With regards to phosphoric acid, I wonder how effective filling the tank with Evapo-Rust would be? Seeing some of the stuff Abom on YouTube has cleaned up, it seems to work exceptionally well, and better/less harful than phosphoric acid. Of course, he's not cleaning up old fuel tanks, but it looks like a great product. It's not all that common in the UK yet (just checked, and Tool Station now sell it), but widely available in the US.

Nickel plating the inside sounds interesting. Interested to know how you get on.
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Andy.
NSR-WORLD.COM

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