The difference can be divided into hot rolling tube, cold rolling tube, cold drawing tube, extruding tube and so on. 1. One. One, one, hot rolled seamless tube is usually consumed on the active tube mill. The solid pipe blank is checked and cleaned out and cut into the required length. It is assured on the end face of the tube blank, then it is sent to the heating furnace and perforated on the piercer. Under the action of the roll and the head, the outer cavity of the tube is gradually formed under the action of the roll and the head, which is called the capillary. Sent to the mill for rolling on the initiative. In the end, all the parts are all thick, the diameter is fixed by the sizing machine, and the specifications are reached. The use of a continuous tube mill to consume hot rolled seamless steel tubes is a leading point. A. Two, for smaller size and better quality of seamless tube, cold rolling, cold drawing or both must accept the essentials of unity. Cold rolling is usually held on a two roll mill. The steel tube is rolled in a circular hole formed by a variable section circular hole and a moving cone. Cold drawing is usually held on a single chain or double chain cold drawing machine of zero. Five ~ 100 T. The difference can be divided into hot rolling tube, cold rolling tube, cold drawing tube, extruding tube and so on. 1. Three, the extruded heating tube will be placed in a closed extruded cylinder, and the perforated bar will move along with the extrusion rod, so that the extruded part will be extruded from the smaller mold hole. This method can consume steel pipe with smaller diameter. Two, variety two. 1. The seamless steel pipe can be divided into hot tube, cold rolling tube, cold drawing tube, extrusion tube and so on. Two. Two. According to the shape, there are circular tubes and special-shaped tubes. In addition to the square tube and the rectangular tube, the special-shaped tube has an elliptical tube, a semicircular tube, a triangular tube, a hexagonal tube, a convex tube, a plum flower tube and so on. Two. Three. According to the difference of material, it is divided into ordinary carbon layout tube, low alloy layout pipe, high quality carbon layout pipe, alloy layout pipe, stainless steel tube and so on. Two. Four, according to a special disposition, a boiler tubes, pipes, tubes and other geological kerosene.  Three, the use of three. One, seamless pipe is all over. As usual, seamless pipe is produced by ordinary carbon layout steel, low alloy steel or alloy steel. The output is the most, and is used as a piping or layout part for transporting fluid. Three. Two. The difference in use of credentials is provided in three categories: A, provided by chemical and machine functions; B, provided by machine function; C, provided by water pressure experiment. According to the steel pipe provided by class A and B, the water pressure test should also be held for the pressure of the liquid. Three. Three, the use of special seamless with boiler with seamless tube, seamless pipe and geological kerosene seamless pipe etc.. Four, specifications and surface quality seamless tube according to GB/T 8162 - 87 delimited four. One, specification: hot tube outer diameter of 32 ~ 630 mm. The thickness of the wall is two. Five ~ 75 mm. The outer diameter of the cold rolling (Leng Ba) tube is five ~ 200 mm. The thickness of the wall is two. Five ~ one or two mm. Four. Two, surface quality: the exterior appearance of the steel tube must not have gaps, folding, rolling, separation, hair lines and scar defects. These defects should be completely removed, and the wall thickness and outer diameter should not be overriding. Four. Three. The two ends of the steel pipe should be cut into right angles and the burrs are removed. Steel tube wall thickness greater than 20 mm to allow hot gas cutting and sawing. The agreement between the two sides of the supply and demand can not be cut. Four. Four, cold - drawn or cold - rolled seamless steel pipe "appearance quality" refer to GB 3639 - 83. Five, physical function inspection of domestic seamless tube, according to two institutions function, ordinary carbon steel produced by a steel GB/T 700 - 88 (but must assure the sulfur content not above zero. 050% and phosphorus content not above zero. 045, the machine should be%) with GB 8162 - 87 numerical table set the. Five. Two. Water pressure experiment provided by water pressure test for domestic seamless pipe. Five. Three. The physical function inspection of the entrance seamless tube is held according to the relevant scale defined by the treaty. Six, check the chemical identity of domestic seamless pipe, according to six chemical identity and the function of the machine, such as chemical identity, 15, 20, 25, 10, 30, 35, 40, four or five and 50 steel should be designated with GB/T 699 - 88. The entrance seamless tube is checked according to the relevant scale defined by the treaty. The chemical identity of 09 MnV, 16 Mn and 15 MnV steel should be delimited by GB 1591 - 79. Six. Two, the detailed analysis of the key to the reference GB 223 - 84 "steel and alloy chemical elucidation key" of the relevant departments. Six. Three. The elucidation of the defects is referred to GB 222 - 84, "the chemical identification of the steel for the chemical analysis of the products and the chemical identity of the products permissible". Seven, an important export environment, seven large amount of seamless pipe entrance as usual.  The important entrance countries are Germany and Japan. European countries such as Romania, Russia, Switzerland, France, Spain, Czech, Yugoslavia, Hungary and other capitals have entrance. There are also a large number of entrances from Argentina and Mexico in South America. 　　Seven. Two, according to the difference requirement of China's cargo unit, there are more than 100 specifications of seamless pipe, and the rare specifications are 15922 mm, 1595 mm, 15918 mm. One by one four. 38 mm, one by four. 310 mm, one by four. 313 mm. The same length is usually five ~ eight m or four ~ seven m. It is important for hot rolled carbon steel layout, ST 35,.ST four or five and ST 65. The minimum diameter of the entrance specification is 305 mm, and the maximum of 47813 mm. Seven. Three, from France and Spain, a large number of smaller, thin wall seamless tubes, such as 183 mm, 223 mm, 26. 93 mm, were imported from France and Spain. The Mannesmann tube mill as usual. Seven. Four, the seamless tube from the entrance of Hungary and Japan,