Forged steel trunnion ball valves are high-performance valves made of forged steel, with a ball fixed within the valve body and sealing achieved through the movement of the valve seat. They are widely used in petroleum, chemical, natural gas, metallurgy, and power industries. Their design features, working principle, and advantages are as follows:
I. Structural Features
Fixed Ball Design: The ball is supported by upper and lower bearings, preventing displacement under pressure. The valve seat uses an elastic element (such as a spring) or media pressure to press the ball firmly, achieving a seal. This design reduces friction, lowers operating torque, and extends service life.
Dual-Seat Seal: Forged steel fixed ball valves typically employ a bidirectional sealing structure, with each valve seat capable of independent sealing, ensuring reliable operation even under high pressure, high temperature, or corrosive media environments.
Fireproof and Anti-static Design: The valve seat sealing ring uses a metal-to-metal secondary sealing structure, maintaining sealing performance even in extreme conditions such as fires. Simultaneously, an anti-static device is installed between the valve body and the valve stem to prevent safety hazards caused by static electricity.
Fireproof and Anti-static Design: The valve seat sealing ring uses a metal-to-metal secondary sealing structure, maintaining sealing performance even under extreme conditions such as fires. Full-bore or Reduced-bore Design
Depending on operating conditions, valves can be designed as full-bore (flow channel matches the pipe's inner diameter) or reduced-bore (flow channel is smaller than the pipe's inner diameter) to meet different flow and pressure requirements.
II. Working Principle
Open State: The ball rotates 90°, connecting the flow channel to the pipe, allowing smooth media flow.
Closed State: The ball rotates 90°, its surface contacting the valve seat sealing surface, cutting off media flow.
Sealing Mechanism: The valve seat presses the ball tightly against the spring preload or media pressure, forming a reliable seal. Some valves are also equipped with a secondary sealing grease inlet, allowing grease to be injected to restore sealing performance when the sealing surface is worn.
III. Advantages and Applications
High Pressure and High Temperature Resistance
Forged steel material possesses high strength and corrosion resistance, suitable for high-pressure (e.g., Class 1500) and high-temperature (e.g., -196℃ to 450℃) conditions, commonly found in long-distance oil and gas pipelines and chemical plants.
Low Flow Resistance and Quick Opening/Closing: The full-bore design minimizes resistance during media flow, requiring only a 90° rotation for easy operation and suitable for frequent opening and closing applications.
Wear Resistance and Long Service Life: The ball and seat sealing surfaces are made of hard alloy or weld overlay technology, offering excellent wear resistance and making it suitable for applications containing solid particles or corrosive media.
Wide Applicability: Handles liquids, gases, steam, and media containing suspended particles, suitable for industries such as petrochemicals, natural gas transportation, metallurgy, power generation, pharmaceuticals, and food processing.
IV. Technical Parameters
Nominal Pressure: Class 150 to Class 2500 (PN16 to PN420)
Nominal Diameter: DN15 to DN1200 (1/2 inch to 48 inches)
Connection Methods: Flange connection, welded connection, threaded connection
Actuation Methods: Manual, pneumatic, electric, hydraulic
Sealing Materials: Polytetrafluoroethylene (PTFE), PPL, Metal Hard Seal