The Equipment Design Process
345
UrFo
Urethane foam
CeGl
Cellular glass
FlEl
Flexible elastomer
MeAm Melamine
The characteristics for the different types and classes of insulations are discussed for each insulation and the recommended uses are discussed in the
following paragraphs.
1. CaSi: calcium silicate (granular insulation):
Its ability to withstand high temperature (up to 1200ºF), coupled
with its mechanical properties, makes CaSi a suitable choice for
steam, condensate, and hot water services. It is not recommended for
use in flammable liquid services due to its very high absorptivity.
CaSi has good mechanical strength, making it suitable for selection where mechanical durability is a consideration. It can withstand
vibration and mechanical/thermal shock.
It is very highly absorptive and can promote corrosion of carbon
steel surfaces. Additionally, the absorbing of water may prevent its
selection in wet environments or wash-down areas. Once water gets
into a jacketed CaSi system, it is difficult — if not impossible — to free
moisture from the insulation. It is not normally recommended for use
on underground piping, nor is it recommended for use over austenitic
stainless steels or in areas where chlorides may invade the insulation
system.
CaSi always contains a certain amount of water, most of which
can be driven off in services over 250ºF. This water vapor driven
out of the insulation, however, may condense and dissolve alkaline
chemicals in the outer part of the insulation. This can cause hidden
corrosion in aluminum jacketing. For this reason and due to its high
absorptivity in general, aluminum jackets used with CaSi should be
specified with a moisture barrier on the inside. This barrier may be
either a coating or treated kraft paper.
To prevent moisture recycle in the insulation, it is recommended
that the insulation temperature be maintained above 212ºF.
CaSi’s K factor (or conductivity) compares favorably with other
types of insulation materials at temperatures of 300ºC (572ºF) or
higher. If it absorbs water, however, the K factor greatly increases
and lowers the effectiveness of the insulation.
2. ExPe: expanded perlite (granular insulation):
Some of ExPe’s properties (e.g., thermal conductivity, density,
and compressive strength) and service characteristics are similar
to those of CaSi, and it is suitable for hot services (up to 1200ºF).
While not quite as strong as CaSi, it has good mechanical strength,
345
UrFo
Urethane foam
CeGl
Cellular glass
FlEl
Flexible elastomer
MeAm Melamine
The characteristics for the different types and classes of insulations are discussed for each insulation and the recommended uses are discussed in the
following paragraphs.
1. CaSi: calcium silicate (granular insulation):
Its ability to withstand high temperature (up to 1200ºF), coupled
with its mechanical properties, makes CaSi a suitable choice for
steam, condensate, and hot water services. It is not recommended for
use in flammable liquid services due to its very high absorptivity.
CaSi has good mechanical strength, making it suitable for selection where mechanical durability is a consideration. It can withstand
vibration and mechanical/thermal shock.
It is very highly absorptive and can promote corrosion of carbon
steel surfaces. Additionally, the absorbing of water may prevent its
selection in wet environments or wash-down areas. Once water gets
into a jacketed CaSi system, it is difficult — if not impossible — to free
moisture from the insulation. It is not normally recommended for use
on underground piping, nor is it recommended for use over austenitic
stainless steels or in areas where chlorides may invade the insulation
system.
CaSi always contains a certain amount of water, most of which
can be driven off in services over 250ºF. This water vapor driven
out of the insulation, however, may condense and dissolve alkaline
chemicals in the outer part of the insulation. This can cause hidden
corrosion in aluminum jacketing. For this reason and due to its high
absorptivity in general, aluminum jackets used with CaSi should be
specified with a moisture barrier on the inside. This barrier may be
either a coating or treated kraft paper.
To prevent moisture recycle in the insulation, it is recommended
that the insulation temperature be maintained above 212ºF.
CaSi’s K factor (or conductivity) compares favorably with other
types of insulation materials at temperatures of 300ºC (572ºF) or
higher. If it absorbs water, however, the K factor greatly increases
and lowers the effectiveness of the insulation.
2. ExPe: expanded perlite (granular insulation):
Some of ExPe’s properties (e.g., thermal conductivity, density,
and compressive strength) and service characteristics are similar
to those of CaSi, and it is suitable for hot services (up to 1200ºF).
While not quite as strong as CaSi, it has good mechanical strength,