Simple broken face

Steel pipe is a kind of hollow long steel, which is widely used as pipelines for conveying fluids, such as oil, natural gas, water, gas, steam, etc. In addition, when the bending and torsion 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 often 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 (seam pipes). According to the cross-sectional shape, it can be divided into round pipes and special-shaped pipes. Round steel pipes are widely used, but there are also some square, rectangular, semi-circular, hexagonal, equilateral triangle, octagonal and other special-shaped steel pipes.

Hydraulic tests are required for steel pipes that are subjected to fluid pressure to verify their pressure resistance and quality. They are qualified without leakage, wetting or expansion under the specified pressure. Some steel pipes must be carried out according to standards or requirements of the buyer. Crimping test, flaring test, flattening test, etc.

Seamless steel tube: Seamless steel tube is made of steel ingots or solid tube billets through perforation and made into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. The specifications of seamless steel pipes are expressed in millimeters of outer diameter * wall thickness. Seamless steel pipes are divided into two types: 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, 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 be up to 6mm, the wall thickness can be up to 0.25mm, and the outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. Rolling has higher dimensional accuracy than hot rolling.

Generally used seamless steel pipes are made of 10, 20, 30, 35, 45 and other high-quality carbon steels such as 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other composite steels that are hot-rolled or cold-rolled Into. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. Seamless pipes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless steel pipes must be used for strength and flattening tests. Hot-rolled steel pipes are delivered in hot-rolled state or heat-treated state; cold-rolled steel pipes are delivered in hot-heated state.

Seamless steel pipes for low and medium pressure boilers: used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water wall pipes and superheated steam pipes for locomotive boilers, large smoke pipes, small smoke pipes and arch bricks Tube and so on. Use high-quality carbon structural steel hot-rolled or cold-rolled (dial) seamless steel pipe. It is mainly made of No. 10 and No. 20 steel. In addition to ensuring the chemical composition and mechanical properties, a hydraulic test, such as crimping, flaring, and flattening, is to be done. Hot-rolled products are delivered in a hot-rolled state, and cold-rolled products are delivered in a heat-treated state.