2. INSULATION MATERIALS AND PROPERTIES

2.8 SUMMARY – INSULATION MATERIALS AND APPLICATION WITHIN THE GENERAL TEMPERATURE RANGES

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Choices of the materials available within each temperature range are based on design conditions (other than thermal) of the installation. See Section 3 for more detailed design information.

LOW TEMPERATURE RANGE (15°C to –75°C)

The major design problems on low temperature installations are moisture penetration and operating efficiency. For applications below 0°C, the insulation material should have low water adsorption

Vapour retarders are extensively used, but in practice it is difficult to achieve the perfect retarder in extreme applications. The pressure of the vapour flow from the warm outside surface to the cooler inside surface is such that, even with waterproof insulation, vapour may diffuse through the material, enter through unsealed joints or cracks, and condense, then freeze and cause damage.

Since the cost of refrigeration is higher than the cost of heating, more insulation is often justified in low temperature applications. Extra thicknesses of insulation, even beyond what would be economically dictated for cold line applications, are sometimes employed to keep the warm surface temperature above the dewpoint, thus preventing condensation from forming.

The low temperature range is further divided into application classifications.

1. Refrigeration (0°C through –75°C)

Water vapour which passes through the vapour-retarder will not only condense, but will freeze. Built up frost and ice will destroy the insulation system.

2. Cold and chilled water (15°C through 0°C)

Unless properly insulated, water vapour will condense on the metal causing corrosion and failure of the insulation assembly. The permeance of the vapour retarder should be no higher than 0.02 Perms.

The insulations generally used in this temperature range are:

a. Cellular Glass

b. Elastomeric Foamed Plastic

c. Glass Fiber

d. Mineral Fiber

e. Phenolic (foamed)

f. Polyethylene

g. Polyisocyanurate

h. Polyurethane

i. Polystyrene

See Insulation Materials Table 1.A.

INTERMEDIATE TEMPERATURE RANGE (15°C TO 315°C)

This temperature range includes conditions encountered in most industrial processes and the hot water and steam systems necessary in commercial installations. Selection of material in this range is based more on its thermal values than with low temperature applications. However, other factors such as mechanical and chemical properties, availability of forms, installation time, and costs are also significant.

The materials generally used in the intermediate range are:

a. Calcium Silicate

b. Cellular Glass

c. Elastomeric Foamed Plastic*

d. Expanded Silica, or Perlite

e. Glass Fiber

f. Mineral Fiber

g. Phenolic*

h. Polystyrene*

i. Polyurethane*

See Insulation Materials Table 1.B.

*The maximum temperature (315°C) exceeds these materials recommended maximum temperature.

HIGH TEMPERATURE RANGE (315°C TO 815°C)

As the refractory range of insulation is approached, fewer materials and application methods are available. High temperature materials are often a combination of other materials or similar materials manufactured using special binders. Jacketing is generally field applied. Industrial power and process piping and equipment, boilers, breechings, exhausts and incinerators fall within this application range. The materials generally used are:

a. Calcium Silicate

b. Cellular Glass*

c. Cements

d. Ceramic Fibers

e. Glass Fibers*

f. Mineral Fiber*

g. Perlite*

See Insulation Materials Table 1.C.

*The maximum temperature (815°C) exceeds these materials recommended service maximum temperature.