Tube diameter and allowable deviation:

  Tube diameter 75mm, allowable deviation:+1.0 －0.5mm；
  Tube diameter 80~90mm, allowable deviation:+0.8 —1.3mm；
  Tube diameter 95~120mm,allowable deviation:+1.0 —1.7mm。

 Tube length：commonly2.3~6m（Bilateral agreement）。
 Tortuosity：When the equipment is not straightened, the local curvature is not more than 10 mm per meter, and the total bending degree is   not more than 1% of the total length。

Tube head chamfer angle:
  Diameter≤96mm，chamfer angle＜6mm；
  Diameter=95~120mm，chamfer angle＜8mm。
  Tube surface peeling or peeling after roughness Ra is 25 micron。
  More than the allowable deviation, not only make the piercing bite conditions deteriorate, and directly affect the quality of the perforation   and mill adjustment.

    The surface quality of steel tube directly affects the surface quality of finished steel pipe. In the production of hot-rolled steel, first of all to conduct strict examination of the tube surface, the outer surface of the tube blank is not allowed to have scar, crack, crack, grooves, folding, dent, handle, holes, pits, sand hole and non metallic inclusion. When the defect depth is more than 0.7~1.0 mm, not burned with defect of billet heating, but the residue in the tube of any defects on the surface of the perforation will expand the deformation process, the defects in the steel pipe on the outer surface of any defect will be extended in the piercing and rolling deformation process, the defects in the outer surface of the pipe to deepen variable length, resulting in waste. The local defects should be cleaned in time, but the depth of the defect treatment shall not exceed 5% of the diameter of the pipe.

Steelmaking Products