service systems at a maximum operating pressure
of 3000 psi and a maximum operating temperature
of 250°F. Flareless fittings are installed to
conserve space and to reduce weight, installation
time, and system cleaning time. Do not use
flareless fittings if you do not have enough space
to properly tighten the nuts or if you have to
remove the equipment or piping for access to the
fittings. An exception to this rule is a gauge board.
It is designed so it may be removed as a unit for
repairs or alterations. Do not use flareless fittings
where you cannot easily deflect the piping to
permit assembly and disassembly.
Before assembly, ensure the tubing end is
square, concentric, and free of burrs. For an
effective fitting, be sure the cutting edge of the
sleeve or ferrule bites into the periphery of the
tube; you can do this by presetting the ferrule.
FLANGE SAFETY SHIELDS
A fuel fire in the MER or an AMR can be
caused by a leak at a fuel oil or lube oil pipe flange
connection. Even the smallest leak can spray fine
droplets of oil on nearby hot surfaces. To reduce
this possibility, FLANGE SAFETY SHIELDS are
provided around piping flanges of inflammable
liquid systems, especially in areas where the fire
hazard is apparent. The spray shields are usually
made of aluminized glass cloth and are simply
wrapped and wired around the flange.
PIPE HANGERS
Pipe hangers and supports are designed and
located to support the combined weight of the
piping, fluid, and insulation. They absorb the
movements imposed by thermal expansion of the
pipe and the motion of the ship. The pipe hangers
and supports prevent excessive vibration of the
piping and resilient mounts or other materials.
They are used in the hanger arrangement to break
all metal-to-metal contact to lessen unwanted
sound transmissions.
One type of pipe hanger you need to become
familiar with is the variable spring hanger. This
is used to support the ship’s bleed air piping. It
provides support by directly compressing a spring
or springs. The loads carried by the hangers are
equalized by adjustment of the hangers when they
are hot. These hangers have load scales attached
to them with a traveling arm or pointer that moves
in a slot alongside the scale. This shows the degree
of pipe movement from cold to hot. The cold and
hot positions are marked on the load scale. You
should check the hangers when they are hot to
ensure that the pointers line up with the hot
position on the load scales. You can adjust
hangers that are out of position by loosening the
jam nut on the hanger rod and turning the
adjusting bolt of the hanger.
INSPECTIONS AND MAINTENANCE
Reasonable care must be given to the various
piping assemblies as well as to the units connected
to the piping systems. Unless the piping system
is in good condition, the connected units of
machinery cannot operate efficiently and safely.
You should be familiar with all the recommended
maintenance procedures and observe the safety
precautions when working on piping systems.
The most important factor in maintaining
piping systems in satisfactory condition is keeping
joints, valves, and fittings tight. To ensure this
condition, you need to make frequent tests and
inspections.
Piping should be tested at the frequency and
test pressure specified following the PMS and the
applicable equipment technical manual. Test
pressure must be maintained long enough to show
any leaks or other defects in the system.
Instruction manuals should be available and
followed for the inspection and maintenance of
piping systems and associated equipment; how-
ever, if the manufacturer’s instruction manual is
not available, you should refer to the NSTM,
chapter 505, for details of piping inspection and
maintenance.
PIPING SYSTEM
IDENTIFICATION MARKING
All piping should be marked to show the name
of the service, destination (where possible), and
direction of flow (fig. 9-60).
Figure 9-60.—Pipe markings.
9-40
