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Low-temperature valves are installed at normal temperatures and operate at low temperatures, experiencing a large range of temperature changes. If it is not designed and installed properly, thermal stress or deformation can easily occur. At the same time, the operating part of the valve is at normal temperature, while the flow-through part is at low temperature. To reduce heat loss, the valve stem is often made quite long, which makes it prone to deformation and getting stuck. Low-temperature valves are usually smooth to operate at normal temperatures, but become tight at low temperatures, to the point where they cannot be opened. What are the main reasons why valves get stuck at low temperatures? 1. During installation, pre-stress is generated due to an improper arrangement of the valve and pipes ； Or the pipeline has poor cold compensation capacity, resulting in changes in valve position at low temperatures ； Or the valve lacks a support, resulting in deformation at low temperatures ； Or the valve may not be fixed properly, causing the cryogenic box to deform at low temperatures and affecting the concentricity between the valve stem and the valve body. 2. In terms of design, due to the different materials of the valve stem and the valve sleeve, their linear expansion coefficients differ. Stainless steel is generally used for valve stems, with a linear expansion coefficient of 1.73×10-6℃-1 ； The valve sleeve is made of brass, with a linear expansion coefficient of 19.9×10-6℃-1; as a result, brass contracts more than stainless steel, and this may cause the threads to get stuck at low temperatures. Especially when a blind rod structure and fine-thread pitch are used, the temperature variation of the threads is large and the thread clearance is small, making it more likely for jamming to occur. 3. During operation, insufficient heating at the valve can lead to freezing at low temperatures due to water entering the valve packing, or the valves may be closed too tightly at normal temperatures, resulting in damage to the threads. How to solve a valve getting stuck at low temperatures? To prevent valve sticking, a stem-type design with coarse triangular threads is advisable ； During installation, a sturdy support should be provided at the valve to prevent the valve from shifting along with the pipeline and causing the valve stem to bend. The valve can be fixed to the insulated box using an elastic connection, thereby preventing the valve stem from deforming and becoming out of alignment with the valve body ； During the cold shutdown period, it is necessary to inspect and adjust the valve installation in a cooled state; if the valve becomes stuck after cooling, the fixing flange of the valve on the shell can be adjusted to enable smooth opening and closing. During operation, the pre-startup heating should be thorough, and when closing the valves, it is important to ensure no leaks by not using excessive force.