Page 228 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION

5.12 CHAPTER FIVE

private agencies may dictate the choice of product that will be used. Some of the consider-
ations are the following:
1. Flammability in the wet or dry state
2. Type of system—solvent or water based (depending on whether the material will attack
the substrate to which it is applied)
3. Recommended dry film thickness
4. Temperature conditions required for application
5. Limitations on toxicity levels while being applied and drying
6. Method of application—brush, trowel, spray, or palm
7. Resistance to chemical and mechanical factors, such as abrasion, temperature, impact,
and expansion
The choice of material is also governed by the size, shape, and location of the surface
to be protected. Large irregular shapes may require a thicker material, which will cling to
surfaces offering no other means of application.
Adhesives are used to permanently bond the insulation either to itself or to the surface
on which it is applied. Each different type of insulation requires its own special type of
adhesive. This information should be obtained directly from the insulation or adhesive
manufacturer, who will recommend the adhesive best suited for the material and service
conditions established by the engineer.
Weather barrier coatings are used to seal an insulation system from the elements, thereby
protecting the underlying insulation from damage. In cold service the use of a breather final
coat over a vapor barrier will prevent liquid water from penetrating the coating while allow-
ing water vapor to pass through. When used on a hot service, a breather coat will allow
the escape of the minimal amount of water vapor trapped inside. When additional strength
or protection is required, glass cloth membranes as well as metal mesh should be used to
reinforce the weather barrier application.
Vapor barrier coatings are used on the outer layer of cold service insulation to inhibit the
passage of water vapor. These coatings are formulated to be used alone as the top coat, or
with factory or field-applied jackets made of FSK, cloth, or other membranes as an adhesive
or sealer.
Lagging adhesives are used to apply cloth lagging both to itself and to the insulation
surface. In some cases, the surface may be rough or irregular, and a sizing may be necessary
to seal the substrate in order for the lagging to adhere properly or for a finish to be correctly
applied. The correct adhesive can fill the rough surfaces and gaps to provide a smooth and
decorative finish. Coatings for application over almost any material used for insulation can
be obtained. Acoustical mastics are available for use as sound barrier coatings, and can be
used alone or with acoustical jacket material.

INSULATION MATERIAL AND THICKNESS
SELECTION

The general criteria needed to make a choice among various insulation materials are as
follows:
1. The reason insulation is needed
2. Service temperature expected
3. Code requirements
4. The location where insulation will be installed

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