Rust a silent killer (of metal that is!)

Any reason s/steel maybe better than copper? Weighs less probably..
Just wondering, like.

I've got a roll of 8mm microbore copper tube in my workshop that's used for heating
I guess they use a cupronickel alloy for brake lines as pure copper may be too soft to safely handle the pressure.
Stainless is anything but soft - if anything, the way it work hardens I'd be wary of using it for fuel lines in an exposed position. No real knowledge here - just thinking out loud

CuNiFe (copper-Nickel-Iron) tubing is recommended for brake lines. Not pure copper, as this has a lower fatigue life. This tubing is used by Volvo and Porsche as OEM.

For fuel lines and hydraulic lines, you could use copper (CuNiFe), stainless or coated-steel. However, Copper is the easiest to work with, but I have read in a few places that there may be issues with fuel reacting with the copper. However, in many old cars fuel lines were usually copper.

http://www.copper.org/applicat…hydraulic_brake_tube.html

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you just need to see the pictures of my roof to prove that!!!!!! - Nice work though and I must check mine