海东竞舜机械设备有限公司

In the current steel pipe industry, there is a lot of further research on the fracture of straight seam pipes, but there is very little research on spiral welded steel pipes, which will take several years. Foreign countries are also starting to do this work, but it has not been introduced to China. The steel pipe factory mainly produces spiral steel pipes. The buried steel pipes nowadays are all spiral steel pipes, so the problem of spiral steel pipe rupture is very serious. So there is very little research on the rupture of spiral steel pipes abroad, mainly due to two reasons: one is that the application of spiral pipes and straight seam pipes is very limited, especially in the study of rupture of important tracheal lines; Another issue is that the study of steel pipe rupture is very rare, so the results of straight seam pipe research are often applied to spiral steel pipes. The research on the rupture of spiral steel pipes is still in its infancy. 
The characteristics of spiral steel pipe rupture: Samples are taken from different directions of the steel pipe, and then subjected to tensile and Charpy impact tests; For pipelines, the maximum principal stress is the circumferential stress, and the direction of maximum driving cracking is generally along the axial direction. But for straight seam pipes, the direction of maximum driving cracking and the minimum resistance to fracture are consistent; Defects in welded pipes are difficult to detect in raw materials, usually in the weld seam or heat affected zone, but their two defects are consistent with the weld seam. The defect direction of straight seam pipes is axial, while the defect direction in spiral pipes is oblique. 
In general, although the tensile test results of spiral steel pipes are basically independent of the sampling direction, if it is a Charpy impact test, it is closely related to the sampling direction; The difference between the rupture of a spiral tube and a straight seam tube is that for a straight seam tube, the driving direction of rupture or expansion must be along the axis and must be mutual. However, for spiral tubes, the direction of maximum driving force and minimum resistance for rupture and expansion is not consistent.