Harbison-Walker High-Alumina Insulating Refractory Brick (Asbestos-Containing Grades)
Product Description
Harbison-Walker Refractories Company was one of the most prominent manufacturers of refractory products in the United States, supplying heat-resistant materials to heavy industry for well over a century. Among its extensive product lines, Harbison-Walker produced high-alumina insulating refractory brick — a specialized class of brick engineered to withstand extreme temperatures while simultaneously providing thermal insulation in industrial furnace and kiln applications.
High-alumina refractory bricks are defined by their elevated aluminum oxide (Al₂O₃) content, which distinguishes them from standard fireclay brick and equips them for use in higher-temperature service environments. The “insulating” designation indicates that certain grades within this family were formulated with a porous, lightweight structure designed to reduce heat loss through furnace walls, lowering fuel consumption and improving thermal efficiency. These characteristics made high-alumina insulating bricks attractive across a wide range of industries, including steel and iron production, cement manufacturing, petrochemical refining, glass making, and ceramic production.
Harbison-Walker supplied refractory products to industrial customers throughout the twentieth century, and its high-alumina insulating brick lines were sold and installed in facilities across the country. The company operated manufacturing plants and maintained a broad distribution network that reached virtually every sector of American heavy industry. As a result, the product’s footprint in industrial settings was extensive, and workers in many different occupational roles came into contact with these bricks during their working lives.
Asbestos Content
Certain grades of Harbison-Walker’s high-alumina insulating refractory brick were manufactured to contain asbestos as a component of their formulation. In refractory manufacturing, asbestos — particularly chrysotile and amphibole varieties — was incorporated into insulating brick grades for several practical reasons rooted in the material properties of asbestos fiber.
Asbestos offered manufacturers heat resistance, dimensional stability at elevated temperatures, and reinforcing tensile strength within the brick matrix. In lightweight, porous insulating grades, where the cellular structure could otherwise compromise mechanical integrity, asbestos fibers served to bind the material and resist cracking or spalling during thermal cycling. Asbestos also contributed to the insulating performance of these products by virtue of its low thermal conductivity.
The use of asbestos in refractory insulating products was consistent with widespread industry practice during much of the twentieth century. Regulatory action, including eventual restrictions under the Clean Air Act and OSHA standards, along with the findings of AHERA (the Asbestos Hazard Emergency Response Act), established the hazardous nature of asbestos-containing building and industrial materials. Documentation associated with Harbison-Walker’s corporate history and subsequent bankruptcy proceedings confirms the manufacture and sale of asbestos-containing refractory products under the company’s name.
How Workers Were Exposed
Workers encountered asbestos-containing high-alumina insulating refractory brick from Harbison-Walker at multiple stages of the product’s life cycle — during manufacturing, installation, maintenance, repair, and demolition of industrial furnaces and high-temperature processing equipment.
Industrial workers generally represent the broad category of those at risk. This encompasses a range of job functions performed in the facilities where these bricks were installed and used:
Bricklayers and refractory masons who cut, shaped, and laid the bricks during initial furnace construction were among those with the most direct and sustained exposure. Cutting and grinding high-alumina insulating brick to fit specific furnace configurations generated respirable dust containing asbestos fibers.
Furnace maintenance and repair crews worked in environments where asbestos-containing bricks had degraded over time due to repeated heating and cooling cycles. Removing damaged or spent brick lining — a routine aspect of industrial furnace maintenance — disturbed the material and released fibers into the air.
Demolition workers tasked with tearing out old furnace linings at the end of a furnace’s service life faced concentrated exposure as entire walls of aged refractory brick were broken apart.
Laborers and helpers working in the same spaces as bricklayers and maintenance crews, even without directly handling the brick themselves, could be exposed through ambient dust generated by those performing primary tasks.
Industrial plant workers in proximity to furnace relining operations — including workers in steel mills, cement plants, glass facilities, and chemical processing plants — may have experienced secondary exposure depending on the ventilation conditions and worksite controls in place at any given facility.
OSHA’s permissible exposure limits for asbestos, established and revised through regulatory action beginning in the 1970s, reflect the recognized hazard of airborne asbestos fiber in occupational settings. Prior to these standards, workers in refractory trades often worked without respiratory protection or engineering controls adequate to limit fiber inhalation.
Diseases associated with asbestos exposure — including mesothelioma, asbestosis, lung cancer, and other asbestos-related conditions — typically manifest decades after the period of exposure, meaning workers exposed to Harbison-Walker high-alumina insulating refractory brick during the mid-twentieth century may only now be receiving diagnoses linked to that exposure.