2. INSULATION MATERIALS AND PROPERTIES

2.4 MAJOR INSULATION MATERIALS

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The following is a general inventory of the characteristics and properties of major insulation materials used in commercial and industrial installations. See the Insulation Property Tables at the end of Section 2 for a comparative review.

1. CALCIUM SILICATE

Calcium silicate insulation is composed principally of hydrous calcium silicate which usually contains reinforcing fibers; it is available in molded and rigid forms. Service temperature range covered is 35°C to 815°C. Flexural and compressive strength is good. Calcium silicate is water absorbent. However, it can be dried out without deterioration. The material is non-combustible and used primarily on hot piping and surfaces. Jacketing is field applied.

2. MINERAL FIBER

a. Glass: Available as flexible blanket, rigid board, pipe covering and other pre-molded shapes. Service temperature range is –40°C to 232°C. Fibrous glass is neutral; however, the binder may have a pH factor. The product is non-combustible and has good sound absorption qualities.

b. Rock and Slag: Rock and slag fibers are bonded together with a heat resistant binder to produce mineral fiber or wool. Upper temperature limit can reach 1035°C. The same organic binder used in the production of glass fiber products is also used in the production of most mineral fiber products. Mineral fiber products are non-combustible and have excellent fire properties..

3. CELLULAR GLASS

Available in board and block form capable of being fabricated into pipe covering and various shapes. Service temperature range is –260C to 200°C and to 650°C in composite systems. Good structural strength, poor impact resistance. Material is non-combustible, non-absorptive and resistant to many chemicals.

4. EXPANDED SILICA, OR PERLITE

Insulation composed of natural perlite ore expanded to form a cellular structure.

Added binders resist moisture penetration and inorganic fibers reinforce the structure. The materials has low shrinkage and high resistance to substrate corrosion. Perlite is non-combustible and operates in the intermediate and high temperature ranges. The product is available in rigid pre-formed shapes and blocks.

5. ELASTOMERIC FOAM

Foamed resins combined with elastomers produce a flexible cellular material. Available in pre-formed shapes and sheets. The upper temperature limit is at 105°C and 82°C for continous operation. Elastomeric insulation is cost efficient for low temperature applications with no jacketing necessary. Resiliency is high. Consideration should be made for fire retardancy of the material.

6. FOAMED PLASTIC

Insulations produced from foaming plastic resins create predominately closed cellular rigid materials. "K" values decline after initial use as the gas trapped within the cellular structure is eventually replaced by air. Check manufacturers' data. Foamed plastics are light weight with excellent cutting characteristics. The chemical content varies with each manufacturer. Available in pre-formed shapes and boards, foamed plastics are generally used in the lower intermediate and the entire low temperature ranges. Consideration should be made for fire retardancy of the material.

7. REFRACTORY FIBER

Refractory Fiber insulations are mineral or ceramic fibers, including alumina and silica, bonded with extremely high temperature inorganic binders, or a mechanical interlocking of fibers eliminates the need for any binder. The material is manufactured in blanket or rigid form. Thermal shock resistance is high. Temperature limits reach 1750°C. The material is non-combustible.

The use and design of refractory range materials is an engineering art in its own right and is not treated fully in this manual, although some refractory products can be installed using application methods illustrated here.

8. INSULATING CEMENT

Insulating and finishing cements are a mixture of various insulating fibers and binders with water and cement, to form a soft plastic mass for application on irregular surfaces. Insulation values are moderate. Cements may be applied to high temperature surfaces. Finishing cements or one-coat cements are used in the lower intermediate range and as a finish to other insulation applications. Check each manufacturer for shrinkage and adhesion properties.