Introduction to spiral steel pipe welds

Spiral steel pipes are single-sided welded and double-sided welded. Welded pipes should ensure that the water pressure test, tensile strength of the weld and cold bending performance meet the requirements.
Butt weld: It is a circular weld formed by connecting two sections of steel pipes together.
Positioning weld: It is a weld used to fix the butt edge before the final welding.
Butt weld of steel strip: The butt weld of steel strip is the weld where the steel plate or steel strip on the spiral seam steel pipe is connected at the head and tail.

Spiral steel pipes are made by rolling low-carbon carbon structural steel or low-alloy structural steel strips into pipe blanks at a certain spiral angle (also called forming angle), and then welding the pipe seams. It can produce large-diameter steel pipes with narrower strips. Spiral steel pipes are used for oil and natural gas pipelines. Spiral steel pipes are single-sided welded and double-sided welded. Welded pipes should ensure that the water pressure test, tensile strength of the weld and cold bending performance meet the requirements.

Spiral seam submerged arc welded steel pipe is formed by bending the hot-rolled strip into a spiral shape, and the inner and outer seams are welded by submerged arc automatic welding to form a spiral seam steel pipe (also called spiral welded pipe, spiral pipe spiral steel pipe). It can be widely used in the production of large-diameter steel pipes for the following reasons:
1) As long as the forming angle is changed, steel pipes of various calibers can be produced with the same width of strip steel;
2) Because it is continuously bent, the fixed length of the steel pipe is not limited;
3) The spiral shape of the weld is evenly distributed on the entire circumference of the steel pipe, so the dimensional accuracy of the steel pipe is high and the strength is also high;
4) It is easy to change the size and is suitable for the production of small batches and multiple varieties of steel pipes.
Since the defect is parallel to the weld, for the spiral pipe, the defect of its weld is "oblique defect". During use, the equivalent defect length in the main stress direction of the steel pipe, that is, the axial direction of the steel pipe, is smaller than that of the straight seam pipe; secondly, since pipeline steel is all rolled steel plate, the impact toughness has a large anisotropy.