2、 Factors affecting the safety of valve body welds
1. Stress concentration at weld root Due to the assembly alignment and positioning requirements of all welded pneumatic ball valve body, there is a circular assembly gap at the weld root, which will lead to a large stress concentration at the valve body weld root. Through finite element analysis and calculation, under the working pressure of 10MPa, it can be clearly observed that a large stress concentration occurs at the root of the weld for the valve body of 20in, 600Lb pneumatic ball valve, and the Von misese stress at the root reaches 275MPa, which has exceeded the yield strength of A105 material and reached about 3 times the normal working stress.

Three eccentric sealing pneumatic butterfly valve As for the pneumatic butterfly valve with three eccentric sealing structure, its sealing principle is also based on the double eccentric structure. At this time, the appearance of love between the valve seat and the centerline of the valve body reappears β The angle offset is slightly different from the above situation. When the sealing surface of the butterfly valve is opened, it will immediately leave the valve seat, while when it is closed, it will directly press the cover tightly. The butterfly valve with this type of structure has a big advantage, that is, it can completely clear the scratches between the two sealing surfaces, which can make the butterfly valve use longer.