Since the rotary piercing deformation characteristics of the tube quality (especially seamless steel pipe surface quality) proposed strict technical requirements. (1) Surface tube directly affects the quality of the outer surface of the finished steel quality. In the hot-rolled steel production, we must first carry out strict inspection tube surface state, the outer surface of the tube is allowed to have scarring, cracks, seams, grooves, folds, dimples, ears, pores, pitting, trachoma and non-metallic inclusions and other defects. When the defect depth of more than 0.7 to 1.0 mm, with tube defects can not be heated and burned, but remains on the surface of the shell will expand any defects in piercing the deformation process, so that any defects are defects in the outer surface of the pipe piercing and rolling deformation process extended so that the defect in the outer surface of the steel pipe to deepen becomes long, resulting in waste. Local defects of the above should be cleared in time, but the process defect depth must not exceed 5% of the tube diameter. (2) Low magnification tube. Tube of internal quality in general are in the low magnification tube for the assessment basis. The low magnification of the tube should not have visible residual shrinkage ≥1 level, FanPi, delamination, bubbles, blisters, non-metallic inclusions, white spots and cracks. After the general loose, center porosity, segregation, subcutaneous bubbles and other defects by standard sample rating shall not exceed the following requirements: the production of general-purpose ordinary carbon steel pipe tube general loose ≤4 grade level segregation center porosity ≤3 ≤3 grade ≤2 mm deep subcutaneous bubbles produces high-pressure boiler tubes, alloy pipe tube general loose loose ≤2 ≤2 grade level center segregation level ≤2 depth subcutaneous bubbles are not allowed. (3) Tube microstructure. Alloy and high-alloy steel pipe production with the special requirements of the tube, in addition to inspecting the low times outside the organization, but also for the microstructure (ie metallurgical high-powered organization) test to determine the non-metallic inclusions (such as sulfide, oxide and carbides) the content and form of distribution, identification band structure and decarburization layer.

Seamless steel pipe diameter with 75 mm, the tolerance is  + 1.0 to 0.5 mm; Seamless steel pipe diameter with 80 to 90 mm, the tolerance is + 0.8-1.3 mm; Seamless steel pipe diameter with 95 to 120 mm, the tolerance is + 1.0 to 1.7 mm. Tube Length: generally 2.3 to 6 meters (by mutual agreement). Bending: straightening device without local bending degree no more than 10 mm per meter, the total curvature of not more than 1.0% of the total length. Degree miter head tube: when the diameter of not more than 96 mm in diameter, cut oblique less than 6 mm; Tube diameter of 95 to 120 mm, cut slope less than 8 mm. Billet surface peeling or after peeling roughness Ra of 25 microns. Exceeds the allowable deviation, not only piercing bite condition deteriorated, but also directly affect the quality of piercing and rolling mill adjustment.

For stainless steel seamless pipe , the three elements of the solution treatment temperature, holding time and cooling rate. Stainless steel seamless solution treatment have what effect? 1: Organization and composition of stainless steel seamless pipe uniform, which is particularly important for raw material, hot-rolled tubes because each section rolling temperature and cooling rate are not the same, resulting in tissue structure is inconsistent. Increased at a high temperature atomic activities, σ phase dissolved chemical composition tends to be uniform, after rapid cooling to obtain a homogeneous single phase. 2: Eliminate work hardening, in order to facilitate continued cold. By solution treatment, recovery distorted lattice, elongated and broken grains recrystallization, to eliminate the internal  stress, the wire tensile strength decreases and the elongation increases. 3: Restore the inherent corrosion resistance of stainless steel pipe. Because cold causes carbide precipitation, lattice defects, the corrosion resistance of stainless steel pipes decreased. After  solution treatment corrosion resistance of stainless steel seamless return to top condition.

Thick-walled seamless steel pipe fracture test is one way of determining the quality of steel. Oral tablets can be broken with the corresponding lateral macrostructure defect inspection of steel. The fracture can be displayed directly tapping the white spots, inclusions, bubbles, implodes, residual shrinkage and other defects. Size and characteristics identified by the grain fracture can be determined steel overheating or burn cases, it can determine the fracture characteristics of steel (ductile fracture and brittle fracture) and judges steel (parts) of the reasons for fracture (fatigue fracture and stress fracture) and the like. There are types of fracture; ductile fracture, brittle fracture, fracture porcelain-like layered fracture, (Tu) shaped fracture, stone-like fracture, fracture of graphite and the like. Parts and components and fracture surface in the manufacturing process due to some reasons which led to damage of the workpiece fracture, and do tension, momentum and other tests in the course of broken, no longer need any preparation and processing, can be directly observed and testing of these natural surface direct observation, direct access to information. Thick-walled seamless steel according to the different types and inspection requirements, fracture test specimen before breaking first heat treated in different ways, according to the heat treatment in different ways, can be divided into pro-fire fracture fracture fracture annealing and quenching fracture and the like.

1. Shoddy walled seamless steel pipe prone to folding. Walled seamless steel folding is formed on the surface of various polyline, this defect is often longitudinally throughout the entire product. 2. Thick-walled seamless shoddy appearance often pockmarked face phenomenon. Pock is due to badly worn groove walled seamless surface irregularities caused by uneven defects. 3. Shoddy thick-walled seamless surface is easy to produce scarring. 4. Shoddy material surface is easy to produce cracks because its blank is adobe, adobe many pores, adobe in the cooling process due to thermal stress, cracks, after after rolling there crack. 5. Shoddy walled seamless steel pipe easily scratched because of shoddy material manufacturers poorly equipped, easy to produce burr, scratching the surface of the thick-walled seamless steel pipe. Depth scratch reduce walled seamless steel pipe strength. 6. Shoddy walled seamless steel pipe without metallic luster, pale red or similar color of pig iron, there are two two reasons, it is blank adobe. 7. Shoddy thick-walled seamless cross ribs thin and low, often sufficient dissatisfaction phenomenon, because manufacturers to achieve large negative tolerance, finished the first few tracks reduction is too large, iron-type small, pass sufficient dissatisfaction. 8. Thick-walled seamless steel pipe shoddy oval cross section, because manufacturers in order to save material, before two of the reduction of finished roll is too large, the strength of this steel is greatly decreased, and does not comply with rebar Dimensions standards. 9. High-walled seamless steel pipe of uniform composition, high cold shear tonnage, smooth and neat end face of the cutting head, and shoddy materials due to the poor material, cut the first end surface there are often off the meat of the phenomenon that is uneven, and no metallic luster . 10. Thick-walled seamless steel pipe shoddy material containing impurities, the density of steel is small, and size tolerance serious, so without a vernier caliper case, you can check it weighed. 11. Shoddy walled seamless steel pipe diameter size fluctuations. 12. High-quality materials and printing trademarks are fairly standard. 13. Three walled seamless steel pipe diameter of 16 or larger thread spacing between the two trademarks are over IM. 14. Shoddy thick-walled seamless steel longitudinal reinforcement often wavy.