How Do I Insulate Steam Pipes?

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The process of applying material to insulate steam pipes can greatly increase the heating efficiency of a steam system. Steam is commonly used in many older homes and buildings to carry heat from the boiler unit. Uninsulated steam pipe distribution and condensate return pipes are a major source of heat loss. Properly insulating these pipes can drastically reduce heat losses by as much as 90 percent. It can also enhance safety because these pipes can get extremely hot.


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Installation Methods

The pipes you'll need to insulate can vary from 1/2 inch to 6 inches in diameter. There is a variety of material you can use to insulate steam pipes, such as polyethylene, neoprene foam and fiberglass. Some other steam pipe insulation products include foil-encased bubble wrap, spray-on ceramic coatings and closed-cell rubber insulation sheets. However, fiberglass insulation is currently the most common product for steam pipe insulation in residential and commercial settings.


Fiberglass is easy to install and can be purchased in insulation sleeves. The insulation is comprised of inorganic fibers, which are bonded with special resin. An aluminum-foil facing or vapor retarder is attached. The insulation is usually available in 3-foot sections.

Seal and secure the fiberglass insulation sleeves with the recommended high-temperature tape. There are also special fiberglass insulation fitting covers that can be installed on elbows or tees in the pipe line. Make sure you purchase the proper size.


Before starting a steam pipe insulation project, be sure that you identify any problems with moisture, including pipe leaks, malfunctioning valves or leaks from tubes. If the insulation gets wet, the water will compromise the integrity of the insulation and it will not do its job.

It may help to first draw a sketch of the pipe layout. You'll need the lengths as well as the diameters of the variety of pipes you are insulating. Identify the fittings such as tees and elbows and the number of fittings that you must insulate.


When working around steam pipes, be cognizant that these pipes can get extremely hot if the system is operating. Wear a high efficiency particulate air (HEPA) respirator, a helmet, work gloves and other protective clothing. Also, be careful that you don't damage insulation that is already in place.



Insulation is often damaged or removed during system repair work and is not properly replaced. Many older steam pipe distribution systems used asbestos as an insulator material. Asbestos looks almost cardboard-like. If older insulation is wrapped around your pipes, and it is brittle or breaking, your insulation may be asbestos, which is a major health risk. Asbestos fibers can become airborne and, if fibers are breathed into the lungs, they can cause irreparable harm and eventual death. If existing insulation is damaged or falling apart, and you are not sure what type of insulation it is, call in an expert to conduct testing.


If you insulate steam pipes in an area where there are water lines, you may have removed the source of heat that kept the water lines from freezing during the winter. It's likely that you will need to insulate the water pipes as well to protect them from freezing.



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