Uniform wall thickness in spiral submerged arc welded steel pipes looks aesthetically pleasing, distributes stress evenly, and is durable. Uneven wall thickness leads to uneven stress distribution, making thinner sections of the pipe more prone to cracking. Uneven wall thickness is a common phenomenon that occurs during the pipe rolling process. It primarily manifests as spiral-shaped unevenness, straight-line unevenness, and uneven thickness at the beginning and end of the pipe. In detail:
First: Uneven wall thickness at the head and tail of spiral submerged arc welded steel pipes.
Causes:
1) Excessive bevel or tortuosity at the front end of the pipe blank, and misalignment of the centering hole, easily lead to uneven wall thickness at the head of the conical spiral submerged arc welded steel pipe;
2) Excessive elongation coefficient during piercing, excessively high roll speed, and unstable rolling;
3) Unstable steel ejection by the piercing mill easily leads to uneven wall thickness at the tail of the tube.
Second: Uneven spiral wall thickness in spiral-seam submerged arc welded steel pipes.
The causes are:
1) Uneven wall thickness caused by misalignment of the piercing mill centerline, unequal inclination angles of the two rolls, or insufficient pre-pressing of the mandrel, typically appearing spirally distributed along the entire length of the conical spiral-seam submerged arc welded steel pipe;
2) Uneven wall thickness caused by premature opening of the centering roll during rolling, improper adjustment of the centering roll, and mandrel vibration, typically appearing spirally distributed along the entire length of the conical spiral-seam submerged arc welded steel pipe.
Post time: Jan-26-2026