"Soft power" on the sealing surface

Date:2018-05-08 Visits:1610
In addition to the corrosion resistance required by the basic media, the most important choice for the metal sealing surface material of the valve is extrusion resistance and scratch resistance. Both must be achieved. Extrusion resistance is the strength requirement, and abrasion resistance is the hardness requirement. However, in order to ensure the sealing performance of the valve during the opening and closing process, a specific sealing pressure that exceeds the sealing pressure is inevitably applied on the sealing surface. In particular, many manufacturers choose the sealing surface as a "line seal", which results in a very large sealing specific pressure. Therefore, if the sealing material is too soft, it is easy to have indentation, and although the sealing material is very hard, but very thin, it is easy to crack. This is the reason why the seal life of some manufacturers is short. In summary, the sealing surface is required to have a certain thickness and considerable hardness. Therefore, surfacing welding with a certain thickness of stellite cemented carbide is the best choice. If you choose a "surface hardening" treatment process such as nitriding, the hardness will increase, but Decreased toughness, on the contrary, is easy to crack, which is not conducive to future sealing surface repair. In addition, in the operating conditions of the regulating valve, once cavitation occurs, any hardness of metal cannot be resisted. Therefore, it is necessary to avoid cavitation in the structure, instead of blindly increasing the hardness of the sealing surface and sacrificing the strength of the material. It can be seen that the choice of valve sealing surface also requires "soft power."