Spiral submerged arc welding steel pipe

Spiral submerged arc welding steel pipe is the strip by the spiral bending forming, with automatic submerged arc welding seam and seam made spiral seam welded steel pipe.

It can be widely used for the following reasons in the production of large diameter steel pipe:

1) as long as the change of forming Angle, you can use the same width of the strip in the production of various diameter of steel pipe;

2) because it is a continuous forming, so the length of steel tube length is not restricted;

3) weld spiral evenly distributed throughout the steel tube on the circumference of a circle, so the size of the steel tube of high precision, the intensity is also higher;

4) equipment cost cheap, easy to change size, suitable for small batch and many varieties of steel pipe production. Spiral steel pipe weld than straight seam length, such as the length of L, the weld length is L/cos (theta)...

The advantages and disadvantages of spiral steel pipe analysis: most of steel tube defects in spiral tube is focused on the weld seam and heat affected zone, long means that the welding defects appear probability is large, it is a long-term constraints of the main causes of spiral weld pipe is more widely used, is also disputed about the spiral pipe and straight seam pipe, especially compared with UOE tube who is superior to the problem. Spiral pipe manufacturing technology development today, we should comprehensively and correctly evaluate and compare, rediscover the spiral pipe welding seam long problem.

In the use process, the principal stress direction of steel tube, namely the axis of the steel tube defect equivalent length is smaller than the straight seam pipe; Second, the pipeline steel are based on rolling steel plate, impact toughness have larger anisotropy, along the rolling direction of the CVN value is perpendicular to the rolling direction of the CVN value is three times higher. Straight seam pipe of principal stress on the direction of perpendicular to the pipe of the lowest impact resistant ability, and the spiral steel pipe stagger the direction of the lowest pipe impact resistant ability, the spiral pipe welding line long disadvantage into advantage