Lagging

Asbestos in Lagging Products

Lagging is a type of thermal insulation that is applied to the surface of conduits (such as steam pipes) or other surfaces (such as boilers) to reduce or prevent the transfer of heat. When it comes to building construction and heating systems, lagging is used to prevent heat from escaping to the outside and causing a fire danger.

Asbestos lagging could take any one of several forms. One of the most common types of asbestos lagging involved the use of a type of asbestos fabric, such as canvas or a specific kind of wrapping material. Spray-on lagging, such as Monokote® (a W.R. Grace product) was also commonly used.

After the use of asbestos in building materials was more or less banned in 1979, domestic producers of thermal lagging found substitutes for asbestos, but the asbestos-based lagging is still found in many buildings and vehicles.

Lagging Products Containing Asbestos

The following partial list of lagging products were known to contain asbestos:

Product Name Start Year End Year
Atlas Turner Asbestos Lagging 1948
Johns Manville Asbestos 85% Magnesia Locomotive Lagging
Johns Manville Asbestos Fire Felt Locomotive Lagging 1900 1906
TBAC Asbestos Lagging 1948

Hazards Associated with Lagging Products

Today, there may be as many as three-quarter million homes and buildings across the U.S. that may contain asbestos lagging. If the material is intact, it may be best to simply leave it alone, or have it encapsulated with a resin polymer to prevent it from becoming friable (a crumbling state in which the material releases asbestos fibers into the environment).

Pipe lagging was also used extensively on board U.S. Navy ships. Sailors who were stationed on board these ships may have been exposed to dangerous fibers that were released from pipe lagging that became worn and brittle with age or that needed to be torn down or replaced. As a result, many veterans are now at risk for developing mesothelioma.


View Sources

Sources

Bowker, Michael. Fatal Deception: The Untold Story of Asbestos (New York: Touchstone, 2003)

Incropera, Frank P. and David DeWitt. Fundamentals of Heat and Mass Transfer (3rd Ed.) (New York: John Wiley & Sons, 1990).

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