When should a metal-seated valve be considered?
Resilient-seated butterfly valves rely on an elastomeric seat to provide an elastic sealing interface and are commonly used for compatible clean media at moderate temperatures. When the service exceeds the verified limits of the selected elastomer, continued use can lead to premature ageing, sealing-surface wear or unacceptable leakage.
Typical signals include sustained temperature near or above the seat material limit, hard particles that may abrade the sealing surfaces, a specified metal-to-metal sealing pair, frequent cycling, or project-specific fire-safety requirements.
Why the sealing system matters
Elastomeric sealing depends on material recovery. Excessive temperature can cause hardening, creep or tearing; particles can abrade the seat during operation; and frequent cycling accelerates fatigue. A metal sealing pair can offer improved temperature, pressure and wear capability, but sealing quality depends more heavily on the verified valve geometry, material pairing and manufacturing accuracy.
Selection checks
Confirm the operating and design temperature, nominal pressure and actual line pressure, the medium and any corrosive or abrasive content, sealing-pair materials, offset geometry, actuation method and the permitted leakage rate. Do not select from the PN designation or temperature alone.
For a D343H configuration, confirm that the flanged connection, metal-seated construction and offset geometry shown in the approved technical documents match the project. Water, steam and oil duties still require material and temperature verification for the actual service.
What triple-offset geometry changes
Triple-offset geometry introduces an additional sealing-cone offset beyond the double-offset arrangement. In a verified design, this allows the disc and seat to disengage rapidly during operation, reducing rubbing between metal sealing surfaces. The exact sealing direction, leakage performance and pressure-temperature capability must follow the approved product configuration rather than the model code alone.
High-temperature and high-pressure duties
Review body, disc and stem materials, thermal expansion, sealing-pair compatibility, packing temperature capability and the actuator’s ambient limits. The valve rating must be checked against actual working pressure and temperature together with the applicable flange and pipeline standard.
Information to provide with an inquiry
- Medium, operating temperature, corrosion, particles or crystallisation
- DN, PN, actual working pressure and flange standard
- Required body, disc, stem, sealing-pair and packing materials
- On/off or modulating duty, power or air supply, feedback and fail position