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Stainless steel tube knowledge science

Date:2018-12-19    View:659      Tag:Stainless steel tube knowledge science

Stainless steel pipes of United Steel Industry Co., Ltd. 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 bimetallic composite pipes for saving precious metals and meeting special requirements. Plating and coating tubes, etc. Stainless steel tubes are available in a wide variety of applications, with different technical requirements and different production methods. The outer diameter of the currently produced steel pipe ranges from 0.1 to 4500 mm and the wall thickness ranges from 0.01 to 250 mm. In order to distinguish the characteristics, the steel pipes are usually classified as follows.


● Production method

Stainless steel pipes are divided into two types according to production methods: seamless pipes and welded pipes. Seamless steel pipes can be divided into hot rolled pipes, cold rolled pipes, cold drawn pipes and extruded pipes. Cold drawing and cold rolling are secondary to steel pipes. Processing; welded pipes are divided into straight welded pipes and spiral welded pipes.


● Section shape

Stainless steel tubes can be divided into round tubes and shaped tubes according to the cross-sectional shape. The special-shaped tube has a rectangular tube, a rhombic tube, an elliptical tube, a hexagonal tube, an eight-sided tube, and various cross-section asymmetric tubes. Shaped tubes are widely used in a variety of structural parts, tools and mechanical parts. Compared with the round pipe, the special-shaped pipe generally has a large moment of inertia and a section modulus, and has a large bending and torsion resistance, which can greatly reduce the structural weight and save steel.

Stainless steel pipes can be divided into equal-section pipes and variable-section pipes according to the longitudinal section shape. The variable section pipe has a conical pipe, a stepped pipe and a periodic section pipe.


● Tube end shape

The stainless steel tube can be divided into a light pipe and a wire tube (threaded steel pipe) according to the state of the pipe end. The wire tube can be divided into ordinary car wire tube (transfer water, gas and other low pressure pipes, using ordinary cylindrical or conical pipe thread connection) and special threaded pipe (oil, geological drilling pipe, for important wire pipe, use Special thread connection), for some special tubes, in order to compensate for the influence of the thread on the strength of the tube end, the tube end is usually thickened (inner thickening, outer thickening or inner and outer thickening) before the wire.


● Use classification

According to the application, it can be divided into oil well pipe (casing, oil pipe and drill pipe, etc.), pipeline pipe, boiler pipe, mechanical structural pipe, hydraulic pillar pipe, gas cylinder pipe, geological pipe, chemical pipe (high pressure fertilizer pipe, petroleum cracking pipe). ) and ships and other pipes.


● Wenzhou Yuesheng Stainless Steel Co., Ltd.

1. Focusing on improving product output, strengthening internal management, improving the scale and grade of the company, further improving the visibility of Wenzhou stainless steel pipes and enterprises, encouraging enterprises to develop into groups, and strengthening the introduction and training of technicians and management personnel. Strengthen the construction of production equipment to ensure and improve product quality.

2. Towards the road of brand development, the number of Wenzhou stainless steel industry and entrepreneurs' credit, shaping Chinese brand awareness.

3. Establish Wenzhou stainless steel pipe production park, gather stainless steel production enterprises, make the above scale, upper grade, create leading, create famous brand, form group production; through mergers, affiliates, shares, joints, etc., realize the Zhejiang Provincial Economic and Trade Department The focus of development is the planning goal.

4. Run the Wenzhou stainless steel professional market. The stainless steel industry is developing rapidly. However, because there is no professional market of a certain scale, it is impossible to recruit tourists from all over the world. Therefore, production enterprises can only set up operations throughout the country, which not only increases the cost of enterprises, but also hinders the development of enterprises. If the professional market is built, the production, sales and service will be integrated into one, which will enable the production enterprises to truly stand on the ground, go to the country and rush out of the country.

Such steel pipes can be divided into two categories: stainless steel seamless steel pipes and stainless steel welded steel pipes (with seam pipes). According to the different manufacturing processes, there are several basic types of hot rolling, extrusion, cold drawing and cold rolling. The shape can be divided into round tubes and shaped tubes. Circular tubes are widely used, but there are also some special-shaped stainless steel tubes such as square, rectangular, semi-circular, hexagonal, equilateral triangle, and octagonal. For steel pipes subjected to fluid pressure, hydraulic tests shall be carried out to test the pressure resistance and quality. No leakage, wetting or expansion shall occur under the specified pressure. Some steel pipes shall be subjected to the crimping test according to the standard or the requirements of the purchaser. , flare test, flattening test. Seamless stainless steel pipe, also called stainless steel seamless pipe, is made of steel ingot or solid pipe blank through perforation, and then made by hot rolling, cold rolling or cold drawing. The specifications of the seamless steel pipe are expressed by the outer diameter * wall thickness in millimeters.

