the FASTENING attaches the insulating material
to the piping and to the lagging.
Insulation covers a wide range of temper-
atures, from the extremely low temperatures of
the refrigerating plants to the very high temper-
atures of the ships waste heat boilers. No one
material could possibly be used to meet all the
conditions with the same efficiency.
The following QUALITY REQUIREMENTS
for the various insulating materials are taken into
consideration by the Navy in the standardization
of these materials:
1. Low heat conductivity
4. Easy molding and installation capability
5. Moisture repellant
6. Noncorrosive, insoluble, and chemically
7. Composition, structure, and insulating
properties unchanged by temperatures at
which it is to be used
8. Once installed, should not cluster, become
lumpy, disintegrate, or build up in masses
10. Hygienically safe to handle
Insulating material is available in preformed
pipe coverings, blocks, batts, blankets, and felts.
Refer to NSTM, Chapter 635, Thermal, Fire,
and Acoustic Insulation, for detailed informa-
tion on insulating materials, their application, and
The insulating cements are comprised of a
variety of materials, differing widely among
themselves as to heat conductivity, weight, and
other physical characteristics. Typical of these
variations are the asbestos substitute cements,
diatomaceous cements, and mineral and slag wool
cements. These cements are less efficient than
other high-temperature insulating materials, but
they are valuable for patchwork emergency repairs
and for covering small irregular surfaces (valves,
flanges, joints, and so forth). Additionally, the
cements are used for a surface finish over block
or sheet forms of insulation, to seal joints
between the blocks, and to provide a smooth
finish over which asbestos substitute or glass cloth
lagging may be applied.
Removable insulation will be found on the
bleed air systems and waste heat boiler systems.
Removable insulation is also installed in the
. Flange pipe joints adjacent to machinery
or equipment that must be broken when
units are opened for inspection or overhaul
. Valve bonnets of valves larger than 2
inches internal pipe size (IPS) that operate
at 300 psi and above or at 240°F and above
. All pressure-reducing and pressure-regu-
lating valves, pump pressure governors,
and strainer bonnets
You should observe the following general
precautions relative to the application and
maintenance of insulation:
1. Fill and seal all air pockets and cracks.
Failure to do this will cause large losses in
the effectiveness of the insulation.
2. Seal the ends of the insulation and taper
off to a smooth, airtight joint. At joint
ends or other points where insulation is
liable to be damaged, use sheet metal
lagging over the insulation. You should
cuff flanges and joints with 6-inch lagging.
3. Keep moisture out of all insulation work.
Moisture is an enemy of heat insulation just
as much as it is in electrical insulation. Any
dampness increases the conductivity of all
4. Insulate all hangers and other supports at
their point of contact from the pipe or
other unit they are supporting; otherwise,
a considerable quantity of heat will be lost
via conduction through the support.
5. Keep sheet metal covering bright and
unpainted unless the protective surface has
been damaged or has worn off. The radia-
tion from bright-bodied and light-colored
objects is considerably less than from
rough and dark-colored objects.
6. Once installed, heat insulation requires
careful inspection, upkeep, and repair.
Replace lagging and insulation removed to
make repairs as carefully as when originally