On the valve hydraulic test bench, the valve strength test and valve sealing test should be carried out before the valve is installed. Perform a 20% spot check on low-pressure valves. If they are unqualified, 100% should be checked, and medium and high-pressure valves should be 100% checked. Common valve pressure test media include water, oil, air, steam, nitrogen, etc. The methods of pneumatic test pressure for various industrial valves are as follows:
Cut-off valve and throttle valve pressure test method.
In the strength test, the shut-off valve and the throttle valve, usually the pulse solenoid valve assembled valve is placed on the pressure test rack, the valve flap is opened, the medium is injected until the specified value, and the valve body and valve cover are checked for sweat and leakage. . The strength test can also be performed separately. The air tightness test is only for shut-off valves. During the test, the stem of the shut-off valve is in a vertical state. When the disc is opened, the medium enters the specified position from the lower part of the disc, and the packing and gasket are checked; after the test is passed, the disc is closed and the other end is opened to check for leakage. If you want to test the strength and tightness of the valve, you can first perform the strength test, then reduce the pressure to the normal value of the tightness test, check the packing and gasket; then close the valve flap, open the outlet, and check whether the sealing surface is leaking.
Research on the pressure test method of gate valve.
The strength test of the gate valve is the same as that of the shut-off valve. There are two ways to detect the air tightness of the gate valve.
First, the gate is opened to increase the pressure in the valve to the specified value; then, the gate is closed, and the gate valve is immediately taken out to check whether the seals on both sides of the gate are leaking, or the test medium is directly injected into the plug on the valve cover until the specified value Value, check whether there is water leakage at the seals on both sides of the three-position solenoid valve gate. The above method is called intermediate pressure test. This method is not suitable for the sealing test of gate valves with a nominal diameter of DN32mm or less.
Second, open the gate to increase the test pressure of the valve to the specified value; then close the gate, open the blind plate, and check if there is any leakage on the sealing surface. Do the above test again until all passes. Before the sealing test of the gate, the packing and gasket of the pneumatic gate valve should be tested for sealing.