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What are the Necessary Characteristics of Valve Packing?

Release time:

Sep 23,2024

    Valve packing is the sealing material that be installed between the valve stem and bonnet, its main role is to prevent the medium from the valve stem and bonnet gap leakage. When the valve is closed, packing through the close contact with the valve stem, forming a sealing barrier to prevent the outflow of media; when the valve is open, packing can adjust its own sealing status with the movement of the valve stem, to ensure that in different valve positions can maintain good sealing.

     Valve packing has the following performance requirements：

     1、Sealability

   Good sealing performance is the core requirement of valve packing. Packing should be able to effectively prevent the medium from leaking from the gap between the valve stem and the valve cover under different pressure, temperature and medium conditions. The sealing performance depends on the packing material, structure and installation process and other factors.

     2、High temperature resistance

   For high temperature valves, the packing should have high temperature resistance. In a high temperature environment, the packing cannot soften, decompose or lose sealing performance. Different packing materials have different high temperature resistance limits, such as graphite packing can be used at temperatures up to 600 ℃, while the high temperature resistance of PTFE packing is relatively low, generally around 200 ℃.

     3、Corrosion resistance

     For valves with corrosive media, the packing should have good corrosion resistance. Packing should be able to resist the erosion of the medium, no chemical reaction or physical change, so as to maintain the sealing performance. For example, in the chemical industry, the valve is often exposed to a variety of strong acids, strong alkalis and other corrosive media, this time should choose a strong corrosion-resistant packing, such as polytetrafluoroethylene, graphite and so on.

      4、 Abrasion resistance

    The valve stem will produce friction with the packing during the switching process, so the packing should have a certain degree of wear resistance. Wear-resistant packing can reduce the wear between the valve stem and packing, and extend the service life of packing and valve stem. Generally speaking, the packing with high hardness and uniform material has better wear resistance.

     5.、Self-lubricating properties

    Packing with self-lubricating properties can reduce the coefficient of friction between the valve stem and packing, reducing the operating torque and also reducing wear and heat generation. Graphite, PTFE and other materials have good self-lubricating properties and are widely used in valve packing.

     6、Compression Resilience

    Packing needs to be compressed during installation to ensure tight contact with the valve stem and bonnet. Therefore, the packing should have good compression resilience, that is, after being compressed can be restored to the original, the performance requirements of the valve packing.

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