The spring PTFE sealing ring achieves initial sealing contact through a combination of mechanical pre-loading and material properties. When installed in the groove between sealing surfaces, the metal spring core generates a pre-tightening reaction force that creates elastic contact stress between the PTFE material and the mating surfaces. This force ensures intimate contact even before system pressure is applied. The PTFE provides the actual sealing surface while the spring maintains consistent contact pressure, compensating for minor surface imperfections and thermal expansion differences. This dual-material design combines the chemical resistance and low friction of PTFE with the mechanical resilience of the spring.
Key Points Explained:
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Dual-material construction
- The seal consists of a ptfe ring bonded to a metal spring core
- PTFE provides chemical resistance and low-friction sealing surface
- Spring provides mechanical support and consistent force application
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Pre-tightening mechanism
- During installation, the spring is compressed within the gland groove
- This compression generates reaction force (pre-load) before system operation
- Creates initial elastic contact stress between PTFE and sealing surfaces
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Contact stress generation
- Spring force deforms PTFE slightly against mating surfaces
- Creates multiple microscopic contact points along the sealing interface
- Compensates for surface roughness (typically 3-5 μm Ra for effective sealing)
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Elastic deformation benefits
- Allows seal to conform to minor surface imperfections
- Maintains contact during thermal cycling (PTFE expands ~10× more than steel)
- Provides immediate sealing before system pressure builds
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Pressure-assisted performance
- Initial contact forms primary sealing barrier
- System pressure later enhances sealing by forcing PTFE against groove walls
- Spring maintains minimum contact pressure during pressure fluctuations
This design approach addresses the fundamental challenge of creating reliable static seals - achieving sufficient interfacial contact pressure while accommodating manufacturing tolerances and thermal effects. The spring's memory ensures the PTFE maintains optimal contact throughout service life.
Summary Table:
| Feature | Function |
|---|---|
| Dual-material construction | PTFE provides chemical resistance; spring ensures consistent contact force |
| Pre-tightening mechanism | Generates initial elastic contact stress before system operation |
| Contact stress generation | Compensates for surface roughness (3-5 μm Ra) via microscopic contact points |
| Elastic deformation | Maintains seal integrity during thermal cycling and pressure fluctuations |
| Pressure-assisted sealing | System pressure enhances sealing while spring maintains minimum contact |
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