Insulating Properties while Mitigating CUI with Aerolon


Corrosion under insulation (CUI) is a recognized problem that costs various industries millions of dollars every year.  Often, CUI goes unnoticed, but when detected, can lead to expensive repairs.  Engineers believed for many years that hot temperatures would keep the substrate insulation dry and that the typical metal cladding around the insulation would prove to be an effective water barrier.  The thinking was that an insulated hot substrate would be problem-free.  Unfortunately, experience has proven otherwise.

Regardless of how well the metal cladding is installed, seams will open up in time, allowing water to seep through.  Once insulation becomes wet, its effectiveness is compromised.  Most insulation does not adhere to the substrate, therefore, a space exists between the substrate and the insulation where water could (and does) collect.  Typical hot surfaces in process industries will fluctuate temperatures (process changes, downtimes, etc.) creating a very corrosive environment of wet and dry; hot and cold.  This thermal cycling in the presence of moisture is extremely corrosive to unprotected steel surfaces.  NACE SP0198, a standard practice and guideline for dealing with this issue, reports the worst corrosive environment is the 140-300°F (60-149°C) range.

This problem may be compounded if the collection of the chlorides/sulfates is in the water that is in the insulation (damp) or on the surface.  These corrosive ions accelerate corrosion and often with catastrophic results (perforated pipes or vessels).

Standard insulation types are often 2-3+ inches thick and are lightweight and porous by design.  These very properties, which make them great insulators, become negative features should they get wet.  While their high thickness makes heat retention 80-90% efficient, many processes do not necessitate this degree of thermal efficiency.  The additional thickness often proves problematic in tight configurations or complex geometries, especially when banded metal cladding is needed.  Even so, when it comes to insulating hot surfaces to protect workers, these thick insulation materials with metal cladding have typically been the answer; albeit a labor-intensive and expensive one.


Aerolon is a liquid-applied, thin-film insulation material from Tnemec Co.  It utilizes the world’s most effective insulating material – aerogel, and has a thermal conductivity value that is even lower than standard insulation, making it a superior insulating material, inch-for-inch.

As Aerolon is a liquid-applied material, it bonds directly to the surface, creating a barrier between the substrate and the insulation.  There is no place for the water to collect or even reach the substrate.  In this manner, Aerolon greatly minimizes any potential for CUI to occur.  Furthermore, since Aerolon uses aerogel material (which essentially traps air within its matrix), the entire film is held together with a water and weather resistant acrylic binder making Aerolon acceptable for exterior use.  No metal cladding is needed; and therefore, the potential for leaks in the cladding is eliminated. 

Aerolon is liquid (spray) applied at a lesser volume than standard insulation, therefore, it is ideal for complex geometries or applications where space is limited.  The thermal efficiency it provides is often sufficient for most projects.  In addition, Aerolon is a perfect alternative to thicker insulations that require cladding for the protection of workers from hot surfaces.  One one or two coats of Aerolon is sufficient to reach the “safe-touch” required to protect workers from burns; a far superior approach than standard insulation with cladding.

Aerolon offers:

1.      Outstanding thermal insulation properties (worker safety and thermal efficiency)

2.      Liquid-applied application for speed

3.      Less thickness (for tight spaces and complex geometries)

4.      Direct substrate bonding to prevent water infiltration

5.      Acrylic binder for water and weather resistance

6.      No metal cladding needed

Engineered Approach

In order to enjoy all the benefits of Aerolon, it must be designed and applied in the correct manner and thickness for your specific job.  Coblaco understands that the right surface preparation and application of Aerolon is critical to its performance and has partnered with Tnemec to make sure that Aerolon delivers for your specific needs. 

Coblaco Services Inc. has been in business since 1978.  We are an industrial services contractor providing solutions for challenging projects. We are best known for:

·         Project Management - We manage our projects so our customers do not have to.

·         Industry Knowledge - Our industry knowledge and certifications lead us to being solutions driven.

·         Responsive - Our ability quickly respond is the result of our ability to scale.

For more information, click on the button below for Aerolon brochure.