1)Add seal grease method
For valves that do not use seal grease, consider adding seal grease to improve stem seal performance.
2)Additional packing method
In order to improve the sealing performance of packing to stem, packing can be added. It usually adopts the form of double layer, multilayer mixed packing, and simply increases the quantity, such as increasing 3 pieces to 5 pieces, the effect is not obvious.
3)Replace graphite packing method
A large number of the use of tetrafluoride packing, because of its working temperature within the range of -20 ~ +200℃, when the temperature at the upper and lower limit, the change is large, the sealing property will be significantly decreased, aging fast, short life. Flexible graphite packing can overcome these shortcomings and long service life. Therefore, some factories will all tetrafluorin packing into graphite packing, even the newly purchased control valve will also be one of the tetrafluorin packing into graphite packing after use. But the return difference of using graphite packing is big, at the beginning some still produce crawling phenomenon, this must consider somewhat.
4)Change flow direction and place P2 on stem end
When delta P is larger and P1 is larger, sealing P1 is obviously more difficult than sealing P2. Therefore, changing the flow direction by changing P1 at stem end to P2 at stem end is more effective for valves with high pressure and large differential pressure. For bellows valves, seal P2 should normally be considered.
5)Adopt lens pad sealing method
For upper and lower cover seal, seat and upper and lower body seal. If the plane seal, in high temperature and high pressure, poor sealing, resulting in leakage, can be replaced by lens pad seal, can get a satisfactory effect.
6)Replace the seal gasket
Up to now, most sealing gasket still USES asbestos board, in high temperature, poor sealing performance, life is short, causing leakage. Encounter this kind of circumstance, can change to wrap gasket, "O" shape annulus, a lot of factories already used now.