Views: 0 Author: Site Editor Publish Time: 2021-02-08 Origin: Site
The rolling method of cold drawn (rolled) thick-walled seamless steel pipe is more complicated than that of hot-rolled (extruded thick-walled seamless steel pipe). Large-caliber boiler tubes have a hollow section and their length is much longer than the diameter or circumference of steel.
According to the cross-sectional shape, it is divided into round, square, rectangular and special-shaped steel pipes; according to the material, it is divided into carbon structural steel pipes, low-alloy structural steel pipes, alloy steel pipes and composite steel pipes. The first three steps of their production process are basically the same.
The difference starts from the fourth step. After the round tube blank is emptied, it must be headed and annealed. After annealing, use a special acid liquid for pickling. After pickling, apply oil. Then it is followed by multiple passes of cold drawing (cold rolling) and then billeting, and special heat treatment. After heat treatment, it is straightened.
After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles, etc. inside the steel pipe, it will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint.
Thick-walled seamless steel pipes are widely used. Thick-walled seamless steel pipes for general purposes are rolled from ordinary carbon structural steel, low-alloy structural steel or alloy structural steel, and have the largest output. They are mainly used as pipes or structural parts for conveying fluids.
According to different purposes, it can be supplied in three categories:
A. According to chemical composition and mechanical properties;
B. According to mechanical performance;
C. According to the water pressure test supply.
Q345D steel pipe is not only used for conveying fluids and powdered solids, exchanging heat, and manufacturing mechanical parts and containers, it is also an economical steel.
For steel pipes supplied in category A/B, if used to withstand liquid pressure, a hydraulic test shall also be carried out. Q345B steel pipes are divided into round and special-shaped seamless steel pipes according to the cross-sectional shape. The special-shaped pipes have square, elliptical, triangular, hexagonal, melon seed, star, and finned pipes.
Special-purpose seamless pipes include seamless pipes for boilers, chemical and electric power, thick-walled seamless pipes for geological use, and seamless pipes for petroleum. Thick-walled seamless steel pipes have a hollow section and are largely used as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, coal gas, water and certain solid materials.
Compared with solid steel such as round steel, steel pipe has a lighter weight when the bending and torsion strength is the same, and it is an economical section steel. Extensively used to manufacture structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycle frames, and steel scaffolding used in building construction. Steel pipes are used to manufacture ring parts, which can improve material utilization, simplify manufacturing processes, and save Steel pipes have been widely used for manufacturing materials and processing man-hours.