The name of the service and destination should
be painted on by stencil or hand lettering, or by
application of previously printed, stenciled, or
lettered adhesive-backed tape. Lettering will be
1 inch high for a 2-inch or larger OD bare pipe
or insulation. For smaller sizes, lettering size may
be reduced or label plates attached by wire or
other suitable means.
Direction of flow will be indicated by an
arrow 3 inches long pointing away from the let-
tering. For reversible flow, arrows are to be shown
on each end of the lettering.
Black is used for lettering and arrows.
However, on dark-colored pipe (including oxygen
piping), white is used.
Markings will be applied to piping in
conspicuous locations, preferably near the
control valves and at suitable intervals so every
line will have at least one identification marking
in each compartment through which it passes.
Piping in cabins and officers wardrooms will not
normally be marked.
PACKING AND GASKET
Packing and gasket materials are required to
seal joints in steam, water, gas, air, oil, and other
lines and to seal connections that slide or rotate
under normal operating conditions. There are
many types and forms of packing and gasket
materials available commercially.
PACKING AND GASKET SELECTION
To simplify the selection of packing and gasket
materials commonly used in naval service, the
Naval Sea Systems Command has prepared a
packing and gasket chart, Mechanical Standard
Drawing B-153. It shows the symbol numbers and
the recommended applications for all types and
kinds of packing and gasket materials.
The symbol number used to identify each type
of packing and gasket has a four-digit number.
The first digit shows the class of service with
respect to fixed and moving joints; the numeral
1 shows a moving joint (moving rods, shafts, valve
stems), and the numeral 2 shows a fixed joint
(flanges, bonnets). The second digit shows the
material of which the packing or gasket is
primarily composedasbestos, vegetable fibre,
rubber, metal, and so forth. The third and fourth
digits show the different styles or forms of the
packing or gasket made from the material.
Practically all shipboard packing and gasket
problems can be solved by selection of the
correct material from the listings on the packing
and gasket chart. The following examples show
the kind of information that you can get from the
packing and gasket chart.
Suppose you are required to repack and
install a valve in a 150-psi seawater service system.
Under the subhead Symbols and Specifications
for Equipments, Piping and Independent Systems,
you find that symbol 1103 indicates a suitable
material for repacking the valve. Notice that the
first digit is the numeral 1, indicating that the
material is for use in a moving joint. Under the
List of Materials, you find the packing is asbestos
For installing the valve, you need proper
gaskets. By use of the same subhead, you find that
symbols 2150, 2151 type II, 2152, and 2290 type
II are all suitable for installing the valve. Notice
that the first digit is the numeral 2, which indicates
that it is designed for fixed joints. Again, by
referring to the List of Materials, you can
determine the composition of the gasket.
Besides the Naval Ship Systems Command
drawing, most ships have a packing and gasket
chart made up specifically for each ship. The ship-
board chart shows the symbol numbers and the
sizes of packing and gaskets required in the ships
piping system, machinery, and hull fittings.
PACKING OF MOVING JOINTS
Valves are components used to control the
transfer of liquids and gases through fluid
piping systems. Most valves have moving joints
between the valve stem and the bonnet. When
fluid is on one or both sides of a moving joint,
the joint may leak. Sealing the joint prevents this
leakage. Sealing a moving joint presents a
problem because the seal must be tight enough
to prevent leakage, yet loose enough to let the
valve stem turn without binding. Packing is the
most common method of sealing a moving joint.
Packing is a sealing method that uses bulk
material (packing) that is reshaped by compression