We all know that the structure of the wafer butterfly valve is very simple and consists of the valve body, the valve plate, the valve seat, the valve stem and the transmission. The materials used will be different because of the different working conditions and media erosion. Let's find out more specifically.
The material of the valve body of the wafer butterfly valve material is gray cast iron (grey iron), codenamed HT, ductile iron (ductile iron), code DI; cast steel, code-named WCB; stainless steel (commonly known as 304, 316/ 316L). Four common valve body material properties Gray iron <Diamond iron <Cast steel < Stainless steel. Cast iron clip-on butterfly valves are often used in materials that have little or no control over operating conditions. The best stainless steel material for the medium has corrosive media pipelines, and also includes some ultra-low temperature and ultra-high temperature media; but the price of stainless steel is also the highest in four materials.
The material of the wafer butterfly valve plate has a certain relationship with the valve body. In the matching wafer-type butterfly valve material, the material of the butterfly plate is at least one grade higher than the material of the valve body. For example, if the valve body is used Gray iron material, then the butterfly plate is at least used to match the use of ductile iron material, because the butterfly plate is located inside the pipe, the erosion of the pipe medium suffered is much more than the valve body, use a higher level of material to ensure The safety of the valve.
The material of the wafer type butterfly valve seat needs to be divided. The common material of the soft seal wafer type butterfly valve seat is EPDM, NBR, and PTFE. EPDM mainly passes water, air and other weak acid and alkaline media. NBR is mainly over oily media, while PTFE is suitable for certain corrosive media. The advantage of these three materials is that they have good sealing performance. The disadvantage is that they are not resistant to high temperatures and pressures. The seat material of the hard-sealed wafer type butterfly valve is made of hard alloy. The advantage is high temperature resistance and corrosion resistance. The disadvantage is that the sealing performance is not good enough.
Compared with the above components, the material of the valve stem is relatively single, and is usually made of stainless steel. The valve stem is a component that connects the transmission device and the butterfly plate. It is made of stainless steel material, anti-corrosion, rust prevention, ensure the normal order of the butterfly plate the opening and closing.