Spiral steel pipe is a spiral steel pipe made of strip steel or coiled plate in a spiral shape, using double-sided submerged arc active welding to weld the inner and outer seams. It can be widely used in water, electricity, and chemical industries for the following reasons In professional production: just by changing the forming viewpoint, steel pipes of various calibers can be produced with the same width of strip steel, which is easy to adjust.
Because it is formed by successive twists and turns, the fixed length of the spiral tube is not restricted, and the length can be set at will. The spiral shape of the weld is evenly distributed on the circumference of the spiral tube, so the spiral tube has high dimensional accuracy and strong strength. It is easy to change the scale and is suitable for the production of small batches and various types of spiral tubes.
The weld seam of spiral steel pipe is longer than the weld seam of the same standard straight seam pipe. Under the same standard wall thickness, the spiral steel pipe receives more pressure. The disadvantage of the welded seam of the spiral steel pipe is the “oblique defect”. During use, the main stress direction of the steel pipe, that is, the equivalent defect length in the axial direction of the steel pipe is smaller than that of the straight seam pipe; secondly, because the pipeline steel is all rolled steel plate, The impact toughness has a large anisotropy, and the CVN value in the rolling direction can be 3 times higher than the CVN value perpendicular to the rolling direction.