stainlees?

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hello members               I nee d to fab. and weld a tank approx 4x10ft. actually its more like a box . It looks like I will have to split and weld in the center, 4ft of weld . This is 12ga. material . My concerrn is the distortion that will happen when weld ing the seam in the center . How can I control this distortion ??. Going to use 030. wire with argon gas.                              Thanks Laurance
Reply:if you are mig welding, you will need a tri mix I think. If you can set up some kind of heat sink, you might be able to control warpage.UA Local 598
Reply:Gee,Maybe you could use a flange making tool (pneumatic?) at the tank or the added sheet, which would allow a lap joint instead of a butt weld. That could probably help eliminate some distortion, too.Peace to you,C. Livingstone
Reply:If possible to weld the seam first and then the ends, so you can use a heat sink/backer bar of some kind on the inside.  You should also backstep the welds, and keep them short.Have we all gone mad?
Reply:with stainless especially when it comes to pressure piping. Less heat input equals less distortion. i would personally do some sort of ribbing on the inside of the tank as to create support and strengthen the tank as a whole. In doing this you also as stated create a bit of a heat sink. Another option is to use a piece of stainless flat bar as a backing on both seams.
Reply:weld down-hill if at all posible, and quick.. material that thin with a mig is a sinch.. don't worry about bead pattern or looks.. just worry about one continuous bead of clean metal.. quick is the key..if you're not livin on the edge, you're takin up too much room..
Reply:Thanks        I appreciate the input Guys . I am going to use 304 stainless sheet unless some information would change my mind > . Is there a reference guide out there that identifies the different classes of stainless steel?Last edited by laurance D; 02-21-2010 at 07:41 PM.Reason: add ? mark
Reply:304 works for most general work. What exactly are you using the tank for? I would suggest welding the pieces you have to scab together before you assemble the box. It will be much easier to back up the welds with a heatsink/strongback.I would suggest welding them down hill as fast as you can with only minimal penetration, flipping the piece over and welding it again from the other side to equalize the distortion. This method also leaves you the option of hammer welding the **** out of it if it doesnt behave.
Reply:With a mig welder on a holding tank of any kind, I suggest you treat your stop starts as you would in a stick weld; grind them at the start/ stops and prep the areas where welds will overlap. You may find that it will be nicely welded, but you have 20 little bitty leaks.I also agree if you are welding any vertical with thin material, run downhill for ease of puddle control and to minimize excess heat input.304 is general material, 308 is standard filler.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Why do you need a seam in the middle?  you can get again stainless in 4'x10's. 304 or316  I would recommend TIG welding on a job like this.   IF you mind your corners on a job like this and your shear is square to the world you can get away with doing a corner to corner weld  with min filler.Last edited by Dualie; 02-22-2010 at 02:39 AM.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.