Page 221 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION 5.5

4. Protection from physical damage
5. Acoustical properties
6. Health and safety requirements
7. Dimensional stability
8. Corrosion resistance
9. Hygiene
10. Installed cost
If a fire were to start inside a building, it is possible that any part of the structure includ-
ing its contents can contribute to the fire either by supporting combustion or generating
smoke if noncombustible. In order to control the amount of combustible material inside
buildings, code limitations for flame spread and smoke developed have been established
for the components used in the interior of fireproof and noncombustible buildings. Material
ratings have been established as follows.
The so-called tunnel test is used to obtain fire-related data for different kinds of insula-
tion. The same test has been given different names by each agency conducting it. They are
ASTM E-84, NFPA 255, and UL 723. The particular material is tested for flame spread,
fuel contributed, and smoke developed. The materials tested are compared to red oak floor-
ing (rated at 100) and asbestos-cement board (rated at zero) in all three categories. Caution
should be used when trying to establish these values separately for the insulation, jacket,
and some adhesives rather than as a complete system. Tests have shown that elements of an
insulation system that have the same values when tested separately may have quite different
ratings when tested as a composite unit.
The generally accepted maximum value for flame spread is 25, and the value for both
fuel contributed and smoke developed is 50. These values are used when the building is
of fireproof construction, which is the predominant type of building. For other kinds of
construction, these values may be different.
Space limitations can be a factor in areas where insulated pipe is to be installed. Different
types of insulation must be evaluated in order to obtain the best compromise between thick-
ness and the k value.
Insulation will protect personnel from being scalded by touching a bare pipe. The insu-
lation and jacket should be selected such that the surface temperature of its exterior will be
no higher than 110°F (43°C).
Protection of the insulating material from physical damage may be a consideration
when insulated piping is installed in an area of a building where there is storage of mate-
rial that is regularly moved or where maintenance operations are carried out next to the
pipe on a regular basis. This protection can be obtained by using a strong jacket or other
insulating material that will not deform after repeated blows. Another consideration might
be the strength of the insulation needed during the time it is being stored, transported, and
installed in a possibly adverse climate or location.
The properties that make insulation effective will also attenuate sound made by the flow
of contents through the pipe. When a pipe is installed where sound transmission could be a
problem, for example, as a theater, adding extra thickness of insulation or special jacketing
could reduce the sound to an acceptable level.
The potential health and safety hazards of insulation and accessories fall into two cat-
egories: (1) those related to storage, handling, and installation and (2) those that occur after
installation. Correct procedures can reduce or eliminate most or all of the problems in the
first category. However, exposure to materials such as asbestos could cause extremely seri-
ous health hazards.
The rate at which any particular insulation system will expand or contract has a definite
effect on efficiency. The possible difference in expansion between the pipe and the insula-
tion may eventually produce voids or gaps after repeated flexing. An insulation with a high

Downloaded from Digital Engineering Library @ McGraw-Hill (www.accessengineeringlibrary.com)
Copyright © 2009 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.