Defects on the outer surface of hot rolled seamless steel tube

　　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.