Step rings are specialized sealing elements used as support or retaining rings in combination with O-rings or other sealing systems. Their main function is to protect the sealing material – usually an elastomer O-ring – from extrusion (bulging into the gap between sealing surfaces) at high pressures. This significantly increases the operational reliability and service life of sealing systems.

They are used in particular in hydraulic and pneumatic applications involving high pressures or large gaps.

The stepped ring has a characteristic asymmetrical shape with a step (hence the name). This geometry ensures that the ring mechanically supports the O-ring on the side away from the pressure, while the sealing effect remains unchanged on the pressurized side.

Typically, the stepped ring is used in pairs (one ring per side of the O-ring) when the pressure direction changes, or on one side when the pressure is constant.

    

PTFE Stepped rings – FiKumer^®-F

• Properties: high chemical resistance, very low coefficient of friction, wide operating temperature range (−200 °C to +260 °C)
• Advantages: virtually no aging, very good sliding properties, ideal for aggressive media
• Disadvantages: low elasticity, therefore only usable as a support element, not as a primary seal
• Applications: Chemical industry, hydraulic systems with high temperatures or aggressive media

 

Polyurethane Stepped rings – FiPur^®

• Properties: high mechanical strength, excellent abrasion and extrusion resistance
• Advantages: highly resistant to fluctuating pressure loads, ideal for dynamic applications
• Disadvantages: limited chemical resistance to hot water and certain chemicals
• Applications: mobile hydraulics, construction machinery, cylinders with high pressure spikes

Thermoplastics Stepped rings – FiMasol^®, e.g. POM, PA

• Properties: high dimensional stability, good wear resistance, easy to process
• Advantages: cost-effective, mechanically robust
• Disadvantages: lower chemical resistance than PTFE
• Application: Standard support rings in hydraulics and pneumatics