Safety valves are used as booster devices, vessels or pipes as an overpressure protection device. When the pressure in the equipment, container or pipeline exceeds the allowable value, the valve will automatically open and then discharge all to prevent the pressure in the equipment, container or pipeline from rising; when the pressure drops to the specified value, the valve should be automatically closed in time to Protect the safe operation of equipment, containers or pipes.
The safety valve can be driven directly by the system pressure at the valve inlet, in which case the mechanical load provided by the spring or hammer overcomes the pressure of the medium acting under the valve flap. They can also be controlled by a mechanism that releases or applies a closing force to open or close the safety valve. Therefore, according to the above driving method, the safety valve is classified into a direct acting type and a pilot type. The safety valve can be opened proportionally over the entire opening height range, or can be opened proportionally over a relatively large opening height range, or can be opened proportionally within a small opening height range and then suddenly opened to the fully open position. Therefore, the safety valve can be divided into proportional and full open. The construction, use and determination of the safety valve shall comply with the regulations or be approved by the statutory authority. Constraints and definitions may vary by specification. When applying a safety valve, the requirements of its applicable code must be followed.
Three possibilities for safety valve to jump and leak
The first one is that your safety valve has a small leak when it is inspected, but it is not easy to find, so a small leak point will expand in the middle of the erosion, the test method is to test the pressure test, the more rigorous method is in the seal In the sealing surface test, the water will cover the sealing surface and the back pressure will be foamed. The safety valve program stipulates that the soft seal must be bubble free and a hard seal may be available, but the bubble generation rate must be within a certain range. This should be done after the calibration is completed, as the safety valve may break the sealing surface during the calibration process.
The second type is the fatigue of the spring. The spring is affected by temperature and environment (if the safety valve is closed, the influence of the medium is also considered). If the reason is the safety valve selection or quality problem.
Third, the pipeline factors, such as vibration and shock, cause the safety valve to be set too high, and the valve core is separated from the valve seat sealing surface, causing damage and slag inclusion. In fact, the safety valve manufacturing requirements are quite high, especially for power station safety valves. Since the sealing force of the safety valve is equal to the spring force - medium pressure, and the general place such as the main steam of the power plant, the feed water pressure and the working pressure safety valve, the actual sealing surface sealing force is not too large, and the low pressure is expected to be good. The sealing surface has a high processing precision and high material requirements.
The third type: the performance of the spring must be very stable, because the higher temperature of the medium will cause the output of the spring to drop, which is not tightly sealed. In particular, steam safety valves have a recoil plate, and a general leak may cause the safety valve to jump, thereby affecting the power supply.
Do not recommend self-maintenance! Safety valves are an important part of ensuring the safe operation of equipment. Only qualified inspection units can inspect and maintain the safety valve. It is recommended to disassemble once a year and submit for inspection.
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