Marinite
Marinite was a Johns Manville high-temperature asbestos board used in naval vessels and industrial settings.
Description
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.
Countries where commonly found
Commercial brands
How to identify
Marinite boards are dense, rigid panels that are typically white, off-white, or light grey. They are heavier and harder than standard asbestos insulating board, reflecting their higher-density calcium silicate composition. Many boards are stamped with "MARINITE" and the Johns Manville (J-M) logo, often along with the specific grade designation (e.g., "Marinite 36"). The boards range from approximately 6mm to 50mm in thickness. In naval settings, look for these boards around boilers, behind electrical panels, on bulkheads, and in fire barrier assemblies. In industrial facilities, check boiler rooms, furnace areas, and high-temperature equipment enclosures.
Health risk & friability
This material has a risk level of 3 out of 5.
It is classified as mixed, meaning it can range from non-friable when in good condition to highly friable when damaged, weathered or disturbed. Professional assessment is essential to determine the current state and appropriate action.
What to do if you find this material
If you encounter Marinite boards in a building, vessel, or industrial facility, do not cut, drill, sand, or disturb the material. Assume any Marinite board contains asbestos until proven otherwise by laboratory analysis. In the US, notify your employer or facility safety officer, who must arrange for a qualified asbestos inspector to assess the material. If asbestos is confirmed, an Operations and Maintenance (O&M) plan should be developed for materials in good condition, or abatement by a licensed contractor for damaged or deteriorating boards. In naval and shipyard settings, specific OSHA and EPA regulations govern asbestos handling. All removal work must comply with NESHAP (National Emission Standards for Hazardous Air Pollutants) requirements.
Frequently asked questions
Does all Marinite board contain asbestos?
Why is Marinite common on navy ships?
Can I file a claim for Marinite asbestos exposure?
Related materials
Other asbestos-containing materials you might encounter.
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Artex
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