Insulation for Pipe and Duct Applications
By Brent M. Husser and Kurt F. Melton, KJWW, Rock Island, Ill. -- Consulting-Specifying Engineer, 10/1/2004
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:
- 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.
- Where is the insulation located? Is it indoors or outdoors?
- 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?
- What are the cost implications for using the insulation? Is it readily available? Is it easy to install? Are large quantities of insulation required?
| 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 |
