Methods of identification of the inferior steel pipe
An inferior steel pipe prone to folding.Pipe fittings|
Folding steel pipe formed on the surface of the broken line, and this defect often throughout the entire product vertical. Of folding because of the shoddy manufacturers pursuit of high efficiency, the reduction amount is too large, resulting in the ears, under a rolling to produce folded, folded products after bending will crack the big decline in the strength of steel.
Two. The appearance of inferior steel pipe often pockmarked face phenomenon.
Ma surface is due to the rolling groove serious wear and tear caused by the steel surface irregularities, uneven defects. Exceeded due to shoddy steel pipe manufacturers to the pursuit of profit, often rolling groove rolling.
3. Shoddy steel pipe surface is easy to produce scarring.
There are two reasons: (1). And shoddy steel pipe material is uneven, more impurities. (2). Shoddy materials manufacturers guide simple equipment, easy to stick to steel, these impurities the bite roller easy to produce scarring.
4. Surface of the inferior material easy to crack, because it blank adobe, adobe stomatal adobe in the cooling
Process due to thermal stress, cracks, and there are cracks after rolling.
5 The inferior pipe is easily scratched because of shoddy steel pipe equipment is very easy to produce glitch, scratch the steel surface. Depth scratch reduce the strength of steel.
6. And shoddy steel pipe without metallic luster, pale red or similar color of the pig iron, two two reasons, it’s blank is adobe. Shoddy material rolling temperature standards, the temperature of the steel is by visual inspection, so that can not be carried out by the provisions of the austenite region rolling, the performance of the steel is naturally not standard.
7. Fine transverse ribs of the inferior steel pipe is low, often sufficient dissatisfaction with the phenomenon, because the manufacturers to reach a large negative tolerance, finished a few of the reduction is too large, iron-type small, pass sufficient dissatisfaction.
8. Shoddy steel pipe cross section appear oval because the manufacturers in order to save materials, finished roll two of the reduction is too large, the strength of this steel is greatly decreased, but does not conform to the standard of rebar Dimensions.
9. Homogeneous high-quality steel, high tonnage of cold shear, cut the head and face smooth and neat, and shoddy materials due to poor material, cut the head end there are often out of meat phenomenon, that is, uneven, and non-metallic luster. And the shoddy material manufacturers cutting head, head and tail
Carbon steel pipe|| and big ears.
10. Shoddy steel pipe material containing impurities, the density of steel is small, but the size of ultra-poor and serious, so in the case of vernier caliper, weighed to check it. For example, for the rebar 20, the national standards set forth in the maximum negative tolerance of 5%, the length 9M single theoretical weight of 120 kg minimum weight should be: 120 X (l-5%) = 114 kg , weighing out the actual weight of a single than 114 kilograms of small, shoddy steel, because it is negative tolerance more than 5%. In general, the whole commensurate with the amount of effect will be better, mainly taking into account the accumulated error and probability theory.
11. Shoddy steel pipe diameter size fluctuations, and the reason is; l steel temperature instability of yin and yang surface. 2, the composition of the steel is uneven. 3, due to the simple equipment, and the foundation of low intensity, the mill bounce. Will appear the same week changes, reinforced discontinuity is easy to produce fracture.
12. The trademark and printing of high-quality tube specifications.
13. Three pipe diameter of more than 16 threads, the spacing between the two trademarks in the IM above.
14. Shoddy steel rebar in the longitudinal reinforcement is often wavy.
15. And shoddy steel pipe manufacturers, there is no traffic, so the packing is relatively loose. Side oval.
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Welded steel pipe standards