In the valve design or use experience, the lifting valve packing is mostly asbestos packing or graphite packing or polytetrafluoroethylene V packing, but these kinds of packing are limited by the number of valve opening and closing, that is, with the number of valve opening and closing Increase, filler will wear, the gap gradually increased, to a certain number (according to statistics will not exceed 2000 times) valve will leak from the packing. After the leakage, it is necessary to repress the packing gland. This scheme is suitable for occasions where the number of valve opening and closing is small.
If the number of times the valve is opened and closed frequently (such as opening and closing 10-30 million times a year), this will undoubtedly increase the use and maintenance costs of the valve.
Is there a design that can still be sealed after the valve is opened or closed 100-200 million times? The answer is yes.
One approach is to add a washer under the packing and add 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-pressed and sealed. This method is currently used to test, can only be opened and closed 50-100 million times without leaking, requiring the user to re-compacting the packing gland during the annual overhaul, can only reduce the usual maintenance.
Another method is to use hydraulic and pneumatic sealing technology to change the original valve design ideas, use oil cylinder seal slip ring at the packing, increase the type 0 seal ring (required to calculate friction, seal specific pressure, in order to determine the slip ring and 0 Number of seals). By using this method, it can achieve up to 2 million times of opening and closing without leaking, but the type 0 sealing ring needs to be aged, the use time is only 5 years, and the cost is high.
If the number of times the valve is opened and closed frequently (such as opening and closing 10-30 million times a year), this will undoubtedly increase the use and maintenance costs of the valve.
Is there a design that can still be sealed after the valve is opened or closed 100-200 million times? The answer is yes.
One approach is to add a washer under the packing and add 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-pressed and sealed. This method is currently used to test, can only be opened and closed 50-100 million times without leaking, requiring the user to re-compacting the packing gland during the annual overhaul, can only reduce the usual maintenance.
Another method is to use hydraulic and pneumatic sealing technology to change the original valve design ideas, use oil cylinder seal slip ring at the packing, increase the type 0 seal ring (required to calculate friction, seal specific pressure, in order to determine the slip ring and 0 Number of seals). By using this method, it can achieve up to 2 million times of opening and closing without leaking, but the type 0 sealing ring needs to be aged, the use time is only 5 years, and the cost is high.
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