The wedge gate leaves the valve seat at the moment of opening, reducing the wear of the sealing surface. The sealing surface is welded with cobalt-based alloy to improve the high temperature performance, fatigue resistance, corrosion resistance and sealing surface hardness of the sealing surface.

Wedge gate valve standard: GB /T12234-2019 Steel gate valve with bolted valve cover for petroleum and natural gas industry. GB/T12232-2005 General valve flange connection iron gate valve. API STANDARD 600-2015.

The gate of the wedge gate valve is divided into: wedge-type single gate. Wedge-type elastic gate. Wedge-type double gate. Common flange cast steel wedge gate valve combination models are as follows:

Flange rising stem wedge elastic gate Z40H

Flange rising stem wedge rigid single gate Z41H

Flange rising stem wedge rigid double gate Z42H

Flange non-rising stem wedge rigid single gate Z45H

Flange non-rising stem wedge rigid double gate Z46H

 

1. Wedge-type single gate, that is, rigid single gate. The gate is an integral wedge, with an inverted T-shaped groove on the upper end of the gate, which is connected to the valve stem through the inverted T-shaped groove. The sealing surfaces on both sides of the wedge-shaped gate are sealed with the valve seats on both sides respectively. The inverted T-shaped groove of the gate and the valve stem are movably connected, which can compensate for the errors caused by processing, so that the gate sealing surface and the valve seat sealing surface fit together better to complete the sealing.

The gates of non-rising stem gate valves and rising stem gate valves are different. The non-rising stem gate has a through hole in the direction of the valve stem axis, which can accommodate the valve stem when the gate is open.

 

2. The wedge-type elastic gate is based on a rigid single gate, and an annular groove is machined on the vertical bisecting surface of the gate, and only the center of the gate is connected together. The gate sealing surface has a certain elastic deformation ability. When the gate is closed, the deviation of the wedge angle between the gate sealing surface and the valve seat sealing surface can be compensated, thereby ensuring the sealing surface effect.

When the high-temperature medium in the pipeline, the gate, valve stem and other parts expand. It may cause the gate to swell and die with the valve seat when it is in the closed position. The gate cannot be opened normally. The elastic deformation ability of the elastic gate is very good to avoid the gate stuck phenomenon.

The elastic gate has good sealing performance and small switching torque, which is suitable for high-temperature pipelines.

 

3. The wedge-type double gate is to disconnect the middle connecting part of the elastic gate, forming two gates on the inlet and outlet sides. The middle is connected to form a wedge gate with a spherical top core. When the gate is closed, since there is a spherical top center structure between the inner sides of the two gates, as the gates descend, the distance between them gradually decreases, and the two gates are pushed outward by the spherical top center structure. The sealing surfaces of the gates at the inlet and outlet are pressed against the valve seat to complete the seal.

When the gate is opened, since the spherical top center structure does not have the inclination of the self-locking effect like the wedge-shaped sealing surface, the two movable gates can move inward under the fluid pressure after the gate is slightly loosened with a small force, and the friction between the gate and the valve seat port is released, which not only saves effort in the opening operation, but also reduces the friction between the gate and the valve seat port, thereby reducing wear.

The gates on both sides are movably connected, and their ability to compensate for deformation far exceeds that of elastic gates. It can better complete the seal with the valve seat and reduce internal leakage. It is not easy to get stuck when the temperature changes, and at the same time reduces the wear of the sealing surface. However, it is easy to bond in easy-to-crystallize, viscous media, affecting the seal.

From wedge-type rigid single gate to wedge-type elastic gate, and then to wedge-type double gate, the automatic compensation of gate and valve seat processing errors has been gradually solved, and the gate valve can adapt to the medium from normal temperature to high temperature. However, the gate structure is becoming more and more complicated, and the cost is getting higher and higher. Therefore, it is best to choose a gate valve that suits your working conditions.