Views: 0 Author: Site Editor Publish Time: 2021-03-31 Origin: Site
Large seamless steel pipe
Seamless steel pipes with small outer diameters can be copied as small-diameter seamless steel pipes. Small-diameter seamless steel pipes can also be divided into: seamless small-diameter steel pipes and straight seams (also known as welding). Seam steel pipes are generally less than 89mm in outer diameter of the steel pipe to more than 4mm; they can be collectively referred to as small-diameter seamless steel pipes.
The difference between the main production large-caliber and the main production small-caliber, the specific breakdown depends on the manufacturer's product range, generally less than 200MM is considered small and seamless.
Seamless steel pipes have a hollow section and are used in large quantities as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter when the bending and torsion strength is the same. It is a kind of economical cross-section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, and bicycles. Steel scaffolds and other steel scaffolds used in building construction are used to make ring parts with steel pipes, which can improve material utilization, simplify manufacturing processes, and save materials and processing man-hours. Steel pipes have been widely used for manufacturing.
The main production processes of large-diameter seamless steel pipes in my country are hot-rolled large-diameter seamless steel pipes and heat-expanded-diameter seamless steel pipes. The maximum specifications of heat-expanded seamless steel pipes are 325mm-1220mm and the thickest is 200mm. For the size of the national standard, the thermally expanded seamless pipe is what we often call the thermally expanded pipe. The steel pipe with relatively low density but strong shrinkage is a kind of waste pipe finishing rolling process in which the diameter of the pipe is enlarged by the cross-rolling method or the drawing method. In a relatively short period of time, thickening steel pipes can produce non-standard and special types of seamless pipes, with low cost and high production efficiency, which is the development trend in the field of international pipe rolling.
GB5310 (Seamless steel pipes for high-pressure boilers) stipulates that steel pipes with outer diameter greater than or equal to 76mm and wall thickness ≥14mm should be subjected to Charpy V longitudinal impact test at 20℃; the average value of the impact energy of the three samples should not be low At 40J, the impact energy of a sample is allowed to be lower than the average value, but not less than 70% of the average value. For steel pipes with outer diameter> 219.1mm and wall thickness ≥ 25mm, transverse mechanical performance test can be used instead of longitudinal mechanical performance test. For Charpy V-shaped transverse impact test at 20℃, it is more convenient to do transverse mechanical performance test for large-diameter pipes.