Type of subdivided steel pipe (seamless steel pipe)
Steel pipe is a kind of hollow long steel, also called steel tube which is used as a pipe for transporting fluids such as petroleum, natural gas, water, gas, steam, etc. In addition, the steel pipe is light in weight and widely used in the manufacture of mechanical parts and engineering structures. Conventional weapons, barrels, shells, etc.
The classification of steel pipes has different classification criteria because of subjective standards. Common cross-section shapes can be divided into round pipes and special-shaped pipes. Circular steel pipes are more widely used, but there are also some squares. Rectangles, semi-circles, hexagons. Equilateral triangles, octagonal and other shaped steel pipes.
According to the production method, the steel pipe is divided into two categories: seamless steel pipe and welded steel pipe. Firstly, the seamless steel pipe is introduced. Generally, the seamless steel pipe is made of high-quality carbon steel such as 10, 20, 30, 35, 45, etc., such as low-alloy structural steel such as 16Mn and 5MnV, or hot-rolled or cold-rolled steel such as 40Cr, 30CrMnSi, 45Mn2 and 40MnB. Seamless pipes made of low carbon steel such as 10, 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipes are used to manufacture mechanical parts, such as the force parts of automobiles and tractors.
The seamless steel pipe is formed by perforating a steel ingot or a solid pipe blank, and then hot rolled or cold rolled. Seamless steel tubes can be subdivided into hot-rolled seamless steel tubes and cold-rolled seamless steel tubes.
1. Hot-rolled seamless steel tubes include: general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes. The outer diameter of the hot rolled seamless pipe is generally larger than 32mm and the wall thickness is 2.5-75mm.
2. Cold-rolled seamless steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes, and special-shaped steel pipes. The cold-rolled seamless steel pipe has an outer diameter of 6 mm and a wall thickness of 0.25 mm. The outer diameter of the thin-walled pipe can be up to 5 mm and the wall thickness is less than 0.25 mm. The cold rolling has a higher dimensional accuracy than hot rolling.
Generally, seamless steel tubes are tested before being sold. Hydraulic tests are required to withstand fluid pressure to test their pressure resistance and quality. Some of them must be subjected to crimping test, flare test, and flattening test according to the standard or the requirements of the purchaser. The hot rolled steel pipe is delivered in a hot rolled state or a heat treated state; the cold rolling is delivered in a heat treated state by heat.