How to Improve the Service Life of Valve Packing?

How is the service duration of the normal valve packing ?

In valve design or usage experience, the packing of rising and falling valves is mostly asbestos packing, graphite packing or polytetrafluoroethylene V-shaped packing. However, these types of packing are restricted by the number of times the valve is opened and closed. That is, as the number of times the valve is opened and closed increases, the packing will wear, the clearance will gradually increase, and after a certain number of times (it is statistically less than 2,000 times), the valve will leak from the packing area. After the leakage occurs, it is necessary to re-tighten the packing gland. This solution is suitable for occasions where the valve is not opened and closed frequently.

The design for the valve packing that to improve the service life of the valve.

If the valve is opened and closed frequently (for example, 100,000 to 300,000 times a year), this will undoubtedly increase the usage and maintenance costs of the valve.

Is there a design that can still maintain a seal after the valve is opened and closed 1 to 2 million times? The answer is yes.

One method is to add a washer below the packing and a spring under the washer (the preload force of the spring needs to be calculated). When the packing wears, due to the action of the spring, the packing will be re-compressed to achieve a seal. Through practical application tests, this method can only ensure no leakage after 500,000 to 1 million times of opening and closing. The user needs to re-tighten the packing gland during the annual overhaul, which can only reduce the regular maintenance.

Another method is to select hydraulic or pneumatic sealing technology, change the original valve design concept, use a cylinder sealing slip ring at the packing area, and add O-rings (the number of slip rings and O-rings needs to be determined by calculating the friction force and the sealing specific pressure). Through practical application, this method can ensure no leakage after 2 million times of opening and closing. However, the O-rings will age, and their service life is only 5 years. At the same time, the cost is relatively high.