Stainless steel pipe is a kind of hollow long circular steel, mainly widely used in petroleum, chemical, medical, food, light industry, mechanical instrumentation and other industrial transportation pipes and mechanical structural components. In addition, the bending and torsional strength are the same, and the weight is light, so it is also widely used in the manufacture of mechanical parts and engineering structures. It is also commonly used for the production of various conventional weapons, barrels, shells, etc. Stainless steel pipes are divided into ordinary carbon steel pipes, high-quality carbon structural steel pipes, alloy structural pipes, alloy steel pipes, bearing steel pipes, stainless steel pipes and bimetal composite pipes, coatings and coated pipes to save precious metals and meet special requirements. There are many kinds of stainless steel pipes, different uses, different technical requirements, and different production methods. The current production of steel pipe diameter range 0.1-4500mm, wall thickness range 0.01 ~ 250mm. In order to distinguish its characteristics, the steel pipe is usually classified according to the following method. Stainless steel pipe according to the production method is divided into seamless pipe and welded pipe two categories, seamless steel pipe can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe and extruded pipe, cold drawing, cold rolling is the secondary processing of steel pipe; The welded pipe is divided into straight seam welded pipe and spiral welded pipe. Stainless steel pipe according to the cross-section shape can be divided into round pipe and shaped pipe. The special-shaped pipe has rectangular pipe, diamond pipe, oval pipe, hexagonal pipe, eight pipe and a variety of cross-section asymmetric pipe. Shaped tubes are widely used in various structural parts, tools and mechanical parts. Compared with the round tube, the shaped tube generally has a larger moment of inertia and section modulus, and has a larger bending and torsional resistance, which can greatly reduce the weight of the structure and save steel. Stainless steel pipe according to the profile shape can be divided into equal section pipe and variable section pipe. The variable section pipe has conical pipe, stepped pipe and periodic section pipe. Stainless steel pipe can be divided into light pipe and wire pipe (with rebar steel pipe) according to the state of the pipe end. Wire pipe can also be divided into ordinary wire pipe (conveying water, gas and other low pressure pipe, using ordinary cylindrical or conical pipe thread connection) and special thread pipe (oil, geological drilling pipe, for important wire pipe, using special thread connection), for some special pipe, in order to make up for the impact of thread on the strength of the pipe end, Tube end thickening (internal thickening, external thickening or internal and external thickening) is usually carried out before wire drawing. Stainless steel pipe is: hot rolled, extruded, cold drawn and cold rolled these basic types, according to the section shape can be divided into round pipe and shaped pipe, widely used is round steel pipe, but there are also some square, rectangular, semicircular, hexagonal, equilateral triangle, octagonal and other shaped stainless steel pipe. For the steel pipe under fluid pressure to carry out hydraulic tests to test its pressure resistance and quality, under the specified pressure does not leak, wet or expansion qualified, some steel pipe also according to the standard or the requirements of the demander flange test, flaring test, flattening test. Seamless stainless steel pipe, also known as stainless steel seamless pipe, is made of steel ingot or solid tube blank perforated into a tube, and then made of hot rolled, cold rolled or cold drawn. The specifications of the seamless steel pipe are expressed by the outer diameter * the wall thickness of millimeters. 201 stainless steel pipe --S20100(AISI.ASTM) 304 stainless steel pipe full name SUS304 stainless steel pipe SUS304 stainless steel pipe belongs to the United States grade of stainless steel pipe, the domestic grade is equivalent to 0Cr19Ni9 stainless steel pipe, usually replaced by 0Cr18Ni9. The mechanism of stainless steel rust prevention is that the alloying element forms a positive potential and no longer has the ability to transport electrons to the oxidizer. 304 material rust phenomenon, there may be the following reasons: The use of chloride ions in the environment. Chloride ions are widely present, such as salt, sweat, sea water, sea breeze, soil and so on. Stainless steel in the presence of chloride ions in the environment, corrosion quickly, even more than ordinary mild steel, chloride ions and alloy elements in the Fe to form a complex, the Fe positive potential is reduced, and then oxidized by oxidizing agents to take away electrons. Therefore, there are requirements for the use of stainless steel environment, and it is necessary to wipe frequently, remove dust, and keep clean and dry. 316 and 317 stainless steels are molybdenum containing stainless steels. The molybdenum content in 317 stainless steel is slightly higher than 316 stainless steel. Because 316 stainless steel contains molybdenum, the overall performance of the steel is better than 310 and 304 stainless steel, under high temperature conditions, when the concentration of sulfuric acid is lower than 15% and higher than 85%, 316 stainless steel has a wide range of uses. 316 stainless steel also has good resistance to chloride erosion, so it is usually used in Marine environments. With the development of social economy, the application of stainless steel pipe has also been more and more widely popularized. Will bring new changes in every field. The theoretical weight formula of stainless steel pipe: W=(outer diameter - wall thickness)x wall thickness x0.02491x length, where the W unit is kg, the outer diameter and wall thickness units are mm, and the length unit is meters (m). Production process Stainless steel welded pipe production process: Raw material - article points - welding pipe - repair end - polishing - inspection (purchase) - packaging - shipment (transport) welded pipe (decoration) raw material - article points - welding pipe - heat treatment - correction, straightening, fix the end - acid - water pressure test, inspection (spurts India) - packaging - shipment (transport) (tube) for piping weld pipe industry hardness Stainless steel pipes are generally used to measure the hardness of Brinell, Rockwell, Vickers three hardness indicators. Brinell hardness in stainless steel pipe standards, brinell hardness is the most widely used, often to indentation diameter to indicate the hardness of the material, both intuitive and convenient. However, it is not suitable for steel pipes of harder or thinner steel. The Rockwell hardness test of stainless steel pipe is the same as the Brinell hardness test, which is an indentation test method. The difference is that it measures the depth of the indentation. Rockwell hardness test is a widely used method at present, and HRC is second only to Brinell hardness HB in steel pipe standards. Rockwell hardness can be applied to the determination of very soft to very hard metal materials, it makes up for the Brinell method is not, is simpler than the Brinell method, can directly read the hardness value from the dial of the hardness machine. However, due to the small indentation, the hardness value is not as accurate as the Brinell method. The Vickers hardness test is also an indentation test method that can be used to determine the hardness of very thin metal materials and surface layers. It has the main advantages of Brinell and Rockwell method, and overcomes their basic shortcomings, but it is not as simple as Rockwell method, and Vickers method is rarely used in steel pipe standards. For annealed stainless steel pipes with inner diameter above 6.0mm and wall thickness below 13mm, W-B75 Wechsler hardness tester can be used, which is very fast and easy to test and suitable for rapid and non-destructive qualification inspection of stainless steel pipes. For stainless steel pipes with inner diameter greater than 30mm and wall thickness greater than 1.2mm, Rockwell hardness tester is used to test HRB and HRC hardness. Stainless steel pipes with inner diameter greater than 30mm and wall thickness less than 1.2mm are tested for HRT or HRN hardness using a surface Rockwell hardness tester. For stainless steel pipes with inner diameter less than 0mm and greater than 4.8mm, Rockwell hardness tester for pipes is used to test HR15T hardness. When the inner diameter of the stainless steel pipe is greater than 26mm, the hardness of the inner wall of the pipe can also be tested with Rockwell or surface Rockwell hardness tester.
