Removal of asbestos coating on pipes and conduits

In old houses built between the late 1920s and the late 1970s, it is common to find asbestos cladding on boiler pipes and conduits. If your house was built during this period, you may find it even if the house or property has been renovated. If the basement is finished, the asbestos covering may be hidden in the walls and you may not even be aware of it.

As long as asbestos is sealed, it is not harmful to you and your loved ones. However, if you are planning to make renovations or if you need to have your heating, ventilation or air conditioning system repaired or replaced, this is a problem and you will need to remove it.

Identification of asbestos coating on pipes and conduits

The coating is in the form of a paper-like material and has the same characteristics as plaster. In some cases, it looks like a textile that wraps around. In older homes, the conduits and pipes were completely covered with asbestos, while later only the elbows and joints were covered. The asbestos coating can even extend to where the floor vent is located. This poses a greater threat because the fibers can be touched, released into the air and easily inhaled.

Use of asbestos coating

Asbestos was used as insulation to cover pipes and conduits. Due to its heat resistance properties, its insulating efficiency has proven to be very high. Because of the high heat that the pipes and hoses give off, something needed to hold up.

The asbestos coating placed on the outside of the heating ducts is less likely to release fibers into the duct because it creates positive pressure. What is of concern, in fact, is the one who resides in the area where asbestos is present. However, the asbestos coating on the outside of the return ducts poses a greater threat since it creates negative pressure and that, if the duct is damaged, fibers can be released and spread in the house.

In asbestos removal cases, hard asbestos is generally handled according to a certain number of safety procedures (zone signaling, insulation, dust control, protective equipment, etc.) and with a bag-glove method, as well as wetting and cleaning exposed metal surfaces and sealing clean surfaces.

What to do with the asbestos coating?

Option 1: Leave the asbestos paper covering in place, possibly covered or spray sealed

Best practice is to leave the exposed material untouched, unless other construction conditions or very poor conditions require removal by a professional. Some asbestos contractors use an aerosol encapsulant or paint where the paper covering is to be left in place.

As long as the asbestos paper remains outside the supply ducts, which are normally under neutral or positive air pressure, the chances that the asbestos of the paper enters the duct system and the building air remain minimal. If, on the other hand, asbestos-containing materials are found inside the duct system or the air handling unit, this would be a different and more serious concern.

Option 2: remove the asbestos paper covering from the conduits, and consider a complete renovation of the conduits

If it is necessary to remove the joint or insulation from a duct covered with asbestos paper for other reasons, such as renovations, reconstruction or damaged, exposed or brittle materials, removal is carried out in respecting the asbestos decontamination precautions.

More often than not, it is much cheaper and easier to remove the entire intact duct from the building than trying to remove only the paper covering followed by cleaning the duct. In summary, in most cases it will be easier and less costly to remove the old asbestos-covered ducts and replace them with new ducts in the same location (if the ducts are still needed) than to try to clean and reuse old ducts.

Treat materials as MPCA, i.e. materials presumed to contain asbestos

This material should be reasonably treated as “material presumed to contain asbestos” or “MPCA”. “Hardened” asbestos paper and paper tape were used to seal air leaks and to lightly cover metal heating ducts generally dating from before 1965 but which may have been used until around 1981.

Current flame retardants to replace paper or asbestos materials used in HVAC ducts

If an application requires flame retardant sealing material, it is possible to replace the asbestos material and even the asbestos paper interlining, i.e. the flame retardant sealing tape for conduits, and the asbestos tape (joint for conduits) used for high temperature operations by a Hi-T silicone waterproof tape, waterproof, chemical, non-combustible (and ozone), which is resistant to carbon dioxide and waterproof air and which can be used to connect the duct cable to the ventilation pipe.