Comparison of Advantages and Disadvantages of Spiral Steel Pipes

Spiral steel pipe is made of strip steel coil as raw material, often subjected to warm extrusion and compression, and bent into a spiral shape. It is welded with internal and external seams using automatic double wire double-sided submerged arc welding technology. The raw materials are strip steel coils, welding wire, and flux.

Steel coils must undergo strict physical and chemical inspections before being put into use. The head and tail of the strip steel are connected by single or double wire submerged arc welding, and automatic submerged arc welding is used for repair welding after being rolled into a steel pipe. Before forming, the strip steel undergoes leveling, trimming, planing, surface cleaning, conveying, and pre bending treatment. The use of an electric contact pressure gauge to control the pressure of the oil cylinders on both sides of the conveyor ensures the smooth transportation of the strip steel.

After welding, radiographic inspection should be conducted on the welds of spiral steel pipes and the intersecting joints of spiral welds. Each steel pipe must undergo a corresponding hydrostatic pressure test, with radial sealing used for pressure. The test pressure and time will be strictly controlled by a steel pipe hydraulic microcomputer detection device, and the test parameters will be printed.

The spiral shape of the weld seam is evenly distributed throughout the circumference of the spiral tube, so the dimensional accuracy of the spiral tube is high and the strength is also strong. Under the same wall thickness specifications, Spiral Steel Pipes can withstand greater pressure. Moreover, as it is a continuous bending process, the length of the spiral tube is not limited and can be arbitrarily set.

The defect of the weld seam of spiral steel pipe is called "oblique defect". During use, the principal stress direction of the steel pipe, i.e. the equivalent defect length in the direction of the steel pipe axis, is smaller than that of the straight seam pipe; Secondly, due to the fact that pipeline steel is all rolled steel plates, the impact toughness has significant anisotropy, and the CVN value along the rolling direction can be three times higher than that perpendicular to the rolling direction.