Outer surface defects of hot-rolled seamless steel pipe.

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.