How to butt weld 2 pipes together straight?

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MOPARoldtimer

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My Toad V8 is running well right now and doesn't seem to have any issues (knock on wood), so I am using it as a driver and have two of my other vehicles under restoration. Both of those cars have their wheels removed, but I need to be able to move them around the shop in order to install overhead lights, so I need to build a steel frame on casters which will attach to these cars' axles. I can do this OK, except that my garage floor is NOT flat, and I need to butt weld two pieces of pipe together to make one long, straight piece. How to make sure they are straight before welding? Clamp something straight to them, obviously, but I am not sure how I would do this in both the horizontal and vertical planes at the same time, and still have room to heat the pipe and weld it. Also, isn't all the stuff I am going to clamp to hold the pipes straight going to act as a big heat sink?

I have been butt-welding pipe together for a long time, but I've never figured out how to weld it straight. I know I really should clamp it to a machinist's table, but don't hold your breath until I get one of those. Suggestions would be welcome. A simple jig, maybe? Thanks a lot.
 
What about inserting a slug between the pipes? It would make it strong and straight at the joint.

Just get a pipe that has the same OD as the ID of the two pieces you are joining together.
 
The angle iron as suggested will do the best job for you. Don't butt the pipes together tight because they'll warp (pull) when you weld them. Instead keep a slight gap between them about a little less than the diameter of your weld rod or wire. Tack the pipes in 4 places with short tack welds then remove the angle iron and finish welding alternate quarters (between the tack welds) and the pipe won't warp crooked. Depending on the wall thickness of your pipe it may take two or three passes to fill the gap. The first pass is called the root pass, the second the hot pass and the final the cover or cap pass. Clean each pass with a wire wheel or brush before each subsequent pass. Helps if you bevel both ends of the pipe slightly before you tack it together. In the field we used a device called a "Jewel Clamp" which was a glorified piece of angle iron with chains and threaded tightening screws that held both ends of the pipe together until the tack welds were in place.
 
its hard to find pipe that fits nicely inside without turning it in a lathe. angle iron works fine
 
attenuated said:
I have used a piece of angle iron and c- clamps and then tack together.

HTH
Click to expand...

Angle, I beam, or channel, anything of such dimension that the pipe will "lay" in

I used to "throw" sheet metal vent into a corner of the basement floor and the wall to get two pieces together straight.

I had a real smart college educated apprentice that couldn't figure that out.
 
I have a buddy that was a pipeline welder and he always said the correct way to weld pipe together was to grind a slight taper on the outer edge so there is a "V" to weld in. He also uses a long piece of angle iron to cradle the pipe, tack welds it in four spots and then welds it up evenly as stated above.
 
Thanks for all your helpful replies. I should have thought of using angle iron.

I'm using oxy-acetylene welding. I've always felt it gives me better control over the weld puddle than a MIG welder does.

We had a Tractor Supply store open up in a town near here recently. I went there, but they denied having any steel pipe. I haven't checked their online catalog, though.

I picked up a lot of 2-1/8" thinwall galvanized pipe that had been the framework of some portable stalls at a horse ranch near here that went broke and closed down. (In this area, keeping horses used to be really popular, but it seem to be a luxury that many can no longer afford.)
 
Be a bit cautious with anything galvanized, the coating is hazardous when you start welding on it, try and keep your head out of the flume, and do it outdoors if possible.
 
"Be a bit cautious with anything galvanized, the coating is hazardous..."

Right. Would a normal painting respirator prevent inhaling these fumes, or should one use a supplied air system, do you think? I've seen plans for making a supplied air system that look pretty simple, plus I also really need one for sandblasting.
 
MOPARoldtimer said:
"Be a bit cautious with anything galvanized, the coating is hazardous..."

Right. Would a normal painting respirator prevent inhaling these fumes, or should one use a supplied air system, do you think? I've seen plans for making a supplied air system that look pretty simple, plus I also really need one for sandblasting.
Click to expand...

For galvanized structural fabrications, the zinc coating should be removed at least one to four inches from either side of the intended weld zone and on both sides of the piece. Grinding back the zinc coating is the preferred and most common method; burning the zinc away or pushing back the molten zinc from the weld area also are effective.

http://www.galvanizeit.org/designin...iderations/welding/welding-after-galvanizing/
 
Yes, the safety types are always going to tell you to remove the zinc coating entirely, which of course is preferable but difficult to do outside an industrial setting. But I don't know how a guy working in his garage would go about removing the zinc coating prior to welding.
 
Used CPAP machines are great for making a supplied air system. I bought a Tyvek hood/mask for about $60 then just a long piece of CPAP tubing. Very nice to have.
 
You did say butt weld, didn't you? You can try it like this, or use the method to light a torch.
:wack:
[ame="http://www.youtube.com/watch?v=0XcoFArR1y8"]fire fart - YouTube[/ame]
 
If you have a sander/grinder, you can take the galvi off that way.

If you're going to weld pipe I suggest what's already been suggested.....V groove it.

The joint should look like this ______/\______

You should get complete joint penetration that way and it should never break.

Oh, put a minimum 1/16" root opening; maximum 3/16"....depending on pipe size.
 
All of the pipe welding advice is good , grinding the ends to be welded at a slight angle and keep a small gap between the pipes . Clamp two pieces of angle , one on each side . I use heavy gauge angle and small enough to give me a decent area to tack , then I turn the pipe to make sure it is still straight and tack on the areas that were covered by the angle previously . Don't rush it , let it cool a bit before you reposition it in the angle .
To fit pipe inside of pipe find a supplier that stocks mechanical tubing and get a chart.
Look at the wall thickness , OD, and ID . You can get a pretty good fit as a rule .
If you can't then get a piece that is slightly over the ID of the tube you are working with and turn it down to fit or have it turned if you don't have the equipment .
Good luck with your project .
 
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