What is the difference between a globe valve and a gate valve?

Valves are control components in fluid conveying systems that have functions such as cutoff, regulation, diversion, prevention of reverse flow, pressure stabilization, diversion, or overflow pressure relief. The valves used in fluid control systems range from the simplest globe valves to various valves used in extremely complex automatic control systems, with a wide variety of varieties and specifications.
Globe valves, gate valves, butterfly valves, check valves, and ball valves are all indispensable control components in various pipeline systems today. Each type of valve has differences in appearance, structure, and even functional use. But there are some similarities in the appearance of globe valves and gate valves, and both have the function of cutting off in pipelines. Therefore, many friends who have little contact with valves may confuse the two. In fact, if you carefully observe, the difference between globe valves and gate valves is quite significant.
1. Structurally
When the installation space is limited, it is important to pay attention to the selection. The gate valve can rely on the medium pressure to tightly close the sealing surface, thus achieving the effect of no leakage. When opening and closing, the sealing surface of the valve core and valve seat always contacts and rubs against each other, making the sealing surface easy to wear. When the gate valve is close to closing, the pressure difference between the front and rear of the pipeline is large, making the sealing surface wear more severe.
2. Working principle
When the shut-off valve is opened and closed, it is an upward stem type, which means that when the handwheel is turned, it will rotate and lift along with the valve stem. And the gate valve rotates the handwheel to make the valve stem move up and down, while the position of the handwheel itself remains unchanged. The flow rate varies, and gate valves require full opening or full closing, while globe valves do not. The shut-off valve has specified inlet and outlet directions; There is no requirement for the inlet and outlet direction of the gate valve.
In addition, the gate valve only has two states: fully open or fully closed, and the opening and closing stroke of the gate plate is large, resulting in a long opening and closing time. The travel of the valve plate of the shut-off valve is much smaller, and the valve plate of the shut-off valve can stop at a certain position during movement for flow regulation. The gate valve can only be used for cutting off and has no other functions.
The structure of a gate valve is more complex than that of a globe valve. From the appearance, under the same caliber, the gate valve is taller than the globe valve, and the globe valve is longer than the gate valve. In addition, there are two types of gate valves: open stem and non rising stem. The shut-off valve is not available.
3. Performance Differences
The shut-off valve can be used for both cut-off and flow regulation purposes. The fluid resistance of the shut-off valve is relatively high, making it difficult to open and close. However, due to the short distance between the valve plate and the sealing surface, the opening and closing stroke is short.
The gate valve can only be fully opened and fully closed. When fully opened, the medium flow resistance in the valve body channel is almost zero, so the opening and closing of the gate valve will be very labor-saving. However, the distance between the gate plate and the sealing surface is far, and the opening and closing time is long.
4. Installation and Flow Direction
The flow direction of the gate valve has the same effect in both directions, and there is no requirement for inlet and outlet direction during installation. The medium can flow in both directions. Globe valves need to be installed strictly in accordance with the direction indicated by the arrow on the valve body. There is also a clear regulation regarding the inlet and outlet directions of globe valves. According to the "Three Chemicals" regulations for valves in China, the flow direction of globe valves is always from top to bottom.
The shut-off valve is low in and high out, and from the appearance, there is a clear pipeline that is not on the same level line. The flow path of the gate valve is on a horizontal line. The stroke of the gate valve is larger than that of the globe valve.
From the perspective of flow resistance, when fully open, the gate valve has a small flow resistance and the load check valve has a large flow resistance. The flow resistance coefficient of a regular gate valve is about 0.08~0.12, with a small opening and closing force, and the medium can flow in two directions. The flow resistance of ordinary stop valve is 3-5 times that of gate valve (official account: pump steward). When opening and closing, it is necessary to forcibly close to achieve sealing. The valve core of the shut-off valve only contacts the sealing surface when it is completely closed, so the wear on the sealing surface is very small. Due to the large flow force, the shut-off valve that requires an actuator should pay attention to the adjustment of the torque control mechanism.
There are two ways to install globe valves. One is that the medium can enter from below the valve core. The advantage is that the packing is not under pressure when the valve is closed, which can extend the service life of the packing and replace the packing when the pipeline in front of the valve is under pressure; The disadvantage is that the driving torque of the valve is relatively large, which is about twice that of the upstream flow. The axial force on the valve stem is large, and the valve stem is prone to bending. So this method is generally only applicable to small diameter globe valves (below DN50), and globe valves above DN200 use the method of medium flowing in from above. (Electric shut-off valves generally use the method of medium entering from above.) The disadvantage of medium entering from above is exactly the opposite of entering from below.
5. Sealing
The sealing surface of the shut-off valve is a small trapezoidal side of the valve core (depending on the shape of the valve core). Once the valve core falls off, it is equivalent to the valve closing (if the pressure difference is large, of course it cannot be tightly closed, but the check effect is still good). The gate valve is sealed by the side of the valve core and the sealing effect is not as good as the shut-off valve, and the valve core falling off will not be equivalent to the valve closing like the shut-off valve.