Methods for identifying fake and inferior hot-rolled large diameter seamless steel pipe

In the construction and industrial sectors, hot-rolled large-diameter seamless steel pipes are essential for various applications due to their high strength and durability. However, fake and inferior steel pipes pose significant risks to safety and structural integrity. Identifying such substandard materials is crucial to ensure the quality and longevity of the project. Below are several methods for identifying fake and inferior hot-rolled large-diameter seamless steel pipes.

Surface Scratches
Fake and inferior hot-rolled large-diameter seamless steel pipes are prone to scratches. This is because manufacturers of low-quality pipes often use simple and outdated equipment that easily produces burrs, leading to scratches on the surface. Deep scratches compromise the steel's strength, making it more likely to fail under stress.

Lack of Metallic Luster
Unlike high-quality pipes, fake and inferior pipes typically lack a metallic shine. Instead, they appear light red or have a surface texture similar to pig iron, indicating poor material quality and inadequate manufacturing processes.

Thin and Incomplete Cross Ribs
Fake and inferior pipes often have thin and low cross ribs. This occurs because manufacturers aim for large negative tolerances to save on material costs. As a result, the cross ribs may not fully form, leaving the pipe unsatisfactory in both appearance and performance.

Elliptical Cross-Section
An inferior hot-rolled large-diameter seamless steel pipe may have an elliptical cross-section. This is a direct result of the manufacturer reducing material use by making the reductions during the first two passes of the finishing roll too large. This reduces the pipe's strength and prevents it from meeting the standard dimensional requirements.

Uneven and Rough End Faces
High-quality seamless steel pipes have uniform composition and are processed with high-tonnage cold shearing machines, resulting in smooth and neat end faces. In contrast, fake and inferior pipes often have uneven and rough ends due to poor-quality materials and ineffective cutting processes. These pipes may also exhibit "big ears" at the head and tail, where the material has not been properly cut.

Presence of Impurities and Low Density
Inferior seamless steel pipes contain a high level of impurities, resulting in a lower steel density and significant deviations in size. This can often be detected without the use of specialized equipment such as vernier calipers, as the weight of the pipe will feel off. Weighing the pipe can help detect fake products, taking into account cumulative errors and the principles of probability.

By using these methods, one can effectively identify fake and inferior hot-rolled large-diameter seamless steel pipes, ensuring the use of high-quality materials in any project.