Leakage at the packing of valve is the most vulnerable parts of the valve.So the valves that is opened or closed by external force are designed with a sealing device,that is , a certain number of packing sealing rings are installed in a stuffing box to achieve sealing effect.
Requirements for packing:
1.good sealing;
2.corrosion resistance;
3.small friction coefficient;
4.comply with media temperature and pressure.
