The commonly used wedge gate structures are divided into three types: elastic wedge, rigid wedge, and wedge type double gate. The sealing surfaces on both sides of the wedge gate have a certain inclination angle with the vertical centerline of the gate, which is called the wedge half angle. The size of the wedge half angle has a significant impact on the performance of the gate valve. When the angle is small, the force required to close the gate valve decreases, but at this time, when the pipeline is deformed due to temperature changes, the possibility of the wedge gate being wedged inside the valve body increases.

1. Elastic wedge

The characteristic of elastic wedge is its simple structure, reliable sealing, and difficulty in being wedged when the medium temperature changes. The machining accuracy requirements for the wedge angle are relatively low. For gate valves using elastic wedge plates, the closing torque should not be too large to prevent exceeding the elastic deformation range of the wedge. Therefore, the valve should be equipped with a limit mechanism to control the stroke of the wedge.

The elastic wedge structure is suitable for medium and small caliber gate valves of various pressures and temperatures. The medium should not contain too many solid particles to prevent them from accumulating in the annular groove of the wedge and affecting its elastic deformation ability.

2. Rigid wedge

The rigid wedge is a single piece solid structure that cannot compensate for changes in valve seat alignment caused by pipeline loads or thermal fluctuations. The machining accuracy of the wedge half angle on both sides of the sealing surface is very high, making manufacturing and maintenance difficult. During operation, the sealing pairs are prone to wear and tear, and the wedge is easily wedged when the temperature changes.

Wedge type rigid gate valves are considered the most economical, and almost all small gate valves up to DN50 (NPS2) use wedge type rigid gate plates, which are generally suitable for low pressure and temperature conditions.

3. Wedge type double gate

The wedge type double gate is composed of two gate plates, which are hinged with a spherical top center to form a wedge shaped gate plate. The angle can be freely adjusted to achieve a good fit with the two valve seats. The wedge angle of the gate seal can be automatically adjusted by the top center spherical surface of the middle link, thus requiring lower machining accuracy for the wedge angle of the sealing surface. When the temperature changes, it is not easy to get stuck or cause scratches. After the sealing surface of the ram is worn, a gasket can be added at the top center to compensate for it, making it easy for maintenance.

The disadvantage is that the structure is complex and there are many parts, which are not suitable for viscous media. Due to the movable connection of the gate, long-term corrosion can easily cause the gate to fall off. Usually installed vertically on pipelines for water and steam media.