Methods to identify inferior steel pipes InferiorSteel pipeEasily folds. Folding refers to the various crease 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; during the next rolling process, folding occurs. Folded products will crack when bent, leading to a significant decrease in the strength of the steel. 2. Inferior steel pipes often have a rough surface. The roughness is caused by severe wear of the rolling grooves, leading to irregular defects on the surface of the steel. Due to profit-seeking by inferior steel pipe manufacturers, rolling grooves are often overused. 3. InferiorSteel pipeThe surface is prone to scabs. There are two reasons: 1. The material of inferior steel pipes is uneven and contains many impurities. 2. The equipment used by inferior material manufacturers is rudimentary, making it easy for impurities to stick to the rollers, which can lead to scabs.
4. The surface of inferior materials is prone to cracks because its billets are made from clay billets that have many pores; during cooling, thermal stress causes cracks that result in visible fissures after rolling. 5. InferiorSteel pipeEasily scratched; this is due to rudimentary equipment at inferior steel pipe manufacturers that easily produces burrs that 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 color for two reasons: first, their billets are clay billets; second, they do not roll at standard temperatures as their rolling temperature is determined visually, making it impossible to roll within specified austenite regions and thus failing to meet performance standards. 7. The transverse ribs of inferior steel pipes are thin and low, often resulting in incomplete filling; this occurs because manufacturers aim for large negative tolerances with excessive pressing in earlier processes and small iron shapes leading to unfilled holes. 8. InferiorSteel pipe's cross-section appears oval-shaped because manufacturers increase pressing amounts in earlier processes excessively in order to save materials; this significantly reduces the strength of such rebar and does not meet standard dimensions for rebar. 's composition is uniform with high tonnage cold shears producing smooth and neat cut ends; however, due to poor quality materials from inferior suppliers, cut ends often show signs of material loss—uneven surfaces without metallic luster—and due to fewer cut ends from these suppliers, large ears may appear at both ends. 's material contains many impurities with lower density and serious dimensional deviations; therefore, without a caliper gauge, it can be weighed for verification purposes. For example, regarding rebar size #20: national standards specify a maximum negative tolerance of 5%. For a standard length of 9M with a theoretical weight per piece being 120 kg, its minimum weight should be: 120 X (1 -5%) =114 kg; if an actual weight measured per piece is less than114 kg then it indicates inferior material as its negative tolerance exceeds5%. Generally speaking weighing multiple pieces together yields better results considering cumulative errors and probability theory issues. 's inner diameter dimensions fluctuate greatly due to several reasons: l) unstable temperature causing yin-yang surfaces;2) uneven composition;3) rudimentary equipment with low foundation strength causing significant bouncing during rolling leading to considerable variations within one circumference which makes such rebars prone to uneven stress resulting in breakage. 's trademark and printing are relatively standardized. 's diameter above #16 has a spacing between trademarks greater than IM. 's longitudinal ribs often appear wavy. 's packaging tends to be loose due lack of cranes at manufacturing sites resulting in an oval shape. | 
