4.1 The longitudinal welds on the same section of the coiled tube should not exceed two; the spacing between the two longitudinal welds should not be less than 200mm.

During tube rolling, the spacing between the two longitudinal seams should be greater than 100mm, and the distance from the outer wall of the branch pipe to the weld should not be less than 50mm.

4.3 The misalignment of the inner wall of the pipe-to-tube joint should not exceed 10% of the wall thickness, and should not be greater than 2mm.

4.4 The circumference and roundness deviation of the rolled tube shall comply with the specifications in Table 5-2.

4.5 The arc length of the rounding plate for the rolled tube should be between 1/6 and 1/4 of the circumference of the tube. The clearance between the template and the inner wall of the tube should comply with the following specifications: the longitudinal joint at the mating point should not exceed 10% of the wall thickness plus 2mm, and should not be more than 3mm. The longitudinal joint 200mm from the end of the tube should not exceed 2mm. The clearance at other locations should not exceed 3mm.

4.6 The vertical deviation of the tube end face from the centerline must not exceed 1% of the tube's outer diameter, nor more than 3mm. The straightness deviation must not exceed 1mm/m. For spiral tubes that cannot be formed with double-sided welds, when the nominal diameter is 600mm or more, it is recommended to perform a bottom weld inside the tube.

4.7 During the coiling process, prevent surface damage to the sheet material. For areas with severe scratches, perform smoothing to achieve a smooth transition, ensuring that the wall thickness at the smoothed area is not less than the designed wall thickness.

④ The misalignment of longitudinal seams in steel pipe coils should not exceed 10% of the wall thickness, nor be more than 1mm; the vertical deviation of the pipe end face from the centerline should not exceed 1% of the outer diameter, nor be more than 3mm; the flatness deviation should not exceed 1mm/m; for pipe coils with a diameter greater than 600mm, two longitudinal weld seams are permitted, with a spacing between the seams greater than 300mm; the circumference deviation and ellipticity of the pipe coils should comply with the specifications in the following table: