Spiral submerged arc welded steel pipe is a belt formed by Spiral bending, welding steel pipe with automatic submerged arc welding joints and sewn spiral joints. It can be widely used for th. . . Spiral submerged arc welded steel pipe is a belt formed by Spiral bending, welding steel pipe with automatic submerged arc welding joints and sewn spiral joints. In the production of large diameter steel pipes, it can be widely used for the following reasons: 1) As long as the forming angle is changed, strips of the same width can be used when producing steel pipes of various diameters; 2) Because it is continuous molding, it is not limited by the length of the steel pipe; 3) The weld spiral is evenly distributed on the circumference of the steel pipe, so the dimensional accuracy of the steel pipe is higher and the strength is higher; 4) The cost of equipment is cheap and the size is changeable. It is suitable for small batch and multi-variety steel pipe production. The weld seam of spiral steel pipe is longer than the straight seam, such as Long L, and the weld length is L/cos (theta). . . Analysis of advantages and disadvantages of spiral steel pipe: the steel pipe defects in spiral steel pipe are mostly concentrated in the weld and heat affected zone, and a long time means that the probability of welding defects appearing is high, which is a long time. The term constraints of the main causes of the Spiral weld pipe are more widely used, and there is also controversy about the spiral pipe and the straight seam pipe, especially compared to the UOE pipe superior to the problem. In today\'s development of spiral pipe manufacturing technology, we should conduct a comprehensive and correct evaluation and comparison of the spiral pipe weld length problem, and re-discover the problem of spiral pipe weld length. During use, the principal stress direction of the steel pipe, that is, the axis of the equivalent length of the steel pipe defect is less than the straight seam pipe; The second is that the pipeline steel is mainly rolled steel plate, and the impact toughness is large, and the rolling direction along the CVN value is 3 times higher than the rolling direction of the CVN value.