1. Valve assembly must be completed after the performance test to check whether the product meets the design requirements and whether the quality standards set by the state. Valve materials, rough, heat treatment, machining and assembly defects are generally exposed during the test. Conventional tests have shell strength test, seal test, low pressure seal test, action test, etc., and according to need, according to the order of one by one test after the next test. 2. Strength test: the valve can be seen as a pressure vessel, it must meet the pressure without the media to withstand the requirements, so the valve body, valve cover and other parts of the blank should not affect the intensity of cracks, loose pores, slag Other defects. Valve manufacturer in addition to rough appearance and internal quality of the rigorous testing, but also by the intensity of each test to ensure that the valve performance. Strength test is usually carried out after assembly. Unstable rough quality or welding parts must be heat-treated, in order to avoid and reduce the test failed due to the various waste, after rough machining of intermediate strength test (often called the hair pump). After the assembly of intermediate strength test assembly, if the user did not request, the valve can no longer strength test. Su valve in order to ensure the quality of the test in the middle strength, the valves are all the last strength test. Test is usually carried out at room temperature, in order to ensure safe use, test pressure P is generally 1.25 to 1.5 times the nominal pressure PN. During the test, the valve is open, one end is closed, the other end is filled with medium and pressure is applied. Check the shell (body, cover) exposed surface, requires the duration of the test (usually not less than 10 minutes) without leakage, can be considered that the valve strength test qualified. In order to ensure the reliability of the test, the strength test should be carried out before the valve is painted. When the water is the medium, the air in the cavity should be drained out. Leakage valve, if the technical conditions allow repair welding repair according to technical specifications, but after welding repair must be re-strength test, and the appropriate extension of the duration of the trial. 3. Seal test: In addition to the throttle valve, whether it is cut off with the valve or regulating valve, should have a certain degree of closure of the seal, so the valve seal test by the Taiwan factory, with a sealed valve to be carried out Seal test. The test is usually carried out at a nominal pressure PN at room temperature. The Su valve is normally operated at 1.1 times PN pressure. To water as the test medium, easy to rust valve, usually according to technical requirements to control water quality, and the residual water after the test blown dry or drying. Gate valve and ball valve due to two sealing pair, it is necessary to conduct two-way seal test. Test, the first valve to open, the channel closed at one end, the pressure introduced from the other end until the pressure rises to the required value of the valve will be closed, and then the plug end of the pressure gradually unloaded and checked. The other end also repeated the above test. Gate valve is another test method is to maintain the test pressure in the body cavity, both ends of the channel from the valve at the same time check the double seal. When testing the check valve, the pressure should be introduced from the outlet end and checked at the inlet end. Seal test, the valve closing torque should be nominal pressure and nominal diameter decision. Manual valves are usually only allowed to close with normal physical strength, but not with the help of other auxiliary equipment, when the hand wheel diameter ≥ 320mm, allowing two people to close. Valves with drive should be tested with the drive. If the technical requirements of the provisions of the closed torque requirements, the need to use force wrench to measure the closing torque. The seal test should be carried out after the strength test of the valve assembly, because not only to check the closing tightness of the valve, but also the tightness of the packing and the flange gasket. The upper seal test is usually carried out together with the strength test. Test and the valve stem to the limit position, the stem and the valve cover sealing surface in close contact, the packing gland after loosening check its sealing. Valves for gas media or drawings Technical requirements for low pressure gas seal test valve, the test standards must be carried out, the test medium is nitrogen or dry and clean air. The test pressure is 0.6MPa. 4. Performance test: test medium with the shell strength test and seal test, the shell strength test and seal test after passing. Manual valve action performance test: the valve is open, the valve cavity pressure to test pressure, with the specified torque to close the valve, reducing pressure on one side of the valve to open the valve in the most unfavorable and the direction of the establishment of pressure, and then The specified moment to open the valve, so at least three times more complete cycle of loading and unloading to check the valve opening and closing of the operation is normal, the action is flexible, the position of the opening and closing instructions are correct; check valve action performance test, In the provisions of the pressure difference for the valve to open the test, the number of tests of not less than 3 times; electric and pneumatic valve performance test, according to the provisions of the valve technical specifications, valve specifications no clear provisions should be rated actuator Operate the valve to complete three complete cycle of loading and unloading. Throughout the test, the valve must operate smoothly and flexibly. The valve must be open and closed, and the position indicator must be correct. 5. Vacuum seal test: Vacuum seal test (or vacuum leak test) is a highly sensitive seal test method. Aerospace and atomic energy industry valves and sealing valves are generally required for high vacuum sealing test. Vacuum test is usually carried out after the valve strength and seal test pass. To ensure the accuracy of the test, the valve should be tested with high cleanliness and precision machining of the sealing surface. And the valve body, valve cover should generally be used forgings. The usual method of vacuum sealing test is helium mass spectrometry. After the valve to be tested is evacuated to the specified degree of vacuum by the vacuum pump, helium gas (helium hood method or helium helium method) is applied outside the valve to be measured. If leak, helium will enter the measured part of the valve, the system of helium mass spectrometer leak detector can be displayed, according to which the leakage rate can be calculated. 6. Micro Leak Test: In recent years, as people's awareness of environmental protection, the world's various agencies on the valve seal made more stringent requirements, especially for the use of media is corrosive, strong radiation, highly toxic Time. One of these is the valve's requirement for fugitive emission. Valve Leak Detection (FE TEST) is mainly to check the valve flange and packing the Department of micro-leaks, valve housing seal test is a kind of. The basic principle of the valve micro-leak detection is: when the valve is in the half-open half-closed state, the helium gas with the specified pressure is passed to the inside of the valve; and the helium mass spectrometer leak detector with the suction probe with good leak rate adjusts the middle chamber And stuffing box parts for testing to see whether the site to meet the leakage rate specified by the user. Valve micro-leakage requirements is a direction of the development of the valve today, this micro-leakage requirements are in line with the requirements of nuclear power valves. (If reproduced, please indicate source)
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