Heat Exchangers..... Preping to weld

admin

I have done this job before, but this time the machine shop built me a jig to keep them straight.  The last batch had some issiues.  They came to me assembled just like in the pic and I  welded them.  Some were not true and square, so my customer had this jig made.  Its nice for me.  First batch they sent 23 and I tigged them.  Next batch was 45, so I bought the positioner for the job and used pulsed spray.  This time there are 80.   These cool air from a compressor in locomotives.  Water goes through the tubes and air goes through the fins.Here is how they came into my shop.  I love it when jobs come on skids!I put then in the jig, remove the blots that hold them together and install the T pins.  If you look at the pic above, there are studs on the bottom, so the T pins and studs line up the two sides of the heat exchanger.Then I add clamps for good fitup.  The sides are pre bent and they do a good job.  Once the clamps are on,  I loosen the over center clamp on top to relieve any stress, then re apply it.Then they get 8 little tacks.  The smaller the better because I have to run over them with the pulsed spray.  I hate tacks, they cause trouble in my welds.  This is why I use Tig.  1/16" filler, Arcmaster 185 set on 125 amps, Red or Gold 1/16 tungsten.  I went through about 20 or so today.   Glad I bought a Sharpie tungsten grinder.Last edited by David R; 01-21-2009 at 07:09 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:I have to flip it over to tack the bottom.  It gets a few more too.These couplings go in the hole.  They supplied me with the tool.  It works nice unless the magnet gets hot, then the couplings can fall in and I have to fish em out.  Tacked in place.  I have not welded the tool to the heat exchanger yet.....Look at the corner to be welded. lower part of the pic.  Its an inside, outside fillet lap pain in the .....  Weld.About 2.5 hours work.  I was moving right along.Next time I will take pics of the welding.....David Last edited by David R; 01-21-2009 at 07:21 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:that is awesome work.insert thoughtful quote from someone else2000 Thermal Arc 300GTSW 3.5 hours1946 Monarch 20 x 54 Lathe1998 Supermax 10x54 Mill2004 Haco Atlantic 1/2" Capacity Lasernot mine but i get to play with it
Reply:Jigs are really nice for alignment, then I guess you've figured out a good sequence for the tacks and welds.  Have they checked out good so far?Nice warm work in the shop."Any day above ground is a good day"http://www.farmersamm.com/
Reply:BTW-  If the tacks are making the weld look funny as you weld over them, because they're already built up material, just make a light pass to notch them with a grinder just before you weld over them.  Not all of them at once, just as you come to them in the sequence.  It works pretty good."Any day above ground is a good day"http://www.farmersamm.com/
Reply:David 'RWW' R:Thanks for taking the time to photo and post. Some of us don't get to see cool things like this from our home garage.Craig in Denver 9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:How difficult would it be to fuse them, rather than add filler for a tack?  If it is doable then I am sure you could run tiny bead right in the seam.here what I'm talking about.  It in only 1/8 material.  I don't know if it would be acceptable for your work.  http://weldingweb.com/vbb/showthread.php...hlight=muntinsLast edited by tapwelder; 01-22-2009 at 12:29 AM.
Reply:That makes real sense.  Tacks always run the chance of being cold anyhow.  If you have the equipment to do it, great idea!I've always tacked because I don't own TIG equipment.  And my fitups aren't as nice as theseLast edited by farmersamm; 01-22-2009 at 12:28 AM.Reason: fitups"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Tapwelder, I'll try it.  It may slow me down and these are piece work, but....  I usually don't fuse carbon steel because I know it doesn't hold much.  It only has to hold till its welded.Farmersam, tig is the cleanest way for me to tack.  Mig would be faster, but I would have nothing but crappy starts to deal with when I weld over them.  Stick is the worst, it leaves slag in places I don't want it.  These have to be air tight.  When I did the last 45, 7 of them had leaks.I have about 30 welded.  The machined plates have some thread cutting oil in them and it smokes and stinks up my shop.  Its so bad that I had to quit. I tried cleaning them, but not much luck, its down in the blind holes with the threads in them.  Today I am going to get a dust collection fan and rig up some fume evacuation system so I can suck the smoke up and blow it out the window.  Thanks for the complimentsDavid Last edited by David R; 01-22-2009 at 06:01 AM.Real world weldin.  When I grow up I want to be a tig weldor.