Defects of Hot Rolled Seamless Steel Pipe
Division
Located on the inner surface of the steel tube, it is vertically distributed, spirally uplifted, and dissected in the form of segregation or fragmentation of massive metals.


Straight internal skin flap
The inner surface of the steel tube is vertically distributed, symmetrically or unilinearly folded, long and locally pierced.


Irregular holes
Located on the surface of the pipeline is vertically distributed. One or two walls are 180 degrees thicker, or the wall thickness at the separation point between the surface of the pipeline and the mandrel is thicker. It is also called the inner drum assembly. (2) The inner garden of steel is hexagonal and uneven in thickness, also known as hexagonal.


Wall contraction
Located on the inner surface of the steel pipe, the inner surface of the steel pipe with the thinnest cross section is depressed, locally thinned, and its wall thickness shrinks seriously, almost tearing.


Roll wound scar
The longitudinal direction of the inner surface of the steel nail is like a scar, a bump or a block of indentation on the surface of the folded inner tube.


Infolding
Located on the inner surface of the end of the pipe, the local or flaky longitudinal spiral or semi-spiral folding is irregular.


roll down
In the concave or convex corrugates on the outer surface of the tube, which are part or full length of the longitudinal surface of the tube wall, the long longitudinal grooves are clearly symmetrical, usually straight lines, and oblique lines alone.


tear
The longitudinal steel surface of the pipe shows different degrees of transverse fracture, with diamond and elliptical holes passing through the tube body.


Folded double seam
The longitudinal surface of the pipe wall inclines to extend into a pair of longitudinal cracks. Sometimes the cracks scattered around the pipe sometimes look symmetrical.


Double-center folding
The longitudinal surface of the pipe wall inclines to extend into a pair of longitudinal cracks. Sometimes the cracks scattered around the pipe sometimes look symmetrical.


Outer fold
The outer tube shows regular folding triangle, double seam straight line single-cut straight or irregular folding. (2) Sewing machine-like or staggered 60, 120 and 180 degrees seam-like folding pipes are generally continuous or discontinuous in the external longitudinal direction; and (3) the external longitudinal folding is on the spiral steel pipe. (4) Longitudinal folding of pipelines through long or short oblique lines seriously staggers two or three or 120 degrees.