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.


Tech & Service of Seamless pipe

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. Seamless pipes dominates 65% of market share in Chinese boiler industry.

How to make seamless pipe(seamless pipe process)?
Hot Piercing Workshop
Piercing process
The cross roll piercing and pilger rolling process in the size range from approx. 250 to 660 mm outside diameter.
Precision cold drawn steel tube production process
Pipe weld cracks
often follow different mechanisms can be divided into two types of thermal cracking and cold cracking.
How to calculate a steel pipe and tube theoretic weight
Calculate a steel pipe?
Pipe fittings are necessary to join together pipes, or to change the direction of an existing pipe.
Pipe beveling
Pipe beveling is the process where an angle is formed between the edge of the end of a pipe or tube and a plane perpendicular to the surface.
Steel pipe cutting machine
Pipe cutting
Cutting tools have a grinding wheel piece cutting machine (also known as toothless saw), hand saw, cutter and other hand tools.
Packing the steel pipes
There are probably hundreds of different methods for packing a pipe, and most of them have merit, but there are two principles that are vital for any method.


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