Boiler Breechings & Flue Gas Ducts — Asbestos Exposure Crosswalk
What This Equipment Is
A breeching is the large rectangular or round duct that carries hot combustion gas from a boiler furnace out to the stack. In a coal-, oil-, or gas-fired power plant the breeching can be 6 to 20 feet across, run hundreds of feet between boiler and stack, and operate at gas temperatures of 300–700°F. Industrial steam plants in refineries, breweries, paper mills, and large manufacturing facilities use smaller breechings serving the same function.
Breechings sit between the boiler and the precipitator (if any), the induced-draft fan, and the stack. The hot ductwork is jacketed in heavy thermal insulation, and the moving sections (expansion joints, dampers, isolation gates) historically used asbestos-bearing seals and packing.
Asbestos Products Historically Used Around Breechings
| Product Category | Where on the Breeching | Notes |
|---|---|---|
| Block insulation | Duct exterior, entire length | Calcium silicate or magnesia |
| Insulating cement | Joints, expansion-joint covers, irregular surfaces | Mixed dry, hand-applied |
| Asbestos-cement panel | Outer jacket / weather lagging | Transite-style panel |
| Expansion-joint cloth | Bellows-style joints absorbing thermal movement | Asbestos cloth fabric |
| Refractory mortar / castable | Internal lining of breeching transitions at boiler exit | See Refractory Mortar |
| Damper-shaft packing | Isolation dampers, modulating dampers | Braided asbestos rope packing |
| Gaskets | Inspection-port covers, instrumentation flanges | Asbestos sheet gasket material |
Why Breeching Work Was a High-Exposure Activity
Breechings live in the hottest, dirtiest sections of a power plant or industrial boiler house. Routine maintenance is hard, dirty, hot work, and major outages — boiler retubing, scrubber additions, ductwork modifications — pull large crews into the breeching environment for sustained periods.
Insulators reinsulating a several-hundred-foot breeching run during an outage worked in dense legacy fiber from the strip-out alongside fresh fiber from cutting new insulation, mixing cement, and patching cement at every joint. Boilermakers cutting and welding new sections of breeching steel disturbed insulation along the cut line. Demolition of an entire ductwork run during major plant modernization released decades of legacy material.
Manufacturers Named in Litigation Involving Breeching-Insulation Products
- Johns-Manville — block insulation, asbestos-cement panel, insulating cement
- Owens-Corning / Fibreboard — block insulation, pipe covering
- Eagle-Picher — block insulation
- Armstrong World Industries — calcium silicate insulation
- Pittsburgh Corning — Unibestos block
- Combustion Engineering — boiler-system insulation products
- Babcock & Wilcox — boiler-system insulation products
Documented Product References
Images sourced from publicly available product-identification reference materials. Inclusion does not constitute a finding of liability against any company.
Trust Funds That May Apply
- Manville Personal Injury Settlement Trust
- Owens-Corning / Fibreboard Asbestos PI Trust
- Eagle-Picher Industries PI Settlement Trust
- Pittsburgh Corning Corporation Asbestos PI Trust
- Armstrong World Industries Asbestos PI Settlement Trust
- Combustion Engineering 524(g) Asbestos PI Trust
- Babcock & Wilcox Company Asbestos PI Trust
Trades Most Exposed at Breeching Work
Insulators (Heat & Frost), boilermakers, iron workers and welders cutting / patching breeching steel, sheet-metal mechanics, laborers doing tear-out and removal during outages, demolition crews.
Jobsites in the Network Documenting Breechings
- Anheuser-Busch Brewery, St. Louis, Missouri — industrial boiler-plant breechings
- Every Missouri power plant in the network
- See companion pages: Boilers, Block Insulation, Refractory Mortar
Compiled from publicly filed asbestos litigation, EPA / state-DNR records, and industry-publication histories. Product and company references reflect what has been alleged or documented in publicly filed litigation. This page does not constitute a finding of liability against any company. Not legal advice; consult a licensed attorney about your specific situation.