Transite asbestos chimneys, ducts, flues, pipes: this article assists in the recognition of transite pipe used for chimneys or heating flues and discusses potential hazards of this material when it is found in buildings. Transite pipe is an asbestos-cement product which was used for both HVAC ducts and for chimney or flue material to vent gas-fired appliances.
This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection. We provide photographs and descriptive text of asbestos insulation and other asbestos-containing products to permit identification of definite, probable, or possible asbestos materials in buildings.
Cement-asbestos transite pipe was also used for water piping in some communities, as we discuss at TRANSITE PIPE WATER SUPPLY PIPING.
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Because asbestos cement transite pipe chimneys may have operating and safety problems, concerns completely separate from asbestos handling questions, readers should see our chimney inspection suggestions at CHIMNEY INSPECTION DIAGNOSIS REPAIR.
While an expert lab test using polarized light microscopy may be needed to identify the specific type of asbestos fiber, or to identify the presence of asbestos in air, dust or drinking water samples, many asbestos-containing building products not only are obvious and easy to recognize, but since there were not other look-alike products that were not asbestos, a visual identification of this material can be virtually a certainty in many cases.
Watch out: Unsafe transite pipe heating flue vents may only be noticed by a careful building inspection such as shown in these rooftop photographs of a transite flue vent pipe which deteriorated, became swollen, and risk becoming blocked. In cold climates with these vents from the 1950's era, the real hazard is not so much asbestos fibers as the dangerous obstruction of the vent/flue by the deterioration of the interior of the pipe. [Photographs above and text just above on transite flue deterioration were provided courtesy of Roger Hankey].
In the transite chimney vent photo at above right we note that the exterior has been painted black. We don't know why, possibly the naturally gray-white transite flue was painted black for cosmetic reasons, or perhaps in an effort to slow down its surface deterioration.
Fire Clearance Requirements for & Label Descriptions of Asbestos Cement or Transite Heating Flues & Chimneys
In use as a gas-fired appliance chimney/vent transite pipe may have been classed as a type "B" flue vent which required 1" clearance from combustibles in some jurisdictions. But as we indicate below, the fire clearance required for transite pipe or cement-asbestos pipe flues and chimneys varied from 1" to 3" and limited temperatures to 330 to 550 F depending on the clearance.
Ervin McKinneykindly provided a copy of a November 1948/1949 Underwriters Laboratories UL List of Inspected Gas, Oil, and Miscellaneous Appliances that includes specifications for Outlet and Vent Piping (540 116). That document indicates that
Asbestos Cement Chimney & Flue Venting Products described in this 1948-1949 document include
Enderle, Inc., Ltd., Frank X., Los Angeles Calif.
Johns-Manville Corp. New York, NY., [Transite or cement asbestos flue vent and chimney piping description]
This same document also describes several other flue gas vent piping products made of vitreous coated steel, asbestos, sand, and cement, sand and pumicite with aluminum collar joints, sheet aluminum tube and asbestos insulating or steel spring spacer with an outer shell of galvanized sheet metal, and other aluminum and galvanized sheet metal piping.
Where transite pipe (asbestos-cement pipe) has been used as a building chimney to vent combustion gases, if the chimney becomes blocked there could be a dangerous carbon monoxide hazard in the building.
The transite pipe chimney - carbon monoxide hazard occurs when the (usually above-roof outdoor portion) of a transite pipe chimney becomes soft with age and exposure to weather, leading to swollen chimney sides and even chimney internal collapse.
The swollen and collapsing transite pipe chimney blocks the venting of exhaust gases from the building heating equipment.
Blocking the venting of exhaust gases, particularly for natural gas or LP gas fired heating appliances, is very likely to interfere with proper combustion at the appliance itself. In turn, this condition results in the production of carbon monoxide at high levels.
The transite flue vents, shown in the photos above & below are passing through a building interior closet.
