Steel pipes are closely related to human life and production activities, and steel pipe production occupies an irreplaceable position in the steel industry. From everyday utensils, furniture, water supply and drainage, gas supply, ventilation, and heating facilities to the manufacturing of various agricultural machinery, the development of underground resources, and the guns, bullets, missiles, and rockets used in national defense and aerospace, all rely on steel pipes.

　　So how should we identify the quality of steel pipes?

       1. Inferior steel pipes are prone to folding. Folding refers to the various fold lines formed on the surface of the steel pipe, and this defect often runs through the entire length of the product. The cause of folding is due to inferior manufacturers pursuing high efficiency, resulting in excessive pressing, which creates ears, leading to folding during the next rolling process. Folded products will crack when bent, and the strength of the steel will decrease.

　　2. Inferior steel pipes often have a rough surface. The rough surface is caused by severe wear of the rolling groove, leading to irregular bumps and depressions on the steel surface. Due to the pursuit of profit by inferior steel pipe manufacturers, the rolling groove often exceeds standards.

　　3. Inferior steel pipes are prone to scabs on the surface. There are two reasons: (1) The material of inferior steel pipes is uneven and contains many impurities. (2) The equipment of inferior material manufacturers is rudimentary, making it easy for steel to stick, and these impurities can cause scabs after biting into the rollers.

　　4. Inferior materials are prone to cracks on the surface, as their billets are made of clay, which has many pores. During the cooling process, the clay billets can develop cracks due to thermal stress, resulting in cracks after rolling.

　　5. Inferior steel pipes are easily scratched because the equipment of inferior steel pipe manufacturers is rudimentary, leading to burrs that can scratch the surface of the steel. Deep scratches reduce the strength of the steel.

　　6. Inferior steel pipes lack metallic luster and appear light red or similar to pig iron. There are two reasons: (1) Their billets are made of clay. (2) The rolling temperature of inferior materials is not standard; their steel temperature is determined by visual inspection, making it impossible to roll according to the specified austenite region, resulting in substandard steel performance.

　　7. The transverse ribs of inferior steel pipes are thin and low, often resulting in incomplete filling. This is because manufacturers aim for a large negative tolerance, leading to excessive pressing in the earlier stages of production, resulting in small iron shapes and incomplete filling of the holes.

　　8. The cross-section of inferior steel pipes is oval-shaped. This is because manufacturers, in order to save materials, apply excessive pressing in the first two stages of production, significantly reducing the strength of this rebar and failing to meet the standard dimensions for rebar.

　　9. High-quality steel has uniform composition, and the tonnage of the cold shearing machine is high, resulting in smooth and neat cut ends. In contrast, inferior materials often have rough cut ends due to poor material quality, leading to uneven surfaces and lack of metallic luster. Additionally, inferior material manufacturers produce fewer cut ends, resulting in large ears at the head and tail.

　　10. Inferior steel pipes contain many impurities, have a lower density, and have serious dimensional deviations. Therefore, without a caliper, they can be weighed for verification. For example, for rebar 20, the national standard specifies a maximum negative tolerance of 5%. When the standard length is 9M, the theoretical weight of a single piece is 120 kg, and its minimum weight should be: 120X(1-5%)=114 kg. If the actual weight of a single piece is less than 114 kg, it is inferior steel, as its negative tolerance exceeds 5%. Generally, weighing the entire batch will yield better results, mainly considering cumulative errors and probability theory.

　　11. The inner diameter dimensions of inferior steel pipes fluctuate greatly due to: 1. Unstable steel temperature with yin-yang surfaces. 2. Uneven steel composition. 3. Due to rudimentary equipment, low foundation strength, and significant bouncing of the rolling mill, there can be considerable variations within the same week, making such rebar prone to uneven stress and easy to break.

　　12. High-quality pipes have standardized trademarks and markings.

　　13. For large rebar with a diameter of 16 or more, the distance between two trademarks is more than 1M.

　　14. The longitudinal ribs of inferior steel rebar often appear wavy.

       15. Inferior steel pipe manufacturers do not have cranes, resulting in loose packaging. The side appears oval.

The above is the distinction between high-quality and inferior steel pipes. Please be vigilant when purchasing and choose high-quality steel.

E-mail :

sales@senruipipefitting.com

Phone/Wechat：

+86-18260553910

Address：

440 meters north of the intersection of Provincial Highway 283 and Xinman Line in Mengcun Hui Autonomous County, Cangzhou City, Hebei Province, China