Pressure test method of check valve
Check valve test state: lift check valve disc axis is in a position perpendicular to the horizontal; swing check valve channel axis and disc axis are in a position approximately parallel to the horizontal line.
During the strength test, the test medium is introduced from the inlet end to the specified value, and the other end is closed. It is qualified if there is no leakage in the valve body and bonnet.
In the sealing test, the test medium is introduced from the outlet end, and the sealing surface is checked at the inlet end. No leakage at the packing and gasket is qualified.
Pressure test method of pressure reducing valve
The strength test of the pressure reducing valve is generally assembled after a single piece test, and it can also be tested after assembly. The duration of the strength test: 1min for DN<50mm; more than 2min for DN65～150mm; more than 3min for DN>150mm. After the bellows and the components are welded, apply 1.5 times the maximum pressure after the pressure reducing valve, and conduct a strength test with air.
The sealing test is carried out according to the actual working medium. When testing with air or water, perform the test at 1.1 times the nominal pressure; when testing with steam, perform the test at the highest allowable working pressure at the working temperature. The difference between the inlet pressure and the outlet pressure must not be less than 0.2MPa. The test method is: after the inlet pressure is adjusted, gradually adjust the adjusting screw of the valve so that the outlet pressure can be changed sensitively and continuously within the range of the maximum and minimum values without stagnation or jamming. For the steam pressure reducing valve, when the inlet pressure is adjusted away, the valve is shut off and the outlet pressure is the highest and lowest value. Within 2 minutes, the rise in the outlet pressure should meet the requirements in Table 4.176-22. At the same time, the pipeline behind the valve The volume meets the requirements in Table 4.18 as qualified; for water and air pressure reducing valves, when the inlet pressure is adjusted and the outlet pressure is zero, the pressure reducing valve is closed and the tightness test is performed. No leakage within 2 minutes is qualified.
