1.The folding is easy to happen with inferior steel tube
Folding is formed on the surface of the pipe line, this kind of defect often throughout the entire product longitudinal. The reason for causing of fold is due to the pursuit of high efficiency, large reduction of the inferior manufacturer, when go on the next rolling, the folding happens, and the folding products will be cracking after bending, and the strength of steel will decreased.
2. The inferior steel tube has pitted surface
Pits is due to the defects of the irregular uneven steel surface caused by the worn groove. Because of the pursuit of profit, the inferior steel pipe manufacturer often appear the overweight groove rolling.
3. The inferior steel tube surface are prone to scarring
For two reasons: (1) the inferior steel pipe material uneven with impurities. (2). The inferior material manufacturer with simple equipment which is easy to stick steel, these impurities after the roll bite are prone to scarring.
4. The surface of the inferior material is easy to have crack for the reason that it’s blank is adobe, and in the process of cooling due to the effect of thermal stress, cracks, after rolling, there is crack.
5. The inferior steel pipe is easy to scratch for the reason that the inferior steel pipe factory has simple equipment which is easy to produce burr and scratch steel surfaces. The deep scratches will reduce the strength of the steel.
6. The inferior steel tube has no metallic luster, it is reddish or similar to the color of the pig iron for its original material is adobe. And the characteristics of steel pipe cannot reach the required standard.
7. The transverse bar of the inferior steel pipe is thin and low, and often appear phenomenon of discontent, because the manufacturers want to achieve big minus tolerance, finished product quality is not in accordance with the standard.
8. The cross-section of the inferior steel tube is oval, because the factory in order to save material, the quantity of the finished product roll is big, the strength of rebar is greatly decreased, but also do not conform to the standard of rebar shape size.
9. The high quality steel composition is uniform, the cold shearing machine has high tonnage, and the cutting head end is smooth and neat, and the material of the inferior manufacturer is poor, cutting head end is not smooth or uneven, and also has no metallic luster.
10. The impurities of the inferior steel pipe is very large, but the steel density is small, and the size out-of-tolerance is serious, so in the absence of vernier caliper, can be checked to weigh it.
11. The inner diameter of the inferior steel pipe is volatile, the reason is: 1. the steel temperature is unstable; 2. the composition of steel is not uniform; 3. Because of the poorly equipped, and low foundation strength, there will be a larger changes within the same week, the steel bar caused by uneven on fracture.
12.The high quality tube logo and printing are specification.
13.The steel pipe diameter more than 16, the spacing between the two trademark all over IM.
14.The inferior steel rebar longitudinal reinforcement often undulate.
15. The inferior steel pipe manufacturer with no traffic, so the packing is loose.