KR Super D Block Insulation

Product Description

KR Super D Block Insulation was a rigid block-form thermal insulation product manufactured by Kaiser Gypsum Company. Produced before 1974, this product was designed for high-temperature industrial applications, most notably for wrapping and insulating pipes, boilers, and other industrial equipment where sustained heat resistance was required. The “block” format distinguished it from flexible or blanket-style insulation, offering a more durable, pre-formed unit that could be fitted around curved and straight pipe sections in demanding industrial environments.

Kaiser Gypsum Company was a subsidiary of Kaiser Industries, one of the major American industrial conglomerates of the mid-twentieth century. The company operated across multiple construction and building materials markets, and its insulation product lines were sold and distributed to industrial facilities throughout the United States during the postwar manufacturing boom. KR Super D Block Insulation was part of a broader product family intended to meet the growing demand for thermal management solutions in refineries, chemical plants, power generation facilities, and heavy manufacturing settings.

As with many industrial insulation products manufactured during this era, KR Super D Block Insulation was produced during a period when the hazards of asbestos were not publicly disclosed and regulatory requirements were minimal. The product was in wide use across industrial settings before federal health and safety oversight for asbestos exposure was formally established.

Asbestos Content

KR Super D Block Insulation contained chrysotile asbestos as a component of its formulation. Chrysotile, commonly referred to as white asbestos, is the most commercially widespread form of asbestos and was extensively used in insulation products throughout the twentieth century due to its heat-resistant properties, tensile strength, and relatively low cost.

Chrysotile fibers were incorporated into block insulation products to enhance their ability to withstand high operational temperatures, improve structural integrity, and extend product service life under industrial conditions. In a rigid block format like KR Super D, chrysotile fibers were typically bound within a mineral or calcium silicate matrix, forming a dense composite material capable of maintaining its shape even in extreme thermal environments.

Although chrysotile was long characterized by industry sources as less hazardous than amphibole forms of asbestos such as crocidolite or amosite, regulatory bodies and scientific research have established that chrysotile asbestos is a human carcinogen. The International Agency for Research on Cancer (IARC), the U.S. Environmental Protection Agency (EPA), and the Occupational Safety and Health Administration (OSHA) all classify chrysotile as a known cause of mesothelioma, asbestosis, and lung cancer. No safe level of occupational chrysotile exposure has been established by these regulatory authorities.

How Workers Were Exposed

Industrial workers who installed, maintained, removed, or worked in proximity to KR Super D Block Insulation were at risk of inhaling asbestos fibers released from the product during its use. The rigid block format of this insulation, while structurally durable in place, was subject to damage, cutting, and disturbance during installation and during maintenance or repair operations at industrial facilities.

The primary exposure pathway involved the generation of airborne chrysotile fibers during mechanical disturbance of the material. When workers cut, shaped, or trimmed block insulation to fit pipe systems or equipment, or when they removed older, deteriorating insulation for replacement or system modifications, the process released microscopic asbestos fibers into the surrounding air. Workers in enclosed or poorly ventilated industrial spaces faced the greatest risk of inhaling these airborne fibers at dangerous concentrations.

Industrial workers in a broad range of settings encountered this product in the course of routine job duties. Pipefitters and insulators who worked directly with the material faced the most direct and sustained exposure. However, other trades and general industrial workers present in the same work areas could inhale secondhand fiber releases without ever handling the product themselves. Workers at refineries, power plants, shipyards, paper mills, steel facilities, and chemical processing operations all represented populations where block pipe insulation of this type was commonly installed.

Chrysotile asbestos fibers are extremely fine and can remain suspended in the air for extended periods after disturbance, increasing the likelihood that workers who were not directly involved in insulation tasks could nonetheless be exposed. Additionally, fibers that settled on clothing and equipment could be re-suspended during later activity, creating secondary exposure risks for the worker and for family members through take-home contamination.

The latency period for asbestos-related diseases typically ranges from 20 to 50 years following initial exposure, meaning that workers exposed to KR Super D Block Insulation before 1974 may only now be developing or receiving diagnoses of mesothelioma, asbestosis, asbestos-related lung cancer, or pleural disease.

Documented Product Identification

The following details are drawn from public asbestos litigation records, manufacturer catalog pages, technical manuals, and corporate history materials. Each item reflects the product as documented in those sources.

Documented asbestos-use period: 1953-1978

Corporate context: Kaiser Gypsum Company, Inc. operated as a manufacturer of gypsum wallboard, ceiling tiles, joint compounds, and related construction products. Service of process was handled through C. T. Corporation System in Los Angeles, California.

Brand identification: Products branded with KAISER GYPSUM name; Null-A-Fire for fire-rated wallboard; Permanente for cement products; Cover-Tex for texture products; K-Spray for spray textures

Documented asbestos components: asbestos fiber, vermiculite containing tremolite, chrysotile fiber.

Documented asbestos-component suppliers: the public records lists the following external suppliers of asbestos-bearing packing, gaskets, and seals used in conjunction with this manufacturer’s equipment — Harrison & Crossfield, Carmonia Chemical Co., Western Chemical Co., Philip Carey, Johns-Manville, Union Carbide, E. S. Browning, WR Grace / Libby, MT, Carey-Canadian Mines, Ltd..

Industries served: construction, building trades, drywall installation, acoustical ceiling installation.

Documented product lines:

• Null-A-Fire Type X Wallboard (1954-1978). 5/8-inch thick interior wallboard used for walls and ceilings to provide partitions and fire resistance. — asbestos components: vermiculite containing tremolite.
• Fire-Rated Mineral Fiberboard (1963-1974). Acoustical ceiling tile and suspended lay-in board with perforated or fissured design for acoustical treatment. — asbestos components: asbestos fiber.
• Fire-Rated Ceiling Tiles. Ceiling tiles sold in boxes of various sizes. — asbestos components: asbestos fiber.
• KAISER GYPSUM Joint Compound (1953-1975). Joint compound for finishing drywall seams. — asbestos components: asbestos fiber.
• KAISER GYPSUM Finishing / Topping Compound (1961-1975). Finishing and topping compound for drywall applications. — asbestos components: asbestos fiber.
• KAISER GYPSUM 3-Purpose Joint Compound (1968-1975). Multi-purpose joint compound for drywall finishing. — asbestos components: asbestos fiber.
• KAISER GYPSUM One-Day Joint Cement (1968-1975). Fast-setting joint cement for drywall work. — asbestos components: asbestos fiber.
• KAISER GYPSUM Pre-Mix Joint Compound (1959-1975). Ready-mixed joint compound for drywall finishing. — asbestos components: asbestos fiber.

Kaiser Gypsum used asbestos in joint compounds, texture products, ceiling tiles, wallboard, and cement products from 1953-1978. Union Carbide supplied CALIDRIA Asbestos (chrysotile) specifically for tape joint compound formulations.