Bonded seals (USIT, USIT Z.C.) are metal washers with a trapezoidal elastomer sealing lip vulcanised to their inner diameter.

Product group: Bonded seal
USIT with inner vulcanised elastomer sealing lip
USIT Z.C. with inner vulcanised elastomer sealing lip and additional centring

Sealing material: Elastomer sealing lip NBR, NB 70
Elastomer sealing lip FPM, FP 70
Colour: NBR 70, black; FPM 70, brown

Washer: Carbon steel SAE 1008 (1.0330)
Stainless steel AISI 304 (1.4301)
Surface protection Zinc plated washer: carbon (Cr VI free) steel 
Colour: Silver-grey

Operational application limits
Temperature NBR -30°C to +100°C
Temperature FPM -15°C to +200°C


The maximum operating pressure is dependent on the design of the seal, the material, the dimensions, the counter surface and the tightening torque. Bonded seals are suitable for up to 25 Mpa pressure without counterbores in the counter surfaces

Counter surface
Surface finish Rmax    ≤ 15 μm Ra        ≤   3.2 μm


By tightening the screws the elastomer sealing lip is compressed, thereby producing the sealing effect on the surfaces to be sealed. It stops the medium from leaking to the outside, thus preventing loss of pressure. In addition, it provides protection against dirt from the outside.

The centring feature of the USIT Z.C. type ensures that the bonded seal is fixed in the correct position for mounting and when tightening the screws, thereby guaranteeing captive mounting.

Application area
Bonded seals are used as static seals for screw connections and flange seals, for example in machine building and container- and apparatus construction.

Benefits of bonded seals:

  •   Simple, captive assembl
  •   Secure sealing
  •   Reusable
  •   Fixation due to inner centring
  •   Cost-effective solution
  •   Controlled compression due to washer
  •   Available in different metal finishes
  •   Stocked for almost all European thread sizes

Media suitability of elastomer sealing lip

Good chemical resistance to mineral oils and greases, hydraulic oils H, HL, HLP, flame-resistant hydraulic fluids HFA, HFB, HFC up to approx. +50°C and water up to max. +80°C.

Good chemical resistance to mineral oils and greases, synthetic oils and greases, engine, transmission and ATF oils up to approx. +150°C, fuels, flame-resistant hydraulic fluids HFD, aliphatic, aromatic and chlorinated hydrocarbons, water up to max. +80°C, excellent resistance to weather, ozone and ageing, very low gas permeability (therefore suitable for vacuum applications), broad chemical resistance.


Loading... please wait
# Vota code Name Application Material Pressure
Temperature °C Sliding Speed (m/s)
usit-ringen/usit-z-c USIT Z.C. ZC USIT (DOWTY SEAL) STATIC STAAL-NBR 600 -30°C +105°C
STAAL-RVS-NBR 600 -30°C +105°C
STAAL-FPM 600 -15°C +200°C
Find product

CB = Custom build (price on request)
* = Stock item
Stock = 0 (and not a Stock* or CB product) -> minimum item value € 10.00

# Description Info Stock Price Add to cart
{{product.number}} {{product.description}} {{product.item_type_name.substring(0, 5)}} {{product.stock}} {{product.price|customCurrency:"€":",":".":2}}