Datasheet
© Freudenberg Simrit GmbH & Co. KG | Technical Manual 2007584
Products I ISC O-Rings and Static Seals
Usit-Rings U, UA, USF
Usit-Ring U
Product description
Metal gasket with internally (U) or externally (UA) 
vulcanised, trapezoidal, rubber-elastic sealing bead for 
static sealing of
Threaded fittings
Flange connections
(USF) with centring diaphragm.
Product advantages
Easy fitting
Force-fit connections
Secure, self-reinforced sealing 
Suitable for high pressures.
Application
Sealing of threaded fittings and flange connections 
e.g. in mechanical engineering.
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Material
Metal ring
Steel SPCC
Steel SPCC-1B
Stainless steel (SUS 304)
Sealing bead
NBR rubber 72 NBR 99041
FKM rubber 75 FKM 99104
Other materials are available on 
enquiry from special production.
Surface protection 
metal ring
SPCC/NBR zinc chrome plated 
(CR VI free coating)
SPCC-1B/NBR zinc chrome plated 
(CR VI free coating)
SPCC/FKM phosphated
SPCC-1B/FKM phosphated
Operating conditions
NBR
Media
Mineral oils (as per DIN 51524), 
hydraulic fluids HFA, HFB, HFC 
(as per VDMA 24320)
Temperature
–30 … +100 °C
FKM
Media
Hot air (+250 °C)
Mineral oils 
(as per DIN 51524, +150 °C)
Hydraulic fluids 
(as per VDMA 24320, +150 °C)
Operating pressure
<100 MPa 
(installation in counter bore)
<40 MPa 
(installation without counter bore
for Ø <40 mm; only USF)
<25 MPa 
(installation without counter bore 
for Ø <40 mm)










