How to improve the service life of valve packing

Lift valve packing is mostly asbestos packing or graphite packing or PTFE V-type packing, but these packings will wear with the increase of valve opening and closing times, and the gap will gradually increase. If it is too large, the valve will leak from the packing after a certain number of times (according to statistics, it will not exceed 2000 times). After leakage, the packing gland needs to be re-tightened.

One way is to add a washer under the packing and a spring under the washer (the preload of the spring needs to be calculated). When the packing is worn out, due to the action of the spring, the packing will be re-compressed to make it sealed. At present, this method can only reach 500,000-1,000,000 times of opening and closing without leakage. The user needs to re-compress the packing gland during the annual overhaul, which can only reduce the usual maintenance.

Another way is to use hydraulic and pneumatic sealing technology, change the original valve design idea, use the oil cylinder to seal the slip ring at the packing, and increase the 0-type sealing ring (the friction force and the sealing specific pressure need to be calculated to determine the slip ring and 0 type seals). Through the use of this method, it can be opened and closed for 2 million times without leakage, but the 0-type sealing ring needs to be aged, the use time is only 5 years, and the cost is relatively high.