fuel hoses, such as fill pipes. All hose clamps
should be of 100 percent 316 stainless.Hose Connections
All fuel-line hose must fasten to proper
barbed connectors specifically intended for
hose. Such hose connections (hose barbs)
must have annular rings, not spiral thread or
crossed, knurled, or X grooves, all of which
can form paths for fuel to leak.
The one exception to the requirement for
barbed connectors is large-diameter hose-
pipe connections, such as for fuel fills of 1^1 / 2 -
inch IPS (DN 40 mm) diameter or larger. In
this case, double^1 / 2 - inch-wide (12.7 mm) hose
clamps are required, with a minimum of(^1) / 2 inch (12.7 mm) between the end of the
hose and the end hose clamp.
Acceptable Hose Clamps
In addition to the preceding hose-clamp size
requirements, hose clamps must have a
mechanical or deformation tightening
mechanism. The clamp should be about
one hose-clamp width from the end of the
hose. Screw-type hose clamps of 316 stainless
are strongly recommended. Hose clamps that
use only spring tension cannot be used.
Fuel-Line Tubing
Older vessels used soft copper tubing with
standard flare connectors for almost all fuel-
line and vent piping. This is still acceptable
according to CFR Yacht and CFR Commer-
cial provided that a ring-spiral loop is built
into the piping before each rigid component
to absorb flex. These metal spirals, however,
can harden and crack over time. Accordingly,
A1 fuel-line hose is greatly preferable. Hose is
also cheaper and easier to purchase and
install. Copper, copper nickel, nickel copper,
and stainless steel are the approved fuel pip-
ing metals. Minimum wall thicknesses for
tubing should be as follows:
Tubing OutsideDiameter Wall Thickness
(^1) / 8 in.to (^1) / 4 in. 0 .032 in.
(^5) / 16 in.to (^3) / 8 in. 0 .035 in.
(^7) / 16 in.to (^1) / 2 in. 0 .042 in.
Tubing OutsideDiameter Wall Thickness
3 .2 mm to 6.3 mm 0 .81 mm
8 mm to 9.5 mm 0 .89 mm
11 mm to 12.7 mm 1 .06 mm
PART TWO:FUEL SYSTEMS
Figure 4-14.
Recommended
hose connectors
(Courtesy ABYC)