There are thin wall balls and hollow balls cast abroad, and there are also castings cast at home, but the quality of castings can not pass the standard. Even as qualified parts, they are far from meeting the technical requirements for ball quality. The other is the ball welded with multiple plates, but it is not suitable for batch production because of many welds and complex process. Our method is to replace the traditional welding method with the once forming technology of pipe cold extrusion for the sphere of DN 100. At present, there are also pipes for forming in China, but the traditional method they use abroad is the hydraulic expansion molding process, which is complex and inefficient. For the production of large balls, we have also found out a different processing method, called plate forming process. This method is used to reduce the dead weight of the pneumatic ball valve and extend the service life of the pneumatic ball valve. The utilization rate of steel is up to more than 60%, almost double the original one. The net weight of the ball after balling is reduced by more than 50%, and there is only one weld, At the non critical non mating surface. It is not difficult to see that the use of thin wall ball and hollow ball technology is not desirable. This not only improves the low-pressure sealing performance, but also extends the service life of pneumatic ball valves. At the same time, the metalworking hours are reduced by more than 2/3 compared with the original.

Blind plate force of compensator fixing support
After the heat supply pipeline device is put into operation, because the pipeline is heated by the heat medium and causes the pipeline to stretch, measures should be taken to compensate the thermal elongation of the pipeline. The compensation methods mainly include the following: natural compensation, casing type compensator, bellows compensator, square or spherical compensator, etc. This paper mainly describes the comparison between the commonly used sleeve type compensator and the new thrust free rotary compensator in engineering cost and operation safety.
1、 Introduction to sleeve type compensator: it is a compensator suitable for straight laying pipeline, which is used to compensate the thermal elongation of pipeline between fixed supports.
For pipes with sleeve type compensators, the thrust on the fixed support is generated from the following aspects.
(1) Degree thrust Pg · m Pg · m due to friction on sliding support= μ In the qL formula, q － calculate the weight of pipe section per unit length? Quasi 529 × 7 rock wool insulation, water filling q=367.92 × 9.8N · m; μ－ Friction coefficient, steel to steel μ＝ 0.3, steel and PTFE plate μ＝ 0.1； L - length of calculated pipe section, m;
(2) Thrust force generated by friction force of sleeve type compensator;
(3) The degree of thrust caused by uneven internal pressure, such as sleeve type compensators are set at both ends of the fixed support, but their pipe diameters are different; Or one end of the pipe section at both ends of the fixed support is provided with valves, blanking plates and elbows, while the other end is provided with sleeve type compensators; When the hydraulic test or operation of the pipeline is stopped, the unbalanced axial force of the pipeline will appear.