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  • Introduction of the related characteristics of high quality seamless steel pipe
  • 2018/1/6number of times read[989]
  • The high quality seamless steel pipe is rolled with solid tube billet after perforation.

    Production method of high quality seamless tube

    According to the different methods of production, it can be divided into hot rolling tube, cold rolling tube, cold drawing tube, extruding tube and so on.

    Hot rolled seamless tubes are generally produced on an automatic pipe mill. After inspecting and removing the surface defects, the solid tube billet is cut into the required length, then centering on the end face of the perforated end of the tube blank, then heated to the heating furnace and perforated on the perforator. When the perforation is rotating and advancing at the same time, the inner cavity of the tube is gradually formed under the action of the roll and the head, which is called the capillary. Sent to the automatic tube rolling mill on rolling. Finally, the whole wall is all wall thick, the diameter is fixed by the sizing machine, and the specification is reached. It is a more advanced method to produce hot rolled seamless steel pipe by continuous rolling mill.

    In order to obtain smaller size and better quality of seamless tube, cold rolling, cold drawing method must be used or combined. Cold rolling is usually carried out on a two roll mill, and the steel pipe is rolled in a circular hole consisting of a variable cross section slot and a moving cone. Cold drawing is usually carried out on a single chain or double chain cold drawing machine with 0.5 to 100T.

    The extruded tube is placed inside the closed extruded cylinder with the extrusion method. The perforated rod and the extruding rod are moving together to squeeze the extruded parts from the smaller die holes. This method can produce steel pipe with smaller diameter.

    Use of high quality seamless tube

    High quality seamless tube is widely used. The general purpose seamless pipe is produced by ordinary carbon structural steel, low alloy structural steel or alloy structural steel. The output is the largest, and is mainly used for conveying fluid pipes or structural parts.

    Three types of supply according to different uses: A, supply according to chemical composition and mechanical properties; B, supply according to mechanical properties; C, supply by water pressure test. The water pressure test should also be carried out for the steel pipe supplied by class A and B, if used to bear the pressure of the liquid.

    The high quality seamless tubes for special purpose are seamless tube for boiler, seamless pipe for geological use and seamless pipe for oil.

    type

    The high quality seamless tube can be divided into hot rolling tube, cold rolling tube, cold drawing tube and extruding tube according to different production methods.

    According to the shape, there are circular tubes and special-shaped tubes. In addition to the square tube and the rectangular tube, there are elliptical tubes, semicircular tubes, triangular tubes, hexagonal tubes, convex tube, plum blossom tube and so on.

    According to the different material, it is divided into ordinary carbon structure tube, low alloy structure tube, high quality carbon structure tube, alloy structure tube, stainless steel tube and so on.

    According to special purpose, there are boiler tube, geological tube, oil pipe and so on.

    Quality and appearance quality of high quality seamless tube

    Seamless tube according to GB/T8162-87 regulations

    Specifications: the outer diameter of the hot rolled tube is 32 ~ 630mm. The thickness of the wall is 2.5 ~ 75mm. The outer diameter of the cold rolling (Leng Ba) tube is 5 ~ 200mm. The thickness of the wall is 2.5 ~ 12mm.

    Appearance quality: there are no cracks, folding, rolling, separation, hair lines and scar defects on the inner and outer surfaces of the steel pipe. These defects should be completely removed, and the wall thickness and outer diameter should not be exceeded by the negative deviation.

    The ends of the steel pipe should be cut into the right angle and the burrs are removed. Steel tube wall thickness greater than 20mm allows cutting and thermal cutting. The agreement between supply and demand can not be cut off.

    The surface quality of the cold - drawn or cold - rolled precision seamless steel pipe is referred to as GB3639-83.

    Chemical composition test of high quality seamless tube

    The chemical composition of domestic seamless pipes, such as 10, 15, 20, 25, 30, 35, 40, 45 and 50 steel, according to chemical composition and mechanical properties, shall comply with the requirements of GB/T699-88. The imported seamless tube is inspected according to the relevant standards stipulated in the contract. The chemical composition of 09MnV, 16Mn and 15MnV steel should be in accordance with the regulations of GB1591-79.

    The specific analysis methods refer to the relevant parts of the GB223-84 "steel and alloy chemical analysis methods".

    The analysis deviations refer to the deviation of the chemical composition of the GB222-84 steel for chemical analysis and the chemical composition of the finished products.

    Physical performance test of high quality seamless tube

    Made of seamless steel pipe according to the performance of the organization, the ordinary carbon steel is made of class GB/T700-88 steel (but must ensure that sulfur content is no more than 0.050% and phosphorus content is no more than 0.045%), and its mechanical properties should conform to the values specified in the GB8162-87 table.

    The domestic seamless pipe supplied by water pressure test must guarantee the water pressure test as stipulated in the standard.

    The physical performance test of the imported seamless pipe is carried out according to the relevant standards stipulated in the contract.

    Main import and export of high quality seamless tube

    Generally, the import of seamless tube is very large. The main importing countries are Germany and Japan. European countries such as Romania, Russia, Switzerland, France, Spain, Czech, Yugoslavia, Hungary and other countries have imported. There are also a small number of countries imported from Argentina, Mexico and other countries in South America.

    According to the different requirements of the units in China, there are more than 100 seamless tube specifications. The common specifications are 15922mm, 1595mm and 15918mm. 114.38mm, 114.310mm, 114.313mm. The length is usually 5 to 8m or 4 to 7m. Is the main structure of hot rolled carbon steel to ST35.ST45 and ST65. The smallest diameter of the import specification is 305mm, and the largest 47813mm.
    .
    From France and Spain, a small number of smaller and thin wall tubes, such as 183mm, 223mm, 26.93mm, etc., were imported from France and Spain. Implementation of the general rules mannasiman steel pipe in germany.

    The seamless tubes imported from Hungary and Japan often refer to DIN2448 and DIN1629.

    In the case of import claims, the quality problems of imported seamless pipe include: chemical composition is not qualified, splitting test is flat, tensile strength is low, serious rust and pits are found.

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