Hardcast asbestos on heating boiler (C) D Friedman Hardcast Asbestos Insulation on Heating Boilers

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Asbestos insulation on heating boilers:

Here we illustrate and discuss the handling of asbestos coatings used to insulate hot water (hydronic) or steam heating boilers.

We use the term "hardcast" asbestos to refer to an asbestos paste or "plaster" that was typically applied in a layer of about 1" or greater, used to completely or partially coat old hot water or steam boilers and used on heat distribution piping at elbows or valves. Our page top photo shows original asbestos insulation coating a coal fired heating boiler that was later converted to oil fuel.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Asbestos Boiler Insulation Photo Examples & Commentary

Hardcast asbestos on heating boiler (C) D Friedman

Asbestos-Insluated Boiler Remediation Strategy: Cleaning vs Replacement

This asbestos-insulated boiler, a second view of the page top heater, is covered with hardcast asbestos insulation in good condition.

But work on the boiler may require disturbing the insulating material, presenting a risk of asbestos exposure. In our experience (DF) the cost of employing a professional asbestos abatement firm to remove the asbestos insulation from this heater, considering the added costs for containment and asbestos waste disposal may be so high that the building owner should instead consider a complete boiler replacement.

The boiler replacement strategy still involves asbestos removal and disposal costs, but because the entire boiler can usually be removed intact, the amount of asbestos distrubance, the asbestos contamintion risk to the building, and the total project costs are likely to be much less than the cost to remove, clean, and re-seal the old boiler.

After adding consideration of the operating efficiency and cost of a coal-burning heaing boiler converted to oil fuel in comparison with the operating efficiency of a new oil or gas fired heater the prospect of a boiler swap-out may be still more appealing.

Hardcast asbestos on heating boiler (C) D Friedman Hardcast asbestos on heating boiler (C) D Friedman

At above left our photograph shows another antique (and converted fuel) oil fired heating boiler covered with asbestos insulation. Even opening and closing the upper fire door for annual boiler cleaning risks disturbing the asbestos insulation.

At above right the photograph shows a similar boiler that has had its asbestos jacket removed. Notice that this boiler is fired by an older low-speed (1725 rpm) oil burner - a system likely to be operating at a lower efficiency than a new modern boiler with a high speed (3450 rpm) burner.

Heating boiler with most asbestos insulation removed (C) Daniel Friedman Heating boiler with most asbestos insulation removed (C) Daniel Friedman

The two heating boilers shown above also have had their insulation removed. But at left we are not sure that the job was performed by a professional. An expert asbestos remediator will set up dust containment and negative air pressure in the work area to protect the building from cross-contamination by asbestos dust. Workers, wearing appropriate protective gear wet and remove the asbestos insulating material, properly bagging it for disposal by an approved asbestos waste hauler.

When asbestos has been removed from the boiler as well as any piping or other asbestos applications in the building, the exposed surfaces are cleaned and sealed, typically with a spray paint coating suitable for high temperature applications.

Watch out: If we find scraps of asbestos paste or lagging remaining in place on the boiler or heating piping we suspect that an amateur asbestos abatement job has been performed.

The risk is that inexpert workers caused asbestos dust cross-contamination in the building. In such cases, additional inspection, testing, and possibly further professional cleaning (typically by damp wiping and HEPA vacuuming of the affected areas and surfaces) are likely to be needed.

Asbestos Insulation Found on Hot Water Heating or Steam Heating Pipes

Photograph of asbestos pipe insulationAsbestos also was very widely used on hot water pipes connected to heating boilers, as we illustrate at left.

We discuss this insulating material separately

see ASBESTOS DUCTS, HVAC a field identification guide to visual detection of asbestos in and on heating and cooling system ducts and flue vents.

Asbestos pipe insulation materials like the insulation shown at page top should have been removed during asbestos abatement, and so form an indication of amateur workmanship, raising the question of asbestos particle contamination in other building areas.

Continue reading about asbestos material removal in buildings in these articles:


Continue reading at ASBESTOS in POOR CONDITION or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Suggested citation for this web page

ASBESTOS BOILER INSULATION at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Questions & answers or comments about what building materials may contain asbestos, visual identification of asbestos-containing materials in buildings, and possible asbestos material identification by testing, use, age, appearance.

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman