Combination Sealing Washers for Hydraulic Systems – Structure, Features and Industrial Applications

Combination Sealing Washers: Structure, Sealing Performance, and Industrial Applications

What Is a Combination Sealing Washer?

A combination sealing washer, also known as a bonded sealing washer, is a composite sealing component consisting of a metal washer and an elastomer sealing ring bonded together through vulcanization.

This design combines the mechanical strength of metal with the sealing flexibility of rubber, creating a highly reliable sealing solution for threaded connections and hydraulic systems.

The washer structure typically includes:

• Metal support ring – provides      structural strength and pressure resistance

• Elastomer sealing ring – ensures      leak-proof sealing under compression

Combination sealing washers are widely used in hydraulic fittings, screw plugs, and threaded pipe connections where static sealing is required.

Common structural forms include:

• Metal + Rubber composite washer (most common type)

• Metal–Metal composite washer

• Non-metal composite washer

However, in industrial hydraulic applications, the metal-and-rubber-bonded washer is the standard configuration.

Key Features of Combination Sealing Washers

High Sealing Reliability

The rubber sealing element compresses against the mating surface, creating an effective leak-tight seal for fluids and gases.

High Pressure Resistance

The metal ring supports the rubber element and allows the washer to operate under pressures up to approximately 40 MPa, making it suitable for demanding hydraulic environments.

Excellent Temperature Resistance

Depending on the rubber material, combination washers can withstand wide temperature ranges.

Typical material performance:

Nitrile Rubber (NBR)
Operating temperature: -20°C to 100°C
Limit temperature: -40°C to 120°C

Fluoroelastomer (FKM / Viton)
Operating temperature: -20°C to 220°C
Limit temperature: -40°C to 240°C

Simple Installation Without Sealing Grooves

Unlike many sealing solutions, bonded washers do not require a dedicated sealing groove, simplifying assembly and reducing manufacturing complexity.

Wide Chemical Compatibility

Combination sealing washers can be used with:

• hydraulic oil

• fuel

• water

• lubricants

• chemical fluids

• gas media

Typical Materials

Combination sealing washers are manufactured using different material combinations depending on the application environment.

Metal Rings

• Carbon Steel

• Stainless Steel 304 (A2)

• Stainless Steel 316 (A4)

Rubber Sealing Elements

• Nitrile Rubber (NBR)

• Fluoroelastomer (FKM / Viton)

These materials provide excellent resistance to oil, corrosion, pressure, and temperature variations.

Standard Sizes and Specifications

Combination sealing washers are available in metric and imperial sizes, making them compatible with global industrial standards.

Common standards include:

• JB982-77 bonded sealing washer standard

• Metric threaded systems

• Inch thread standards used in US and UK hydraulic fittings

They are typically used with:

• hydraulic pipe fittings

• ferrule fittings

• screw plugs

• threaded pipe joints

Installation Guidelines

Proper installation is essential to ensure optimal sealing performance.

Recommended installation practices include:

Clean the sealing surfaces
Ensure both the mating surfaces and the washer are free from oil, dust, or debris.

Apply an even tightening force.
Bolts or plugs should be tightened evenly to ensure uniform compression of the rubber sealing ring.

Check surface roughness
Recommended sealing surface roughness is typically Ra 3.2 – Ra 6.4.

Avoid deformation during storage.
Washers should be stored flat and protected from mechanical damage.

Advantages of Combination Sealing Washers

Compared with traditional single-material gaskets, combination sealing washers offer several advantages.

Improved Sealing Performance

The elastomer ring provides flexible sealing while the metal washer maintains structural integrity.

Longer Service Life

The composite structure distributes load and reduces wear on the sealing surface.

High Pressure and Temperature Capability

Suitable for demanding environments such as hydraulic and fuel systems.

Cost-Effective Sealing Solution

Simple structure and easy installation make bonded washers a highly economical sealing component.

Industrial Applications and Engineering Solutions

Combination sealing washers are widely used in industrial sectors that require reliable fluid sealing in threaded connections.

Hydraulic Systems

Used for sealing:

• hydraulic pipe fittings

• valve connections

• oil ports

• hydraulic plugs

They prevent leakage in high-pressure hydraulic circuits.

Automotive Industry

In automotive systems, bonded washers are commonly used for:

• engine oil system sealing

• brake hydraulic connections

• fuel line sealing

• transmission systems

They ensure leak-free performance under vibration and pressure fluctuations.

Oil and Gas Equipment

Combination sealing washers are used in:

• pipeline connections

• pump systems

• oil distribution equipment

Their resistance to oil, fuel, and chemicals makes them ideal for this industry.

Industrial Machinery Manufacturing

They are widely used in:

• heavy machinery

• industrial equipment

• hydraulic power units

• automation machinery

Their simple installation and high sealing reliability make them a preferred sealing solution in mechanical systems.

Why Choose High-Quality Combination Sealing Washers?

High-quality bonded sealing washers provide:

• stable sealing performance

• resistance to high pressure and temperature

• compatibility with global thread standards

• long service life in industrial environments

Selecting the correct material, size, and sealing design is essential for achieving optimal sealing performance in hydraulic and fluid systems.

 If you are looking for high-quality sealing washers, spring washers, or custom fastener solutions, our engineering team can provide professional technical support.

Website: https://www.juxinfasteners.com