On Sep 20, 10:26 am, Gene Kearns
wrote:
On Wed, 19 Sep 2007 04:53:06 -0700, Warren penned the following well
considered thoughts to the readers of rec.boats:

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.

Yes, the vibration will eventually cause the annealed tubing to work
harden and crack. New technology is available that will not have this
problem with vibration.... synthetic hoses. However, all of this
technology has service limits. When I removed the 1987 fuel fill and
vent lines from my boat a couple of years ago, they were hard and
cracked.

Properly installed copper may well outlast the rubber, but how do you
check it for condition? How many people know how to remove and anneal
these tubes the way old mechanics did?

I would also have concerns over the possibility of corroded brass
fittings (dezincification) and dissimilar metal corrosion from contact
between ferrous and non-ferrous metals (or maybe even aluminum and
copper).

--

Grady-White Gulfstream, out of Oak Island, NC.

Homepagehttp://pamandgene.idleplay.net/

Rec.boats at Lee Yeaton's Bayguidehttp://www.thebayguide.com/rec.boats
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I think it is unlikely that soft copper lines would deteriorate enough
to be an issue during the typical life of an engine or even several
engines. If you are really concerned how about using steel line
instead. You can flare it with the same tools used to flare copper.
And you can use steel fittings which will reduce the likelyhood of
disimilar metal corrosion. But it will be more suseptible to rust
unless you use stainless. That might be cost prohibitive if you have
a lot of it. The marine approved flexible hose is probably the best
solution overall and it is fairly easy to inspect and replace with
ordinary tools.