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Hot-rolled seamless steel pipe defects

Hot rolled seamless steel pipe

Hot-rolled seamless steel pipe production base deformation process can be summarized as three stages: perforation, extension and finishing.
a. Inner surface defects

1. An inner flap: presenting a straight line, a spiral or a semi-helical sawtooth defect on the inner surface of the steel pipe.
2. inside scarring: scars in the steel pipe inner surface, generally easily peel off.
3. Warping: a straight line or intermittent small nail-like tilt leather. Often seen in the capillary head, and easy to peel.
4. inside straights: a straight shape scratch with a certain width and depth.
5. inner edge: a straight shape protrusion with a certain width and depth.
6. inner drum kits: a super and regular protrusion and outer surface is not damaged.
7. Pull pits: a regular or non-regular pit and the outer surface without damage.
8. internal thread (this defect produced only at Accel units): spiral traces often seen in the thin-walled tube surface, and there are obvious rugged feelings.

b. outer surface defects
1. An outer fold: the outer surface of the pipe presents a layered folded spiral.
2. separation: presenting a spiral shape or blocky delamination and cracking.
3. external scarring: scars on the outer surface.
4. pock surface: steel surface showed uneven pits.
5. Line: a substantially symmetrical or asymmetrical linear rolling marks.
6. Hairline: a continuous or discontinuous hairy fine lines.
7. net cracks: scaly small cracks.
8. scratches: linear or spiral-shaped groove-like defects.
9. touch deflated: the outer surface of the steel pipe rendered in a convex outer concave phenomenon, and pipe wall thickness without injury.
10. bumps: collision irregular scars.
11. straightening recess: steel spiral concave outer surface.
12. rolled off: longitudinally local or long presentation in a convex outer concave folds, the outer surface into strips depression.
13. crack:opened the rupture surface phenomenon, much produced in the thin-walled tube.

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