Various valve pressure test methods (two)

1. Pressure test method of butterfly valve
The strength test of the pneumatic butterfly valve is the same as that of the globe valve. The sealing performance test of the butterfly valve should introduce the test medium from the medium flow end, the butterfly plate should be opened, the other end should be closed, and the injection pressure should reach the specified value; after checking that there is no leakage at the packing and other seals, close the butterfly plate, open the other end, and check the butterfly valve. It is qualified if there is no leakage at the plate seal. Butterfly valves used to regulate flow may not be tested for sealing performance.

2. Pressure test method of plug valve
① When carrying out the strength test of the plug valve, the medium is introduced from one end, the rest of the passages are closed, and the plug is rotated to each working position of the fully open one by one for the test. If no leakage is found in the valve body, it is qualified.

② During the tightness test, the straight-through cock should keep the pressure in the cavity equal to that of the passageway, rotate the plug to the closed position, check from the other end, and then rotate the plug 180° to repeat the above test; three-way or four-way plug valves The pressure in the cavity and one end of the passage should be kept equal, the plugs are rotated to the closed position in turn, the pressure is introduced from the right-angle end, and the inspection is carried out from the other end at the same time.

Before the plug valve test, it is allowed to coat a layer of non-acid thin lubricating oil on the sealing surface, and it is qualified if no leakage and enlarged water droplets are found within the specified time. The test time of the plug valve can be shorter, generally 1-3 minutes according to the nominal diameter. The plug valve for gas should be tested for air tightness at 1.25 times the working pressure.

3. Pressure test method of diaphragm valve
Diaphragm valve strength test Introduce the medium from either end, open the disc, and close the other end. After the test pressure rises to the specified value, it is qualified if there is no leakage from the valve body and bonnet. Then reduce the pressure to the tightness test pressure, close the valve disc, open the other end for inspection, and if there is no leakage, it is qualified.

4. Pressure test method of globe valve and throttle valve
For the strength test of globe valve and throttle valve, usually put the assembled valve in the pressure test frame, open the valve disc, inject medium to the specified value, and check whether the valve body and valve cover are sweating and leaking. The strength test can also be carried out on a single piece. The tightness test is only for the stop valve. During the test, the valve stem of the stop valve is in a vertical state, the valve disc is opened, the medium is introduced from the lower end of the valve disc to the specified value, and the packing and gasket are checked; after passing the test, the valve disc is closed, and the other end is opened to check whether there is leakage. If the strength and sealing test of the valve is to be done, the strength test can be done first, and then the pressure is reduced to the specified value of the sealing test, and the packing and gasket are checked; then the valve disc is closed, and the outlet port is opened to check whether the sealing surface is leaking.

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