Now, many factories in the boring machine by marking the processing of the ball shaft hole. Because the ball shaft hole processed by this method is not the working position of the ball in the valve, the error is large. Failed to meet the drawing requirements. The overall error generated after assembly has a serious impact on the sealing, resulting in valve leakage. It can be seen that if the coaxiality of the upper and lower shaft holes is low, the upper and lower shafts and composite bearings are involved in the assembly to eliminate interference. Only increase the radial dimension of the bearing. Make the contact between the ball and the valve seat produce clearance. The soft sealing pneumatic ball valves such as rubber and tetrafluoroethylene can still meet the requirements of sealing without leakage, but the opening and closing torque and seal ring wear are increased. For the metal sealed pneumatic ball valve, sealing without leakage cannot be achieved. Because the spherical shaft hole is processed by scribing correction. The coaxiality error is 6 ram, and leakage occurs after assembly. In order to meet the requirement of coaxiality, after the sphere is processed, the shaft hole shall be processed on the CNC boring machine or digital display boring machine. Because the diameter accuracy of the boring machine spindle is high, the ball center can be found directly. After the shaft hole on one side is processed, the boring machine workbench rotates 180 degrees, and the spindle of the boring machine is used to calibrate again to process the shaft hole on the other side. The shaft hole processed by this method has high position accuracy and small coaxiality error. The ball of pneumatic ball valve is generally chrome plated on the surface of 1Cr18Ni9Ti or carbon steel. Since the spherical surface has sharp corners formed by channels and shaft holes, according to the electroplating principle, the coating on the sharp corners is thicker, and the deviation between the actual thickness and the average thickness is about 30% or more. Although the ball was grinded after turning, after electroplating, the coating thickness was uneven, and the roundness of the ball was out of tolerance, resulting in leakage between the valve seat and the ball of the metal sealed pneumatic ball valve,

It has been found after previous earthquakes abroad that in earthquakes, the storage tank and the pipeline connected to it experienced absolute displacement, resulting in great stress, which caused the pipeline to bear excessive force and torque at the equipment, pipe fittings, fixed supports, etc. connected to the pipeline. In serious cases, the tank body could be damaged, resulting in an accident of liquid storage leakage. In order to increase the stress, the pipeline system must be designed to be flexible enough to overcome the above damage. The pneumatic butterfly valve is flexible enough to reduce the stress in the pipeline, increase the thrust of the pipeline on the tank and support, and thus maintain the tank.
1. If the steel temporarily alternates cold and hot tasks, then under the thermal stress caused by the temperature difference change outside the material, large cracks will occur and expand from time to time, initially leading to splitting. Therefore, the thermal fatigue function of steel should be considered for structures and pipelines under the condition of rough temperature changes.
2. Under the action of low temperature, the cementite in the carbon steel will migrate and gather due to the energy obtained, forming the cementite with coarse grains and inclusion in the ferrite. The cementite will gradually change from lamellar to spherical, which is called spheroidization. Because the strength of graphite is extremely low and it is presented in sheet form, the strength of the material is greatly reduced. The addition of brittleness is called graphitization of materials. The carbon steel will be graphitized in the environment above 425 ℃ for the time being. It is more clear when the temperature is higher than 475 ℃. The maximum operating temperature of SH3059 regular carbon steel is 425 ℃, and the maximum operating temperature of GB150 regular carbon steel is 450 ℃.