d'Lima,
you need the right tool for the job!
cold wire feed TIG, shown loaded with steel, but works all day long in aluminum, pulsed TIG down to 0.023" wire on 1mm sheet. But will carry 300A pulsed, single pass w/ 5/32" tungsten on 1/4" to 1/4" plate.
fast, relaxing and consistent welds.
outside corner on 0.080" to 0.100" 5086; w/ 3/32" pure tungsten, 0.030" 5356 filler wire, 12ft^3 argon, gas lens, pulsed. Almost as fast as MIG and very low fatigue.
With all that said.... OTC in their wisdom - no longer offers this gun in the US!!! I have scoured the internet to buy the few that I've collected, and some welding distributors may be willing to try to important one from JApan where they are an off-the-shelf item!!!
I'm currently welding hull seams on a 34'er of welded aluminum- all 5086 using 5356 filler. Overhead TIG is somewhat tiring, and
very difficult with two handed TIG.... I don't do it very well. But with this gun I've put in hundreds of feet of beads overhead- no other way for me to get that work done. Pushing 70, I get tired just looking at work! so having the wire feed TIG is a life-saver for me.
You might look at a cold wire feed TIG system; CK has one that might work? If you can find someone to sell one of these?- tanks, boxes, and brackets become 10-20 minutes work. If you're fixtured for the boxes you show, a cold wire feed system will sure reduce your welding time/effort.
I don't think 5052 will autogenous weld as shown. There are some very light wt tanks where the edges are flanged deeply- the two flanges are held together and they are just floated/fused/autogen' but they sure use a lot of the flange (5 or 8 thicknesses) to obtain a weld. So the 0.060" thick flange uses from 3/8" to 1/2" of the material (width) to obtain a weld!! Outside any experience I have to offer.
Hope you figure a way to reduce your weld time/effort/fatique!
Cheers,
Kevin Morin
Kenai, AK