In modern people's life, steel pipe is closely related to human life. Steel pipe is not only used for conveying fluid and powdery solids, exchanging heat energy, manufacturing mechanical parts and containers, but also a kind of economic steel. It can reduce the weight, save 20 ~ 40% of the metal, and realize the industrial mechanized construction. Using steel pipe to manufacture highway bridge can not only save steel, simplify construction, but also greatly reduce the area of protective coating and save investment and maintenance cost. Therefore, no other type of steel can completely replace steel pipe, but steel pipe can replace part of the profile and bar. Steel pipe is much more important to the development of national economy and the improvement of human life quality than other steel. From People's Daily appliances, furniture, water supply, gas supply, ventilation and heating facilities to the manufacturing of various agricultural machinery appliances, underground resources development, national defense and aerospace guns, bullets, missiles, rockets and so on are inseparable from steel pipes.

Since steel pipe is so important, let's understand the problems of inferior steel pipe, and then we can better avoid it.

1. Poor quality steel pipe is prone to folding. Folding is a variety of broken lines formed on the surface of the steel pipe, which often runs through the longitudinal length of the product. The reason for the folding is that because of the pursuit of high efficiency of fake and inferior manufacturers, the amount of pressure is large, the ear, the next rolling will produce folding, folding products will crack after bending, the strength of steel greatly decreased.

2. The appearance of inferior steel pipe often has pockmarked surface phenomenon. Pockmarks are irregular and uneven defects on the steel surface caused by serious wear of rolling groove. Because of inferior steel pipe manufacturers seek profit, often appear groove rolling the most exceed the standard.

3. The surface of inferior material is easy to crack, the reason is that its billet is adobe, adobe pores, adobe in the process of cooling due to the role of thermal stress, crack, after rolling there are cracks.

4. Inferior steel pipe has no metallic luster, showing light red or similar color of pig iron, the reason has two points two: one is that its billet is adobe. Second, the temperature of shoddy rolling material is not standard, their steel temperature is measured visually, so that it can not be rolled in accordance with the provisions of the austenite area, the performance of steel naturally can not reach the standard.

5. The cross section of inferior steel pipe is oval, the reason is that the manufacturer in order to save materials, the pressure of the finished roller in front of the two is large, the strength of this rebar decreases greatly, and it does not meet the standard of the shape size of rebar.

6. Inferior steel pipe material contains impurity much, the density of steel slants small, and the size is out of tolerance serious, so below the circumstance that does not have vernier caliper, can undertake weighing check to it. For example, for rebar 20, the national standard stipulates that the maximum negative tolerance is 5%. When measuring 9M, its theoretical weight of a single rod is 120kg. Its minimum weight should be 120X (L-5%) = 114kg. In general, integer quantities work better, mainly because of cumulative errors and probability theory.

7. The trademark and printing of quality tube are more standard.

8. The longitudinal bars of fake steel rebar are often wavy.

Understanding the above points, I hope it will be helpful for you to choose your own quality pipe. If you need help, please contact Huatian Steel Pipe.