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How To Improve Valve Life
Jan 09, 2019

  How to improve valve life

  In the valve design or experience, the lift valve packing is mostly asbestos packing or graphite packing or polytetrafluoro V type packing, but these kinds of packing are limited by the number of valve opening and closing, which is the number of times the valve is opened and closed. Increase, the filler will wear, the gap will gradually increase, and the valve will leak from the packing until a certain number of times (according to statistics, it will not exceed 2000 times). After the leak, it is necessary to retighten the packing gland. This solution is suitable for occasions where the valve opening and closing times are not many.

  If the valve is frequently opened and closed (such as opening and closing 100,000-300,000 times a year), this will undoubtedly increase the use and maintenance cost of the valve.

  Is there a design that can still be sealed after the valve has been opened and closed for 1 to 2 million times? The answer is yes.

  One method 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 packing will be re-pressed and sealed by the action of the spring. At present, this method can only achieve 50-100 million opening and closing without leakage, and requires the user to re-press the packing gland during the annual overhaul, which can only reduce the usual maintenance.

  Another method is to use hydraulic and pneumatic sealing technology to change the original valve design idea. Use the cylinder seal slip ring at the packing to increase the 0 type seal ring (you need to calculate the friction force and seal specific pressure to determine the slip ring and 0 Number of seals). This method can achieve 2 million times of opening and closing without leakage, but the 0-type sealing ring should be aging, the use time is only 5 years, and the cost is high.