I want to make a pipe pole with larger diameter pipe on the bottom and with a smaller diameter on top.
Is there a way to weld something like this together?
The only way I could think of was to have the smaller diameter pipe run the entire length and use some sort of bushing at both ends of the larger diameter. Making the welds there.
Is there a slick way other than this?
Thanks.
No sliding, right? Then why not just slide the smaller pole into the larger pole for as long as you figure you need to, and weld up a lap joint right around the smaller pipe at the joint? Ideally, you can find some pipe that just barely doesn't fit into the larger size (e.g. 3/4" pipe that won't quite fit into 1" pipe, both sch 40) and you can grind a flat on the 3/4" pipe to fit over the weld and make it just go in, then it will be pretty tight. If you got a 3/4" pipe to go in say 6" then it won't be any less resistant to crumpling in cantilever than it would be if it were completely inside the bigger pipe. (This just from intuition) - GWE
I was not clear.
I wanted to use something like four inch on the bottom and two inch on the top, something with a gap. And no sliding.
Thanks.
I worked at a place that did this for big highway signs. They cut holes in the lower pipe so they could weld the two pipes more than just at the top of the lower pipe. The pipe diameters were different enough that they had to weld in spacers on the bottom of the upper pipe to fill the gap, and get the top of the lower pipe red hot so they could hammer bend the lip in enough to weld a joint.
If the two sizes of pipe are very close, then it is relatively simple. I still suggest plug welding (drill hole in the lower pipe and then weld the two pipes together and fill in the hole.) Weld all around at the top of the upper pipe and you are done. Assuming 20 foot pipes, I would probably overlap them 2 to 3 feet, so the assembled height would be 37 or 38 feet high, assuming two pipes.
Richard
st> I want to make a pipe pole with larger diameter pipe
How strong does it need to be? Any reason you can't use a reducing coupling and screw it together and avoid welding completely?
If this is common steel pipe and you're a decent welder, you don't need any overlap. Cap the large pipe with a disc and fillet weld the smaller to it. As long as the cross section of the welds is larger than that of the pipe, and you follow good welding practice, the joint will be as strong as the pipe.
Ned Simmons
If the fit is sloppy, weld a disc to the bottom of the smaller pipe that will just fit into the larger. Drill 3 holes around the circumference of the larger about 2 feet from the top. Insert the smaller until the disk is visible through the holes. Nice rosette welds. Another disk (same OD as large pipe) at the top with a hole for the smaller pipe. Weld to suit.
If the fit is tight, forget the disks.
If you are using bushings, weld the bushings to the smaller pipe. Drop the smaller pipe inside the larger one and weld the top bushing to the larger pipe. If you really need to weld the other bushings or if the top bushing won't be flush with the larger pipe, I would think a plug weld would do the trick.
Steve.
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