Is there such a big difference between rising stem gate valve and concealed stem gate valve? A must-have for engineers!

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Rising stem gate valves and concealed stem gate valves are the two most commonly used types in the gate valve family. The core difference between the two is concentrated in the movement mode of the valve stem. This structural difference further extends to multiple dimensions such as protective performance, installation requirements, maintenance difficulty, applicable scenarios, etc. Below, from the core features to practical applications, the differences between the two are disassembled one by one to help quickly differentiate and select. 01 Differences in structure and valve stem movement The core feature of the rising stem gate valve is that the valve stem moves up and down synchronously with the lifting and lowering of the gate plate, and the threads on the valve stem are directly exposed to the outside of the valve body. When the valve opens, the gate rises and the valve stem extends upward from the top of the valve body. ； When the valve is closed, the gate plate descends and the valve stem retracts into the valve body. The opening degree of the valve can be directly judged by the extended length of the valve stem. Contrary to the concealed stem gate valve, the valve stem only rotates and does not rise or fall with the gate. The threads on the valve stem are hidden in the valve body and cooperate with the thread structure inside the gate. The rotation of the valve stem drives the gate plate to move up and down to realize the opening and closing of the valve. Viewed from the outside, the valve stem of the concealed stem gate valve always maintains a fixed length, and the lifting process cannot be directly seen. 02 Differences in performance and usage characteristics (1) Judgment of switching status The switching status of the rising stem gate valve is intuitively visible without additional markings. Only by extending or retracting the valve stem, you can quickly determine whether the valve is open or closed, as well as the extent of the opening. It is especially suitable for scenes with clear visual requirements for valve status, such as fire protection systems, pumping stations, etc. Operators can quickly check the valve status. It is impossible to judge the switching status of concealed stem gate valves directly by appearance, because the valve stem does not rise or fall, and can only be judged by the opening indication on the valve or the operating feel. If the indication indicates falling off or is blurred, misjudgment may easily occur, increasing the risk of operation. (2) Protective performance: The stem thread of the rising stem gate valve is exposed to the outside and is easily affected by the external environment, such as erosion by dust, water vapor, and corrosive gases. After long-term use, the thread is prone to rust, jamming, and even damage by external collisions. The protective performance is relatively weak and is more suitable for indoor, clean environments. The thread of the concealed stem gate valve is completely hidden in the valve body and is isolated from the external environment. It can effectively avoid the erosion of dust and corrosive media, and has better protection performance. It is suitable for outdoor, underground, or harsh environments where the medium itself is corrosive and contains impurities. (3) Installation space requirements: Because the valve stem of the rising stem gate valve needs to rise and fall when switching, sufficient stem lifting space must be reserved at the top of the valve body, otherwise it will affect the normal opening and closing of the valve. It is not suitable for installation under the suspended ceiling, in narrow equipment gaps and other places with limited space. The valve stem of the concealed stem gate valve does not rise and fall, but only rotates. There is no need to reserve lifting space at the top. The overall structure is more compact and is very suitable for scenes with small installation spaces, such as underground pipe networks, ship engine rooms, and equipment-intensive piping systems. (4) Maintenance Difficulty and Cost The threads of the rising stem gate valve are exposed and are relatively convenient to maintain. The threads can be cleaned and greased directly on a daily basis to reduce jamming and rust. There is no need to disassemble the entire valve during maintenance. The maintenance cost is low and the maintenance efficiency is high. The threads of the concealed stem gate valve are hidden in the valve body, and the threads cannot be directly contacted for daily maintenance. If problems such as thread jamming and rust occur, the entire valve needs to be disassembled for maintenance. Maintenance is difficult, time-consuming, and the maintenance cost is relatively high. (5) Applicable media and occasions Clear stem gate valves are more suitable for pipelines transporting clean media such as clean water, oil, and natural gas, because such media will not block or corrode exposed threads. Common application scenarios include water plants, pumping stations, fire protection systems, clean pipelines in the petrochemical industry, and water supply and drainage systems in high-rise buildings, etc. Concealed stem gate valves are suitable for transporting sewage, mud, wastewater containing impurities, and corrosive media in the chemical industry. Such media will not directly contact the valve stem threads, which can avoid thread damage. Common application scenarios include municipal sewage pipe networks, underground pipelines, ship pipelines, chemical corrosive media transportation pipelines, etc. (6) Cost: From the perspective of manufacturing cost, the structure of the rising stem gate valve is relatively complex, and the valve stem processing accuracy requires higher requirements, so the cost is relatively high. ； The concealed stem gate valve has a relatively simple structure, low processing difficulty, and relatively affordable cost. It is suitable for large-scale, low-cost pipeline laying scenarios. 03 Selection suggestions (1) If the scene requires intuitive judgment of the valve switching status, the medium is clean and free of impurities, convenient maintenance is prioritized, and the installation space is sufficient, the rising stem gate valve is preferred, such as fire protection systems, pumping stations, clean medium transportation pipelines, etc. (2) If the installation space is small (such as underground, equipment gaps), the medium contains impurities or is corrosive, or requires outdoor or underground installation, concealed stem gate valves are preferred, such as municipal sewage pipe networks, chemical corrosion pipelines, ship engine rooms, etc.