DIN 3570 Galvanized Rubber Coated U Bolt Insulating Rubber Lined U Bolt

Description

What is a Rubber Coated U Bolt?

A Rubber Coated U Bolt is a specialized fastening component that combines the structural strength of a traditional U-shaped bolt with the protective and insulating benefits of a rubber coating. These U-bolts feature a thick layer of rubber or elastomer molded over the metal, providing vibration dampening, corrosion resistance, electrical insulation, and surface protection.

The U-bolt design consists of a curved “U” section with threaded arms that secure objects using nuts. The rubber coating enhances functionality in environments where metal-on-metal contact must be avoided, or where shock absorption and noise reduction are required. These bolts are widely used in automotive, marine, construction, and industrial applications where both clamping force and material protection are essential.

Materials

Rubber coated U bolts are constructed from two primary components: the metal core and the rubber coating.

Metal Core Materials:

• Carbon Steel (Grade 4.8, 8.8, or 10.9): Provides high tensile strength for heavy-duty applications.

• Stainless Steel (304 or 316): Offers superior corrosion resistance for marine and chemical environments.

• Galvanized Steel: Zinc-coated for rust prevention in outdoor applications.

Rubber Coating Materials:

• Natural Rubber (NR): Excellent flexibility and vibration absorption but less resistant to oils and chemicals.

• Neoprene (CR): Good resistance to oils, weather, and moderate temperatures.

• EPDM (Ethylene Propylene Diene Monomer): Superior UV, ozone, and weather resistance, ideal for outdoor use.

• Nitrile Rubber (NBR): Oil and fuel-resistant, commonly used in automotive applications.

• Silicone Rubber: High-temperature resistance (up to 230°C/450°F), used in extreme environments.

Surface Finishes

The rubber coating itself acts as a protective layer, but the underlying metal may have additional treatments:

• Hot-Dip Galvanizing: For carbon steel U-bolts in corrosive environments.

• Electro-Galvanizing: A thinner zinc coating for moderate corrosion resistance.

• Passivation (Stainless Steel): Enhances corrosion resistance without affecting rubber adhesion.

• Powder Coating (Under Rubber): Sometimes used for extra durability before rubber molding.

Specifications

Rubber coated U bolts come in various sizes and configurations to suit different clamping needs:

• Diameter (Thread Size): Ranges from M6 to M24 (or 1/4″ to 1″ in imperial sizes).

• Leg Length: Typically 50mm to 300mm, depending on application.

• Inside Width (U-Span): Adjustable from 20mm to 150mm to fit pipes, tubes, or mounting brackets.

• Rubber Thickness: Usually 2mm to 5mm, depending on insulation and cushioning requirements.

• Thread Type: Fully or partially threaded, with coarse or fine threads.

• Temperature Range: Varies by rubber type (e.g., EPDM: -40°C to 120°C, Silicone: -60°C to 230°C).

Applications

Rubber coated U bolts are used in industries where vibration dampening, electrical isolation, or surface protection is critical:

• Automotive & Trucks: Securing exhaust systems, shock absorbers, and fuel lines while reducing noise and vibration.

• Marine & Offshore: Mounting pipes and equipment on boats, preventing galvanic corrosion.

• Construction & HVAC: Fastening pipes, ducts, and structural elements without metal abrasion.

• Electrical & Telecom: Isolating cable trays and conduits to prevent short circuits.

• Railway & Transportation: Absorbing shocks in rail fastening systems.

• Industrial Machinery: Reducing vibration in pumps, motors, and conveyor systems.

Excellent Case: Vibration-Free Exhaust System Mounting in Heavy-Duty Trucks

Challenge:

A truck manufacturer faced persistent complaints about excessive noise and vibration in the exhaust system. Traditional metal U-bolts transmitted engine vibrations into the cabin, causing discomfort for drivers and premature fatigue in exhaust components.

Solution:

The company switched to EPDM rubber coated U bolts with a high-strength carbon steel core. The thick rubber layer acted as a vibration isolator while maintaining a secure grip on the exhaust pipes.

Outcome:

• Noise Reduction: Cabin noise decreased by 30%, improving driver comfort.

• Vibration Dampening: Reduced stress on exhaust welds and joints, extending system lifespan.

• Corrosion Resistance: The EPDM coating protected against road salt and moisture, preventing rust.

• Easy Installation: The U-bolts were installed using standard wrenches, requiring no special tools.

• Cost Savings: Fewer warranty claims due to broken exhaust mounts.

This application highlights how rubber-coated U-bolts solve multiple engineering challenges—combining structural integrity with noise and vibration control in demanding environments.

Conclusion

Rubber coated U bolts offer a unique combination of strength, protection, and vibration isolation, making them indispensable in automotive, marine, and industrial applications. By selecting the right metal core and rubber compound, engineers can ensure long-lasting performance in harsh conditions. Whether silencing a truck’s exhaust or preventing corrosion on a ship’s piping, these specialized fasteners deliver reliability where conventional bolts fall short.