Marinite

Marinite was a line of high-temperature asbestos insulation boards manufactured by Johns Manville, one of the largest asbestos product companies in the United States. Developed in the 1940s, Marinite boards were specifically engineered for applications requiring fire resistance and thermal insulation in extreme environments, and they became a standard specification material for the US Navy and industrial facilities.

The product line included several grades, such as Marinite 36, Marinite I, and Marinite XL, each formulated for different temperature ranges and structural requirements. The boards were composed of asbestos fibers (primarily chrysotile, with some formulations containing amosite) bound in a calcium silicate matrix, with asbestos content typically ranging from 15% to 50% depending on the grade.

Marinite boards were used extensively in naval vessel construction for bulkhead insulation, fire barriers, and equipment enclosures. In industrial settings, they served as boiler room insulation, furnace linings, electrical panel backing, and fire protection in power plants and refineries. The boards were valued for their combination of structural strength, thermal performance, and fire resistance.

The health consequences for workers who fabricated, installed, or maintained Marinite boards were significant. Cutting and fitting the boards generated substantial amounts of asbestos dust. Navy veterans, shipyard workers, and industrial maintenance personnel who worked with Marinite have been among the largest groups filing asbestos injury claims against Johns Manville.

Johns Manville filed for bankruptcy in 1982 due to the overwhelming volume of asbestos personal injury lawsuits, becoming one of the first major corporations to do so. The Manville Personal Injury Settlement Trust was established to compensate victims. Johns Manville was subsequently acquired by Berkshire Hathaway and continues to operate today as a building products manufacturer, though it no longer uses asbestos in any products.