PTFE enveloped clamp seals

PTFE enveloped clamp seals are clamp seals consisting of a PTFE outer envelope and an elastomer core.

The advantage of the PTFE enveloped clamp seals is its PTFE envelope which provides almost universal chemical resistance.

The elastomer core provides elasticity and a good seal over time.

As for the clamp seal, the dimensions of the PTFE enveloped clamp seals are defined by different standards depending on the country and the use:

  • Clamp seal according to DIN 32676
  • Clamp seal according to ISO 1127
  • Clamp seal according to SMS ISO 2852
  • Clamp seal according to BS OD/BS4825-3
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Four profiles for PTFE enveloped clamp seals are available:

  • Clamp seal type A (flanged)
  • Clamp seal type B (not flanged)
  • Mini clamp seal
  • Micro clamp seal

The PTFE enveloped micro clamp profile or PTFE enveloped µ clamp is only for ferrules with an external diameter of 25 mm.

For a ferrule with an outer diameter of 34 mm, the clamp is called PTFE enveloped micro clamp.

For a ferrule outer diameter from 50.5 mm on, the name of the seal is PTFE enveloped clamp seal. (type A or B).


With improved chemical resistance over clamp seals, PTFE enveloped clamp seals provide a tight seal in the connection of production piping in areas such as:

  • Food and beverage
  • Chemical industry
  • Medical sector
  • Pharmaceutical sector

The fitting consists of two ferrules, a collar or a clamp for assembly and a PTFE enveloped seal for clamp fitting. This structure ensures a simple and fast disassembly and reassembly.

Materials and approvals

The PTFE enveloped clamp seals consist of a PTFE envelope and a 1mm thick elastomer core with a hardness of 60 Shore A.

The PTFE enveloped clamp seal is FDA, CE 1935/2004, USP VI, 3A, W270, WRAS and EU 2023/2006 approved.

Techné offers PTFE enveloped clamps seals in PTFE/EPDM, PTFE/FKM, PTFE/MVQ.

As the elastomer core is not in contact with the product, Techné has chosen to offer an FDA-certified elastomer core only.