Well, welding would definitely be the strongest choice, but I suggest going weldless.
Reason being the difference in thickness between an Aluminum coupling and the wall thickness of most Aluminum pots makes for a tricky weld. An experienced Aluminum welder should have little trouble. If you've never welded Aluminum this is not a project you want to take on.
If the pots wall is of a heavy duty construction it's pretty easy to do.
The other issue is with warpage. The pot will most likely be warped where the coupling is welded to the pot. The shrinking stresses will pull that pots wall where ever it wants it to go.
Unless you can get to the back side of the coupling to weld, a full-pen weld on Aluminum is even harder. This will result in a weld with incomplete penetration.
Of coarse if this pot is for the hot side of your brewery than it's not a big deal, but who wants to see the seam of an incomplete weld? Plus debris will tend to collect in that seam.
Weldless fittings although not as strong will make the most sense for Aluminum.
They will look better aesthetically and you can remove them if you want to clean around the joint. In addition you'll save money by not having to pay for the welding, and possibly make a mess of your nice pot.
There's a lot of guys that say they can weld, but few that I call a "Welder"