Gate valves and globe valves are two types of shut-off valves that are extremely common in everyday industrial applications. Although their functions are similar, but in the working principle, design features and applicable scenes have significant differences.
First, let’s understand these two valves from the working principle. The design of the gate valve is characterized by its handwheel rotation, the valve stem will be up or down movement, thus driving the spool to open or close the pipeline. This design makes the gate valve in the opening of the fluid flow resistance is small, because the spool and the valve seat sealing surface between the contact area in the opening process gradually decreases. Globe valves, on the other hand, are designed to rotate the valve stem (and attached spool) together and up or down by rotating the handwheel. During closing, the spool of a globe valve needs to be forced into close contact with the sealing surface of the valve seat in order to achieve a sealing effect.
Visually, gate valves are usually shorter and taller than globe valves, especially open stem gate valves, which require a higher installation space. The sealing surface of the gate valve has a certain self-sealing ability, i.e., the spool will closely fit the sealing surface of the valve seat under the action of medium pressure to prevent leakage. However, the spool and seat sealing surfaces of a gate valve will always be in contact and rub against each other during opening and closing, which can lead to wear of the sealing surfaces, especially when the valve is close to closing.
In contrast, the sealing surfaces of a globe valve only come into contact with each other when the valve is fully closed. This design reduces the amount of relative slip between the spool and the sealing surfaces, thereby reducing sealing surface wear. However, it is worth noting that if there is debris between the spool and the sealing surface, or if the closing condition is not tight, the high velocity of the medium flushing may still cause the sealing surface to wear.
When installed, the globe valve can choose to enter from below or above the spool depending on the direction of media flow. The advantage of entering from below is that the service life of the packing (a sealing material) can be extended, but the disadvantage is that the driving torque is larger and the valve stem is easily bent. Therefore, this method is usually only applicable to small-diameter manual globe valves. Motorized globe valves, on the other hand, tend to be accessed from above.
In the field of application, gate valves and globe valves have their own advantages. Gate valves are commonly used in steam pipelines and large-diameter water supply pipelines due to low resistance to fluid flow. Globe valves, on the other hand, are more commonly used in small passages where a high degree of leak tightness is required, due to their better shut-off seal and simple construction.
In general, although both gate valves and globe valves are used to cut off or connect the medium of the valve, but their working principle, design features and applicable scenes are different. Understanding these differences helps us to choose the right type of valve according to the actual needs.