201 stainless steel tube--S20100 (AISI.ASTM) , 304 stainless steel tube full name SUS304 stainless steel tube, SUS304 stainless steel tube is a stainless steel tube of American grade material, domestic grade is equivalent to 0Cr19Ni9 stainless steel tube, usually replaced by 0Cr18Ni9. The mechanism of stainless steel rust prevention is that the alloying elements form a positive potential and there is no longer the ability to transport electrons to the oxidant.


● There is rust in the 304 material, which may be due to the following reasons:

1. The presence of chloride ions in the environment of use.

Chloride ions are widely present, such as salt, sweat, sea water, sea breeze, soil, and so on. In the environment of chloride ion, stainless steel corrodes quickly, even more than ordinary low carbon steel. Chloride ion forms a complex with Fe in the alloying element, which reduces the positive potential of Fe and is then oxidized by the oxidant to remove electrons.

Therefore, there is a requirement for the use environment of stainless steel, and it is necessary to wipe frequently to remove dust and keep it clean and dry.

316 and 317 stainless steels are molybdenum-containing stainless steels. The molybdenum content of 317 stainless steel is slightly higher than that of 316 stainless steel. Since 316 stainless steel contains molybdenum, the total performance of this steel is better than that of 310 and 304 stainless steel. When the concentration of sulfuric acid is lower than 15% and higher than 85% under high temperature conditions. , 316 stainless steel has a wide range of uses. 316 stainless steel also has good resistance to chloride attack and is therefore commonly used in marine environments.

With the development of social economy, stainless steel pipes have been widely used. It will definitely bring about new changes in various fields.

The theoretical weight formula of stainless steel tube: W = (outer diameter - wall thickness) x wall thickness x0.02491x length, where W unit is kg, outer diameter, wall thickness are all in mm, length unit is meter (m).


● Production process

Stainless steel welded pipe production process:

Raw materials - slitting - welding pipe - trimming - polishing - inspection (printing) - packaging - shipping (storage) (decorative welded pipe)

Raw materials --striping--welding pipe--heat treatment--correction--straightening--trimming--pickling--hydraulic pressure test--inspection (printing)-packaging--shipping (warehouse) (welding pipe industrial piping pipe)


● Hardness

Stainless steel pipes are generally measured by Brinell, Rockwell and Vickers hardness indexes.

● Brinell hardness

Among the stainless steel pipe standards, Brinell hardness is the most widely used, and the hardness of the material is often expressed by the indentation diameter, which is both intuitive and convenient. However, it is not suitable for steel pipes of harder or thinner steel.

● Rockwell hardness

The stainless steel tube Rockwell hardness test is the same as the Brinell hardness test. The difference is that it measures the depth of the indentation. The Rockwell hardness test is a widely used method in which HRC is used in steel pipe standards only after Brinell hardness HB. Rockwell hardness can be applied to the determination of metal materials from very soft to very hard, which makes up for the Brinell method. It is simpler than the Brinell method and can directly read the hardness value from the dial of the hardness machine. However, the hardness value is not as accurate as the Brinell method because of its small indentation.

● Vickers hardness

The stainless steel tube Vickers hardness test is also an indentation test method for measuring very thin metal materials and surface layer hardness. It has the main advantages of Brinell and Rockwell methods, and overcomes their basic shortcomings, but it is not as simple as the Rockwell method. The Vickers method is rarely used in steel pipe standards.

● Hardness testing

The stainless steel tube has an inner diameter of 6.0mm or more and an annealed stainless steel tube with a wall thickness of 13mm or less. It can be a W-B75 type Vickers hardness tester. It is very fast and simple to test and is suitable for rapid and non-destructive inspection of stainless steel pipes. The stainless steel tube with an inner diameter of more than 30 mm and a wall thickness of more than 1.2 mm is tested by a Rockwell hardness tester to test the hardness of HRB and HRC. Stainless steel tubes with an inner diameter of more than 30 mm and a wall thickness of less than 1.2 mm are tested with a surface Rockwell hardness tester to test HRT or HRN hardness. For stainless steel pipes with an inner diameter of less than 0 mm and greater than 4.8 mm, the HR15T hardness is tested using a special Rockwell hardness tester for pipes. When the inner diameter of the stainless steel tube is larger than 26 mm, the hardness of the inner wall of the tube can also be tested by a Rockwell or surface Rockwell hardness tester.



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