The advantage of gate valves that has a flexible wedge for mounting inside pipeline from aoaltwar's blog

A Gate valve is really a linear motion on-off or shut-off valve. The gate-valve covers a disc or wedge having two seating surfaces that will in contact using the valve seats produce a seal for stopping the flow check here. The pressure differential between your upstream flow direction and downstream side of wedge causes the wedge or disc to push against the downstream seat creating more effective sealing within the downstream side on the wedge. Gate valve sits dormant to regulate flow as erosion of disc and seat could cause leakage. A gate valve in partially open or closed position is additionally susceptible to vibration.

The shut-off part in the gate valve was created in the form of the wedge, that is flexible, with multiple plates or rigid.

Let us look at each with the subcategories:
Rigid wedge
To ensure a top hermiticity of gate valves, it is strongly recommended to choose a stiff wedge. In this case, you have to pay attention on the accuracy of wedge processing, that enables to coordinate the seat angle while using wedge angle without obstacles. In addition to that, rigid wedge application might result in dangerous events like gate jamming, or there is problems while using opening of gate valves regarding temperature fluctuations, corrosion build-up or sealing damages.

Wedge with 2 plates
The wedge includes several plates that happen to be securely guaranteed to each other and are also situated with an angle. Thanks to self-adjustment, the problem on the gate hermiticity inside closed position could be avoided.

Flexible wedge
Connected with the elastic part, the plates can clamp down and enhance the sealing tightness in closed position. The advantage of gate valves having a flexible wedge for mounting from the pipeline is there is no need of the complex adjustment on the valve body.

The varieties of rising-stem gate valve is usually divided into wedge disc gate valve and parallel disc gate valve based on the sealing surface configuration. Wedge disc gate valve is usually divided into: single disc type, double disc type and elastic disc type; parallel disc Type gate valve is usually divided into single disc type and double disc type. According on the thread position in the valve stem, it could be divided into rising-stem gate valve and non rising-stem gate valve.

When the rising-stem gate valve is closed, the sealing surface are only able to rely about the medium pressure to seal, that's, only rely about the medium pressure to press the sealing surface from the disc for the valve seat within the other side to guarantee the sealing on the sealing surface, and that is self-sealing. Most gate valves adopt forced sealing valve, that is certainly, once the valve is closed, the disc need to be forced for the valve seat by external force to guarantee the tightness with the sealing surface.