Back-up rings are used with static, as well dynamic applications. However, they have no sealing function.
Extrusion of O-rings or X-Rings under the influence of pressure should be avoided with the back-up ring.
Manufacture of back-up rings in various materials is possible.

Special Features:
  • Simple groove geometry
  • Easy assembly
  • Multitude of materials of construction
  • Individual sizes possible
  • Bridging of large sealing gaps
  • High areas of temperature
  • Neutral to fluctuations in temperature


We recommend the use of back-up rings for one or more of the following conditions in service: pressure over 5 MPa (50 bar)

  • Larger sealing splits
  • Higher stroke frequency
  • High temperature fluctuations
  • Pulsating pressures
  • STR (recommended assembly / mounting sizes for O-rings)
  • Back-up rings of the STR series are produced from special polyurethane elastomer through a
    special process. The material - hardness 95 shore A - has excellent extrusion resistance.
    It is, however, possible to use endlessly manufactured back-up rings for external
    sealing applications due to their
    memory effect. These back-up rings are meant for automatic assembly. Special
    anti-ageing additives in the material are also effective in dry air and oil.

AF-100, 110, 120, 140 and AF-150

Rings of this series are produced by turning, and we recommend specific explanations according to specific applications ( see below) 

Part Design Application
STR endless internal/external sealing static
AF-120 endless internal/external sealing dynamic
STR slotted internal/external sealing static
AF-110 slotted internal/external sealing dynamic
AF-110 slotted internal/external sealing static
AF-100 spiral internal/external sealing static
AF-100 spiral internal/external sealing dynamic
AF-140 concave (endless) internal/external sealing static
AF-140 concave (endless) internal/external sealing dynamic
AF-150 concave (slotted) internal/external sealing static
AF-150 concave (slotted) internal/external sealing dynamic
Material overview for back up rings:
  • AF-1012 - Virgin PTFE 
  • AF-1022 - PTFE with additive
  • AF-2426 - PTFE with carbon
  • AF-4125 - PTFE with glassfiber
  • AF-5640 - PTFE with bronze/additive