In general, the valve should be installed before the valve hydraulic test bench for valve strength test and valve seal test. The commonly used media for valve pressure test are water, oil, air, steam, nitrogen, etc. The pressure test methods for various industrial valves including pneumatic valves are as follows:
01 Pressure test method of stop valve and throttle valve
For the strength test of stop valve and throttle valve, the assembled valve is usually placed in the pressure test rack, the valve disc is opened, the medium is injected to the specified value, and the valve body and valve cover are checked for sweat and leakage. Can also be a single piece of strength test. Only stop valve shall be used for tightness test. During the test, the valve stem of the stop valve is in a vertical state, the valve flap is opened, and the medium is introduced from the bottom end of the valve flap to the specified value, and the packing and gasket are checked; after being qualified, close the valve flap and open the other end to check whether there is leakage. If the valve strength and sealing tests are to be done, the strength test can be done first, then the pressure is reduced to the specified value of the sealing test, and the packing and gasket are checked. Then close the valve clack and open the outlet end to check whether the sealing surface leaks.
02 Pressure test method of gate valve
The strength test of the gate valve is the same as that of the stop valve. There are two methods for sealing test of gate valve.
① Open the gate to increase the pressure in the valve to the specified value; then close the gate, immediately take out the gate valve, check whether there is leakage at the seal on both sides of the gate or directly inject the test medium into the plug on the valve cover to the specified value, and check the seal on both sides of the gate. The above method is called intermediate pressure test.
② Another method is to open the gate to make the valve test pressure rise to the specified value; then close the gate, open one end of the blind plate, check the sealing surface for leakage. Turn the head again and repeat the above test until it is qualified.
03 Pressure test method of plug valve
① when the plug valve strength test, the medium from one end of the introduction, closed the rest of the passage, the plug in turn to the fully open the working position of the test, the valve body found no leakage is qualified.
② During the sealing test, the straight-through cock should keep the pressure in the cavity and the passage equal, rotate the plug to the closed position, check from the other end, and then rotate the plug by 180 ° to repeat the above test; the three-way or four-way cock valve should keep the pressure in the cavity and one end of the passage equal, rotate the plug to the closed position in turn, introduce the pressure from the right-angle end, and check from the other end.
04 Pressure test method of check valve
Check valve pressure test state: lift check valve disc axis in a position perpendicular to the horizontal; swing check valve channel axis and disc axis 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 to see that the valve body and valve cover have no leakage.
For the tightness test, the test medium is introduced from the outlet end, and the sealing surface is inspected at the inlet end. No leakage at the packing and gasket is considered as qualified.
05 Pressure test method of pressure reducing valve
The strength test of the pressure reducing valve is generally assembled after the single-piece test, or after the assembly test.
② The sealing test shall be carried out according to the actual working medium.
