Fuel tank - metal selection

[Hawke]

The time has come to replace the 40 year old, patched up fuel tank on my Hawke DL11. I was going to make it out of 1.6mm 5005 H34sheet.

What's the consensus?

[DanW]

Is a fuel cell out of the question? They are required here, then we cover them with 16gauge alu sheet for additional protection.

That ally is a good choice. It has good corrosion resistance and it's relatively easy to work, but still has some strength.

[Hawke]

Thanks Dan. Fuel cells are not a requirement here for the class I run in. Il’l be cranking up the new welder now.

[T540]

If you're running in Australia then look at Motorsport Australia Schedule N Clause 4.1.

5005 Aluminium minimum thickness 2.0mm.

[S Lathrop]

2 mm aluminum seems a bit thick but if that is the rules then that is what you have to use.

When I first started working on race cars in the l1t3 1960's we still had aluminum tanks and I built several. Recently I build fuel thanks for an airplane. One thing I did that was different than how the tanks for my plane were designed is to make all the welded joints a butt weld. that is the 2 pieces of metal are welded so that the pieces being welded are end to end and the weld is along a flat surface. This required that the edges of the tank where I was welding were bent at 45 degrees. The alternative would be to roll the edges so that the weld was in the middle of a curved surface.

Along the straight edges, I bent the edges 45 degrees with a 3/8" edge or lip. The adjoining side was bent the same. This makes welding much easier as it really reduces the distortion of the edges as they are being welded.

I chose to weld my tanks this way as a hedge against the tanks developing cracks along the welded edges.

When I first did tanks I gas welded them and I would recommend that you consider gas welding. The weld is a lot less brittle and the bead is infinitely nicer on the side opposite of the weld than a TIG weld.

[Hawke]

Thanks for all your help.

Steve, I can gas weld Aluminium, but it is so much easier to TIG it, and I just bought a TIG machine along with some fancy accessories.

[S Lathrop]

Thanks for all your help.

Steve, I can gas weld Aluminium, but it is so much easier to TIG it, and I just bought a TIG machine along with some fancy accessories.

I did my airplane tanks with TIG for the same reason, easier. Also it had been decades since I did any aluminum gas welding

[jchracer]

If you do a lot of TIG butt welding, I backside Argon purge will keep the opposite side looking nice and will result in better weld properties. If you are creative, the setup can be pretty simple.

[S Lathrop]

If you do a lot of TIG butt welding, I backside Argon purge will keep the opposite side looking nice and will result in better weld properties. If you are creative, the setup can be pretty simple.

I do have a "flux" that helps with the back side of TIG welding. I have done back purging and it really makes the job go better.

[GAC]

Even if not required, the fuel cell is the single greatest safety improvement in racing history. I would strongly recommend using one. It will also add value to the car when you look to sell it.


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