Butterfly valve, gate valve, globe valve, working principle and pressure test method of various valves

Globe valve

working principle

The closing principle of the globe valve is to rely on the valve stem pressure to make the disc sealing surface and the valve seat sealing surface closely fit to prevent the medium from flowing.

The shut-off valve only allows the medium to flow in one direction and is directional when installed. Its structural length is greater than that of the gate valve, and the fluid resistance is large, and the sealing reliability is not strong during long-term operation. There are three types of globe valves: straight-through, right-angle and direct-flow oblique globe valves.

Stop valve function

The cut-off valve, also called the cut-off door, plays an important role in cutting off and throttling the medium in the pipeline.

The globe valve is a very widely used valve. The reason why it is so popular is that the friction between the sealing surfaces during the opening and closing process is small, it is relatively durable, has a small opening height, is easy to manufacture, and is convenient to maintain. It is not only suitable for medium Low pressure, but also suitable for high pressure.

Pressure test method

In the strength test, the assembled valve is usually placed in the pressure test rack, the valve flap is opened, the medium is injected to the specified value, and the valve body and bonnet are checked for sweat and leakage. The strength test can also be performed on a single piece.

During the sealing 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. Check the packing and gasket; after passing the test, close the valve flap and open the other end to check for leakage leak.

If both the valve strength and tightness tests are to be done, the strength test can be done first, then the pressure is reduced to the specified value of the tightness test, and the packing and gaskets are checked; then the valve flap is closed and the outlet end is opened to check whether the sealing surface is leaking.