Transite-asbestos piping used as plumbing vents or as chimneys for gas-fired appliances such as gas furnaces becomes swollen and deteriorated due to condensation of the water vapor in the combustion gases being vented, especially above the roof line or in a cold attic.
The acidic flue-gas-condensate combined with the effects of frost in cold climates causes a delamination and swelling and blockage of the transite pipe chimney-flue.
A blocked or constricted flue vent pipe can cause production of dangerous or even fatal carbon monoxide gas in the building.
While the transite pipe shown above was in use as an exhaust flue (what is the fire rating and fire clearance required?), this material was also used in some buildings for both exposed air ducts and for in-slab duct work (SLAB DUCTWORK) for heating and air conditioning systems, as shown in the photos below.
Transite pipe, which contains significant percentage of asbestos fibers, was often used for heating ducts and on occasion heating and cooling ducts in older buildings.
The transite pipe was used in a buried-in-slab construction methods which placed the transite piping below or in a building floor slab, and asbestos-containing transite pipe ducts were also used in exposed areas such as shown in the crawl space photographs above. [Photo above showing transite duct material is provided courtesy of Thomas Hauswirth, a Connecticut home inspector.]
At CHIMNEY INSPECTION DIAGNOSIS REPAIR we describe chimney inspections in detail.
Asbestos hazards of transite duct or chimney piping: Cementious duct material may contain asbestos. What is this "cement"
duct work made of? Cement and asbestos fibers.
Transite pipe typically contains about
15% to 25% asbestos fibers, typically fibrous chrysotile asbestos.
Health Hazards from Handling Transite Pipe or Asbestos Cement Piping for Vents, Chimneys, or Air Ducts
Where are the chief health risks with cementious asbestos materials?
Transite pipe, whether it has been used as an air duct, flue vent, chimney, or water pipe, is still a cementious material that is unlikely to release high levels of airborne fibers when it is in good condition.
Touching transite pipe, or simply removing and disposing of an intact section of this material from a building by carrying it outside should not release a significant level of airborne asbestos fibers unless:
In summary, if it has become soft and friable, or if transite pipe is damaged or is cut mechanically (such as by using power equipment), friable, airborne asbestos fibers may
be generated - a health and potentially a costly cleanup concern.
Incorrect spellings of transite piping or transite duct material that we've seen include transit pipe, transit ducts, Transide pipe, transide ducts, tranisite pipe, and transight pipe. "Transite" is the correct spelling.
I am hoping that you might be able to offer us some direction. We have a family cottage constructed in the 1950s and added on to until the 80s. Last year, my parents had contractors redoing the roof and asked them to remove an old oil stove as well. The contractors had a difficult time removing the chimney pipe and sent a piece of the metal crashing into the cottage as they wrestled with the stovepipe atop the roof. This sent debris, mostly looking like soot, all over the kitchen.
Recently, however, my concern has risen because I was looking at old pictures and now see that there was a piece of pipe that looks alot like asbestos cement at the exposed part of the chimney. As I was not there when it was demolished I asked my parents who believe the potential transite part was broken apart during demolition. Now I am concerned that there may be asbestos contamination in the cottage itself.
Unfortunately, we, including my toddler, have spent some time there since. What steps can we take to evaluate any contamination inside the building and clean it? Thank you for any suggestions you might have.
I trust you understand that with no data on level of material release nor exposure any opinion about the actual risk level in the case you describe would be nonsense.
What you can do is
Someone not concerned for tossing your money at a problem to reduce their risks (the other people's money or OPM problem) might suggest swab and air tests in the building for asbestos contamination.
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Frequently Asked Questions (FAQs)
[delete] (Apr 2, 2014) dan lackey said:
is there an e p a aproved methode to seal transite pipe used for heating duct in a slab foundation home
Not that I can find Dan but you can take a look at these sources:
1. ASBESTOS TRANSITE DUCTWORK - sealing transite air ducts in slabs
2. SLAB DUCTWORK - sealing air ducts in slabs - general issues
3. Code of Federal Regulations: Chapter 40; Part 763 -- Asbestos
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