In heavy machinery and hydraulic presses operating above 250 bar, sealing reliability determines system performance. The critical question: Are compound seals (like Glyd Rings) more reliable than traditional single seals?

Single Seals: Three Fundamental Limitations

Standard O-rings and U-cups struggle in high-pressure environments for three reasons:

Extrusion: High pressure forces soft seal material into metal clearance gaps, causing "nibbling" and rapid failure.

Friction: Pressure compresses single seals harder against metal surfaces, creating stick-slip motion and system instability.

Heat Buildup: Thick polyurethane seals trap heat rather than dissipating it, accelerating material degradation.

Compound Seals: Engineered Superiority

Compound seals combine two specialized components: a hard PTFE sealing ring and an elastomeric energizer (O-ring). This architecture delivers four advantages:

Anti-Extrusion: The rigid PTFE ring bridges clearance gaps, preventing the soft energizer from extruding—handling pressure spikes to 600 bar.

Independent Activation: The protected O-ring maintains elasticity indefinitely, providing continuous preload even as the PTFE face wears.

Low Friction: PTFE's natural lubricity eliminates stick-slip, reduces heat, and prevents seals from freezing to rods after inactivity.

Pressure Distribution: Load distributes evenly through the incompressible O-ring, ensuring consistent sealing force regardless of fluctuations.

Real-World Performance

In a 300-ton hydraulic press, single U-cups typically fail within months due to extrusion and heat hardening. Compound Glyd Rings and Step Seals maintain efficiency for years, resisting extrusion while enabling precise control.

Selection Guidelines

For optimal results:

Material: PTFE bronze for mineral oils; carbon-filled PTFE for water-glycol

Energizer: NBR to 400 bar; FKM for extreme temperatures

Hardware: Maintain tight extrusion gap tolerances (≤0.5mm above 400 bar)

The verdict: For dynamic high-pressure applications, compound seals aren't just better—they're essential for operational reliability.