How to improve the service life of valve packing
Writer： admin Time：2021-03-26 20:53 Browse：℃
How to improve the service life of valve packing
In the valve design or use experience, the lifting valve packing is mostly asbestos packing or graphite packing or polytetrafluoroethylene V-type packing, but these kinds of packing are limited by the number of valve opening and closing, that is, with the increase of valve opening and closing times, the packing will be worn, the gap will gradually increase, to a certain number of times (according to statistics will not exceed 2000 times), the valve will leak from the packing. After leakage, it is necessary to compress the packing gland again. This scheme is suitable for the occasion where the number of valve opening and closing is not much.
If the valve is opened and closed frequently (such as 100000-300000 times a year), it will undoubtedly increase the use and maintenance cost of the valve.
Is there a design that can seal the valve after 1-2 million times of opening and closing? The answer is yes.
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, the spring will compress the packing again to make it sealed. At present, this method has passed the use inspection, and can only open and close for 500000-1000000 times without leakage. It needs the user to re press the packing gland during the annual overhaul, which can only reduce the usual maintenance.
Another way is to choose the hydraulic and pneumatic sealing technology, change the original design idea of the valve, use the cylinder sealing slip ring at the packing, and add the 0-type sealing ring (the number of slip ring and 0-type sealing ring can only be determined by calculating the friction and sealing pressure). By using this method, it can be opened and closed for 2 million times without leakage, but the 0-type sealing ring is aging, the service time is only 5 years, and the cost is high.
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