For general pneumatic ball valves, the seal seat is generally made of pure PTFE. Although it has the advantages of excellent chemical stability and extremely low friction coefficient, the hardening technology of hard sealed pneumatic ball valves and the modified design of seal seats are very deficient in high-temperature compressive strength, especially in wear resistance.

What are the common causes of pneumatic butterfly valve fracture
Under the daily working condition, the pneumatic butterfly valve is often fatigued and cracked by cyclic load. This kind of crushing is normal failure, and routine inspection should be strengthened to strictly implement the designation of forced replacement. At the same time, the hose shall be installed according to the specification to prevent additional stress such as hose seizure and distortion caused by improper installation and shorten the service life.
In addition to inevitable normal failure, improper environment and installation will also cause the fracture problem of pneumatic butterfly valve, which will constitute failure.
1. Environmental impact
Under the influence of the wet atmospheric medium containing chloride ions along the coast and the tensile stress, the outer screen of the pneumatic butterfly valve suffered from chloride ion stress corrosion and fracture in some parts, and then broke after pitting in some parts, which is a slow and slow process of fracture. When the last remaining steel wire is not enough to bear the internal pressure and heat shrinkage load of the bellows, it will be pulled off by overload. Without the support of wire mesh, the bellows broke in the weak area of the weld due to transient excessive bending deformation, which led to hose fracture.
2. Improper installation, resulting in broken wire mesh
During the installation of the hose, due to improper installation or high pressure, the hose will be stretched and twisted. When the stress caused by stretching or twisting exceeds the ultimate strength of the hose wire mesh sleeve, the mesh sleeve at the trinity welding part of the hose or the mesh sleeve at other parts will be pulled off, and then the bellows will be stretched and crushed, causing crude oil disclosure.
3. False welding constitutes pulling off of wire mesh sleeve
Due to the welding quality, the bellows, ring and wire mesh sleeve in the process of trinity welding constitute a part of the faulty welding of steel wire (over burning or final welding). In this way, after the hose is installed into the pipeline, due to the uneven stress on the steel wire, under the medium pressure, the steel wire at the faulty weld will pull off first, which will pull off the entire steel wire mesh sleeve, causing the failure of the bellows drum and the risk of attack.
4. The welding quality defects of the pneumatic butterfly valve connector (internal connection department) constitute the failure of the hose. When the hose body is welded with the hose connector, when the operation is improper, the welding defects will occur, and these defects are difficult to find in the pressure test inspection. When the hose is connected to the medium pipeline, it will crack or break at the defect due to fatigue and other reasons after durable application, and finally form the medium disclosure of the walk pipeline.
5. The pneumatic butterfly valve connector (internal connection department) was corroded and failed, causing the hose medium to disclose that the pneumatic butterfly valve connector materials were 1Crl8Ni9Ti or SUS304 stainless steel. Inclusions (such as silicates, oxides, etc.) in stainless steel are sometimes distributed in a chain shape. When they are affected by the heat of welding or contaminated by acidic media, they will form through micropores to reveal the media in the hose. To prevent such failure, it is recommended to select qualified stainless steel joint materials and reasonable welding process.