aluminum tank design ideas

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I'm looking for suggestions on design ideas for a small rectangular aluminum fuel tank. I'm not looking for fancy just simple ideas for strength and longivity.I'm thinking of making the bottom and two sides out of one piece.Would it be stronger to set the sides in for a fillet weld or just fit-up for a corner weld? Will either way be better or worse as far as warping?  I'm planning on using 1/8" 3003 aluminum unless otherwise suggested. My fill neck is a 4" aluminum nipple that is at least a 1/4" thick.Would I be better off welding a ring to the bottom then mechanically fastening to the tank? I can weld the thick nipple to 1/8" just worried about warping up the top of the tank.I've seen some tanks where the tank was raised where the filler neck was.I'm sure that would reduce warping but not sure how to raise a area like that.Suggestions welcome. Thanks guys
Reply:Hello Showdog75, I have attached a very simple tank design that would probably serve your purpose well. You essentially shear/cut two pieces of material and then put 2 bends in each piece and make up the sort of tank that I have shown(like interlocking C's). By tacking in ample spots before welding it out you stand a good chance of minimizing any warpage. The fillet welds will be adequately strong for most any application. I also believe that your proposed fill cap assembly will work just fine with the 1/8" material that you plan on using. If the tank is much more than 10 gallons or so you might consider providing some internal baffles to reduce slosh and help to prevent cracking. Good luck and best regards, Allan Attached Imagesaevald
Reply:Can't help you much with the design and strength issues.But I will tell you to put baffles in it.  Even in a small tank.  Liquid sloshing around can bust a tank in a hurry.
Reply:Originally Posted by kcb37Can't help you much with the design and strength issues.But I will tell you to put baffles in it.  Even in a small tank.  Liquid sloshing around can bust a tank in a hurry.
Reply:Standard material is generally 5052 aluminum.Thickness is determined by the size.As far as the nipple weld warping the top, that would depend on how big of an area the top is and where you place it.They are normally welded though. This subject hits pretty close to home for me. In the past week I have done 3 tank repairs.2 Cigarettes and a Baja.Miller Dynasty 700Miller 350P with Aluma-pro push-pullMiller 280 Dynasty with expansion card Dynasty 200 DXMigMax 215 Enuff power and hand tools to create one of anything..... but mass produce nothing!!!
Reply:Along with the '2 Cs' type Aevald mentioned (i sometimes use that for header tanks) simplest design i use is along these lines, main body folded from a single piece with two ends...I usually avoid sharp corners (this was tiny, couple of gallons, made to fit in a cubby hole for an eberspacher heater) but do similar things with radiused bends and cross braked/bead rolled flanged end tanks. It's 1.5mm 1050-h14, filler neck is 3mm wall. Bead roller caused more distortion than the welding as i didn't bother pre stretching the beadsThis is more representitive of the type tanks i normally do but falls under fancy rather than simple. I prefer to radius corners and use butt welds, strength/stiffness and fatigue resistance  through geometry and all that. Top and bottom both made from three pieces (no welds have been sanded out)That's 2mm 1050 and circa 10 gallons ('full fat' UK gallons, about 12 US i think). 3103 (UK version of 3003) is a pita to get hold of locally but i would've made the top in 1.5mm if i'd used 3103.Distortion shouldn't be an issue when welding the filler neck in unless there's a large expanse of shapless material. If you wanted to eliminate the chance of putting a nasty  ripple in it could make/buy a 'belling die' (those hole swages used to stiffen lightening holes) or knock up something simple to put a pressing in it- a couple of chunks of hardwood and a router will work fine to make a simple version (1 metal thickness) of the sender relief in the VW tankNot got any pics to hand but there's a partially made tank that falls neatly between these two examples on my table at the mo. Pretty much rectangular (albeit with radius bends) but for several reasons i made the main body in two halves... Red line is a horizontal baffle (not necessary if using foam), while the extra joint makes for an extra 600mm of weld it's more than compensated for IMO by the extra stiffness and ease of assembly... access for installing baffled fuel pick up/internal plumbing plus the three pieces can be rivetted together. End tanks will be radiused but could also be flanged like top pic, top will be bead rolled to stiffen and provide location for mounting straps. Again all 2mm thick and about 10 (real ) gallons
Reply:Very nice tanks there hotrodder. True craftsmanship. Best regards, Allanaevald
Reply:Cheers Allan