SAWH steel pipe used in the production and often there will be some quality problems, in some respects that affect the normal use, the need for the identification of quality spiral steel pipe, according to certain methods and performance testing, can have important practical use in the role, then how to identify counterfeit spiral steel pipe approach: the appearance of the phenomenon often Pock. Generally speaking, commensurate with the amount of whole would be better, mainly taking into account the accumulated error and probability theory this problem. Any inadequacies in the above points please add, we welcome the knowledge to discuss the steel in the continuous exchange in progress. Ma rolling groove surface is due to severe wear and tear caused by uneven irregular spiral steel pipe surface defects. Spiral steel pipe
manufacturers as inferior to the pursuit of profit, most often excessive rolling rolling groove. Easy to produce surface scarring.
High-quality spiral pipe homogeneous. Cold shear tonnage of high-end smooth and neat cutting head, and inferior material because the material is poor, cut the meat off the head and face often have the phenomenon that is uneven, and no metallic luster. And because of shoddy materials manufacturers products less cutting head, big ears will be sub-head and tail. Diameter size fluctuations. The reason is; l, yin and yang steel surface temperature instability. Steel composition uneven. Fold is formed on the surface of spiral steel pipe line, this defect often throughout the product vertical. Have folded due to shoddy manufacturers for high efficiency, the amount of pressure is too large, resulting in the ears, under the fold to produce a rolling, folding of the product after bending will crack, the strength of large thick-walled spiral pipe down. Easily scratched.
No metallic luster. Pale red color of pig iron or the like, for two reasons: the temperature of rolling shoddy material non-standard, their steel temperature is visual, so can not be required for rolling the austenite region, the performance of seamless steel pipe naturally can not be reached. Appear before the oval-shaped cross section. The reason is the manufacturers in order to save materials and finished products before the two rollers of rolling reduction is too large, which greatly decreased the strength of steel, but steel does not conform to the standard dimensions. There are two reasons:. Shoddy uneven spiral steel pipe material, impurities. Shoddy materials manufacturers guide and guard equipment simple, easy to stick steel, these impurities into the roll bite is easy to produce scarring after.
As poorly equipped, low intensity ground, bouncing a large mill. There will be changes in the same week a larger diameter, this discontinuity is easy to produce steel fracture. 11 material containing impurities. The density of steel is too small, and the size tolerance serious, so in case there is no caliper, you can check it weighed. For example, rebar 20, the national standards set forth in the most negative tolerance of 5%, cut-9M single theory when it weighs 120 kilograms, its minimum weight is: 120 X (l-5%) = 114 KG, weighing out the actual weight of a single smaller than 114 kg, it is inferior seamless steel pipe, because it is more than 5% negative tolerance.
The reason is poorly equipped and inferior materials manufacturers, easy to produce glitch, scratch the surface of spiral steel pipe. Seamless steel pipe to reduce the intensity of deep scratches. Prone to collapse. Thin and low horizontal bars. Phenomenon often fully satisfied, because the manufacturers to achieve large negative tolerance, a few of the finished product before the pressure is too large amount of iron-type small, hole fully satisfied. Prone to crack. Because it is blank adobe, adobe pores more, adobe in the cooling process due to thermal stresses, cracks, after rolling through the cracks there.
