The wall thickness of the spiral seam submerged arc welded steel pipe is uniform and looks good, and the force is uniform and durable. A phenomenon that is easy to occur in the process of steel pipe rolling and adjustment, the uneven wall thickness of steel pipes is mainly reflected in the appearance of helical uneven wall thickness, linear uneven wall thickness, and thick and thin wall thicknesses at the head and tail. Details are:
One: uneven wall thickness of head and tail
Causes: 1) The front end of the spiral seam submerged arc welded steel pipe billet has a large inclination and excessive bending, and the centering hole of the billet is not correct, which is easy to form uneven wall thickness of the conical steel pipe head; If the rotation speed is too high, the rolling will be unstable; 3) The unsteady steel throwing of the piercer may easily cause uneven wall thickness at the end of the capillary tube.
Two: helical wall thickness uneven
The causes are: 1) The uneven wall thickness caused by the adjustment of the uneven rolling centerline of the piercer, the inclination of the two rolls, or the too-small amount of reduction in front of the plug, usually spreads in a spiral shape along the full length of the tapered steel pipe; 2) During the rolling process, the uneven wall thickness caused by the premature opening of the centering roll, improper adjustment of the centering roll, and chattering of the ejector rod, usually spread in a spiral shape along the entire length of the conical steel pipe.