Application and design requirements of medium and high temperature pneumatic ball valves in foreign power plants Pneumatic ball valves were only used for normal temperature and low temperature pipelines in the past, and their maximum operating temperature generally did not exceed 150 degrees. At present, some products abroad have been applied to power plant pipelines with medium temperature (above 260 ℃) and high pressure above 0.5MPa. In the near future, it is possible to replace expensive gate valves and globe valves.

Selection of Information of Bellows Rotary Compensator and Its Arrangement in Urban Heat Supply Network
The reason why the bellows compensator contraction joint is widely used in many industries is that in addition to considering good compensation ability, reliability is the key to the bellows compensator contraction joint. However, the reliability is guaranteed through multiple links such as design and manufacturing, and the neglect of any link will lead to the reduction of the life of the compensator and even failure.
Most consumer enterprises of bellows compensator shrink joint analyze the causes of bellows shrink joint failure, and find that the failure during operation is mainly manifested in two ways: corrosion leakage and instability deformation, of which corrosion failure is the most. From the dissection of corrosion failure bellows, it is found that corrosion failure is usually divided into pitting corrosion perforation and stress corrosion cracking, of which chloride ion stress corrosion cracking accounts for about 95% of the total corrosion failure. Therefore, correct selection of bellows manufacturing data and structure, reasonable design of waveform parameters and fatigue life, assurance of device quality and other measures can greatly improve the safety and reliability of bellows compensator contraction joints.
In design, the stability of bellows should be considered to prevent the instability of bellows rotary compensator. The material shows that the compensation amount of bellows depends on its fatigue life. The higher the fatigue life, the smaller the single wave compensation amount of bellows. In order to reduce the cost and improve the single wave compensation, the lower the allowable fatigue life, the greater the longitudinal bending stress of the bellows caused by displacement, and the higher the comprehensive stress, which greatly reduces the stability of the bellows. When the allowable service life of the bellows design is low, not only the meridian comprehensive stress is high, but also the circumferential stress is relatively high, which makes the bellows enter plastic deformation quickly, leading to the instability of the bellows and causing failure.
In addition to design, the selection of bellows information is also quite critical. For the selection of materials used for bellows, in addition to the working medium, working temperature and external environment, the possibility of stress corrosion, the impact of water treatment agent and pipeline cleaning agent on the data, etc. should also be considered, and on this basis, the welding and forming of bellows data, as well as the performance cost ratio of the data should be separated, so as to select the applicable bellows manufacturing data that meet the working conditions.