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Folding Defects: Inferior thick-walled seamless steel pipes are prone to folding defects, characterized by various linear folds on the surface that often run longitudinally through the entire product. These defects occur due to the excessive reduction in thickness by unscrupulous manufacturers aiming for high efficiency, leading to edge formations which result in folding during subsequent rolling processes. These folds can cause the pipes to crack upon bending, significantly reducing their strength.

Surface Roughness: The surfaces of substandard thick-walled seamless steel pipes often exhibit rough, uneven textures known as "hemp patterns." These occur due to severe wear and tear on the rolling grooves, which substandard manufacturers frequently overlook in their pursuit of profit, resulting in irregular surface defects.

Scarring: Substandard thick-walled seamless steel pipes are susceptible to surface scarring. This can be attributed to two main factors:

1. The uneven material composition with numerous impurities.

Inadequate and simple guide equipment in substandard manufacturing facilities, which leads to steel adhering to the rollers and forming scars.

Cracks: Cracks frequently appear on the surfaces of inferior materials. This is because the raw billets used are of poor quality, containing numerous air pockets. These billets develop cracks due to thermal stresses during cooling, which are then exacerbated by the rolling process.

Scratches: Inferior thick-walled seamless steel pipes are prone to scratches due to the rudimentary equipment used by substandard manufacturers, which often produces burrs. Deep scratches can significantly reduce the strength of these pipes.

Lack of Metallic Luster: Inferior thick-walled seamless steel pipes lack metallic luster, appearing reddish or similar to cast iron. This occurs because:

2. The raw billets are of poor quality.

The rolling temperatures are not precisely controlled and are often judged by eye, preventing proper rolling within the prescribed austenitic range, thus failing to meet performance standards.

Thin and Low Reinforcement Ribs: Inferior thick-walled seamless steel pipes often have thin and underfilled transverse ribs. This happens because the manufacturers aim to achieve a larger negative tolerance by excessively reducing the thickness in the initial rolling stages, resulting in insufficient filling of the mold.

Oval Cross-Sections: The cross-sections of inferior pipes are often oval. This is due to excessive reduction in thickness in the final rolling stages to save material, which greatly diminishes the pipe's strength and fails to meet dimensional standards.

Uneven Cut Ends: High-quality pipes have uniform composition, high tonnage cold cutting machines, and smooth, even cut ends. In contrast, inferior pipes often have irregular, uneven cut ends with no metallic luster due to poor material quality and minimal cutting. The head and tail ends frequently have large burrs.

Impurities and Density: Inferior thick-walled seamless steel pipes contain many impurities and have a lower density. They also exhibit severe dimensional discrepancies. Without a vernier caliper, these can be identified by weighing and comparing the pipes.