Corrugated Metal Gaskets (CMG) are gaskets that we often see in heat exchangers where we see a lot of radial shear. Generally, we recommend using Kammprofile gaskets in heat exchanger applications, but due to the high volume use we see in applications, we will detail corrugated metal gaskets.

What is a Corrugated Metal Gasket (CMG)?

Corrugated metal gaskets are available for special flanges such as heat exchangers. Nevertheless, CMG should not be applied to pipe flanges (standard ANSI flanges) without proper engineering consideration. Even with engineering considerations, we still recommend better sealing products such as spiral wound or kammprofile gaskets rather than corrugated metal gaskets!

They are metal sheets that manufacturers make corrugated metal cores from. Gaskets should be used with soft sides, which basically means flexible graphite (that's what the gasket companies call it, we call it graphite), or another filler material on each side, like PTFE.

The corrugated metal core can be made of conventional gasket materials such as carbon steel, 304 stainless steel, 316 stainless steel (if higher temperature is required), and other high temperature resistant materials.

The filler material usually has a graphite finish. Other non-asbestos fillers are suitable for this gasket, but in petrochemical applications, we only see graphite facings.

While we're less familiar with the use of corrugated metal gaskets outside of petrochemical applications, many companies say these gaskets are also made with compressible sealing elements designed to resist high temperatures, corrosive chemicals, and thermal cycling.

NOTE: We will not be discussing - Ring Joint Gaskets (RTJ), Elastomeric Gaskets, Compression Packing, O-Rings, Gaskets and Plain Graphite Gaskets. If you would like to know more about this type of gasket, click here.

Where can I not use CMG?

Unfortunately, some manufacturers recommend using corrugated gaskets instead of spiral wound gaskets on pipe flanges. These applications are not a good idea, especially with ASME B16.5 flanges.

They are not considered a sealing product superior to spiral wound gaskets because they are not as resilient to thermal cycling. This is because the recovery of spiral wound gaskets is better for pipe flanges and CMG is not commonly used as a sealing product for these flanges.

Previous papers have stated that graphite seals can burst when thermally cycled, and there is no recovery. With helically wound gaskets, the graphite sealing element is packed between the windings and has a better chance of resealing the flange.

What is the best use of CMG?

We see CMG and kammprofile gaskets in some expansion joints in heat exchangers and petrochemical applications. CMG is suitable for heat exchangers and expansion joints because of their good resistance to free radical shear and some compressibility and recovery.