A metal-seated ball valve uses a metal seat as its sealing surface. Its core design feature is a metal-to-metal (or specially treated hardened) contact seal, making it suitable for demanding applications involving high temperatures, high pressures, severe corrosion, or the presence of solid particles. The following are its key features and operating principles:
Core Structure and Components
Valve Body and Bonnet
The pressure-bearing components of the main body are typically made of cast steel, stainless steel, or special alloys to ensure pressure and corrosion resistance.
Ball (Opening and Closing Device)
A metal ball with a through hole (such as stainless steel or tungsten carbide coating) has a hardened surface (spraying or grinding) to ensure high hardness and wear resistance.
Metal Seat
This key component forms a sealing pair with the ball. Made of a matching material (such as stainless steel or carbide), it is precision-ground to achieve a metal-to-metal seal.
Elastic Compensation Component
Spring/Disc Spring: Preloads the valve seat to compensate for clearance caused by thermal expansion or wear. Metal Elastic Ring: Provides a buffer against deformation under high-temperature conditions, preventing the ball from seizing.
Valve Stem and Actuator
The valve stem transmits rotational torque (manual, pneumatic, or electric), and the actuator drives the ball to rotate 90° to open or close.
Sealing Principle
Static Sealing
When closed, the ball's through-hole is perpendicular to the pipe, and the metal valve seat, under the spring preload, presses against the ball, forming an initial seal.
Dynamic Pressure Assist
Media pressure pushes the valve seat further against the ball, achieving a pressure-tight seal (the higher the pressure, the more reliable the seal).
High-Temperature Adaptability
Elastic elements (such as metal elastic rings) absorb thermal expansion and deformation, preventing seal failure at high temperatures.
Bidirectional Sealing Design
Most structures support bidirectional sealing (such as DBB/DIB designs) upstream and downstream, ensuring leak-free media.
Performance advantages
| Features | Detail |
|---|---|
| High pressure resistance | The metal sealing surface can withstand pressures above 42.0 MPa (420 bar) |
| High temperature resistance | Applicable temperature up to 550℃ (such as Q41Y valve) |
| Wear-resistant and erosion-resistant | Hardened ball and seat resist erosion by granular media (such as double scraper design to scrape away impurities) |
| Long life | Metal materials are resistant to aging and can automatically compensate for wear through elastic elements |
Applications
- Energy Industry: High-temperature steam pipelines, oil and gas transportation systems.
- Chemical Industry: Process control for highly corrosive media (acids and alkalis) and processes containing catalyst particles.
- Power System: Boiler feedwater, high-temperature flue gas treatment.
- Demanding Operating Conditions: Coal chemical industry, multiphase flow media, and applications requiring fire safety (metal seals eliminate combustion risks).
