Seamless steel pipe is perforated by the whole round steel, and the steel pipe with no weld on the surface is called seamless steel pipe. According to the production method, the seamless steel pipe can be divided into hot-rolled seamless steel pipe, cold-rolled seamless steel pipe, cold-drawn seamless steel pipe, extruded seamless steel pipe, pipe jacking and so on. According to the section shape, the seamless steel pipe is divided into two kinds of round and shaped, shaped pipe has square, oval, triangle, hexagonal, melon seed, star, fin tube and many complex shapes. The maximum diameter is 900mm and the minimum diameter is 4mm. According to different uses, there are thick wall seamless steel pipes and thin wall seamless steel pipes. Seamless steel pipe is mainly used for petroleum geological drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and high-precision structural steel pipe for automobiles, tractors and aviation.

Straight seam welded pipe, steel pipe made of hot or cold rolled steel plate or steel strip coil welding, straight seam welded pipe on the welding equipment are called straight seam welded pipe. (Because the welding of the steel pipe is a straight line, so named).

Carbon structural steel is carbon steel containing less than 0.8% of carbon, this steel contains less sulfur, phosphorus and non-metallic inclusions than carbon structural steel, mechanical properties are better.
Carbon structural steel can be divided into three types according to the carbon content: low carbon steel (C≤0.25%), medium carbon steel (C 0.25-0.6%) and high carbon steel (C > 0.6%).
Carbon structural steel is divided into normal manganese content (manganese content 0.25%-0.8%) and high manganese content (manganese content 0.70%-1.20%) two groups according to different manganese content, the latter has better mechanical properties and processing properties.

Carbon structural steel is carbon steel containing less than 0.8% of carbon, this steel contains less sulfur, phosphorus and non-metallic inclusions than carbon structural steel, mechanical properties are better.
Carbon structural steel can be divided into three types according to the carbon content: low carbon steel (C≤0.25%), medium carbon steel (C 0.25-0.6%) and high carbon steel (C > 0.6%).
Carbon structural steel is divided into normal manganese content (manganese content 0.25%-0.8%) and high manganese content (manganese content 0.70%-1.20%) two groups according to different manganese content, the latter has better mechanical properties and processing properties.

Spiral welded pipe: The low carbon carbon structural steel or low alloy structural steel strip is rolled into a tube blank according to a certain helix Angle (called forming Angle), and then the pipe seam is welded together, which can produce large diameter steel pipe with a narrower strip. The specification is expressed by the outer diameter * wall thickness, and the welded pipe should ensure that the water pressure test, the tensile strength of the weld and the cold bending performance should meet the requirements.

Carbon steel pipes are divided into hot rolled and cold rolled (drawn) steel pipes.
Hot rolled carbon steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes.
Cold rolled (dial) carbon steel pipe in addition to general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, other steel pipe, also includes carbon thin-wall steel pipe, alloy thin-wall steel pipe, stainless thin-wall steel pipe, special-shaped steel pipe. The outer diameter of the hot-rolled seamless pipe is generally greater than 32mm, the wall thickness is 2.5-75mm, the outer diameter of the cold-rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, the outer diameter of the thin-walled pipe can be 5mm, the wall thickness is less than 0.25mm, and the size accuracy is higher than that of the hot-rolled seamless pipe.