Bonded seals

Bonded seal, also known as BS connection seal, hydraulic seal ring, or washer, is a steel ring with a vulcanized elastomer lip (NBR, HNBR, FKM, or EPDM). The Bonded seal ring provides an effective sealing solution for: under pressure, vibration, in rather extreme temperature use.

Techné's Bonded seal conform to ISO 4042 for coating.

Applications of Bonded seal rings are diverse: they can be used for sealing fittings, screws, or threaded plugs. Due to their robust structure, Bonded seals can also replace copper gaskets as they can withstand higher pressures. Bonded seals can be used in other assemblies subjected to high pressures which require perfect sealing.

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The Bonded seal consists of two parts: an outer metal part and an inner elastomer lip.

The metal part of a Bonded seal is chosen based on the pressure and oxidation attacks it will endure. Tensile tests are conducted to characterize its pressure resistance. Techné provides the metal part in the following steels:

  • DC01-270 steel with Zn coating
  • DC01-590 steel with ZnNi coating
  • AISI 304 stainless steel with Zn coating
  • AISI 216 stainless steel with ZnNi coating
  • AISI 316 L stainless steel with passivation
  • Other steel grades available upon request

Depending on the fluid to be sealed, the pressure to be withstood, and the environment the Bonded seal is aimed at, Techné offers different elastomer materials:

  • NBR 80±5 IRHD
  • HNBR 80±5 IRHD
  • FKM 80±5 IRHD
  • EPDM 80±5 IRHD

Upon request, other hardness options can be provided: 70, 85, and 90 IRHD.

Main applications

The TBS seal is the most common and adapts to all types of fittings and threads: AS, ISO, metric, and inch. The standard Techné TBS ring is offered in NBR or FKM 80±5 IRHD with a DC01-270 steel ring. Other materials are available upon request (metal or elastomer).


The self-centered TBS seal (SCR = self-centered) is similar to the TBS. It features an elastomer inner ring that allows it to center on the thread. For vertical installations, the BS ring is appreciated for its leak tightness. Techné offers the self-centered TBS ring in NBR or FKM 80±5 IRHD with a DC01-270 steel ring. Other hardnesses or materials are available upon request (metal or elastomer).


The KDS seal is composed of a steel ring treated for high-pressure resistance and an adhered elastomer lip. The shape of the metal part provides not only chemical but also mechanical adhesion to the elastomer. Its L-shaped outer form allows the KDS ring to be mounted in Banjo fittings.


The TGM 1000 seal has a similar design to the TBS seal and differs in its better pressure resistance.

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