Mechanical seamless steel tubes must meet high dimensional accuracy, excellent mechanical properties, and a good surface condition, as required for their use. For bearing tubes, higher wear resistance, uniform structure, and strict tolerances for internal and external diameters are essential. In addition to standard mechanical property tests, low magnification, fracture surface, annealing structure (spheroidal, reticulated, striped), non-metallic inclusions (oxides, sulfides, speckled, etc.), decarburization layer, and hardness indices must also be tested.

High-pressure seamless steel pipes for the fertilizer industry are commonly used to transport chemical media (such as synthetic ammonia, methanol, urea, etc.) under corrosive conditions with pressures ranging from 2200 to 3200 MPa, operating temperatures from -0 to 400°C. Therefore, in addition to being able to withstand high pressure, they should also possess strong anti-corrosion properties, good surface condition, and mechanical properties. In addition to mechanical property, flattening, and hydrostatic tests, intergranular corrosion tests, grain size analysis, and more stringent non-destructive testing should be conducted based on different steel grades.