The clearance between the valve seat and the valve body groove is the basic condition to ensure the normal operation of the pneumatic ball valve. When selecting the clearance, it is necessary to consider that the uniform mid length of the precompressed valve seat should be within the total elastic deformation range. For this reason, the formula:; Average valve seat diameter;; Allowable stress of cross section of valve seat within elastic deformation range, for PTFE valve seat,; Elastic modulus of valve seat material, for PTFE valve seat,.

Why is the wire mesh sleeve of the metal braided hose damaged?
The stainless steel wire mesh sleeve is mainly used to maintain the bellows and accept the medium pressure (mainly axial force) in the bellows. The mesh sleeve is wrapped outside the corrugated pipe, and both ends are welded with the corrugated pipe, end ring and joint. What are the reasons for the damage of wire mesh sleeve of large diameter pneumatic butterfly valve?
(1) The wire mesh sleeve is pulled off due to faulty welding. Due to the welding quality, the corrugated pipe, ring and wire mesh sleeve in the trinity welding process form a part of steel wire false welding (over burning or last welding). In this way, after the hose is installed in the pipeline, due to the uneven stress on the steel wire, under the effect of the medium pressure, the steel wire at the faulty weld will pull off first, so that the entire wire mesh sleeve will pull off, which will lead to the failure of the bellows drum and the risk of occurrence. Tianjin high-pressure oil pipe manufacturer believes that in order to eradicate this situation, the welding quality should be improved. Before the hose leaves the factory, the water pressure and air tightness test should be stopped, and the hose can leave the factory only after it is qualified.
(2) The wire mesh is broken due to improper device. During the installation of the hose, the hose will be stretched and twisted due to improper installation or too high pressure. When the stress generated by stretching or twisting exceeds the ultimate strength of the hose wire mesh sleeve, the mesh sleeve at the welding part of the hose trinity or the mesh sleeve at other parts will be pulled off, thus causing the outer drum of the bellows to be stretched and damaged, causing medium leakage Therefore, it is required that the design and model selection should be accurate, and the device should be correct.