Flexitallic Offers Vermiculite as a High-Temperature, Oxidation-Free Gasketing Material

A problem with high-temperature (above 1,000°F) gasketing applications is that the gasket eventually loses its integrity. Graphite, which is often used in such applications, degrades, and can do so very rapidly in the presence of oxygen. Now, Flexitallic LP (Houston, TX) is proposing the use of the high-tech version of a common mineral-vermiculite-as an alternative. The company says that its gaskets are rated to 1,600°F. The inorganic nature of the material makes it immune to oxidation, and the gasket retains its sealing ability even at 2,900 psi.

Pablo Rodriguez, U.S. product manager, says that the product, brandnamed Thermiculite, is the result of eight years of research at Flexitallic. The company sought to simulate exfoliated graphite (exfoliation is the process of chemical and physical treatment to create a layered, expanded structure) but without the oxidation problem of that material. It found that vermiculite, a metal oxide mineral commonly used for insulation and for soil conditioning, could be exfoliated in a structure similar to graphite (see figure). Thermiculite has been tested in laboratories for sealability, low porosity and stability against thermal oxidation, and in field installations at a nuclear power plant and at a turbine-to-boiler flange at an oil refinery.

Flexitallic is using this type of Vermiculite in its new Thermiculite sheet gasket.

The material is being sold as 40×40-in., or 60×60-in., sheets, in thicknesses of 0.03125 to 0.125 in. Flexitallic will also provide precut rings or other shapes for standard gasketing applications. Rodriguez says that the material is "somewhat more expensive" than graphite.

By Nick Basta

For more information: Flexitallic L.P., 6915 Highway 225, Houston, TX 77536. Tel: 713-356-3600; Fax: 713-356-3601.