Difference Between Ductile Iron Disc and Stainless Steel Disc of Butterfly Valve

Butterfly valve is a common control device in pipeline system, which mainly consists of three parts: valve body, valve stem and valve plate. The valve plate is driven by the valve stem and rotates 90 degrees along the center line of the pipeline to open or close the pipeline. Butterfly valve has the advantages of simple structure, small volume, light weight, easy operation, reliable sealing, etc. It is widely used in water conservancy, petroleum, chemical industry, metallurgy, electric power and other industries.

Butterfly valve disc material is one of the important factors affecting the performance and life of butterfly valve. Different disc materials have different physical properties and corrosion resistance and are suitable for different fluid media and environmental conditions. Therefore, choosing the right disc material is the key to ensure the normal operation and extended service life of butterfly valves. This article will compare the differences between ductile iron discs and stainless steel discs for butterfly valves from the following aspects:

Material Properties

Ductile iron is an iron alloy made of nodular graphite, which has higher strength and toughness than ordinary gray cast iron. The advantages of ductile iron discs are low price, low switching torque, good sealing and high wear resistance. The disadvantages of ductile iron discs are low hardness, poor ductility, and easy fracture or cracking.

Stainless steel is a type of steel containing chromium or other alloy elements, which has extremely high oxidation resistance and corrosion resistance. The advantages of stainless steel discs are high strength, hardness, and ductility, and can be adapted to a wide range of chemical and environmental applications. The disadvantages of stainless steel discs are their high price, high switching torque, poor sealing, and tendency to generate frictional heat.

Corrosion Resistance

Ductile iron has a certain degree of corrosion resistance in air, water or other weakly corrosive media, but it is easily eroded or rusted in strong corrosive media such as acids, alkalis and salts. Therefore, ductile iron discs generally need additional coating or plating to improve their corrosion resistance. For example, some ductile iron discs are coated with epoxy resins to protect the valve from long-term erosion and corrosion in many different applications.

Stainless steel is extremely resistant to corrosion in air, water or other weakly corrosive media, and retains its luster and integrity even in strong corrosive media such as acids, alkalis and salts. As a result, stainless steel trays do not require additional coatings or plating to improve their corrosion resistance. For example, stainless steel discs will not rust even when placed in areas of high humidity or directly under water. This property makes them an excellent choice for coastal areas where salt water is corrosive.

Economical

Ductile iron is a relatively inexpensive metal and therefore the cost of ductile iron discs is low. In terms of service life, ductile iron discs save energy and maintenance costs due to their good sealing and wear resistance, which can reduce leakage and wear. However, ductile iron discs, in terms of corrosion resistance, may require more frequent replacement or repair due to their lower oxidation and chemical resistance, thus increasing the investment at a later stage.

Stainless steel is a relatively expensive metal and therefore the cost of stainless steel discs is also higher. Stainless steel pan in terms of service life, due to its excellent corrosion resistance and strength, can work for a long time in a variety of harsh conditions, without the need to replace or repair, thus reducing the later investment. However, stainless steel discs in terms of sealing, due to its poor sealing and susceptibility to frictional heat, may lead to leakage and wear, thus increasing energy and maintenance costs.

Conclusion

In summary, the difference between ductile iron discs and stainless steel discs for butterfly valves is mainly in terms of material properties and corrosion resistance. Ductile iron discs are cheaper and have similar strength to steel, but may require additional coatings or plating to resist corrosion. Stainless steel discs are more expensive, but have excellent corrosion resistance and can be adapted to a wide range of chemical and environmental applications. The choice of disc material depends on the application and fluid medium. For example:

• If the fluid medium is a weakly corrosive medium such as water, air, oil, etc., and has a high requirement for sealing, then a ductile iron disc can be selected.
• If the fluid medium is acid, alkali, salt, seawater, sewage and other strong corrosive media, and high requirements for corrosion resistance, then you can choose stainless steel plate.
• If the fluid medium is medium corrosive medium, and the requirements for strength and ductility are high, then you can choose nickel aluminum bronze plate.

Butterfly Valve Suppliers and Manufacturers

VALTECCN is a professional butterfly valve supplier and manufacturer with many years of production experience and technical strength, offering high quality butterfly valve products in various specifications and materials.VALTECCN’s butterfly valves have the following characteristics:

• Compact structure, light weight and easy installation;
• The valve plate is made of high quality material with special treatment on the surface, which has good wear resistance and corrosion resistance;
• the valve stem adopts double-headed card structure, firmly connected with the valve plate without top wire;
• Seals are made of imported rubber or tetrafluoro materials, with good sealing effect and service life;
• Various driving methods, such as manual, electric, pneumatic and hydraulic;
• Wide range of application, can be used in water conservancy, petroleum, chemical, metallurgy, electric power and other industries.

If you are interested in our products, or have any questions or needs, please feel free to contact us. Our contact information is as follows:
E-mail: [email protected]
Website: www.valteccn.com
Thank you for your reading and attention, looking forward to cooperating with you!