A steel pipe made of a single piece of metal with no seams on the surface is called a seamless steel pipe. According to the production method, seamless pipes are divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, and jacking pipes. According to the cross-sectional shape, seamless steel tubes are divided into two types: round and special-shaped, and special-shaped tubes have various complex shapes such as square, oval, triangular, hexagonal, melon-shaped, star-shaped, and finned tubes. The maximum diameter is up to 650mm and the minimum diameter is 0.3mm. Depending on the application, there are thick-walled tubes and thin-walled tubes. 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. General purpose seamless steel tubes are rolled from ordinary carbon structural steels, low alloy structural steels or alloy structural steels with the highest yield, and are mainly used as pipes or structural parts for conveying fluids. .2. There are three types of supplies according to different uses: a. Supply according to chemical composition and mechanical properties; b. Supply according to mechanical properties; c. Supply according to hydraulic test. Steel pipes supplied by Types a and b, if used to withstand liquid pressure, are also subject to hydrostatic testing. 3. There are many kinds of seamless pipes for special purposes, such as seamless pipes for boilers, seamless pipes for chemical power, seamless steel pipes for geological use and seamless pipes for petroleum.
Seamless steel pipes are widely used. General purpose seamless steel tubes are rolled from ordinary carbon structural steels, low alloy structural steels or alloy structural steels with the highest yield, and are mainly used as pipes or structural parts for conveying fluids. .2. There are three types of supplies according to different uses: a. Supply according to chemical composition and mechanical properties; b. Supply according to mechanical properties; c. Supply according to hydraulic test. Steel pipes supplied by Types a and b, if used to withstand liquid pressure, are also subject to hydrostatic testing. 3. There are many kinds of seamless pipes for special purposes, such as seamless pipes for boilers, seamless pipes for chemical power, seamless steel pipes for geological use and seamless pipes for petroleum.
Widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolds used in construction, etc. Steel pipes are used to make ring parts, which can improve material utilization, simplify manufacturing processes, and save materials and processing Man-hours have been widely used to manufacture steel pipes.
The production process of general seamless steel pipe can be divided into cold drawing and hot rolling. The production process of cold rolling seamless steel pipe is generally more complicated than hot rolling. Sizing test, if the surface does not respond to cracks, the round pipe will be cut by a cutting machine, and cut into a billet with a length of about one meter. Then enter the annealing process. Annealing should be pickled with acidic liquid. When pickling, pay attention to whether there is a large amount of foaming on the surface. If there is a large amount of foaming, it means that the quality of the steel pipe cannot meet the corresponding standards. In appearance, the cold-rolled seamless steel pipe is shorter than the hot-rolled seamless steel pipe. The wall thickness of the cold-rolled seamless steel pipe is generally smaller than that of the hot-rolled seamless steel pipe, but the surface looks brighter than the thick-walled seamless steel pipe. Much rougher, and the caliber does not have too many burrs.
The delivery state of hot-rolled seamless steel pipes is generally delivered after heat treatment in the hot-rolled state. After passing the quality inspection, the hot-rolled seamless steel pipe must be strictly hand-selected by the staff. After the quality inspection, the surface must be oiled, followed by multiple cold-drawing experiments, and the perforation experiment must be carried out after the hot-rolling treatment. , If the perforation diameter is too large, it will be straightened and corrected. After straightening, it is sent to the flaw detector by the transmission device for flaw detection test, and finally it is labeled, arranged in specifications and placed in the warehouse.