EPDM Bonded Washers: Key Features, Benefits & Uses

What Are EPDM Bonded Washers?

EPDM bonded washers combine a metal washer with a layer of EPDM rubber permanently bonded to one side. This creates a versatile sealing solution that addresses multiple fastening challenges at once.

The metal component provides structural support and load distribution. The EPDM rubber creates a weatherproof seal that prevents water infiltration, reduces vibration, and protects against corrosion. Together, they deliver performance that neither material could achieve alone.

EPDM is an abbreviation for Ethylene Propylene Diene Monomer. It’s an artificial rubber compound with a superior resistance to UV rays, ozone, temperature extremes, and moisture. When bonded to a metal washer, the result is a heavy duty fastener that is supported in difficult outdoor and industrial environments.

Unlike other systems that require several parts such as metal washers, rubber gaskets, and lock washers, EPDM bonded washers combine the functions of these into one single component. This streamlines assembly, cuts costs, and enhances reliability.

Key Features of EPDM Bonded Washers

UV and Ozone Resistance

EPDM's most valuable property is its exceptional resistance to ultraviolet radiation and ozone exposure. Although many rubber configurations break down quickly when exposed to the light, EPDM can withstand years of UV radiation, making it ideal for outdoor applications.

This resistance is vital for outdoors application, such as roofing, outdoor equipment, and long-term installations in direct sunlight. The materials of natural rubber would crack and become ineffective in several months, while EPDM can last for many years.

The molecular structure of EPDM includes no bonds vulnerable to ozone attack. This allows fasteners to stay in place, even in high-ozone areas near electrical equipment or close to heavily polluted urban areas.

Temperature Resilience

EPDM rubber maintains stability across an extremely wide temperature range, typically from -40°F to 250°F (-40°C to 121°C). This in turn makes EPDM bonded washers perfect for severe weather and conditions with high temperature fluctuations.

The material stays flexible at low temperatures where other rubbers become brittle. This cold-temperature performance is crucial for outdoor installations in northern climates or refrigeration applications.

EPDM won't become brittle and crack while it's exposed to high temperatures. The repeated temperature change doesn’t produce seal failure as in traditional materials.

Chemical Resistance

EPDM has excellent chemical resistance to many acids and bases, as well as other chemicals through which other rubber materials would otherwise break down. It’s especially resistant to water, steam, alkalis, mild acids and polar substances like alcohols. This makes EPDM bonded washers ideal for plumbing, chemical processing equipment, and industrial machinery where chemical exposure is inevitable. The sealing properties remain stable even after prolonged contact with substances that would destroy other materials.

Abrasion Resistance

EPDM's durability includes excellent abrasion resistance, allowing bonded washers to withstand friction and mechanical wear during installation and service. It's useful in applications where vibration or movement would tend to cause wear.

During installation, the EPDM layer resists damage from tightening that might tear softer materials. In use, it prevents seal damage due to movement of the application or thermal expansion/contraction of the sealing material.

Conical Design

Most EPDM washers are conical and offer better seal properties over flat designs. This shape is what compacts around irregular or rough surface configurations to provide more effective seals.

As the fastener is turned, the cone shape groups itself into a tighter mass through its spring-like action and reseals. This construction guarantees optimum sealing even in cases where tightening torque is different between bolts.

Benefits of EPDM Bonded Washers

Reliable Sealing

The main advantage lies in better sealing performance under different conditions and applications. The compressible nature of EPDM, along with adequate compression make for excellent weather seals that block out water and remain unaffected by air and dirt.

The integrated design eliminates gasket misalignment or displacement risks during installation. The permanent bond ensures the sealing element stays properly positioned.

Enhanced Durability

The combination of metal support and EPDM environmental resistance creates exceptionally long-lasting fastening systems. Installations using EPDM bonded washers often outlast alternatives by years or decades.

Resistance to environmental degradation means seal properties remain stable rather than gradually deteriorating. The shock-absorbing properties reduce stress concentrations, extending substrate life and reducing fastener loosening risk.

Reduced maintenance requirements contribute to overall durability. Installations that don't need periodic seal replacement or re-tightening are less likely to experience problems.

Corrosion Resistance

Bonded EPDM washers offer superior corrosion protection for fasteners and the substrate material. The EPDM sheeting acts as a moisture block hider that stops water from penetrating the fastener threads and substrate.

This protection is valuable when using steel fasteners outdoors where galvanic corrosion might be problematic. The isolation can minimize the need for expensive corrosion resistant fastener materials.

Uses of EPDM Bonded Washers

Construction & Roofing

Metal roofing and siding installations represent one of the largest markets for EPDM bonded washers. The combination of weatherproofing, UV resistance, and durability makes them ideal for securing panels while preventing leaks at fastener penetrations.

