Usit ring

Sectional drawing of a Usit ring with a sealing bead on the inside

Installation of a self-sealing washer

A Usit ring is a metallic flat seal consisting of a steel support ring with a sealing bead vulcanized on the inside or outside. The self-sealing washers are among the rubber-metal composite seals ( English Bonded Seal ). They are used for the static sealing of flange connections and screw connections against overpressure . The trapezoidal, rubber-elastic bead can be attached to the inside or outside of the metal ring. "Usit" is the brand name of Carl Freudenberg KG in Weinheim. Similar products are also available on the market under the name sealing washer or sealing washer.

The original patent for the screw seal has expired.

Areas of application

Usit rings are mainly used in industry and wherever high tightness is required or high pressure prevails. The areas of application include

• Automotive engineering
• Hydraulic and pneumatic systems
• Engine technology
• mechanical engineering
• Pressure vessel construction
• Facade construction

Technical characteristics

The properties of Usit rings include

• Self-reinforcing seal
• Resistance to high pressure , unlike copper rings
• Positive connection

construction

With the installation method shown, pressures up to 400 bar can be sealed , with installation in a recess up to 1000 bar. A surface roughness of at most Rmax <15 µm, Ra <3 µm is required for this.

The installation should take place with a defined torque ( torque wrench ).

Alternatives

• Self-sealing screws (O-ring on the screw head)

literature

• Material information on bonded seals, including Usit rings: PDF
• Karl Trutnovsky: Contact seals on moving machine parts . Springer Verlag , 1958, ISBN 978-3-662-00606-1 , p. 90 ( limited preview in Google Book search).
• G. Pahl, W. Beitz, H.-J. Schulz, U. Jarecki: Pahl / Beitz construction theory: Basics of successful product development. Methods and application . 5th edition. Springer Verlag , 2013, ISBN 978-3-662-09186-9 , pp. 354 ( limited preview in Google Book search).

Web links

• Animation: Self-reinforcement using the example of a self-sealing washer

Individual evidence

1. ↑ M. Pollermann: Components of the physical technology . 2nd Edition. Springer Verlag , 2013, ISBN 978-3-642-65284-4 , pp. 166 ( limited preview in Google Book search).
2. ↑ Simrit Technical Manual 2007 . Freudenberg Simrit GmbH & Co. KG, 2007, p.  607 ( online, PDF ).
3. ↑ Entry for registration number 302011068976 at the German Patent and Trademark Office (online at register.dpma.de)
4. ↑ https://register.dpma.de/DPMAregister/pat/register?AKZ=E811010115&CURSOR=0
5. ↑ http://www.google.com/patents/EP0058211B1?cl=de
6. ↑ z. B. Seelbolt from APM Hexseal