The stringent requirements of the quality of the tube and pipe varieties, uses and perforation methods. Tube quality requirements for general-purpose pipe can be relaxed, while the important use of steel and high-alloy steel pipe of the quality requirements must be strict. Perforation methods with better stress conditions or smaller deformations may require slightly lower surface and internal quality requirements of the tube without affecting the performance of the tube.
If the perforation deformation is large, the surface quality and internal quality of the tube should be strictly required. In short, the technical requirements of the tube is to ensure the quality of the steel pipe and the smooth progress of the production process as the basis to determine, and will vary with the perforation method, with the technical conditions of the pipe increased. The technical conditions of various tube can be found in the standard and technical agreement. For example, automatic tube rolling machine tube blank requirements are as follows:
(1) Bending of any part of the tube is less than or equal to 6mm / m, the incision gradient of the tube end is less than or equal to 6 ~ 8mm, and the end flattening of the tube is less than or equal to 8% Dp.
(2) The tube surface shall not be cracked, Scales, folds, non-metallic inclusions and shrinkage cavities. Not allowed to have a height or depth of more than 0.5mm of small grooves, pockels, ears and the height of more than 1mm double-sided ears. Tube blank defect cleaning depth of not more than 0.05Dp;
(3) Tube microstructure: not allowed to have ≥ 1 level shrinkage hole, air bubbles, skin, white spots and cracks. For the general carbon structural steel billet, the general loose ≤ 3, the center loose ≤ 3, segregation ≤ 3, subcutaneous bubbles ≤ 2.
