Any other verticle up MIG patterns?

admin

Right now at work I am building a bunch of parts out of some pretty heavy plate, something i'm not very used to, it's mostly a stainless TIG shop. One of the parts I am making are 4' long 6"x6" 1/2" wall square steel tube. They have a 13"x13" 1 1/2" thick plate welded on each end, looks like a big "I". There are also gussets from the plate to the tube. The ends of the tube have a 1/2" bevel. And this is welded all the way around with a 1/2" weld. So what I have been doing is doing a root pass in the bevel, flat, just to get it about level, then running one 1/2" weld verticle up. The customer on this job is very picky about looks, so it has to have one cover pass, it cant be multiple passes. I am doing the christmas tree pattern. It looks good, but I cant keep it perfectly consistent. Does anyone have any suggestions, or any other patterns to try. I'm using a 3 phase 350 amp miller XMT, short arc mode, .035 wire, 75/25 gas, i'm at about 17.8 volts right now. Thanks.
Reply:You could just use a simple z weave.  It is much easier to keep consistent.
Reply:Originally Posted by weldrwomnYou could just use a simple z weave.  It is much easier to keep consistent.
Reply:If at all possible you should be turning your work to weld on the flat or horizontal.  Heavy plate over 3/4 inch should be preheated to at least 200 F.    Something like this whould be done with self shielding flux core if you have to run verticals.  If you were able to run flat you could use around 27 volts and a high argon gas. ... at least 80 percent.    From what I can tell you are doing pretty good to get even a half decent weld with such small wire and single pass caps.
Reply:Thanks all for the suggestions. I ended up using .045 wire, about 19 volts, and running a single downhill Z weave cover, it came out real nice, much easier to keep consistent. I ran a root pass in the bevel, then one hot pass, and then the cover. The root pass was flat, the hot and cover pass were downhill.
Reply:I'm not one to post on message boards much but I read this yesterday and it's been bugging me. I don't know what the application for your weldment is but if you and your customer ( who is picky about looks) are going by the AWS Structural Code D.1 you'll see that that short-circuit, downhill, and fillet welds over 3/8" in a single pass for GMAW, FCAW and SMAW are a no-no. I'd stand those pieces up and use a 71T-1 with your gas and run multiple passes in the flat position. Take a look around at large welds on heavy equipment, piping, pressure vessels, structurals, etc. If they aren't sub-arc welded, they are multi-pass. And they have a lot more going for them than just good looks.Just my opinion