Self-centring U-rings are axially static sealing elements for use on screw joints, valves, flanges
and hydraulic applications, including simple alignment. They consist of a metal ring with a vulcanised-on, trapezoidal elastic sealing bead. When the fastener is tightened, the elastic sealing bead is compressed between the two flat surfaces. The thickness of the metal ring limits the maximum compression of the seal. When additional pressure is applied to the sealing point, the sealing bead is pressed further against the flat surfaces, thereby further enhancing the sealing effect.

U-rings are not suitable for use as thread locks.

Steel version:

Washer steel 1.0330.

Elastomer NBR, Shore 70A.


Stainless steel version:

Washer stainless steel 1.4301.

Elastomer EPDM, Shore 70A, FDA-compliant.

Steel version

Washer steel 1.0330, electro zinc-plated.

Elastomer NBR, black.


Stainless steel version:

Washer stainless steel $s14301bright.

Elastomer EPDM, black.

Flat, undamaged sealing faces are essential for a reliable seal. The maximum permissible surface roughness is Rmax ≤ 15 µm or Ra ≤ 3 µm. A seal can only be guaranteed to function securely and correctly if it is fitted carefully and professionally.

Process pressures:
≤ 100 MPa when fitted into a recess.
≤ 40 MPa when fitted without counterbore by ø < 40 mm.
≤ 25 MPa when fitted without counterbore by ø > 40 mm.

NBR: -30°C to +80°C.
EPDM: -40°C to +130°C.

Further dimensions and materials.