Steel pipe is a hollow long strip of steel, which is widely used as a pipeline for transporting fluids, such as oil, natural gas, water, gas, steam, etc. In addition, when bending and torsional strength are the same, the weight is lighter, so it is also widely used Used in the manufacture of mechanical parts and engineering structures. It is also commonly used to produce various conventional weapons, barrels, shells, etc.
Classification of steel pipes: steel pipes are divided into two categories: seamless steel pipes and welded steel pipes (seamed pipes). According to the cross-sectional shape, it can be divided into round tubes and special-shaped tubes. Round steel tubes are widely used, but there are also some square, rectangular, semicircular, hexagonal, equilateral triangle, octagonal and other special-shaped steel tubes. For steel pipes under fluid pressure, a hydraulic test is required to check their pressure resistance and quality, and no leakage occurs under the specified pressure. Wetting or expansion is qualified, and some steel pipes are also subject to crimping tests according to standards or requirements of the buyer. . Flaring test. Flattening test, etc.
Seamless steel pipe: seamless steel pipe is made of steel ingot or solid tube billet through perforation to make capillary tube, and then hot rolled, cold rolled or cold drawn. The specifications of seamless steel pipes are expressed in millimeters of outer diameter * wall thickness. There are two types of seamless steel pipes: hot-rolled and cold-rolled (dial) seamless steel pipes. Hot-rolled seamless steel pipes are divided into 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. Cold-rolled (dial) seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high-pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, as well as carbon thin-walled steel pipes and alloy thin-walled steel pipes. Stainless thin-walled steel pipes. Special-shaped steel pipes. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-75mm. The diameter of cold-rolled seamless steel pipe can reach 6mm, and the wall thickness can reach 0.25mm. Rolling has higher dimensional accuracy than hot rolling. Generally, seamless steel pipes are made of high-quality carbon structural steel such as 10.20.30.35.45, low-alloy structural steel such as 16Mn.5MnV, or composite structural steel such as 40Cr.30CrMnSi.45Mn2.40MnB by hot rolling or cold rolling. 10.20 and other low carbon steel seamless pipes are mainly used for fluid conveying pipes. Seamless tubes made of medium carbon steel such as 45.40Cr are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors. Generally, seamless steel pipes are used to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in a hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in a heat-treated state.
Post time: Jun-21-2023