What is a Dowty Bonded Seal?
Dowty bonded seals (also known as bonded washers) are high-performance sealing components designed to provide a reliable, leak-proof seal around bolts and threaded connections. Widely used in hydraulic, pneumatic and fluid systems, these seals combine the strength of a metal washer with the sealing performance of an elastomeric inner ring. This dual construction ensures excellent resistance to pressure, vibration and fluid leakage.
What is a Dowty Bonded Seal?
A Dowty bonded seal is a metal washer with an integrated rubber sealing element, designed to seal around bolts, screws or fittings.
- Outer ring: metal (typically steel or stainless steel)
- Inner ring: elastomer (e.g. nitrile rubber)
When compressed, the rubber element forms a tight seal between surfaces, preventing fluid leakage even under high pressure. Bonded seals are commonly used in hydraulic systems due to their ability to withstand pressures of up to 10,000 PSI in some applications
Key Features of Dowty Seals
- Provides a leak-proof seal for bolts and threaded fittings
- Suitable for high-pressure hydraulic systems
- Combines metal strength with rubber sealing performance
- Resistant to oil, fuel, water and hydraulic fluids
- Easy to install with no special machining required
- Available in standard and self-centring designs
Types of Bonded Seals
Standard Bonded Seals
Designed for general sealing applications where alignment is controlled by the assembly.
Self-Centring (Self-Locating) Seals
Feature an additional lip to ensure accurate positioning during installation, improving sealing reliability.
Materials & Specifications
Dowty bonded seals are available in a range of material combinations:
Metal Options
- Carbon steel
- Stainless steel
- Zinc-plated steel
Elastomer Options
- Nitrile (NBR) – general-purpose oil and fuel resistance
- Viton (FKM) – high temperature and chemical resistance
- EPDM – water and weather resistance
- Silicone – extreme temperature flexibility
Available in BSP, metric and custom sizes, with options for bespoke designs to suit specific applications.
Applications of Dowty Bonded Seals
Hydraulic Systems
- Pumps and valves
- Hydraulic cylinders
- Fluid power equipment
Automotive & Engineering
- Fuel systems
- Oil systems
- Brake and transmission components
Industrial Equipment
- Machinery and plant equipment
- Pipe fittings and connectors
- High-pressure assemblies
Bonded seals are widely used across industries because they provide a simple and effective sealing solution without the need for complex groove designs.
Why Choose Dowty Seals Over Standard Washers?
Compared to standard washers or O-rings, Dowty seals offer:
- Improved sealing under pressure
- Reduced risk of leakage and failure
- Easier installation and maintenance
- Better performance in dynamic and high-pressure environments
They are a proven solution for critical sealing applications where reliability is essential.
FAQs About Dowty Bonded Seals
1. What is a Dowty seal used for?
A Dowty seal is used to create a leak-proof seal around bolts and threaded connections, commonly in hydraulic and fluid systems.
2. What is the difference between a bonded seal and a washer?
A bonded seal includes a rubber sealing element bonded to a metal washer, providing sealing capability, whereas a standard washer only distributes load.
3. What pressures can Dowty seals handle?
Dowty bonded seals can handle very high pressures, with some designs suitable for up to 10,000 PSI depending on materials and application.
4. Are Dowty seals reusable?
They can be reused if undamaged, but for critical applications it is recommended to replace them to ensure sealing performance.
5.What materials are Dowty seals made from?
They are made from a metal outer ring (steel or stainless steel) with a bonded elastomer inner ring such as nitrile, Viton or EPDM.
For more information or to discuss your Bonded Seals requirements please contact our Technical Department via email or call 01226 273700.