Processing Sealing Surfaces of Triple Eccentric Metal Seated Butterfly Valves

A valve is a pipeline accessory used to control and transport media. Valves are widely used in industrial and agricultural development, cutting-edge defense technology, transportation, and everyday life. A triple eccentric metal seated butterfly valve is a high-performance valve commonly used in industrial pipeline systems, offering excellent sealing performance and wear resistance. Processing the sealing surfaces of triple eccentric butterfly valves is crucial to ensure their reliability and service life. This article details the processing methods of the sealing surfaces of triple eccentric metal seated butterfly valves, including the design, material selection, processing technology, and quality control.
 

Designing sealing surfaces of triple eccentric metal seated butterfly valves involves unique characteristics. Their sealing principle achieves line contact through the triple eccentric structure, ensuring an excellent sealing effect. This design effectively reduces wear on the sealing surface and extends the valve's service life.
 

The triple eccentric structure includes axial eccentricity, conical eccentricity, and circular eccentricity. Axial eccentricity refers to the valve stem axis deviating from the butterfly plate's centerline, allowing the butterfly plate to quickly detach from the sealing surface when opening, thereby reducing friction and wear. This design allows butterfly valves to generate less operating torque, improving operating efficiency. Conical eccentricity refers to the tapered design of the butterfly plate’s sealing surface relative to the valve body sealing surface. The conical sealing surface achieves line contact sealing when closing, thereby improving the sealing effect. The conical eccentricity design allows the sealing surfaces to gradually approach each other during the closing process, forming a good seal. Circular eccentricity refers to the butterfly plate moving along an arc trajectory during closing, gradually fitting the valve body's sealing surface. This design ensures the sealing surface achieves optimal contact when closing, further improving sealing performance.
 

Engineers have two main options: conical or spherical. The choice between these shapes depends on the specific requirements of the application. Conical sealing surfaces are typically used in high-pressure environments where a tight seal is essential. The angled design of the conical surface distributes pressure evenly, ensuring a secure connection. Spherical sealing surfaces are preferred for applications where self-cleaning ability is important. The curved shape allows debris or impurities to be easily flushed out, maintaining optimal performance over time. This makes spherical sealing surfaces ideal for media containing contaminants that could compromise seal integrity.
 

Choosing sealing surface materials directly affects the sealing performance and durability of butterfly valves. Sealing surfaces are primary made from cemented carbide, stainless steel, and special alloys. Cemented carbide has high hardness and wear resistance, making it suitable for environments with high temperature, high pressure, and corrosive media. Common cemented carbides include cobalt-based alloys and nickel-based alloys. Stainless steel has good corrosion resistance and mechanical properties, making it suitable for most industrial media. Commonly used stainless steel grades include 304, 316, and 316L. For specific working conditions, special alloys such as Monel and Hastelloy can be selected to ensure excellent corrosion resistance and high-temperature performance.
 

The processing technology of the sealing surface is crucial for ensuring its quality and performance. Common processing methods include turning, grinding, and spraying. Turning is the most common preliminary processing method, where the sealing surface is initially formed and finished by a CNC lathe. Turning requires high precision and a high finish to ensure sealing surface tightness. Grinding is an important process for precision processing of the sealing surface, usually carried out by a surface grinder or a cylindrical grinder. Grinding achieves a better surface finish and dimensional accuracy to ensure sealing performance. For sealing surfaces that require special wear and corrosion resistance, plasma spraying or supersonic flame spraying technology can be used to apply cemented carbide or special alloys on the substrate to form a hard protective layer.
 

Quality control of the sealing surface is crucial to ensuring the reliability of the triple eccentric metal seated butterfly valve. It mainly includes size detection, surface finish detection, hardness testing, and sealing tests. The size of the sealing surface is measured by precision instruments to ensure it meets design requirements. Commonly used measuring tools include three-coordinate measuring machines and roughness meters. The surface finish directly affects sealing performance. A surface roughness meter is used to measure the finish of the sealing surface to ensure it meets standard requirements. The hardness of the sealing surface material directly impacts its wear resistance. The hardness of the sealing surface is measured by a hardness tester to ensure it has sufficient wear resistance. After the valve is assembled, a sealing test is required to ensure the sealing surface achieves a good seal under working conditions. Commonly used test methods include water pressure and air pressure tests.
 

The processing methods of the sealing surface of the three-eccentric metal seated butterfly valve involves design, material selection, processing technology, and quality control. Through scientific design and strict process control, the sealing performance and service life of the butterfly valve can be effectively improved, ensuring its reliability and stability under various complex working conditions. In the future, with continuous advancements in materials science and processing technology, the sealing surface processing of the triple eccentric metal seated butterfly valve will become more refined and efficient, providing more reliable protection for the safe operation of industrial pipeline systems.