Regarding the sealing type of the control valve spool
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Regarding the sealing types for control valve spools, there are metal sealing, soft sealing, and abrasive sealing. What does each of these sealing methods entail? Also: Does a metal seal equate to a hard seal?
A soft seal refers to a sealing material that is \"soft\", such as rubber or PTFE, while a metal seal involves sealing surfaces made of metal; in most cases, tungsten carbide or chromium carbide is sprayed onto the substrate and then ground to achieve sealing. A hard seal does not necessarily mean a metal seal; sometimes it is just a term game used by manufacturers.
A soft seal refers to a sealing material that is “soft,” with materials such as rubber and polytetrafluoroethylene being used for this purpose. Due to limitations in its structural properties, it is not suitable for applications requiring high temperature and pressure resistance, as well as corrosion and wear resistance. Metal sealing refers to a sealing surface made of metal; generally, tungsten carbide, chromium carbide, etc. are sprayed onto the substrate and then ground to achieve sealing. A hard seal is not necessarily a metal seal
Generally, they are divided into hard-sealed and soft-sealed types. When making a choice, the state of the medium, temperature, pressure, and sealing grade are the main factors to consider. The grinding seal mentioned by the poster is a type of hard seal; it is used to provide sealing performance for valves when ordinary machining precision is not sufficient to meet the required design standards. Metal seals are also considered hard seals, while essentially all non-metallic seals fall under the category of soft seals.
A soft seal refers to a sealing material that is “soft”. Due to limitations in its structural properties, it is not suitable for applications requiring high temperature and pressure resistance, as well as corrosion and wear resistance.
Metal sealing refers to a sealing pair made of metal materials, such as STL, or directly using metal materials like stainless steel. A soft seal generally refers to non-metallic materials, or sealing components made of materials that are relatively soft, with a hardness much lower than that of metals. Such as PTFE, rubber, etc. Grinding is generally used for hard-seal applications, as it is difficult to achieve a good seal with hard seals; therefore, grinding is necessary. Grinding can be done on the valve seat, on the valve stem, or by grinding both the valve stem and the valve seat together, with the latter method yielding the best results. A metal seal is not necessarily the only option; ceramic hard-seal technology is now well-developed as well, and it can operate at higher temperatures with excellent results!