Hollow strip of round steel - stainless steel tube

Hollow strip of round steel - stainless steel tube

Stainless steel pipe is a kind of hollow long circular steel, mainly widely used in petroleum, chemical, medical, food, light industry, mechanical instruments and other industrial transportation pipeline and mechanical structure parts. In addition, in bending, torsional strength is the same, light weight, so it is also widely used in the manufacture of mechanical parts and engineering structures. Also commonly used for furniture kitchenware.

hardness

Stainless steel pipes are commonly used to measure the hardness of Brinell, Rockwell, Vickers three hardness indexes.

Brinell hardness

In the stainless steel pipe standard, Brinell hardness is the most widely used, often to indentation diameter to indicate the hardness of the material, both intuitive and convenient. But for harder or thinner steel pipe is not suitable.

Rockwell hardness

The Rockwell hardness test for stainless steel pipe is the same as the Brinell hardness test. 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 standard. 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, more simple than Brinell method, can be directly from the hardness machine dial read hardness value. However, because of the small indentation, the hardness value is not as accurate as the Brinell method.

Vickers hardness

The Vickers hardness test for stainless steel tubes 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 process and overcomes their basic disadvantages, but it is not as simple as Rockwell process and Vickers method is rarely used in steel pipe standards.

Hardness testing

For annealed stainless steel pipes with inner diameter above 6.0mm and wall thickness below 13mm, W-B75 Wechls hardness tester can be used. The test is very fast and simple, which is suitable for rapid and nondestructive qualified inspection of stainless steel pipes. The HRB and HRC hardness of stainless steel tubes with inner diameter greater than 30mm and wall thickness greater than 1.2mm are tested by Rockwell hardness tester. For stainless steel tubes with inner diameter greater than 30mm and wall thickness less than 1.2mm, use surface Rockwell hardness tester to test HRT or HRN hardness. For stainless steel pipes with inner diameter less than 0mm and greater than 4.8mm, the hardness of HR15T is tested by Rockwell hardness tester dedicated to pipe. When the inner diameter of the stainless steel pipe is greater than 26mm, Rockwell or surface Rockwell hardness tester can also be used to test the hardness of the inner wall of the pipe.

classification

Stainless steel pipe according to the material is divided into ordinary carbon steel pipe, high quality carbon structure steel pipe, alloy structure pipe, alloy steel pipe, bearing steel pipe, stainless steel pipe and bimetallic composite pipe, coating and coating pipe to save precious metals and meet special requirements. There are many kinds of stainless steel tubes, different uses, different technical requirements, production methods are also different. The current production of steel pipe outside diameter range 0.1 -- 4500mm, wall thickness range 0.01 ~ 250mm. In order to distinguish their characteristics, steel pipes are usually classified as follows.

Mode of production

Stainless steel pipe according to the production method is divided into seamless pipe and welded pipe two categories, seamless steel pipe can also be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe and extrusion pipe, cold drawing, cold rolling is the secondary processing of steel pipe; Welded pipe is divided into straight seam welded pipe and spiral welded pipe.

Section shape

Stainless steel pipe according to the cross section shape can be divided into round pipe and special-shaped pipe. Special-shaped tube has rectangular tube, diamond tube, elliptic tube, hexagonal tube, eight party tube and a variety of cross-section asymmetric tube. Profiled 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, has a larger bending and torsional resistance, can greatly reduce the weight of the structure, 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.

Pipe end shape

Stainless steel pipe can be divided into light pipe and wire pipe (with spiral 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 (petroleum, geological drilling pipe, for important wire pipe, using special thread connection), for some special pipe, in order to make up for the influence 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.

Classification of use

According to its use, it can be divided into oil well pipe (casing, tubing and drill pipe, etc.), pipeline pipe, boiler pipe, mechanical structure pipe, hydraulic prop pipe, gas cylinder pipe, geological pipe, chemical pipe (high-pressure fertilizer pipe, oil cracking pipe) and ship pipe.

production

Stainless steel welded pipe production process:

Raw materials -- strip -- welded pipe -- repair end -- polishing -- inspection (printing) -- packaging -- shipping (warehousing) (decorative welded pipe).

Raw material - article points - welding pipe, heat treatment, correct, straightening, fix the end, pickling, water pressure test, inspection (spurts India) - packaging - shipment (transport) (tube) for piping weld pipe industry.