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Test processes
The matching relationship test between pressure of the hydro-cylinder and pressure of the medium and temperature is relatively complicated, and the specific test procedures are implemented according to technical requirements.

(1) First, put the valve in a semi-closed state, and start the hydraulic station. Turn on the electric heater. Meanwhile, use cold air to send air to the cooling pipe of the valve stem, valve core and valve seat. When the thermocouple shows that the temperature is 505℃, close the valve and open the gas cylinder regulating valve and the deep control valve. Pressurize the inner cavity by using a high pressure nitrogen cylinder as the pressure source, and inlet pressure of valves are ensured by the gas cylinder regulating valve and deep control valve. When the sealing surface of the valve leaks, the leaked gas will enter the distilled water bottle through the needle valve at the outlet end, resulting in generating bubbles. The leakage amount is measured by the flow meter. When the pressure gauge shows that the pressure is 1MPa, operate the solenoid valve to make oil enter the hydro-cylinder that controls the valve stem of the thermal valve. Gradually increase pressure of the hydro-cylinder from low to high to seal the valve. Observe the distilled water bottle. If there is no bubbles, the valve is sealed. Record the working pressure of the hydro-cylinder at this time. Use this pressure to test 3 times continuously, and the effect is very close. This value is listed as the official test value.

(2) The second test is to keep the temperature in the valve body constant. Increase the test pressure of the inner cavity of the valve body inlet end to 2MPa, then the sealing surface of the valve body will leak (the distilled water bottle having bubbles). Slowly increase the working pressure of the hydro-cylinder until there are no bubbles. Repeat 3 times and record the working pressure of the hydro-cylinder at this time.

(3) According to the above method, the pressure of the inner cavity at the inlet end of the valve body is 4MPa, 6MPa, 8MPa, 10MPa and 12MPa. After adjusting the pressure of the reducing valve each time, record the working pressure of the hydro-cylinder.

(4) According to different temperatures, adjust the working pressure of the hydro-cylinder until 35 different temperature and pressure tests are completed. Records of 35 working pressure of hydro-cylinders are obtained to complete the test.

(5) Table 1 is a set of test data. The working pressure of the valve is 1MPa, 2MPa, 4MPa, 6MPa, 8MPa, 10MPa and 12MPa, and the working temperatures of the valve is 505℃, 611℃, 715℃, 809℃ and 900℃. Combine the working pressure with the working temperature and perform 35 tests totally. According to the test data results, the allowable sealing pressure of STL hard alloy at high temperature can be calculated. In the actual application of the valve, on the premise of ensuring the sealing performance, a reasonable driving force can be applied to the valve driving mechanism to increase the service life of the valve. The test results have been effectively verified by the working condition system.

Conclusion
The development and testing of high pressure and ultra high temperature hydraulically controlled globe valves are complex systems. Outstanding structures, material selections, heat insulation, cooling systems and hydraulic automatic control systems can provide a reliable operating basis for users.

 
Dec 07,2020
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