Calcium Silicate Board (Asbestos)
Rigid calcium silicate insulation boards and pipe sections containing asbestos, used for high-temperature applications.
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Description
Asbestos calcium silicate board is a rigid, lightweight insulation material composed of calcium silicate reinforced with asbestos fibres, typically amosite or chrysotile. The asbestos content usually ranges from 6 % to 20 %, although some formulations contain higher concentrations. The product was manufactured as flat boards, pre-formed pipe sections (half-shells), and block insulation for high-temperature industrial and commercial applications.
Calcium silicate insulation was widely used from the 1940s through the mid-1980s. As flat boards, it served as fire-rated wall linings, ceiling panels, and partition cladding. As pipe sections, it provided thermal insulation for hot-water and steam piping in industrial plants, power stations, and large commercial buildings. Block forms were used to insulate boilers, tanks, and process equipment.
The material is classified as mixed friability. Intact calcium silicate board is relatively stable and unlikely to release fibres during normal use. However, the material becomes significantly more hazardous when it is cut, drilled, sanded, broken, or when it deteriorates due to age, moisture, or mechanical damage. Crushed or powdered calcium silicate produces fine dust containing respirable asbestos fibres.
One notable concern with calcium silicate insulation is that it closely resembles modern, non-asbestos calcium silicate products. Visual identification alone is unreliable. Many contemporary insulation boards are also made from calcium silicate without asbestos, and the products are nearly indistinguishable in appearance. Positive identification requires laboratory analysis via polarised light microscopy (PLM).
Well-known asbestos-containing calcium silicate products include Johns-Manville Thermo-12 and Owens-Corning Kaylo, both of which were subjects of extensive litigation in the United States. In the UK, removal of calcium silicate pipe sections and boards may be classified as licensed or non-licensed work depending on the condition and scope. Good-condition calcium silicate insulation can often be managed in situ under a formal asbestos management plan.
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Marques commerciales
Comment l'identifier
Calcium silicate board is a rigid, lightweight, chalky-white or off-white material that is denser than AIB but lighter than concrete. Pipe sections appear as moulded half-shells clamped around piping. The surface is smooth and may be covered with canvas, paint, or a metal jacket. It can be confused with modern non-asbestos calcium silicate boards, so laboratory testing is essential for any pre-1985 installation.
Risque sanitaire et friabilité
Ce matériau a un niveau de risque de 3 sur 5.
Il est classé comme mixed, ce qui signifie qu'il peut varier de non friable en bon état à hautement friable lorsqu'il est endommagé, altéré ou perturbé. Une évaluation professionnelle est essentielle pour déterminer l'état actuel et l'action appropriée.
Que faire si vous trouvez ce matériau
If calcium silicate insulation is in good condition and undisturbed, it can be managed in place with appropriate labelling and regular inspection. Do not cut, drill, or break the material. If work requires disturbing it, have it sampled and tested first. Removal should be carried out by a competent contractor with appropriate controls based on the material condition and local regulatory requirements.
Questions fréquentes
Does all calcium silicate board contain asbestos?
What is Johns-Manville Thermo-12?
Is calcium silicate insulation as dangerous as pipe lagging?
How is calcium silicate pipe insulation removed?
Matériaux associés
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Asbestos Insulating Board (AIB)
Low-density board containing up to 40 % asbestos, used for fire protection, partitions, and ceiling tiles.
Asbestos Millboard
Dense asbestos-fibre board used as a heat shield behind boilers, stoves, and electrical equipment.
Asbestos Pipe Lagging
Fibrous thermal insulation applied to pipes, boilers, and ductwork, containing up to 100 % asbestos.
Sprayed Asbestos Coating (Limpet)
Spray-applied asbestos insulation used for fireproofing steel structures, boiler rooms, and ceilings.
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