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how to "accurately" weld pipe to plate


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Over the years I've had to butt weld a pipe to a plate top and bottom, usually for a tool stand or roll around cart. I set it up using a square and magnets and tack with mig. Sometimes this works OK and then sometimes not so OK. Yesterday was not so ok. Any ideas to improve on what I'm doing??? Also, how can I parallel the two plates? THX

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The end of the pipe must first be cut square. Wrap a piece of heavy paper around it tightly, aligning the edge of the paper. Scribe a line around the pipe and cut, grind or file to that line. If possible drill a hole in the plate centered on the pipe and run threaded rod through the plate and pipe to clamp it for welding. Tack weld on opposing sides in several places and weld in segments on opposing sides to equalize warpage.

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I would take a straight edge draw an "X" corner to corner

take your compass draw a circle the size of the pipe and tack it up depending on the thickness of the plate a piece of aluminum clamped on or another piece of steel tacked on may reduce the warpage.


if the pipe isnt straight though this wont make them line up,

take a machined piece of flat bar and put it on edge and double check the straightness of the pipe

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the pipe must be square as well how are you cutting it?


with an angle grinder you will need to have one square end to measure off or a pipe gauge

what i would do is measure it a few times to the same lenght around the pipe and put a few dots and connect the dots around the pipe

score the pipe with the wheel 360 degrees cut only though the thickness of the pipe not through the pipe otherwise you will likely throw it off square

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You can also jig the two plates and fit the pipe between. Your magnets can then keep the pipe on marks top and bottom (or left and right) and tack weld around, recheck then finish weld while still supported. If your pipe is slightly out of square then it won't translate to the finished piece as long as the error is small. If your error is too large you end up with an opening on one edge.

I don't weld regularly but I have done this once a few years ago. I used some 2x4s and drywall screws to build my jig with minimal cutting. The finished table was functional, true, and to design. That my welds were ugly is a separate issue.

Phil

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Another idea is to have a piece of angle iron cut square. lay the pipe in the angle and hold the flat on the end of the angle, tack it in three spots, weld it.

I have a piece of angle with a piece welded along the spine that I use to clamp in a vice that allows me better hands free working.

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Welding a pipe to a plate; Of course a square cut is best, but assuming you don't have that, here is the procedure,
Stand the pipe upon the plate, note the way it is leaning. Tack at the high spot. Square up, tack opposite first tack. Square side to side, tack one side, 1/2 way between first two tacks, Check for square again, if still square, tack opposite from third tack. You are now almost ready to weld. Because a strong weld can break a weak tack, revisit your tacks and make sure they are plenty solid. Weld. Repeat at other end for parralel plates.

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I like Arftists procedure when using pipe that is not perfectly square. Even that is hard to get perfect though. Your second tack usually shrinks and pulls out of square a little, usually we learn to overcompensate a little. Way I used to do it was pretty much like Arftist describes except for the second tack I would hammer the end of a welding rod into a little wedge and use that to get the plate square. This solid material in the gap keeps the weld from pulling. You just tack right at the rod/wedge and melt it off.

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I like Arftists procedure when using pipe that is not perfectly square. Even that is hard to get perfect though. Your second tack usually shrinks and pulls out of square a little, usually we learn to overcompensate a little. Way I used to do it was pretty much like Arftist describes except for the second tack I would hammer the end of a welding rod into a little wedge and use that to get the plate square. This solid material in the gap keeps the weld from pulling. You just tack right at the rod/wedge and melt it off.


Good point Grant. With a large gap it is a good idea to use a solid filler to prevent shrinking, as you say.
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Back up a sec. I understand what you are trying to do, but I dont understand the problem.... Are you having trouble with the pipe being centered on the plates? The plates being perpendicular to the pipe? The plates being square and parallel with each other? The welds not holding up to what you are doin???

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Fast and easy way to square frames and uprights. Just as Arftists said pipe does not have to be perfectly square, if fact if it is you still will have to use the hinge method unless you can clamp the pipe securely. On the frame tack and measure corner to corner.

19027.attach

19028.attach

Edited by Digr
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well it would all depened on what it is going to be for now the right way would be cut pipe square bevel the edge space it tack it in many places then a root pass (as this is not to warp it with less heat) then the fillet weld then cap it with 7018 now if its not a big deal cut it square take a 1/8 welding rod nock the flux off bend it into a v and space the pipe with the rod then tack the pipe all the way around many spots on the plate this lets the pipe expand and contract when welding at least thats what i was taught in welding school and the pipe fitters

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Welding a pipe to a plate; Of course a square cut is best, but assuming you don't have that, here is the procedure,
Stand the pipe upon the plate, note the way it is leaning. Tack at the high spot. Square up, tack opposite first tack. Square side to side, tack one side, 1/2 way between first two tacks, Check for square again, if still square, tack opposite from third tack. You are now almost ready to weld. Because a strong weld can break a weak tack, revisit your tacks and make sure they are plenty solid. Weld. Repeat at other end for parralel plates.


I usually use this method if doing a one time job or repair. If i have multiple plates to do I'll make a jig.
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