Spiral welded pipe: It is made by rolling low-carbon carbon structural steel or low-alloy structural steel strip into a tube blank at a certain spiral angle (called forming angle), and then welding the tube seam. It can produce large-diameter steel pipes with narrow strip steel. Its specifications are expressed by outer diameter * wall thickness. The welded pipe should ensure that the water pressure test, tensile strength of the weld and cold bending performance meet the requirements.

Advantages of spiral welded pipes:

(1) The same width of strip steel can be used to produce steel pipes of different diameters, especially narrow strip steel can be used to produce large diameter steel pipes.

(2) Under the same pressure conditions, the stress borne by the spiral weld is smaller than that of the straight weld, which is 75% to 90% of that of the straight weld pipe, so it can withstand greater pressure. Compared with the straight weld pipe of the same outer diameter, the wall thickness can be reduced by 10% to 25% under the same pressure.

(3) The dimensions are precise, the diameter tolerance generally does not exceed 0.12%, the deflection is less than 1/2000, and the ovality is less than 1%. Generally, the sizing and straightening processes can be omitted.

(4) Continuous production is possible. In theory, unlimited length steel pipes can be produced, and the loss of cutting heads and tails is small, which can increase the metal utilization rate by 6% to 8%.

(5) Compared with straight welded pipes, it is flexible to operate and easy to change varieties and adjust.

(6) The equipment is light in weight and has low initial investment. It can be made into a trailer-type mobile unit to produce welded pipes directly at the construction site where the pipeline is laid.

(7) Easy to achieve mechanization and automation.