In the 1930s, the United States invented butterfly valves, which were introduced to Japan in the 1950s and not widely adopted in Japan until the 1960s. However, their promotion in China began after the 1970s. The main characteristics of butterfly valves are: small operating torque, small installation space, and light weight. Taking DN1000 as an example, butterfly valves are about 2T, while gate valves are about 3.5T, and butterfly valves are easy to combine with various driving devices, with good durability and reliability. The disadvantage of rubber sealed butterfly valves is that when used for throttling, improper use can cause cavitation, resulting in rubber seat peeling, damage, and other situations. Therefore, the correct selection should be based on the requirements of the working conditions. The relationship between the opening of butterfly valves and flow rate is basically a linear proportional change. If used to control flow, its flow characteristics are closely related to the flow resistance of the piping. For example, if two pipelines are installed with the same valve diameter and form, but the pipeline loss coefficient is different, the flow rate of the valve will also vary greatly. If the valve is in a state of large throttling amplitude, the back of the valve plate is prone to cavitation, which may damage the valve. Generally, it is used at an angle of 15 °. When the butterfly valve is in the middle opening position, the opening shape formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and different states are formed on both sides. One side of the butterfly plate front end moves in the direction of water flow, while the other side moves against the direction of water flow. Therefore, one side of the valve body and the valve plate form a nozzle shaped opening, and the other side forms a throttle hole shaped opening. The nozzle side has a much faster flow rate than the throttle side, and negative pressure is generated below the throttle side valve, often causing rubber seals to fall off. The operating torque of butterfly valves varies due to differences in opening degree and valve opening and closing direction. For horizontal butterfly valves, especially large diameter valves, the torque generated by the difference between the upper and lower water heads of the valve shaft due to water depth cannot be ignored. In addition, when the elbow is installed on the inlet side of the valve, a bias flow is formed, and the torque will increase. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the action of water flow torque.
China has numerous valve industry chains, but it is not a strong valve country. Overall, China has entered the ranks of the world's major valve countries, but in terms of product quality, there is still a long gap between China and a strong valve country. The phenomenon of low production concentration in the industry, low research and development capabilities for valves that match high-end products, and low manufacturing technology level in the valve industry still exists, and the import and export trade deficit continues to expand. There are definitely not so many valve companies that can truly survive in the market. But this high-speed oscillation in the valve industry will bring huge opportunities, and the result of the oscillation will make market operations more rational. The road to localization of high-end valves is exceptionally bumpy. Basic components have become a shortcoming that hinders the high-end development of China's manufacturing industry. During the 12th Five Year Plan period, the government will continue to increase the localization of high-end equipment components. Here we select several key and representative valve industries mentioned in the Implementation Plan for feasibility analysis of import substitution. From the analysis, it can be seen that the feasibility of valve import substitution varies greatly among different sub industries, and high-end valves urgently need more policy guidance and scientific research support.
The valve industry plays a very important role in the development of the national economy as an important link in the equipment manufacturing industry. Due to the gap between China's domestic valve manufacturing industry and the international advanced level, many key valves with high parameters, high temperature, high pressure, and high weight have always relied on imports. For example, the European OMAL brand has always been the main choice for the domestic valve application industry. In order to promote the localization of valves, after the State Council issued the "Several Opinions on Accelerating the Revitalization of Equipment Manufacturing Industry", relevant departments of the country have made a series of major deployments in accordance with the requirements of major equipment localization made by the country. Led by the National Development and Reform Commission, the China Machinery Industry Federation and the China General Machinery Industry Association have jointly deployed and formulated valve localization plans for major equipment in related fields, and have coordinated with relevant departments multiple times. Nowadays, valve localization has formed a consensus in the domestic valve industry. Actively adopting international standards for product design; Absorbing excellent design structures from abroad (including patented technology); Product testing and performance inspection are strictly conducted in accordance with international standards; Absorb foreign production process experience and attach importance to the research and promotion of new materials; Clarifying the technical parameters and operating conditions of imported high parameter valve products is a way to accelerate the localization process, promote the continuous updating of valve products, and comprehensively achieve the localization of valves. With the acceleration of the restructuring of the valve industry, the future industry will be a competition between the quality and safety of valve products and product brands. Products will develop towards high technology, high parameters, strong corrosion resistance, and high service life. Only through continuous technological innovation, development of new products, and technological transformation can we gradually improve the technical level of products, meet domestic equipment requirements, and fully realize the localization of valves. Under the huge demand environment, China's valve manufacturing industry is bound to present better development prospects.
