On Sep 19, 4:53?am, Warren wrote:
Currently copper pipes are used for all diesel fuel lines.

I have a concern regarding their use between boat mounted fittings and
engine mounted fittings. Will the vibration of the engine cause an
eventual failure of these lines? These lines are about 2 feet long
and, from memory, there are three of them. All the lines are quarter
inch in size.

It's common and correct practice to use copper tubing for diesel fuel
lines. You describe your rigging as "pipe", which could have joints in
it.
There should be no joints in your fuel lines. If you are extremely
concerned (and without seeing your setup it's hard to imagine why you
would be) I believe there is some ABYC approved specialized hose that
could be used instead.