Written By: Michelle Whitmer,
Last modified: June 7, 2021
Quick Facts
  • Years Produced:
    1938–1980s
  • Places Used:
    Heating, ventilation and air conditioning systems for buildings
  • Toxicity:
    High
  • Asbestos Use Banned:
    No
  • Friable:
    Yes

How Were Asbestos Ductwork Connectors Used?

The ducts that circulate air for heating and cooling are usually connected to HVAC machinery by flexible duct connectors made of durable fabric. For many decades, textiles woven from asbestos fibers were the primary material for this application.

Metal air ducts connect all the rooms in a home or building to HVAC equipment. When ducts are attached to heaters, air handlers and air conditioners directly, the noise and vibrations produced by the equipment may rattle throughout the entire ventilation system.

This problem is prevented by installing a flexible duct connector between the machinery and the ductwork. These connectors must absorb constant vibrations and resist hot and cold air circulated by HVAC systems, ideally lasting as long as the HVAC system itself.

For several decades during the mid-20th century, manufacturers used asbestos to make heat-resistant flexible duct connectors. Asbestos fibers are durable and fireproof, yet flexible enough to be woven into fabric. During the 1980s, manufacturers began using other heat-resistant materials to make duct connectors. International companies may still use asbestos in duct connectors, and there are no regulations to prevent them from entering the U.S. 

Unfortunately, many old buildings still contain degrading asbestos materials in HVAC systems, and the tradesmen who work with these materials are at risk of developing mesothelioma or other asbestos-related diseases.

Types of Asbestos Ductwork Connectors

Coarse Fabric Duct Connector

Duct connectors were originally manufactured as simple strips of coarse fabric woven from nearly pure asbestos yarn, which were secured to metal duct joints by clips or rivets.

Tape Duct Connector

Flexible asbestos tape of varying widths was used to seal and connect ductwork.

Vinyl or Rubber-Coated Duct Connector

More sophisticated asbestos duct connectors were coated with rubber or vinyl to provide a more airtight seal.

Paper Duct Connector

Asbestos paper was used as duct wrap insulation in HVAC systems around ductwork in basements and attics of older homes and buildings. This material often contained about 15% chrysotile asbestos.

Other asbestos-containing materials were used in HVAC systems, including asbestos cement, millboard and insulation. Asbestos cement transite pipe was typically used as an air duct rather than a connector. Asbestos millboard was used as a heat shield on walls and ceilings around HVAC systems. Asbestos wrap insulation was sometimes used inside ducts to improve heating or cooling efficiency.

Companies Connected to Asbestos Ductwork Connectors

Diseases Asbestos Ductwork Connectors Can Cause

During the height of asbestos use in America, flexible duct connectors commonly contained significant amounts of chrysotile asbestos.

The factory workers who produced these connectors suffered the worst asbestos exposure, followed by the construction tradesmen who installed, repaired or removed asbestos duct connectors on a regular basis. Occupational asbestos exposure is the No. 1 cause of work-related deaths in the world.

Exposure to asbestos in ductwork is known to cause the following diseases:

  • Mesothelioma
  • Lung cancer
  • Ovarian cancer
  • Laryngeal cancer
  • Asbestosis

Furthermore, aging and constant exposure to temperature extremes causes duct connector material to become friable, or easily crumbled into inhalable dust. Over time, even rubberized or vinyl-coated asbestos duct connectors can deteriorate to the point of releasing asbestos fibers into the air.

Microscopic asbestos dust has no scent, and exposure generally does not cause symptoms to develop until decades later. Because duct connectors are perfectly positioned to affect all the air in a building, degrading asbestos duct connectors pose a serious asbestos exposure risk.

If you are diagnosed with an asbestos-related disease it is important to seek the medical advice of a specialist. Treating these diseases early improves chances of long-term survival.

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Compensation for Exposure to Asbestos Ductwork Connectors

Manufacturers of asbestos products are held liable through the U.S. court system for the diseases their products cause. Decades of personal injury lawsuits and wrongful death lawsuits revealed these companies were aware of the dangers of asbestos and decided to use the material despite its known health effects. Many people who develop asbestos-related diseases after years of working with toxic duct connectors have received compensation by suing manufacturers.

  • A San Francisco jury awarded $2 million to retired sheet metal worker Genaro Garcia in a mesothelioma lawsuit filed against Duro Dyne in 2005. Garcia was exposed to Duro Dyne’s asbestos flexible duct connectors throughout his 48-year career.

A mesothelioma lawyer can review your case and guide you on the types of legal claims you may qualify to file. You may be eligible to file a lawsuit and multiple claims with asbestos trust funds.

Abatement and History of Asbestos Ductwork Connectors & Flexible Connectors

Abating asbestos duct connectors should only be performed by licensed asbestos abatement professionals. Do not attempt to abate this type of asbestos product yourself. Asbestos duct connector materials become friable with age and may release a significant amount of asbestos into the air. 

If you believe asbestos duct connectors are in your home or place of work, hire a licensed professional to do the job to avoid unnecessary asbestos exposure among your family or coworkers. 

American ductwork manufacturers phased out the use of asbestos during the 1980s and switched to cotton canvas or fiberglass mesh to make flexible duct connectors. 

Manufacturers began testing asbestos duct connectors as early as 1938 when the Johns Manville Corporation wrote about their advantages in the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Journal. In 1951, as air conditioning systems were starting to become popular and affordable for homes, the National Fire Protection Agency officially recommended asbestos for flexible duct connectors.


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