Gaskets and Sheet Jointings

Fluolion Envelope Gaskets

A resilient material encased in a thin cover of PTFE. The resulting gasket combines the inertness of virgin PTFE with the mechanical properties of the insert material.

Fluolion Envelope Gaskets

James Walker supplies three envelope designs...

  • Fin Type
  • Machined Square Type
  • Folded Tape Type

Typical applications
Flanged joints handling highly aggressive fluid media that would otherwise swiftly destroy the integrity of other materials. Often used with soft insert material on glass-lined pipework systems. Also used in food processing, where cleanliness and non-contamination are essential.

Fin Type

  • Standard design: most economical envelope gasket.
  • Suits majority of applications where highly abrasive madia are not used and turbulent flow will not create problems.
  • Needs clearance between insert and envelope inside diameter to enable insert to be fitted.

Machined Square Type

  • Provides continuity with pipeline bore for smooth flow.
  • Recommended where flange sealing width is restricted or thick inserts are used.
  • Supplied with serrated surface.

Folded Tape Type

  • Has smooth surface finish - tape of PTFE is folded and joined by welding.
  • Used for diameters over 300 mm.
  • Can be adapted to non-circular planforms.


  • Covers: virgin Fluolion PTFE. 
  • Inserts: compressed non-asbestos fibre, synthetic rubber-proofed woven cloth, and lamninated combinations of these.

Service capability
Maximum temperature: typically +260°C for PTFE envelope, but also dependent on filler material.

How it is supplied
Custom made to suit all standard flanges and and non-standard shapes.

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