The development of steel pipe production technology began with the rise of the bicycle manufacturing industry, the development of petroleum in the early 19th century, the manufacture of ships, boilers, and aircraft during the two world wars, the manufacture of thermal power boilers after the two world wars, the development of the chemical industry, and the development of petroleum The drilling and transportation of natural gas has strongly promoted the development of the steel pipe industry in terms of variety, output and quality.
While steel pipes are developing rapidly, some fake and inferior steel pipe products have appeared one after another on the market. So how to accurately and accurately identify the quality of steel pipes?
1. Fake and inferior steel pipes often have pitting on the surface.
Pitted surface is the irregularity of the surface of the steel due to the serious wear of the rolling groove. Because the counterfeit and inferior steel pipe manufacturers are pursuing profits, the groove rolling manufacturing often exceeds the standard.
2. The cross-section of the counterfeit steel pipe is elliptical. The reason is that in order to save materials, the reduction of the first two passes of the finished roll is too large. The strength of this kind of screw steel is greatly reduced, and it does not meet the standard of the shape of the steel .
3. The composition of good steel is uniform, the tonnage of the cold shear is high, and the end face of the cutting head is smooth and tidy. However, due to the poor material, the end face of the cutting head often has meat loss, that is, it is uneven and has no metallic luster. Moreover, because the products of the fake and inferior material manufacturers have few cuts, big ears will appear at the ends.
4. The inner diameter of the fake and inferior steel pipe fluctuates greatly, and the reason is: l, the steel temperature is unstable and there is a positive and negative side. 2. The composition of steel is not uniform. 3. Due to the simple equipment and low foundation strength, the rolling mill bounces greatly. There will be large changes within the same week, and the uneven force of such steel bars is prone to fracture.
5. Counterfeit and inferior steel pipes are easy to scratch because of the simple equipment of the manufacturers of fake and inferior steel pipes, which can easily produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of steel.
6. Fake and inferior steel pipes are prone to scars.
There are two reasons: (1) The material of the fake and inferior steel pipe is uneven and there are many impurities. (2) Fake and inferior material manufacturers have simple guide and guard equipment, which is easy to stick to steel. These impurities will easily cause scars after biting the roll.
8. The trademarks and printing of steel pipes are relatively standardized.
9. The longitudinal ribs of counterfeit steel rebar are often wavy.
After understanding the above information, I believe you will be much easier when choosing to buy steel pipes.