Overview
The D643H Pneumatic Hard-Sealed Butterfly Valve is a type of valve that utilizes a metal hard-sealed structure and is driven by compressed air to actuate the disc in a 90° rotary motion, enabling the opening, closing, or regulation of pipeline media. This valve employs a three-dimensional eccentric or multi-eccentric design principle, allowing the disc sealing surface and the valve seat sealing surface to quickly separate and engage during operation, significantly reducing friction and wear. Its transmission mechanism uses the torque output from the pneumatic actuator to drive the valve stem, which precisely rotates the disc within the valve body. Both the valve seat and the disc sealing pair are made of metal materials (such as stainless steel, hard alloys, etc.), processed through specialized techniques to form a high-hardness metal-to-metal seal. The D643H Pneumatic Hard-Sealed Butterfly Valve is particularly suitable for demanding applications involving high temperatures, high pressures, corrosive media, and fluids containing fine solid particles. It is widely used in critical pipelines across industries such as power generation, metallurgy, petrochemicals, and urban heating systems.

Product Illustration of D643H Pneumatic Hard Seal Butterfly Valve

Features

Metal Hard-Seal Structure
1、The valve seat and disc sealing surfaces are treated through processes such as overlay welding with stainless steel, Stellite alloy, or hard material coating, forming a highhardness metal sealing pair. This design offers excellent wear and erosion resistance, with a service life significantly exceeding that of softsealed butterfly valves.

2、MultiEccentric Design
Utilizing singleeccentric, doubleeccentric, or tripleeccentric construction, the disc instantly separates from the seat during valve operation, achieving frictionfree opening and closing. This results in low operating torque and minimal wear on the sealing surfaces.

3、HighTemperature and HighPressure Performance
The metal hardseal structure enables the valve to withstand higher operating temperatures (typically up to 425°C or above) and higher working pressures, making it suitable for hightemperature and highpressure media such as steam, thermal oil, and hot flue gas.

4、Pneumatic Rapid Control
Equipped with a highperformance pneumatic actuator (piston or vane type), the valve provides fast opening and closing speeds. It supports remote automatic control and integration with DCS/PLC systems to meet automated process control requirements.

5、Excellent Sealing Performance
Relying on the wedgelike compression effect generated by the eccentric design, the valve ensures tight contact of the metal sealing surfaces when closed. It offers reliable bidirectional sealing, with leakage levels reaching ANSI Class VI or higher standards.

6、Corrosion and Abrasion Resistance
The high hardness of the metal sealing surfaces, combined with the option of corrosionresistant alloy materials or surface hardening treatments for the valve body and key components, effectively resists medium corrosion and erosion from solid particles. Suitable for slurry or fluegas pipelines containing dust or particulate matter.

7、FireSafe Design
Selected models incorporate firesafe functionality. In the event of a fire, the metal sealing pair can maintain a certain degree of sealing performance even after any soft sealing materials are destroyed, preventing largescale media leakage. Complies with firesafety standards such as API 607.

8、Long Service Life and Low Maintenance
Thanks to minimal friction and high wear resistance, the valve delivers extended service life. Maintenance intervals are prolonged, allowing for longterm maintenancefree operation under normal conditions, significantly reducing overall lifecycle costs.