Static seals

Frequently asked questions — Static Seals

• How do I choose between NBR, FKM and EPDM for an industrial application?

  Material selection depends on chemical compatibility with the fluid and the service temperature. NBR nitrile is suited to mineral oils and fuels between -30 and +100 °C. FKM Viton is required for resistance to aromatic hydrocarbons up to 200 °C, while EPDM is specifically recommended for hot water, steam or glycol brake fluids.
• What is the technical difference between the ISO 3601 and AS 568 standards for O-rings?

  The distinction lies in the measurement system used for the dimensions. The ISO 3601 standard defines the G and BS series in metric standard, based on the dimensions of grooves and bosses. Conversely, the AS 568 standard, identified by series ranging from 001 to 481, uses dimensions expressed in inches.
• When is it preferable to use a quad-ring seal rather than a conventional O-ring?

  The quad-ring, or X-ring, has an X-shaped cross-section that generates two sealing lines per face. This configuration is advantageous for reducing friction and increasing torsion resistance compared with a standard O-ring. Although it is preferred for certain dynamic applications, it can replace the O-ring when these technical characteristics are required for system integrity.
• Which solution should be preferred to ensure sealing under a screw head without machining a groove?

  The bonded seal, also known as a USIT washer, is the suitable solution for this configuration. This device combines a metal ring with an integrated O-ring type sealing element. This design allows sealing under a screw head or nut without requiring a dedicated housing to be machined during mechanical design.
• Which flat gasket materials are recommended for high-temperature steam conditions?

  For applications involving extreme pressures or high temperatures such as steam, material selection is decisive for sealing industrial flanges. Expanded graphite gaskets should be used, as they are specifically designed for these thermal conditions. For extreme pressures, metal-reinforced composite gaskets are also recommended within the range of cut flat gaskets.