The cone shape allows for a finished appearance, when installed with crowned profiles often associated with metal roofing. Weather-tight seals reduce the possibility of moisture from entering and are also useful in building envelope applications such as wall panels, fascia, and trim.

Automotive Industry

EPDM bonded sealing washers are used for automotive exterior trim, body panels, and underbody applications. It’s resistant to road chemicals, temperature extremes and vibration which are the major conditions of automotive.

Temperature resistance and for sealing against oil mist and coolant vapours in the engine compartment area. They are used by trailer and RV manufacturers for bonding exterior panels to reduce the need for rivets, screws, or snaps.

Plumbing & HVAC

Plumbing fixture mounting and pipe support applications benefit from water resistance and vibration damping. The washers prevent water infiltration at wall and floor penetrations while reducing noise.

HVAC equipment mounting requires vibration isolation and weather sealing. EPDM bonded washers answer to both of these needs and perform well against temperature changes. Outdoor equipment such as condensers need fasteners that deal with constant moisture and temperature cycles.

Electrical & Electronic

Electrical enclosure mounting relies on EPDM bonded washers to maintain weatherproof seals. The material's electrical insulating properties provide additional safety benefits.

They are very common in solar panel mountings due to their UV resistance and weatherproofing and long-lasting property. These plants are expected to run for 20-30 years without maintenance.

Industrial Machinery & Equipment

Heavy equipment uses EPDM bonded washers for mounting covers, guards, and access panels. They provide weather sealing while damping vibration that might cause fastener loosening.

Process equipment in chemical plants benefits from EPDM's chemical resistance and ability to maintain seals despite temperature variations. Agricultural equipment exposed to dust, moisture, and extreme temperatures requires durable fastening solutions.

Marine & Outdoor Applications

Marine equipment functions in harsh conditions including moisture, salt spray, and UV radiation. EPDM bonded washers provide excellent performance, especially when paired with stainless steel for maximum corrosion resistance.

Fasteners with durability for the everchanging weather and exposure in docking, recreation equipment, signs or insulation need an environmentally friendly and cost effective system.

Advantages Over Alternative Washers

Compared to standard metal washers with separate rubber gaskets, EPDM bonded washers eliminate installation complexity and reduce gasket displacement risk. The permanent bond ensures proper alignment and consistent performance.

Neoprene bonded washers do not provide the UV and ozone resistance that EPDM offers. For outdoor applications subject to UV variation, EPDM provides significantly longer service life.

Compared with plastic screws and nuts or acme nuts and bolts, EPDM bonded washers give you greater load bearing capacity combined with excellent sealing because of its integrally-formed metal core. This combination is desirable in structural applications where both strength and weather-proofing are desired.

Standard rubber washers without metal reinforcement lack the load distribution and structural support provided by bonded washers. The metal core prevents over-compression while ensuring proper load transfer.

Practical Tips for Using EPDM Bonded Washers

Choose the right washer size and metal thickness according to your needs. Washers that are too small cannot support the load, and washers that are too large may not seal properly on a curved surface.

Place washers EPDM side down against the substrate to form a weatherproof seal. If installed backward, the sealing function is removed and may damage the rubber.

Tighten in accordance with the materials and screws used. If it is over tightened then the EPDM or dimple layer can be damaged, but, if under tightened then insufficient seal compression may result.

When working with nuts and bolts metric or imperial measurements, ensure dimensional compatibility between washer bore and fastener diameter. Mismatched sizes compromise both sealing and structural performance.

Keep EPDM bonded washers in a cool, dry area and out of sunlight until ready to be used. Although EPDM is environment resistant, the properties can be affected by correct storage.

For critical applications, consider stainless steel washers with EPDM bonding for maximum corrosion resistance. This combination provides the longest service life in marine or highly corrosive environments.

Conclusion

EPDM bonded washers represent an engineered solution that addresses multiple fastening challenges through intelligent material selection and integrated design. The combination of metal structural support and EPDM environmental resistance creates a versatile component suitable for demanding applications across numerous industries.

With excellent characteristics of resistance to UV, temperature, chemical and weathering, EPDM rubber is the best choice for outdoor construction, automotive products, and industrial equipment where long-term performance is needed.

Knowing how properly selected and installed inserts perform enables the full value of these application-specific fasteners to be achieved. When replacing traditional mechanical fasteners or as an integral part of new designs, you owe it to yourself and your customers to consider EPDM bonded washers in all applications where the sealing, vibration dampening or corrosion resistance is a critical factor. If you have any other questions or need help, contact our Nutty nuts team today for more information.