1/2 of the previous bead.

Height, test jig, restriction, etc will all dictate which hand I use. There is no RIGHT OR WRONG. Only what gets you around the pipe with the most control.

If you are finger resting, make sure you allow yourself pleanty of travel or be prepared to either stop or relocate your fingertips. keeping the proper electrode angle is something that can only come with practice. No need for even welding. Just turn the power off and try to go around the pipe keeping the tungsten nearly always pointing towards the center of the pipe. (This angle can vary but it will give y ou something to pay attention to). Practice BOTH sides to determine which is the hardest then practice that twice as much.

Gap is an item of preference. I usually just fit it up and adjust the machine and what I am doing to "match" the gap. When I start on the bottom tack, once it begins to look like its melting, I start moving. Fitup, Amperage, electrode angle, wire size can all affect the root appearance. If you walk over the wire, watch for swirling of a little spot on thge puddle, that usually indicates you are breaking the walls down. If you keyhole, you are breaking the walls down without a doubt however you have to add enough filler metal to keep the root contour you need. I prefer a smaller wire when keyholing 3/32" or feeding through the gap. And 1/8" if walking over the wire.

The tig portion is ONLY one bead normally (for the Union BM tests I have taken) so stick is gonna be the bulk of the welding. 

The ability to maintain the correct rod/electrode angle is something you have to get control of. The length of the rod, angle of the rod in the stinger, freedom of movement, vision etc will all play a part in how easy going around the pipe is. Start in a bind and finish easy is something I keep in mind when welding.

Many people may try to discourage you because of your lack of experience. I suggest filing that away with other advice you may receive. Store it for later reference but test it out !

Here are some random rambling thoughts .

Be aware of bead placement. Since you already have the skill to make a bead, the only thing that must be controlled is where you put it. Avoid leaving deep valleys in a joint.

Don't be afraid to add an extra pass on top to make it fill evenly.

Be aware of how you start and stop and where they are located. The SMAW will all have starts on the bottom. You can stagger them somewhat to minimize the hump. Dry rods and proper starting techniques will minimize defects at the starts.

Choke up on the rod some to minimize "wiggling" if you have to but remember if you can weld from bottom to top, you can eliminate one stop on the sides.

Keep your lens clean.

If the test jig is adjustable, GET IT LIKE YOU LIKE IT. If it swings, move it to where it favors your weakest side. Don't worry as much about having the top low but maybe more about having the bottom high enough that you can see it well and come up the side to the top with little effort.

Use a file in the end of the pipe, vice grips or anything if the person giving the test doesn't care. This can be used as a rest.

Use whatever size rod you can handle. 1/8" burns hotter and travels farther for the same length of electrode. Sometimes that helps, sometimes it doesn't .

If a hole opens in the root when you are putting the 2nd pass in, DO NOT STOP. Keep going and concentrate the heat on the sides. It will probably seal up just fine. Let the inspector look for it. Its what he gets paid for.

Thin flush roots are more subject to melting through than those with a little MEAT. in them . I suggest finding how much they are allowing (The boiler code allows 5/32" of internal reinforcement for a .250 wall tube) but some inspectors are "Smarter" than the code or thir projects are more "critical" and will often limit you to 1/16" max with no allowed internal concavity (also not in accordance with what the code allows).

Understand that many inspectors are evaluating you abilities as you test. It may not be just how your welds looks. Its my opinion thet there is something to be said for confidence without arrogance.

Hopefully something here will help and one thing I keep in mind is that no matter how many tests I fail, I'm still a welder and God, my wife and kids still love me !

HAve a good one and keep practicing!
Parent - By JHarlos (**) Date 10-16-2008 23:41
good advice on all parts.
Parent - - By abrahamx (*) Date 10-21-2008 17:27
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.
Parent - By K.Sexton26 (**) Date 10-21-2008 18:40
The standard test is usually 2 3/4 OD 5/8s wall thickness, let the coupon cool before you put the stringers on the cap.
Up Topic Welding Industry / General Welding Discussion / welding 2" pipe

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