Flask Seals

Industry Specific Flask Seals – FKM, PTFE, EPDM, Silicone

For over 50 years M Barnwell Services has supplied  Seals to the world’s leading Nuclear, Pharmaceutical, Energy, Aerospace & Defence and Petrochemical companies. As the UK’s largest independent stockist and distributor of fluid seals our customers can be confident that they receive the correct product for their application.

Flask Seals are used across several industries and applications where airtight, chemical-resistant, or thermal-stability are critical. In circumstances where the transportation of radioactive or nuclear materials is necessary, Flask Seals provide the perfect solution to transporting these safely and securely.

Industries

• Pharmaceutical – O-Rings & Gaskets (often Silicone or PTFE)
• Chemical – Viton™, Kalrez®, or PTFE seals for chemical compatibility.
• Petrochemical – Viton™, Kalrez®, or PTFE seals for chemical compatibility.
• Aerospace & Defence – (e.g. Viton™, FFKM)
• Food & Beverage – Food-grade silicone or EPDM stoppers.
• Energy – Chemically resistant elastomers, sometimes multilayer seals.

Flask seals are used in the nuclear industry, particularly in the handling, storage, and transport of radioactive materials. In this context, the term “flask” usually refers to shielded containers or transport flasks designed to safely contain nuclear materials like spent fuel, radioactive isotopes, or waste.

Key Uses of Flask Seals in the Nuclear Industry:

1. Transport Flasks for Spent Nuclear Fuel

• These flasks are large, heavily shielded containers.

• Seals (Gaskets or O-rings) ensure airtight and radiation-tight closure to prevent the escape of radioactive gases or particles.

• Seals must withstand:

  • Radiation exposure

  • Extreme temperatures

  • Mechanical stress

  • Chemical exposure (e.g., from coolant or decontamination fluids)

2. Hot Cells and Shielded Transfer Systems

• Smaller flasks and transfer casks use seals to maintain containment during remote handling of radioactive materials.

3. Waste Storage Containers

• Long-term waste storage uses flanged metal drums or vitrified waste flasks with high-integrity seals.

• Some systems use double O-ring seals with leak detection between them.

Seal Material Requirements in Nuclear Applications:

• Radiation resistance: Must not degrade under gamma or neutron radiation.

• Thermal stability: Some nuclear processes involve high or fluctuating temperatures.

• Chemical compatibility: Must resist nuclear-grade acids, coolants, or cleaning agents.

• Long-term integrity: Especially for dry cask storage, seals must last decades.

Common compounds:

• Viton™ 75 Shore A

• Viton™ GLT 75 Shore A

• EPDM 75 Shore A

• Silicone 60 Shore A

E & OE. M Barnwell Services endeavours to make sure all the content is correct. Information has been gained from manufacturing partners.

Viton™ is a trademark of The Chemours Company FC, LLC. M Barnwell Services does not manufacture Viton™ products. There are many grades of DuPont® Viton™ that we have available such as Viton™, Viton™ A, Viton™ B, Viton™ GF, Viton™ GLT, Viton™ GFLT, Viton™ ETP. Common colours include Black, Brown and Green in a variety of shore hardness.