Aerospace & Defence

Fluid sealing products for the Aerospace and Defence industry

M. Barnwell Services supplies critical seals for use in both Aerospace and Defence. All products meet the standards required for these industries.

We are continuously researching, designing, enhancing and distributing a diverse range of parts that are critical to the NATO (stock numbers NSN), NES 337 (Naval Standard) UK Ministry of Defence (MOD), AS9100 Rev.C, AMS, EN, NFL and DEF STAN specifications. Bespoke O Rings and special mouldings can be produced to meet the specific requirements of your application.

More certifications and standards include EN9100: Quality management in aviation, ISO 2685 and AC20-135: Fire protection aviation, Nadcap, REACH and RoHS: Environmental protection, and ITAR Capabilities.

Challenges for the Aerospace & Defence Industry

The Aerospace and Defence Industry presents some of the most demanding challenges for sealing technology due to extreme operating environments and conditions and the the critical nature of applications.

Extreme Environment

Seals in this industry must perform reliably under conditions that rapidly cycle between extreme:
- Temperature – Seals must maintain integrity in high altitude (as low as $- 26 8^{\circ} C$ / $- 45 0^{\circ} F) to jet fuel heat (over 300^{\circ} C / 572^{\circ} F)$
- Pressure – Hydraulic systems for landing gear and flight control operate at extremely high pressures, often over 5000psi. Seals must be designed to prevent extrusion without generating excess friction
- Motion – These seals are often subjected to constant, high-frequency vibration and high-speed reciprocating/rotary motion. This can lead to accelerated wear and friction

Operational/Design Requirements

Due to the need to maximise fuel efficiency, every component in an aircraft/spacecraft must be as lightweight as possible
A critical issue is to ensure there is zero leakage of oil. This failure can cause cabin depressurisation which is a major health and safety concern.
High friction in dynamic seals wastes energy, generates heat that degrades the seal and causes rapid wear. Seals designed with low-friction materials, such as PTFE, extend operational life
Hermetic Seals seals are used to provide an airtight, gas-tight seal to prevent moisture and contaminants from damaging highly sensitive electronic systems

Safety, Regulation and Maintenance Concerns

All seals used in Aerospace and Defence applications must meet extremely strict industry standards and military specifications for fire resistance, material properties and performance
Elastomeric seals are susceptible to embrittlement and loss of resilience if they are stored improperly or used beyond their shelf life.

These challenges are being combated by focusing on innovative seal designs and latest manufacturing techniques to ensure reliability under increasingly extreme operating conditions.

Using the newest and most advanced materials, looking beyond traditional sealing solutions and continuously researching the latest in industry advancements allows for sealing technology to be continuously developed and refined.

Aerospace and Defence materials

Bonded Seals

Bonded seals (also known as Dowty seals) or washers, are used in the Aerospace & Defence Industry to create a reliable, leak-proof seal between two surfaces, typically in hydraulic or pneumatic systems. They are designed to prevent fluid or gas leakage in high-pressure environments which is critical in this industry, where safety and performance are principle.

Bonded seals/Sealing washers are used to seal joints in hydraulic systems that operate under high pressure, ensuring there are no fluid leaks, as well as preventing leaks in fuel lines and connections. The pressure they are able to withstand is dependant on the size and material chosen. Temperatures range from -30°C to 100°C for NBR Rubber seals and -15°C to +200°C in the case of FKM seals.

Further information on Specialist Products

NATO Stock Numbers List – Oil Seals
NATO Stock Numbers List – O Rings

Sealing Washers – British Imperial Standard range
Sealing Washers – German Metric Standard range
Sealing washers – French Metric range

Find out more about our specialist range of Aerospace Compliance Seals.

Popular products supplied include:

Packaging, industry standard and bespoke solutions are offered.

When it comes to quality fluid sealing products we are one of the most reliable sources in the industry.

We can also provide onsite consultation, sample identification and technical support for your requirements.