Regarding the materials for valve seats/sealing surfaces, could someone explain why these materials are used?

The material selection for the valve seat/sealing surface is intended to meet the requirements under specific operating conditions, including the properties of the medium, temperature, pressure, corrosivity, etc. For the material combination you mentioned, it is a common choice for valve sealing materials. 16Mn is a low-carbon structural steel with good strength and weldability, suitable for general temperature and pressure conditions. ENP (electroplated nickel) is a surface treatment method that enhances the corrosion resistance of metal materials and provides some protection in environments containing sulfuric acid. RPTFE (reinforced polytetrafluoroethylene) is a material based on polytetrafluoroethylene, featuring excellent chemical resistance and temperature tolerance, as well as good adaptability in environments containing aqueous crude oil and sulfuric acid. STL6 is a stainless steel material with excellent corrosion resistance, making it particularly suitable for use in highly corrosive environments. In summary, this material combination can meet the requirements in aqueous crude oil and sulfuric acid-containing environments, exhibiting good corrosion resistance and temperature tolerance. However, the specific material selection still needs to be adjusted and confirmed based on the specific operating conditions and valve type. .

Material of the valve seat body: 16Mn. Surface treatment of the valve seat body material: ENP. Material of the sealing surface: RPTFE+STL6 (dual-sealing structure of RPTFE and cemented carbide)

ENP generally refers to electroless nickel plating, while STL6 denotes cobalt-based Stellite grade 6 cemented carbide, which is typically used for steam and petrochemical valve seat surfaces.