The butterfly valve was invented in the United States in the 1930s. It was introduced to Japan in the 1950s and was not widely used in Japan until the 1960s. It was not popularized in my country until the 1970s. The main features of butterfly valves are: small operating torque, small installation space and light weight. Taking DN1000 as an example, the butterfly valve is about 2T, while the gate valve is about 3.5T. The butterfly valve is easy to combine with various drive devices and has good durability and reliability. The disadvantage of rubber-sealed butterfly valves is that when used for throttling, cavitation will occur due to improper use, causing the rubber seat to peel off and be damaged. Therefore, how to correctly select it depends on the working conditions. The relationship between the opening of the butterfly valve and the flow rate is basically linear. If it is used to control the flow rate, its flow characteristics are also closely related to the flow resistance of the piping. For example, if the valve caliber and form of the two pipelines are all the same, but the pipeline loss coefficient is different, the flow rate of the valve will also be very different. If the valve is in a state of large throttling amplitude, cavitation is prone to occur on the back of the valve plate, which may damage the valve. It is generally used outside 15°. When the butterfly valve is in the middle opening, 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. The front end of the butterfly plate on one side moves in the direction of the water flow, and the other side moves in the direction of the water flow. Therefore, the valve body and the valve plate on one side form a nozzle-shaped opening, and the other side is similar to a throttle hole-shaped opening. The nozzle side has a much faster flow rate than the throttle side, and negative pressure will be generated under the valve on the throttle side, and the rubber seal will often fall off. The operating torque of the butterfly valve varies due to the different openings and the opening and closing directions of the valve. The torque generated by the difference between the upper and lower water heads of the horizontal butterfly valve, especially the large-diameter valve, due to the 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 the water flow torque.
China has many valve industry chains, but it is not a valve power. Generally speaking, my country has entered the ranks of the world’s valve powers, but in terms of product quality, my country is still a long way from being a valve power. The industry still has low production concentration, low R&D capabilities of valves matching high-end products, and low manufacturing technology level in the valve industry, and the import and export trade deficit continues to expand. There are definitely not so many valve companies that can really survive in the market. However, this high-speed shock in the valve industry will bring huge opportunities, and the result of the shock will make the market operation more rational. The road to localization of high-end valves is extremely “bumpy”. Basic parts have become a shortcoming that restricts the development of my country’s manufacturing industry to high-end. During the 12th Five-Year Plan, the government will continue to increase the localization of high-end equipment parts. Here we select several key developments in the “Implementation Plan” and representative valve industries for feasibility analysis of import substitution. From the analysis, it can be seen that the feasibility of import substitution of valves in various sub-industries varies greatly, and high-end valves urgently need more policy guidance and scientific research support.
The valve industry plays a very important role as an important link in the equipment manufacturing industry in the development of the national economy. Since the level of my country’s domestic valve manufacturing industry is still a certain distance away from the international advanced level, many key valves with high parameters, high temperature and high pressure, and high pound level have always relied on imports. For example, the European OMAL brand has always been the main choice of 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 state departments have made a series of major deployments in accordance with the requirements of the state for the localization of major equipment. Led by the National Development and Reform Commission, the China Machinery Industry Federation and the China General Machinery Industry Association have deployed and formulated a valve localization plan for major equipment in related fields, and have coordinated with relevant departments many times. Now the localization of valves has formed a consensus in the domestic valve industry. Actively adopt international standards for product design; absorb foreign excellent design structures (including patented technologies); product testing and performance inspection are strictly carried out in accordance with international standards; absorb foreign production process experience and attach importance to the research and promotion of new materials; clarify the technical parameters and working conditions of imported high-parameter valve products, etc. are ways to accelerate the localization process, promote the continuous updating of valve products, and fully realize the localization of valves. With the acceleration of the pace of restructuring in the valve industry, the future industry will be a competition between valve product quality and safety and product brands. Products will develop in the direction of high technology, high parameters, strong corrosion resistance, and long life. Only through continuous technological innovation, development of new products, and technological transformation can the product technology level be gradually improved to meet the domestic device matching and fully realize the localization of valves. Under the huge demand environment, my country’s valve manufacturing industry will surely show better development prospects.
Post time: Nov-02-2024
