How to distinguish the quality of insulated steel pipes

The development of steel pipe production technology began with the rise of the bicycle manufacturing industry. The development of oil in the early 19th century, the manufacturing of ships, boilers, and airplanes during the two World Wars, the manufacturing of thermal power boilers after the two World Wars, the development of the chemical industry, and the drilling and transportation of oil and natural gas all strongly promoted the development of the steel pipe industry in terms of variety, output, and quality.
Along with the rapid development of steel pipes, some counterfeit and inferior steel pipe products have also emerged in the market. So how to correctly and accurately identify the quality of steel pipes?
1. Fake and inferior steel pipes often have a rough appearance.
Matte surface is a defect on the surface of steel that is irregular and uneven due to severe groove wear caused by rolling. Due to the pursuit of profit by manufacturers of fake and inferior steel pipes, there are often instances of excessive groove rolling and manufacturing.
2. The cross-section of fake and inferior steel pipes is elliptical. The reason is that the manufacturer, in order to save materials, has a larger pressing amount in the first two passes of the finished product roller, which greatly reduces the strength of this type of threaded steel and does not meet the standard for the external dimensions of threaded steel.
3. The composition of good steel is uniform, the tonnage of the cold cutting machine is high, and the cutting end face is smooth and neat. However, for fake and inferior materials, due to poor material quality, the cutting end face often has the phenomenon of peeling flesh, that is, unevenness, and no metallic luster. Moreover, due to the fact that counterfeit and inferior material manufacturers have fewer product cuts, large ears may appear at the beginning and end.
4. The inner diameter size of fake and inferior steel pipes fluctuates greatly due to the following reasons:; l、 Steel temperature instability has both positive and negative sides. 2. The composition of steel is uneven. 3. Due to the rudimentary equipment, low foundation strength, and large bouncing of the rolling mill. There may be significant changes within the same week, which can cause uneven stress on the steel bars and lead to fracture.
5. Fake and inferior steel pipes are prone to scratches due to the crude equipment of the manufacturers, which can easily produce burrs and scratch the surface of the steel. Deep scratching reduces the strength of steel.
6. Fake and inferior steel pipes are prone to scar formation on their surfaces.
There are two reasons: (1) The material of the fake and inferior steel pipes is uneven and contains many impurities. (2) The guide equipment of fake and inferior material manufacturers is simple and easy to stick to steel, and these impurities can easily cause scars when they bite the rolling mill rolls.
8. The trademark and printing of steel pipes are relatively standardized.
9. The longitudinal bars of fake and inferior steel threaded steel often have a wavy shape.