Flexible graphite sealing products – GRA-FLEX
The material
It can be seen as a paradox that graphite, a very soft and pliant substance, is formed of the same element – carbon – which produces the diamond, the hardest material known in nature. The difference between the two materials is all in their crystalline structure: while diamond shows a tetrahedral crystal lattice (sp3 hybridisation) symmetric in the three directions, graphite’s structure is hexagonal (sp2 hybridisation), with carbon atoms tightly bonded within the planes and loosely bonded between the planes. Such an asymmetry is the cause of the peculiar anisotropy found in the mechanical, thermal and electrical properties of the graphite, as well as of its inherent lubricity.
Thermo-mechanic strength: this characteristic leads to excellent retention of the gasket stress, even at very high temperature and in presence of thermal and dynamic cycles and shocks. Because the gasket creep is so low, bolt re-tightening is no longer necessary.
Chemical resistance: GRA-FLEX is resistant to most media, including steam, hydrocarbons and most acids. Exceptions are strong oxidizing fluids
Temperature stability: since the material elasticity is due to its own physical structure and not to elastomeric components, this remains suitable from cryogenic (-200°C) to extremely high temperatures (+3000°C in inert or reducing atmosphere)
Conformability: GRA-FLEX good conformability allows its use with practically any type of flange, including light, very large size, irregular and poorly planar flanges, without the need of high gasket thickness.
No ageing: GRA-FLEX does not lose its resiliency with time, either in storage or in service, even if exposed at high temperature. GRA-FLEX gaskets are thus recommended for joints that may relax over time.
Fire resistance: being free of organic components, GRA-FLEX gaskets are ideal for applications where the seal must be retained during and after a fire, such as with toxic or flammable media.
Health safety: GRA-FLEX does not contain toxic or polluting components, not any type of fibres, and is compatible with any environment.
