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With the rapid advancement of industrial technology, stricter requirements have been placed on the valve industry. Especially for butterfly valves used with low-temperature media, in addition to meeting the performance standards of ordinary valves, it is crucial that they ensure reliable sealing at low temperatures, exhibit flexibility in operation, and satisfy other specific requirements associated with valves used in low-temperature environments. With the rapid advancement of industrial technology, stricter requirements have been placed on the valve industry. Especially for butterfly valves used with low-temperature media, in addition to meeting the performance standards of ordinary valves, it is crucial that they ensure reliable sealing at low temperatures, exhibit flexibility in operation, and satisfy other specific requirements associated with valves used in low-temperature environments. As is well known, butterfly valves possess a series of advantages such as a compact structure, small size, low weight (they can be 40%–50% lighter than gate valves with the same pressure and diameter), low fluid resistance, and rapid opening and closing. However, in some low-temperature installations in our country, such as natural gas liquefaction equipment, air separation equipment, and pressure swing adsorption equipment used in the chemical industry, over 80% of the valves employed are globe valves or gate valves, with very few butterfly valves being used. The main reasons analyzed are the poor sealing performance of the metal-sealed butterfly valves at low temperatures, as well as other issues such as improper design that lead to internal and external leakage of the medium. These problems severely affect the safety and proper operation of these low-temperature devices, failing to meet their requirements. With the continuous development of low-temperature equipment in our country, the requirements for low-temperature valves are increasing. To meet the needs of market economy development, structural improvements have been made to metal-sealed butterfly valves, resulting in the creation of a three-eccentric all-metal butterfly valve with high sealing performance (Figure 1); this valve has already been patented. It can meet the requirements regardless of whether the medium is at high or low temperatures. Now, taking into account its structural characteristics, only a brief introduction to its low-temperature performance will be provided. I. Requirements for the sealing performance of low-temperature disc valves: There are mainly two reasons for leaks in low-temperature valves; one is internal leakage ； The second is external leakage. 1) The main reason for internal leakage in valves is the deformation of the sealing pair at low temperatures. When the temperature of the medium drops to a level that causes a phase change in the material, this results in volume changes, which in turn cause the sealing surfaces that originally had high grinding precision to warp and deform, leading to poor sealing at low temperatures. We conducted low-temperature tests on DN250 valves using liquid nitrogen at -196°C; the butterfly plate material was 1Cr18Ni9Ti (without low-temperature treatment). It was found that the warping deformation of the sealing surface reached approximately 0.12 mm, which is the main cause of internal leakage. The newly developed butterfly valve has been changed from a planar seal to a conical seal. The valve seat is an oblique conical elliptical sealing surface, which forms a sealing pair with the circular elastic sealing ring mounted on the butterfly plate. The sealing ring can float radially within the butterfly plate groove. When the valve is closed, the elastic sealing ring first makes contact with the short axis of the elliptical sealing surface. As the valve stem rotates, it gradually pushes the sealing ring inward, forcing it to make contact with the long axis of the inclined conical surface, until ultimately the elastic sealing ring is in full contact with the elliptical sealing surface. Its sealing is achieved through the deformation of an elastic ring. Therefore, when the valve body or butterfly plate deforms at low temperatures, this deformation is absorbed and compensated by the elastic sealing ring, preventing leakage and jamming. When the valve is opened, this elastic deformation disappears immediately, and there is virtually no relative friction during the opening and closing process, thus ensuring a long service life. 2) External leakage of the valve: One reason for this is that when the valve and the pipeline are connected using flanges, leakage occurs due to relaxation resulting from the asynchronous contraction of the materials in the gasket, connection bolts, and other fittings at low temperatures. Therefore, we changed the connection method between the valve body and the pipeline from flange connection to a welded structure, thereby preventing leaks at low temperatures. The second is leakage at the valve stem and packing. F4 is generally used as the packing for most valves, as it has good self-lubricating properties and a low friction coefficient (the friction coefficient against steel is 0.05–0.1). Its unique chemical stability also contributes to its widespread use. But F4 also has its shortcomings; one is its strong tendency to develop cold streams ； Secondly, it has a high linear expansion coefficient; cold contraction occurs at low temperatures, leading to leaks. This results in excessive freezing at the valve stem, thereby preventing the valve from opening properly. The low-temperature butterfly valve developed for this purpose features a self-compressing sealing structure; by taking advantage of the high expansion coefficient of F4, it achieves sealing capabilities at both normal and low temperatures through a pre-designed gap. II. Design requirements for the valve body and valve stem bushings: 1) Structural shape of the low-temperature valve housing. The correct selection of materials is of utmost importance for the proper and reliable operation of valves. Compared with globe valves and gate valves, the structural features of butterfly valves not only prevent deformation caused by irregular shapes, uneven shell wall thickness, cold contraction at low temperatures, and thermal stress, but also result in a low heat capacity due to their small size and the essentially symmetrical shape of the valve body ； The amount of cooling energy consumed is also low ； Its regular shape facilitates insulation measures for the valve. The newly developed DD363H disc valve is designed and manufactured with full consideration for the specific requirements of valves used in low-temperature environments, in order to ensure their reliable operation at such temperatures. For example, the material used for the valve body is 1Cr18Ni9Ti austenitic stainless steel, which has a cubic crystal structure. 2) Selection of valve stem bushings: According to user feedback, in some low-temperature valves, sticking and seizure occur at the rotating parts during operation. The main reasons for this are improper selection of matching materials, too small a cold gap, as well as issues related to machining precision. A series of measures were taken when developing low-temperature valves to prevent the occurrence of the above phenomena. For example, we have selected SF-1 type composite bearings with a low friction coefficient and self-lubricating properties for the upper and lower bushings of the valve stem, which enables them to meet the specific requirements of valves used in low-temperature environments. Metal-sealed butterfly valves possess characteristics that some ordinary valves do not have. In particular, it features low flow resistance, reliable sealing, fast opening and closing, and a long service life. The sealing force of the triple-eccentric metal-sealed butterfly valve developed by our company comes from the deformation of the elastic ring to achieve sealing; as a result, no medium pressure is required, allowing it to be used for two-way sealing. Due to some of the characteristics of butterfly valves, they will receive more attention from people. In the future, more butterfly valves will be used in low-temperature equipment.