Selecting Pipe Insulation for Hot Applications
The temperature range for hot industrial piping systems could be loosely defined as 350°F to 1200°F. Let’s take a look at the most common insulation options in that range.
Aerogel insulation allows the user to accomplish a given level of thermal efficiency at a lower thickness than any other insulation suitable for hot systems. It’s offered in blanket form with common thicknesses or 5mm or 10 mm.
The blanket construction allows for fast field fabrication and reduced physical inventory-on-hand requirements. Manufacturers of aerogel insulation argue that it installs faster than traditional insulation materials. That argument holds even more validity for large piping or tank installs.
Aerogel insulation is also hydrophobic, or highly resistant to liquid water penetration. Water vapor however, is able to pass through it which can be beneficial when water does find a way to the insulated surface. Aspen Aerogels introduced their aerogel insulation over a decade ago. Recently, Armacell and Lewco have entered the market with their own product.
Calcium silicate insulation has long been a popular choice for hot applications, predominantly for its durability and consistent thermal performance in the industrial setting. This granular insulation lacks the binding agent found in fibrous insulations that can degrade over time .
Though its cementitious composition can absorb and hold against the pipe’s surface, manufacturers of calcium silicate argue that their integral corrosion inhibitors react with water to create a physical barrier on the pipe’s surface and buffer the pH. Consequently, the corrosion process is significantly slowed.
Johns Manville Industrial Group has been the primary manufacturer of calcium silicate insulation supplying the U.S. and Canada in recent years. Newer to market is Thermal Pipe Shields with their filter pressed calcium silicate that is marketed as having less voids than molded calcium silicate and increased structural strength.
Cellular glass is a rigid closed cell insulation which is impermeable to water and moisture. It also offers notable durability and abuse resistance. Although it’s not quite as common for hot systems as it is for cold, Owens Corning produces versions that can withstand up to 900°F operating temperatures.
Howred Corporation and Johns Manville Industrial Group manufacture expanded perlite products. This type of insulation is sought after for its rigidity, consistent thermal performance and hydrophobic properties.
Expanded perlite performs well in abuse prone, industrial settings and provides superior resistance to water and moisture intrusion. Its composition does not allow for water to be absorbed and retained.
Fiberglass pipe insulation and mineral wool (or stone wool) insulation fall into this category. The fibrous construction of these materials gives them excellent thermal performance. Another significant advantage is the price point. Mineral fiber insulations take the prize for the lowest cost material which makes them popular when budget is of high concern.
Johns Manville, Knauf Insulation and Owens Corning make fiberglass pipe insulation that can be on installed on systems up to 1000°F. Mineral wool pipe insulation is available for systems up to 1200°F and is more common than fiberglass in the industrial environment. Mandrel wound versions are offered by companies including: Johns Manville Industrial Group, Owens Corning Paroc and Rockwool International (Roxul).
Mineral wool is also available in the form of v-groove pipe insulation. The term “v-groove” refers to the v-shaped sections that are removed in the fabrication process to allow an otherwise flat board to take on a circular shape. V-groove mineral wool boasts additional savings when compared to the higher cost process of producing mandrel wound pipe covering. Rock Wool Manufacturing has centered their business model around the v-grooved product model.
Visionary Industrial Insulation is a manufacturer that winds needled e-glass insulation into pipe sections on a mandrel. Their pipe insulation delivers superior thermal efficiency (at a higher cost) for an equivalent thickness of calcium silicate or expanded perlite. Its fibrous structure enables it to hold water, but it’s available with a hydrophobic coating.
There are a number of different pipe insulations suitable for high-temperatures. It’s important to understand the benefits and downfalls of all of them in the specification process. I encourage you to reach out to the salespeople representing these companies and hear their stories. The knowledge you gain will help you make better informed decisions as you are faced with new applications and system demands in the future.
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