welding thick stuff to thin stuff - need advice

[cross6]

I've got to weld some 3/16" thick flanges to some 22 gauge pipe - it's a butt weld.


I'm using a Hobart handler 125 flux cored mig welder.

I assume I'm gonna have to zig zag and dwell on the 3/16 - and also position it so my welds will want to undercut the 3/16 and not the pipe.


But my prob is I'm afraid that .035 wire will burn through the pipe - however if I use .030 or less it won't penetrate the 3/16" flanges

any tips?

[bob a job]

Hi
Well to my experience here in the uk. Small welders are not very good under 160. If you aren’t experienced at welding you will blow the pipe.

But how about drilling the flange the size of the pipe then fit the pipe into the flange so that the pipe is flush with the flange face. Then you can run a heavy weld then grind it flush. This way the flange and pipe are burned in together.

[HuFlungDung]

There's a couple of tricks: turn the voltage and wirespeed way down and weld in gobular transfer mode. You don't really need penetration of the flange, all you need is enough heat to wet the surface and make the puddle stick. Grind the weld area of the flange first to ensure best adhesion.

Don't weld in the horizontal down position. Weld in vertical down mode, maybe with a little more heat and wirespeed than would be safe in horizontal mode for this thin material. This would be like welding on the side of the pipe, with the joint in a vertical plane.

If you burn through, don't restart in the hot hole you've made. Turn the pipe a bit and continue on. Move quite fast, so that you stay ahead of the puddle. Any droop in the puddle will tend to weld the joint in vertical down mode, instead of just falling away. You can always go around again and patch the holes, grind it a bit, then do a beautification pass.

[cross6]

Originally Posted by HuFlungDung There's a couple of tricks: turn the voltage and wirespeed way down and weld in gobular transfer mode. You don't really need penetration of the flange, all you need is enough heat to wet the surface and make the puddle stick. Grind the weld area of the flange first to ensure best adhesion. Don't weld in the horizontal down position. Weld in vertical down mode, maybe with a little more heat and wirespeed than would be safe in horizontal mode for this thin material. This would be like welding on the side of the pipe, with the joint in a vertical plane. If you burn through, don't restart in the hot hole you've made. Turn the pipe a bit and continue on. Move quite fast, so that you stay ahead of the puddle. Any droop in the puddle will tend to weld the joint in vertical down mode, instead of just falling away. You can always go around again and patch the holes, grind it a bit, then do a beautification pass.

You mean weld with the gun in the vertical down position - and the flange flat on my welding table?

This is what I was planning on doing - welding straight down onto the flange and run a nice fat bead so that it would kiss the pipe

[HuFlungDung]

No, I mean weld with the flange standing up as if held in a vise. The bead is run with a vertical down motion starting at a position a little above "3 o'clock" on the flange and sweeping downwards a little ways towards "4 o'clock".

[jphagen]

Well I would try a horizontal weld, the flange down flat, and since you are using flux
core wire, weld the 3/16 up over and down then stop wait about 3 sec. then do another, What you do is start a pool and keep it flowing along the line. ie melt a little
the before it cools too much start it again, this way you keep the heat going.
The other way is to use a copper strip inside to take up the extra heat.
The other way is to use .023 wire, it will give you much greater heat control.
If I had my choice I would tig it, otherwise ox/acl for greater control.
Note depending on your application you could always silver solder it.. Just a question of
applicaton.