Metal-rubber washers

Efficient sealing of industrial fasteners

What are metal-rubber washers?

The metal-rubber washers are sealing elements designed to guarantee the tightness of threaded joints, especially in industrial applications where a reliable mechanical fastening and, at the same time, a barrier against fluids or contamination is required.

They are composed of a metal base that provides mechanical resistance, and a vulcanized elastomer lip which acts as a seal. This design allows the elastomer to deform against the surface when the bolt torque is applied, creating a watertight seal.

Its use is common in hydraulic, pneumatic and process applications, although in sectors such as the food and pharmaceutical require versions with a special hygienic design.

The importance of sealing in fasteners

In demanding industrial environments, conventional fasteners can become a critical point for accumulation of dirt, moisture or corrosive agents. Without a proper sealing system, the following may form biofilms, corrosion or compromise the cleanliness of the system.

The metal-rubber washers are the solution to protect these sensitive areas, improving the service life of the fastener and guaranteeing the process safety.

Our choice at Epidor: Hygienic Usit®.

At Epidor, we have selected the Hygienic Usit® Hygienic Usit as our main reference in metal-rubber washers for hygienic applications. This solution, developed by Freudenberg Sealing Technologies, combines a washer with a stainless steel 1.4404 (AISI 316L) with a elastomer cord which completely seals the dead volume under the screw head.

In addition to meeting the requirements of the consortium EHEDG, Hygienic Usit® allows CIP, WIP and SIP cleaning processes to be carried out without disassembling the fastener.

Characteristics and information about our metal-rubber washers

Benefits of metal-rubber washers

Effective sealing of screw heads and threaded joints.
Prevention of leaks, corrosion and residue accumulation.
Available in materials compatible with aggressive media and cleaning products.
Certified options for food, beverages, pharmaceuticals and chemicals.

Elastomer materials available

70 EPDM 291 (black)Versatile compound for the process industry.
70 EPDM 217676 (blue)Pigmented for visual traceability.
70 EPDM 253815 (white)Formulation in demand in pharmaceutical environments.
Fluoroprene® XP 45Fluorinated elastomer with high chemical and thermal resistance.
Other options such as NBR and FPM available in variants for standard applications.

Certifications and standards (depending on version)

FDA 21 CFR 177.2600
EC Regulation 1935/2004 (food contact)
Validated EHEDG cleaning method

Standard sizes available

M4, M5, M6, M8, M8, M10, M12 and M16 (others on request)

Variants according to type of application

Inner (U) or outer (UA) design of sealing lip
Materials available: NBR, FPM, and based on steel o stainless steel

FAQ's about metal-rubber washers

What industrial applications require the use of metal-rubber washers?

They are especially useful in hydraulic systems, pneumatics, process equipment, food and pharmaceutical machinery, where a tight and reliable threaded connection is required.

What is the service life of a metal-rubber washer?

It will depend on the type of elastomer, chemical environment, temperature and frequency of disassembly. In static applications and with controlled cleaning, their service life can be very long.

Can metal-rubber washers be reused?

Not recommended. Although they may retain their shape in some applications, sealing capability may be compromised after disassembly, especially in hygienic environments.

Do you need metal-rubber washers for your project?

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