Insulation for Pipe and Duct Applications

Insulation is available in numerous materials suitable for various applications. Many variables play a part in selecting the insulation for a specific application. When selecting insulation, review the following questions:

By Brent M. Husser and Kurt F. Melton, KJWW, Rock Island, Ill. October 1, 2004

Insulation is available in numerous materials suitable for various applications. Many variables play a part in selecting the insulation for a specific application. When selecting insulation, review the following questions:

  1. What is the temperature difference between the fluid being conveyed and its environment? This can range from 20°F to more than 2,000°F.

  2. Where is the insulation located? Is it indoors or outdoors?

  3. What is the insulation’s environment like? Does it need a protective jacket to guard it from humidity, building occupants, etc.? Is it located in a high traffic area?

  4. What are the cost implications for using the insulation? Is it readily available? Is it easy to install? Are large quantities of insulation required?

Insulation Types

Fiberglass Mineral Wool Elastomeric Cellular Foam Polyisocyanurate Hydrous Calcium Silicate
Application Primarily used indoors with a vapor barrier. Can be used for piping or ductwork. Durability is low. Loses insulation effectiveness when wet. Installers are required to take protective measures for installation. Primarily used in high temperature applications such as generator exhaust stacks and incinerator breechings. Commonly used in Europe in lieu of fiberglass. Also used in equipment such as sound attenuators. Primarily used for cold applications such as refrigerant piping, chilled-water piping, chiller evaporator bundles, storage tanks and exterior ductwork. Maintains insulation effectiveness when wet. No protective requirements for installers. Primarily used in cold applications. Good vapor resistance and will maintain insulation characteristics when wet. Durable product for easy maintenance when provided with PVC jacketing. Primarily used in high temperature applications such as generator exhaust stacks, incinerator breechings, boiler flues and grease exhaust ducts.
Outdoor Use Not recommended without weathertight covering Not recommended Not recommended without UV protective covering Not recommended without weathertight covering Not recommended without weathertight covering
Recommended Temperature Restrictions 0°F to 450°F Ambient (70 °F) to 1,200°F 0°F to 140°F -250°F to 200°F Ambient (70 °F) to 1,200°F
Vapor Resistance No vapor resistance without vapor covering No vapor resistance without vapor covering Good vapor resistance Good vapor resistance No vapor resistance
K-Value/Inch 0.24 K-value at 75°F 0.30 K-value at 200°F 0.28 K-value at 75°F 0.19 K-value at 75°F 0.40 K-value at 300°F
Approximate Cost Lowest Cost 60% to 80% higher than fiberglass. Ceramic fiber for high temperatures 30% to 60% higher than fiberglass based on pipe size and insulation thickness 5% to 40% higher than fiberglass based on fitting cost and size 60% to 80% higher than fiberglass. For high temperatures