[Shorn]

I have a length of 2" OD (~.067 wall thick.) aluminum tubing that I need to extend by 2 ft or so. The application requires virtually no structural strength other than to support its own 10' length after the extension. But in eeds to be straight and the joint smooth. My initial thought was to have it TIG welded. (I have a TIG but my TIG skills are as yet undeverloped. So I would be sending it out to a fab shop or similar.) But the more I've thought on it, i wasn't sure if such a thin wall application would be a good use for TIG. Also, I have no idea whether the piece is 6061 or 6063. I have ordered a short length of 6061 but now am not sure if 6061 can be welded to 6063. And replacing the entire tube with a new 10' length is way too pricey. My fall back plan is to cobble together a mechanical splice joint using threaded rod, insertable "plugs", washers, nuts...
I am interested in anyones thoughts or ideas on this, as it should be obvious that TIG and aluminum+TIG is not my strong suit.

[Otto Nobedder]

First, welcome aboard!

Second, TIG is the only process I would recommend for that. MIG aluminum is too hot a process for thin wall tube short of robotic welding or a real master (both are expensive).

Third, 6061 will weld to 6063 just fine in your application. I can think of four fillers I'd choose from; 4043, 4047, 4943, and 5356. Unless the part is to be anodized, 4043 will be fine, commonly available, and (relatively) easy.

If your TIG aluminum skills are "undeveloped", I agree with you farming this out. If you can make five or six coupons of this to practice on, then you might give it a go, but this is not beginner stuff unless you're willing to use a backing ring, and then you still may not have a straight piece when you're done. Aluminum shrinks in interesting ways when welded.

Steve S

[MosquitoMoto]

Welcome Shorn.

I agree with Otto, if you are still developing your aluminium skills, this task represents quite a challenge.

Jody has an 'aluminium pie cut welding' video that has a lot of good info, but at this stage I feel that farming the job out might be a good idea.


Kym

[PeteM]

If it isn't all that important, I'd just take a couple of pieces of flat bar, tap and drill them, then countersink a couple of screws into the flat bar from the outside, affixing them to the inside, then slide the top piece over and screw that to the flat bar.

[Shorn]

Thanks for the replies! Yup, I had quickly ruled out tackling the TIG work myself, esp after watching Jody's latest video on welding 6061 aluminum. But, given that, I wanted to confirm that this was a doable job for skilled TIG welder. And PeteM, I think I understand your description of an alternative solution. And it gave me another idea for a purely mechanical butt joint.

[Olivero]

yeah, Tigging it should not be too difficult if its a practiced welder, ALuminum is one of those metals that can go really wrong, really fast.

If your looking for a good joint, clean and all I would weld it, I would not slap a clamp on it, but that;s just me. I like things welded because then they are done, no more messing around, its just one piece now, don't have to worry about screws coming loose, falling out, stripping, galling, etc.

[Shorn]

Once I have the "extension" tubing i ordered, if the fit mates well with the long one, i'm going to hunt down a good TIGger. Plan B is for an internal mechanical "plus shaped" (+) splint made of hardwood that will fit tightly in each tubing section. Then countersink and screw through the tubing walls. But a TIG join(t) would be much more "elegant". (The outer surface of the joined tubing must be smooth, so an external splint won't work.)

[dunkster]

You could also make up a tube sleeve, say 6 or 8 inches long, with an OD sized to just slip into both pieces to be welded. It would be burned into during welding and be permanent, much like a chill ring in a pipe joint....as well as adding strength which is a good thing since temper will be lost.

[Shorn]

Tube in a tube - i thought about that, especially if a TIG weld was in the mix, mostly to back up the weld and add a litle stiffness. Much like you describe. But finding an OD that fits snugly would be tough I think, since I'm dealing with two different tubes that, while they (should) have the same OD, the ID may be different. Not riuling anything out at this point though. But Plan B is looking better. See attached. Spline is into tubing 13". The other (exposed) 13" would fit into the new added tube and both would be screwed in thru the tube wall.

[Olivero]

That right there seems like a genius way to do butt welds on same diameter pipe.... or at least tack them.

[Shorn]

I got a referral from my local,welding supplies dealer for a good TIGger and talked about the project with him. (BTW, the shorter tube to be added mated up well using the spline shown.) He pointed out that leaving the wood in there during the weld would likely compromise the joint because of the smoke... and possibly fire(!). Obviously, I'll leave it up to him to determine the best way to guarantee good alignment. The spline would,by itself, have provided a decent and strong joint, once screws were used to secure it to the two tubes. But the charge to do the TIG work is well worth doing a better job.