A gate valve is the most widespread type of industrial valves for pipelines. Its application area is very wide. The gate valves operated with a handwheel or with the help of electric actuators are popular. A pneumatic or a hydraulic actuator can be applied as well.
Gate valves are usually distinguished by the construction of their shut-off parts, according to which the following valve types exist:
The shut-off part of the gate valve is designed in the form of a wedge, which can be flexible, with multiple plates or rigid.
Let us have a look at each of the subcategories:
To ensure a high hermiticity of gate valves, it is suggested to choose a stiff wedge. In this case, it is important to pay attention to the accuracy of wedge processing, which allows to coordinate the seat angle with the wedge angle without obstacles. In addition to that, rigid wedge application may cause dangerous events like gate jamming, or there can be problems with the opening of gate valves in case of temperature fluctuations, corrosion build-up or sealing damages.
The wedge consists of several plates which are securely bound to each other and are situated at an angle. Thanks to self-adjustment, the problem of the gate hermiticity in the closed position can be avoided.
Connected with an elastic part, the plates can clamp down and improve the sealing tightness in closed position. The advantage of gate valves with a flexible wedge for mounting in the pipeline is that there is no need of a complex adjustment of the valve body.
Its sealing surfaces are situated parallelly to each other, and there are two plates as well.
The knife gate valve is mainly distinguished through its peculiar construction and shut-off parts design. A knife gate valve is preferred when the face-to-face dimension has to be as small as possible. In the open position, no valve parts should be situated inside the pipe.