Best Way To Butt Join Square Tubing

[wvpolekat]

I may be needing to join two pieces of 3" square tubing. Fairly heavy stuff.

What is the best way to do this? Build a "collar" and weld it over the joint? Just bevel them and weld the seam?

 

[Shield Arc]

Personally I like open root. Either pipe or tube.

 

[crazyal]

I would grind each end down to make a bevel. Leave about an 1/8" gap and make multiple weld passes.

 

[Shield Arc]

Here is a pretty good video about working with square tubing.
The guy is kind of a nut:laughing:, but he knows how to fabricate!

YouTube - The Fabricator Enters the Twi1ight Zone! - Episode 7

 

[JB4310]

Here is a pretty good video about working with square tubing.
The guy is kind of a nut:laughing:, but he knows how to fabricate!

YouTube - The Fabricator Enters the Twi1ight Zone! - Episode 7

Yeah he's a whackadoodle, but a good teacher. His mig sounds sooo smooth.

Makes sense, weld into the area of more metal to dissipate heat and avoid distortion.

Great for those angle splices, but what about OP's butt splice? I've had trouble (understatement) with butting schd 40 pipe, wicked distortion!

Maybe like tightening wheel lug nuts, weld from one side to the other, keep staggering as opposed to continuous around?


JB.

 

[Shield Arc]

but what about OP's butt splice? I've had trouble (understatement) with butting schd 40 pipe, wicked distortion!

Maybe like tightening wheel lug nuts, weld from one side to the other, keep staggering as opposed to continuous around?

Welding opposite quarters of pipe is a good way to help control distortion on a butt joint.

Depends on what you're building, sometimes placing an estimated amount of heat on the opposite side before welding, (pre-weld heat shrink) is also very helpful. Depending on what you're building, sometimes there is nothing you can do except post weld heat shrinking.

 

[Wayne_H]

I'd also use some angle iron and clamp your sqaure tube to that while you tack the four corners. Should not be too hard.

Wayne

 

[Egon]

There has been many a but weld made on pipes of all sizes and schedules.

Bevel, line up, four tacks, root pass, secondary passes, cap pass. Grind out the tacks just before the root pass.

 

[MBDiagMan]

In reading this thread, I can't help from commenting based on something I saw on a TV documentary.

The show was called "American Craftsmen" I think and was on HDTV I think.

On the show they hand built a large, two engine, wooden boat to an incredible level of quality. They never said what it cost, but if it was a half million dollars it wouldn't surprise me.

Anyway, they completed this incredibly valuable boat and were delivering it several hundred miles away, towing it there on a shiny new custom built trailer. On the trip, a trailer axle broke, and luckily it was a tandem axle trailer.

When they showed closeups of the failure, it was where they had widened the square tube axle with a butt splice of square tubing. It was incredible to see such a failure that could have destroyed such an expen$ive item, not to mention jeopardize the safety of all the people that had to share the road with them.

The only reason I went through all this was to stress the attention that should be paid to such a welding step. If the joint is to be made on something that if it fails it is simply an inconvenience, you can take an experimental approach. If it's something with safety at risk, be much more sure of your actions and don't treat the job lightly.

My $0.02,

 

[Car Doc]

I have a bad habit of over engineering things and what came to my mind when I read "a butt weld on sq tubing" was a liner welded in first and then inserted and then butt welded and probably a plug weld or 4. my 2c