6.For globe valve and choke valve

When it comes to the strength test of the globe valve and the choke valve, the assembled valve is usually placed in the pressure test frame. Then, open the wedge, inject the medium to the specified value, finally check if the body and the bonnet of the valve‘sweat’or leak.

Only the globe valve can be put in the sealing performance test. During the test, keep the stem vertical; open the wedge. Introduce the medium from the down end to the specified value; check the packing and gasket. If the valve is clear, close the wedge and check the other end.

If the valve strength and sealing test are both required. Do the strength test first. Then turn down the pressure to the specified value of the sealing test, check the packing and gasket; then close the wedge. Check the outlet end whether the sealing surface is leaking.

7.For gate valve

The strength test of the gate valve is the same as that of the globe valve. There are two methods for the gate valve sealing test.

Open the wedge, turn up the inner pressure to the specified value; Then close the wedge, immediately take out the gate valve, check whether there is leakage at the seals on both sides of the gate, or directly inject the test medium into the plug on the valve cover to the specified value, check the seals on both sides of the wedge. This method is called the 'intermediate pressure test'. This method should not be carried out to the gate valve less than DN32.

Another method is to open the gate and increase the test pressure to the specified value; then close the gate and open the blind disc(flange cover) at one end to check whether the sealing surface leaks. Then turn around the valve and repeat the above test until it is qualified.

The sealing test to the packing and gasket of the pneumatic gate valve should be conducted before the gate sealing test.

8.For safety valve

The strength test of the safety valve is the same as that of other valves.  When testing the lower part of the body, the pressure is introduced from the inlet end and the sealing surface is closed; when test the upper part of the body and the bonnet, the pressure is introduced from the outlet end and the other end is closed. The valve body and bonnet are qualified if no leakage happens in the given time.

More articles about testing methods of various valves:

Pressure testing methods of various valves Ⅰ

Pressure testing methods of various valves Ⅱ