Asbestos in Sheet Packings, Gaskets, and Sealing Products

One of the many forms of asbestos used in industrial settings of the last century was the wide range of sealing products for the automotive industry, including plumbing, heating, woodstoves, and even the US space program. Manufacturers produced asbestos gaskets until public awareness of asbestos-related diseases increased and motivated them to replace the toxic mineral.

Asbestos-based gaskets were widely used to seal pipes or machinery pieces in engines employed in heavy industry. They offered the benefit of heat and fire resistance and maintained their original form when exposed to high temperature - a needed behavior in effectively sealing hydraulic or pneumatic equipment. Asbestos sealings prevented plants from significant expenses due to their durability and versatility and were present in products such as:

  • presses
  • valves
  • hoists
  • autoclaves
  • pumps
  • machinery

Asbestos packing was a compressible and resilient material mainly used to seal moving parts, while asbestos gaskets were used in equipment handling liquids or gases. Seals and gaskets made with asbestos are generally classified by the method of application or type of construction:

  • asbestos seals and packings
  • asbestos-fiber sheeting
  • asbestos rope and felt seals
  • asbestos compression packings
  • asbestos oil-retainer seals

While packings and gaskets are not new, manufacturing and engineering problems associated with applying different types of asbestos-based seals emerged throughout the years. Because of the continually growing field of hydraulics and pneumatics, there has been a need for specialty packings and gaskets with varying characteristics and designs to meet the many functioning variations in mechanisms:

  • temperature
  • pressure
  • medium of operation
  • lubrication availability
  • operation speed
  • operation space and motion

Resistance to chemicals made chrysotile and crocidolite asbestos fibers necessary components in gaskets and packings along with binder materials such as:

  • natural rubbers
  • synthetic rubbers
  • asphalt
  • phenolic resin
  • plasticizers

Asbestos can expand and contract similarly to the metal it contacts when exposed to heat or cold, making it a must in the manufacturing industry. Moreover, the toxic material combines the resistance to high pressure, heat, and chemical gases. It is why asbestos surpasses all other materials with these properties. Chrysotile fibers were added to make seals with all these characteristics, as these fibers' softness, silkiness, and slipperiness made them precisely the components for them.

Such asbestos fibers could be twisted or braided into different shapes conforming to packing's or gasket's requirements. The braided forms or asbestos fabrics could also be coated or impregnated with other compounds: rubberized and graphited braided asbestos packing was suitable for high-pressure and high-temperature applications.

Asbestos cloth is one of the bases for sheet packing of various shapes and sizes - sheet asbestos packing is one of the first applications of asbestos in the form of packing. This type of packing was manufactured with different combinations, such as:

  • wire-reinforced asbestos fabric
  • graphite-impregnated asbestos fabrics
  • cloth woven of asbestos yarn with a metal core

Asbestos-Related Diseases Caused by the Installation and Removal of Contaminated Sealing Products

Industrial workers and individuals operating in fields that manipulate or use machinery containing asbestos gaskets and seals are at a constant risk of asbestos exposure. Workers most likely encounter asbestos gaskets when repairing or maintaining old engines or industrial machinery. DIY auto mechanics are also at risk of exposure to old asbestos gaskets when manipulating parts sealed with such gaskets, including:

  • pipes
  • pumps
  • compressors
  • valves
  • boilers
  • engine cylinder heads
  • heat exchangers
  • condensers

While modern gasket manufacturers now use heat-resistant substitutes for asbestos, reports from the EPA concluded that the import of chrysotile asbestos is still running, and the toxic mineral is legally used in manufacturing sheet gaskets and other gaskets. Moreover, most manufacturers operate internationally, and it remains legal to import asbestos gaskets. But thankfully, many American gasket distributors are selling asbestos-free gaskets and, by doing so, protecting their workers and customers.