Development of metal plane sealing butterfly valve

**Foreword** In recent years, with the rapid development of modern industry, the application of butterfly valves has expanded significantly. Initially used in low-pressure water supply systems, they are now widely employed in media with temperatures ranging from -184°C to over 538°C and pressures that have increased from low to high. These valves are now commonly found in various industries such as air separation, chemical processing, metallurgy, and wastewater treatment. As the demand for larger sizes, higher performance, and longer service life grows, traditional rubber or plastic-sealed butterfly valves are increasingly showing limitations due to their susceptibility to wear, aging, and failure under continuous operation. For example, in modern air separation plants that rely on cryogenic separation principles, the process involves a molecular sieve pre-purification stage. The operating pressure typically ranges between 0.5 to 0.9 MPa, while the medium temperature fluctuates between 10°C and 200°C. The switching valves in these systems are large in size, operate frequently, and require reliable sealing. However, the rubber seals used in conventional valves tend to wear out quickly, leading to frequent maintenance and replacement challenges. To address these issues, our company has developed a series of **metal-enhanced pneumatic sealing butterfly valves**, which have been granted a national practical patent (Patent No.: ZL 97 2 24037.3). This new type of valve offers improved durability, reliability, and performance, making it ideal for demanding industrial applications. --- **Features of the Metal Seal Pneumatic Butterfly Valve** 1. **Lever-type Opening and Closing Mechanism**: This design reduces relative sliding between the sealing surfaces, minimizing wear and extending the service life of the valve. 2. **Connecting Rod Force Amplification Mechanism**: This mechanism ensures maximum torque output when the valve is closed, providing self-locking capabilities for enhanced safety and reliability. 3. **Metal Sealing Structure**: The use of metal seals offers superior corrosion and wear resistance, making the valve suitable for high-temperature environments and ensuring long-term performance. 4. **Optimized Key Components**: The valve can withstand over 1 million opening and closing cycles, meeting the rigorous demands of frequent operations. 5. **Non-contact Electromagnetic Reed Switch Control System**: This system provides high signal sensitivity, accuracy, and compatibility with remote control, pneumatic control, and automatic control systems. It also allows for unattended operation, reducing the need for manual intervention. --- **Structure and Working Principle** **3.1 Lever-Type Opening and Closing Mechanism** As shown in Figure 1, the lever-type structure allows the butterfly plate to rotate around a fixed pivot point. When the valve is closed, the spindle and lever are fastened with a conical pin, and the lever drives the butterfly plate into contact with the seat, creating a tight seal. The compression spring helps maintain the seal by pressing the disc against the fulcrum. This design minimizes sliding friction and improves sealing efficiency. **3.2 Connecting Rod Force Actuator** The connecting rod actuator, as illustrated in Figure 2, uses an air-driven piston to generate torque through a mechanical linkage. The system is designed so that the torque increases as the valve approaches the fully closed position, matching the required sealing force during operation. This feature ensures optimal performance throughout the valve’s cycle. **3.3 Flat Seal Structure** Unlike traditional spherical seals, this valve employs a flat metal seal, offering better control over sealing interference. The seal is made from stainless steel with carbide surfacing, while the seat ring is composed of copper-based alloys or cobalt-based welding materials. These materials provide excellent corrosion and wear resistance, allowing the valve to operate reliably in a wide temperature range (-40°C to 300°C). Due to the lever mechanism, the valve achieves a plane-to-plane contact seal, acting like a cam mechanism. This design not only enhances sealing but also allows for automatic compensation for wear, significantly extending the service life of the valve. --- **Test Results and Application** In April 1997, our company successfully developed the first PN1.0MPa DN300 pneumatic butterfly valve. The performance and field simulation tests showed: - **Performance Test**: Gas source pressure: 0.4 MPa; Pipeline pressure: 0.95 MPa; Medium temperature: Room temperature; Open times: 1500 (required: 1000); Action time: 10 seconds. - **Simulated Field Conditions Test**: Gas pressure: 0.4 MPa; Pipeline pressure: 0.7 MPa; Temperature: 150°C; Open times: 8000 (required: 1000); Action time: 10 seconds. After testing, no leakage was detected, and all components remained intact. Since then, we have expanded our product line to include PN1.0MPa DN400, PN1.6MPa DN150/DN200, and even larger sizes for major projects such as the 15,000 cubic meter air separation plant in Tianjin. These valves have performed exceptionally well, gaining the trust of users and replacing imported alternatives. Our valves are now widely used in air separation, chemical, metallurgical, and gas pipeline industries. Especially in natural gas pipelines, the metal-seal pneumatic butterfly valve provides excellent sealing, fire safety, minimal maintenance, and cost-effectiveness—making it an ideal choice for large-diameter applications. Through real-world use, the valves have met all design specifications and are now supplied to both domestic and international markets. With continued innovation and proven performance, the metal-seal pneumatic butterfly valve is poised to become a market leader in the future.

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SODIUM CHLORIDE

TIANJIN LIHE TRADING CO.,LTD , https://www.lihecorp.com