Seamless steel pipes are manufactured by piercing a solid round billet, resulting in a pipe with no weld seam on the surface. Based on the manufacturing process, seamless steel pipes can be classified into hot-rolled seamless pipes, cold-rolled seamless pipes, cold-drawn seamless pipes, extruded seamless pipes, and push-fit pipes, among others. According to the cross-sectional shape, seamless steel pipes are divided into round pipes and special-shaped pipes. Special-shaped pipes include square pipes, elliptical pipes, triangular pipes, hexagonal pipes, melon-seed-shaped pipes, star-shaped pipes, and finned pipes. The largest diameter is 900 mm, while the smallest is 4 mm. Depending on their application, seamless steel pipes are further categorized as thick-walled or thin-walled. Typically, seamless pipes can withstand 20% higher working pressure than welded pipes of the same material grade and size.