API 6D Piston Seals for Ball Valves
API 6D piston seals are designed to provide long-term, reliable sealing performance in demanding ball valve applications. By combining a helical wound spring with a high-performance polymer jacket, these seals deliver consistent sealing force, chemical resistance, and stability under extreme temperature and pressure conditions.
Structure and Materials
Seal Jacket Materials: Virgin PTFE, filled PTFE, UHMW-PE, PEEK.
These polymers offer superior chemical and heat resistance compared with elastomers.
They are compatible with most chemical fluids, solvents, hydraulic oils, and lubricating oils.
Their low thermal expansion ensures long-lasting sealing performance.
Spring Energizer: Helical wound spring.
Available in Stainless Steel, Elgiloy, and Hastelloy.
The spring overcomes the limited elasticity of PTFE, UHMW-PE, and PEEK, providing constant load compensation even under wear, shrinkage, or tolerance variations.
Optional Anti-Extrusion Ring:
Required when pressure exceeds 900 LBS, protecting the sealing lip from extrusion damage.
Performance and Applications
Designed for both static and dynamic sealing (reciprocating or rotating).
Service Temperature: –196℃ to +300℃
Pressure Range: Vacuum to ultra-high pressure 70 MPa
Speed Capability: Up to 20 m/s
This makes API 6D piston seals an excellent choice for high-temperature corrosive fluids, low-temperature cryogenics, and critical sealing applications in oil & gas.
Advantages
API 6A FF/HH Immersion Tested – validated material reliability.
High-load helical spring with small deflection range.
Compatible with closed grooves due to minimal elastic deformation.
Rigid spring acts as energizer to resist low-temperature shrinkage.
NACE-approved energizers available for oil & gas environments.
Working Conditions
Temperature range: –50℃ to +200℃
Pressure ratings: 150LB, 300LB, 600LB, 900LB, 1500LB, 2500LB
Mediums: Gas, water, hydrocarbons, chemicals
Applications
API 6D certified ball valves
Oil & gas pipelines and processing plants
LNG systems and cryogenic equipment
Petrochemical refineries
High-pressure chemical processing valves
