Insulation covers a wide range of temperatures.
through quickly and eventually the packing
They range from the extremely low temperatures of
will become rags.
the r e f r i g e r a t i n g plants to the very high
temperatures of the ship's boilers. No one material
4. Do NOT use packing with a rubber binder
could possibly be used to meet all the conditions
bind, thereby developing excessive frictional
with the same efficiency.
heat. The use of flexible metallic packing is
The following quality requirements for the
recommended. Or, you may use a lead-base
various i n s u l a t i n g materials are taken into
plastic packing alternated with the flexible
metallic packing.
consideration by the Navy in the standardization of
these materials:
5. On hydraulic lifts, rams, and accumulators,
use a V-type packing or O-ring. For water,
this packing should be frictioned with crude,
reclaimed, or synthetic rubber. For oils, the
Noncombustibility
packing s h o u l d b e f r i c t i o n e d w i t h
oil-resistant synthetic rubber.
Lightweight material
6. Do NOT use a plastic packing, such as
Easy molding and installation capability
symbol 1433 or 1439, alone on worn
equipment or out-of-line rods; it will not
Moisture repellent
hold. Use a combination of 1433 with
e n d rings of plain braided asbestos
Noncorrosive,
insoluble, and chemically
(1103) or flexible metallic packing (1430).
inactive
These will be satisfactory for temporary
service until defective parts can be repaired
or replaced.
properties unchanged by the temperatures
at which it is to be used
7. Do NOT use a soft packing against thick or
sticky liquids or against liquids having solid
Once installed, it should not cluster, become
particles. This packing is too soft to hold
lumpy, disintegrate or build up in masses
back liquids, such as cold boiler fuel oil, and
from vibration
it usually gets torn. Some of the solid
particles may be suspended in these liquids.
Verminproof
They will embed themselves in the soft
packing. These particles then act as an
Hygienically safe to handle
abrasive on the rod or shaft. Flexible
m e t a l l i c packing is best for these
Insulating material is available in preformed
conditions.
pipe coverings, blocks, batts, blankets, and felts.
NSTM, chapter 635, contains all of the insulating
materials, along with their application and
INSULATION
precautions.
The purpose of insulation is to retard the
INSULATION AND CEMENTS
transfer of heat FROM piping that is hotter than
the surrounding atmosphere or TO piping that is
The insulating cements are composed of a
cooler than the surrounding atmosphere. Insulation
variety of materials. They differ widely among
helps to maintain the desired temperatures in all
systems. In addition, it prevents sweating of piping
other physical characteristics. Typical variations
that carries cool or cold fluids. Insulation also
are the asbestos cements, diatomaceous cements,
protects personnel from being burned by hot
and mineral and slag wool cements. These cements
surfaces. Piping insulation is the composite piping
are less efficient than other high-temperature
covering that consists of the insulating material,
insulating materials. However, they are valuable for
lagging, and fastening. The insulating material
patchwork emergency repairs and for covering
offers resistance to the flow of heat. The lagging,
small irregular surfaces, such as valves, flanges,
usually of painted canvas, is the protective and
and joints. The cements are also used as a surface
confining covering placed over the insulating
finish over block or sheet forms of insulation,
material. The fastening attaches the insulating
to seal joints between the blocks, and to provide a
material to the piping and to the lagging.
15-25