Seamless steel pipes are perforated from whole round steel, and steel pipes without welds on the surface are called seamless steel pipes. According to the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, and top pipes. According to the cross-sectional shape, seamless steel pipes are divided into two types: round and special-shaped. Special-shaped pipes include square, oval, triangular, hexagonal, melon seed, star, and finned pipes. The maximum diameter is 900mm and the minimum diameter is 4mm. According to different purposes, there are thick-walled seamless steel pipes and thin-walled seamless steel pipes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemical industry, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

Seamless steel pipes are widely used.
1. General-purpose seamless steel pipes are rolled by ordinary carbon structural steel, low-alloy structural steel or alloy structural steel, with the largest output, and are mainly used as pipelines or structural parts for conveying fluids.

2. According to different purposes, it can be supplied in three categories:
a. Supply according to chemical composition and mechanical properties;
b. According to mechanical performance;
c. According to the water pressure test supply. Steel pipes supplied according to categories a and b. if used to withstand liquid pressure, shall also be subjected to a hydraulic test.

3. Special-purpose seamless pipes include seamless pipes for boilers, chemical and electric power, seamless steel pipes for geology, and seamless pipes for petroleum.

Seamless steel pipes have a hollow section and are used in large quantities as pipelines for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter in flexural and torsional strength and is an economical section steel. Widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycle frames, and steel scaffolding used in construction. Steel pipes are used to make ring parts, which can improve material utilization, simplify manufacturing procedures, and save materials and processing. Working hours.

There are two main production processes for seamless steel pipes (cold rolling and hot rolling):
①Main production process of hot-rolled seamless steel pipe (△main inspection process):
Tube billet preparation and inspection△→tube billet heating→perforation→tube rolling→pipe reheating→fixed (reduced) diameter→heat treatment△→finished tube straightening→finishing→inspection△(non-destructive, physical and chemical, bench inspection)→in storage

②Main production process of cold-rolled seamless steel pipe:
Blank preparation → pickling and lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection → storage