The seamless steel pipe is a long strip of steel having a hollow section and no seams around it. The steel pipe has a hollow section and is used as a pipe for conveying fluid. The high-frequency welded pipe is cold-pressed into a square tube with a certain width of steel strip, and then welded with high-frequency welding, which is generally made by cold-rolling, and the surface of the hot-rolled plate is rough. Oxide, thickness tolerance is not allowed.
Seamless steel tubes are divided into two types: hot rolled and cold rolled (dial) seamless steel tubes. Hot-rolled 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 pipe in addition to general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, other steel pipes, also includes carbon thin-walled steel pipe, alloy thin-walled steel pipe；Stainless thin-walled steel pipe and special-shaped steel pipe. The outer diameter of hot-rolled seamless pipe is generally larger than 32mm, the wall thickness is 2.5-75mm, the outer diameter of cold-rolled seamless steel pipe can be up to 6mm, the wall thickness can be up to 0.25mm, the outer diameter of thin-walled pipe can be 5mm, and the wall thickness is less than 0.25mm. Cold rolling is more accurate than hot rolling.
Generally used seamless steel pipe: it is made of 10, 20, 30, 35, 45# and other high-quality carbon steel such as 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot-rolled or cold-rolled. . Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipes are used to make mechanical parts, such as the force parts of automobiles and tractors. Generally, seamless steel pipes are required to ensure strength and flattening test. The hot rolled steel pipe is delivered in a hot rolled state or a heat treated state, and the cold rolled steel is delivered in a heat treated state.
The purpose of high-frequency welded pipe is welded pipe. Straight-slot high-frequency welded steel pipe has the characteristics of relatively simple process and rapid continuous production, and has wide application in civil construction, petrochemical, light industry and other departments. It is mostly used to transport low-pressure fluids or to make various engineering components and light industrial products.
High-frequency welding is based on the principle of electromagnetic induction and the skin effect, proximity effect and eddy current effect of alternating charge in the conductor, so that the steel at the edge of the weld is locally heated to a molten state, and the extrusion of the roller causes the butt weld to achieve crystal indirect. In order to achieve the purpose of weld welding. High-frequency welding is a kind of induction welding (or pressure contact welding), which does not require weld filler, no welding splash, narrow welding heat affected zone, beautiful welding and good welding performance, so it is affected in the production of steel pipe. A wide range of applications.
High-frequency welded pipes are divided into the following four types:
1. Welded steel pipe for low-pressure fluid transportation is also called general welded pipe, commonly known as black pipe.
2. Galvanized welded steel pipe for low pressure fluid transportation, also known as galvanized electric welded steel pipe, commonly known as white tube.
3. Ordinary carbon steel wire bushings are steel pipes used to protect electric wires in electrical installations such as industrial and civil buildings, installation machinery and equipment.
4. Straight seam electric welded steel pipe is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe.
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