1. Conduct the following tests on each valve:
(1) Normal temperature shell strength test; normal temperature and low pressure upper seal test; normal temperature and low pressure seal test;
(2) Low-temperature upper seal air tightness test (when there is an upper seal); low-temperature air seal test, etc. to ensure that the entire low-temperature valve meets the standards;
(3) Perform low-temperature treatment on the main components and conduct low-temperature impact tests on each batch of samples to ensure that the valve will not be brittle under low-temperature conditions and can withstand the impact of low-temperature media;
(4) Low-temperature (cryogenic) valves are subject to low-temperature treatment and impact testing in accordance with corresponding material specifications;
(5) The conduction resistance between the valve body and the valve stem or the trim and the valve body is less than 1 ohm.
2. Low temperature valve testing equipment:
Cryogenic valve test device, liquid nitrogen storage device, cryogenic treatment tank
3. Low temperature valve test method:
(1) Preparation before test
Remove oil stains from valve parts, wipe them clean and assemble the valve in a clean, dust-free and oil-stained environment; tighten the bolts to the predetermined torque and tension values, and record the values; use a suitable thermocouple with The valve is connected so that the temperature of the valve can be monitored throughout the test.
(2) Test
Install the valve in the test container and connect it well. Make sure that the valve packing is in a position where there is no vaporized gas at the top of the container. Conduct an initial system verification test at room temperature with the specified medium gas and a large valve seat test pressure to ensure that the valve is in the appropriate position. state, and then start the test by immersing the valve in liquid nitrogen for cooling. The level of the liquid at least covers the connection between the valve body and the valve cover, and helium is continuously supplied to the valve during the entire cooling process. During the cooling process, the temperature of the valve is monitored using thermocouples installed in appropriate locations. The valve reaches stability at the test temperature. Use a thermocouple to measure the temperature to ensure that the valve temperature is uniform. Conduct an initial verification test using helium at a large valve seat test pressure at the test temperature. Conduct a valve seat pressure test on the inlet side of the valve. For valves that can seal in both directions, test the two valve seats separately. Put the valve in the open position, close the needle valve on the outlet side of the valve, and raise the pressure in the valve cavity to the valve seat test pressure. Keep the pressure to the specified requirements, and check whether there is leakage at the valve packing and the connection between the valve body and the cover. There should be no leakage. Return the valve to room temperature, and then perform a normal temperature sealing test. After the test is completed, clean and dry the valve and leave the factory after passing the inspection.
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