Detailed design and manufacture

AFT Fluorotec is a registered and approved processor of VICTREX PEEK materials. We can design and manufacture an almost limitless range of VICTREX PEEK back up rings (BUR’s) as well as PTFE rings. 

We can manufacture to customer drawings/specifications and design back up rings to suit your specific applications. Many materials can be used but primarily VICTREX® PEEK is used in back up rings.



We use VICTREX® PEEK due to its temperature, creep, chemical and fatigue resistance combined with its compressive strength and thermal stability.

Find out more about the properties of Victrex PEEK
What is Victrex PEEK?


The benefits of backup Rings

Backup rings provide additional extrusion resistance and prevent damage to O-Rings and seals. Back up rings can be used in all applications but primarily are added when higher pressures or pressure spikes, higher temperatures and/or larger extrusion gaps form part of the operating conditions. Higher temperatures generally lower a seals extrusion resistance. Installing a PEEK back up ring can normally combat this.

Back up rings are not seals themselves, but are used in conjunction with O-rings or other seals in high-pressure applications. Back up rings are installed in the downstream side of the gland, however can be installed either side of the O-ring to give a high performance double acting seal.

Plain PEEK back up rings

  • Flat-faced rectangular section rings similar to washers
  • These are dimensioned to neatly fit the radial cross section of the seal groove
  • Length (thickness) can be to BS or ASTM standards or specified to suit any application
  • Can be supplied as solid rings or with a scarf cut to allow easy installation in closed grooves

Contoured PEEK back up rings

  • A step up in performance over plain PEEK back up rings
  • Designed with a concave or contoured face on one side and a flat face on the other
  • The contoured face has a greater contact area with the O-Ring and provides better grip and support than a standard flat option.
  • Length (thickness) can be to BS or ASTM standards or specified to suit any application
  • Can be supplied as solid rings or with a scarf cut to allow easy installation into closed grooves

Positively actuated back up rings

  • Automatically forced (actuated) by the system pressure both axially and radially to blank the extrusion gap
  • Can be integrated into a seal design or they can be specially shaped individual items
  • Often in the form of two individual rings, which work against each other to completely eliminate any gap
  • Can be supplied as a solid rings or with a scarf cut to allow installation into closed grooves

Back up ring - Material Selection

Whilst Virgin PEEK is the mainstay of backup ring materials, other materials can be used. For example Acetal may be used in applications which are high pressure but do not require the chemical or temperature resistance of VICTREX PEEK

Virgin PTFE or Glass filled PTFE may be used where medium pressure and chemical resistance form the criteria but temperature is not an issue. At the other end of the scale, filled VICTREX PEEK materials such as Glass filled VICTREX PEEK or Carbon Filled VICTREX PEEK may be used to offer increased compressive strength and extrusion resistance over Virgin PEEK.

VICTREX PEEK is inert to all common solvents and resists a wide range of organic and inorganic liquids. VICTREX PEEK has a maximum continuous working temperature of 260°C and retains its mechanical properties up to 300°C in steam or high pressure applications. 

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