What Are The Reasons for Uneven Wall Thickness of Spiral Seam Submerged Arc Welded Steel Pipes

The spiral seam submerged arc welded steel pipe has a uniform wall thickness, looks good, is evenly stressed, and is durable. The spiral seam submerged arc welded steel pipe has uneven wall thickness and uneven stress on the steel pipe. The thin parts of the steel pipe will easily break. The uneven wall thickness of the steel pipe is A phenomenon that easily occurs during the rolling adjustment process of steel pipes. The uneven wall thickness of steel pipes is mainly reflected in uneven spiral wall thickness, uneven linear wall thickness, and thicker or thinner wall thickness at the head and tail.

First: Uneven wall thickness at the head and tail
Cause:
1) The front end of the spiral seam submerged arc welded steel pipe blank is cut at an inclination, the bend is too large, and the centering hole of the pipe blank is not aligned, which can easily lead to uneven wall thickness at the head of the tapered steel pipe;
2) When piercing, the elongation coefficient is too large, the roller speed is too high, and the rolling is unstable;
3) Unstable steel casting by the punching machine can easily cause uneven wall thickness at the end of the capillary tube.

Second: Uneven spiral wall thickness
The causes are:
1) Uneven wall thickness caused by adjustments such as the incorrect rolling center line of the piercing machine, unequal inclination angles of the two rollers, or too small the amount of pressure before the head, usually distributed in a spiral along the entire length of the tapered steel pipe;
2) Uneven wall thickness caused by the premature opening of the centering roller, improper adjustment of the centering roller, and vibration of the ejector during the rolling process is usually distributed in a spiral along the entire length of the tapered steel pipe.