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Why cannot globe valves and gate valves be used interchangeably? However, globe valves and gate valves share some similarities in appearance, and both are used to shut off flow in pipelines; as a result, many people who are not familiar with valves tend to confuse the two. This article explains the differences between globe valves and gate valves. I. Structurally, when the installation space is limited, certain considerations should be taken when selecting a valve: Gate valves can rely on the pressure of the medium to press tightly against the sealing surface, thereby preventing leaks. When the valve is opened or closed, the valve core and the sealing surface of the valve seat are in constant contact and in friction with each other; as a result, the sealing surfaces wear out easily. When the gate valve is near its closed position, there is a large pressure difference before and behind the pipe, which further accelerates the wear of the sealing surfaces. The structure of a gate valve is more complex than that of a globe valve. In terms of appearance, for the same diameter, a gate valve is taller than a globe valve, while a globe valve is longer than a gate valve. Additionally, gate valves are divided into those with exposed stems and those with concealed stems, whereas globe valves do not have this distinction. II. Working Principle: When a stop valve is opened or closed, it uses a rising stem design; that is, when the handwheel is turned, it rotates and moves up and down along with the stem. A gate valve operates by turning a handwheel, which causes the valve stem to move up and down, while the position of the handwheel itself remains unchanged. The flow rates vary; gate valves require to be fully open or fully closed, whereas globe valves do not. Globe valves have specified inlet and outlet directions, while gate valves have no such requirements. Furthermore, gate valves can only be in either fully open or fully closed positions; the stroke for opening and closing the gate is large, resulting in a long time required for such operations. The travel distance of the valve disc in a globe valve is much smaller, and the valve disc of a globe valve can stop at a certain position during movement to regulate flow. A gate valve can only be used for shutting off flow; it has no other functions. III. Performance differences: Globe valves can be used for both shutting off flow and regulating flow. Gate valves have relatively high fluid resistance, making it difficult to open and close them; however, the distance between the valve disc and the sealing surface is short, resulting in a short opening and closing stroke. Since a gate valve can only be in an fully open or fully closed position, when it is fully open, the flow resistance of the medium within the valve body’s passage is almost zero; therefore, operating a gate valve requires very little effort. However, the distance between the gate and the sealing surface is large, which results in longer operation times. IV. Installation and Flow Direction: The gate valve functions equally in both directions; there is no requirement regarding the inlet or outlet direction for installation, and the medium can flow in either direction. Gate valves must be installed strictly in the direction indicated by the arrows on the valve body. There is also a clear specification regarding the inlet and outlet directions of gate valves: according to China’s regulations on valve standards, the flow direction of gate valves must always be from top to bottom. A globe valve has low inlet and high outlet; visually, it is clear that the pipes are not on the same horizontal level. The flow channel of a gate valve is on a horizontal line, and its stroke is greater than that of a globe valve. From the perspective of flow resistance, gate valves have low flow resistance when fully open, while globe valves have high flow resistance. The flow resistance coefficient of a regular gate valve is approximately 0.08~0.12; it requires little force to open and close, and the medium can flow in both directions. The flow resistance of a standard globe valve is 3-5 times that of a gate valve. To achieve sealing when opening and closing, forced closure is required; in a globe valve, the valve disc comes into contact with the sealing surface only when it is completely closed, which results in minimal wear of the sealing surface. For globe valves that require an actuator due to high flow forces, attention should be paid to adjusting the torque control mechanism. There are two ways to install stop valves. In one method, the medium can enter from below the valve core; the advantage of this is that the packing is not under pressure when the valve is closed, which helps to extend its lifespan. It is also possible to replace the packing while the pipeline ahead of the valve is still under pressure ； The disadvantage is that the driving torque of the valve is relatively high, about twice that of the flow coming from above; the axial force on the valve stem is large, causing it to bend easily. Therefore, this method is generally only suitable for small-diameter globe valves (below DN50); for globe valves with a diameter of DN200 or more, the approach of allowing the medium to flow in from above is used. (Electric globe valves generally use a method in which the medium enters from above.) The disadvantages of the method with medium entering from above are exactly the opposite of those of the method with medium entering from below. V. Sealing: The sealing surface of the stop valve is a small trapezoidal side surface on the valve core (depending on the shape of the valve core); once the valve core comes loose, it means the valve is closed (of course, it won’t seal tightly if there is a large pressure difference, but its check function remains good). Globe valves rely on the side surfaces of the valve core gate to achieve sealing; their sealing performance is not as good as that of globe valves. Moreover, if the valve core comes loose, it does not result in the valve closing in the same way as with globe valves.