Stainless steel pipe is a kind of hollow long round steel, which is widely used in industrial transmission pipelines and mechanical structural components such as petroleum, chemical industry, medical treatment, food, light industry, machinery and meters. In addition, when the bending and torsional strength are the same, the weight is light, so it is also widely used for manufacturing mechanical parts and engineering structures. It is also commonly used as furniture and kitchenware.

hardness

The hardness of stainless steel pipes is usually measured by Brinell, Rockwell and Vickers hardness indexes.

Brinell hardness

Among the standards for stainless steel pipes, Brinell hardness is the most widely used, and the hardness of the material is often expressed by the indentation diameter, which is intuitive and convenient. But it is not applicable to steel pipes made of relatively hard or thin steel.

Rockwell hardness

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. HRC is second only to Brinell hardness Hb in steel pipe standards. Rockwell hardness can be used to measure metal materials from very soft to very hard. It makes up for the shortcomings of the Brinell method and is simpler than the Brinell method. It can directly read the hardness value from the dial of the hardness machine. However, because of its small indentation, the hardness value is not as accurate as that of the Brinell method.

Vickers hardness

Vickers hardness test of stainless steel pipe is also an indentation test method, which can be used to determine the hardness of very thin metal materials and surface layers. It has the main advantages of Brinell method 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.

Hardness test

For annealed stainless steel pipes with an inner diameter of more than 6.0mm and a wall thickness of less than 13mm, the w-b75 Vickers hardness tester can be used. It is very fast and simple to test, and is suitable for rapid and nondestructive 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 shall be used to test HRB and HRC hardness. For stainless steel pipes with inner diameter of more than 30mm and wall thickness of less than 1.2mm, the HRT or hrn hardness shall be tested by surface Rockwell hardness tester. For stainless steel pipes with inner diameter less than 0mm and greater than 4.8mm, the hr15t hardness shall be tested with a special Rockwell hardness tester for pipes. When the inner diameter of the stainless steel pipe is larger than 26mm, the hardness of the inner wall of the pipe can also be tested by Rockwell or surface Rockwell hardness tester.

Stainless steel pipe is a kind of economical section steel and an important product in the steel industry. It can be widely used in life decoration and industry. Many people in the market use it to make stair handrails, window guards, railings, furniture, etc. There are two common materials, 201 and 304.

Accounting for about 8% - 16% of the total steel, it is widely used in the national economy. Because the steel pipe has a hollow section, it is most suitable for conveying liquid, gas and solid; At the same time, compared with round steel of the same weight, steel pipe has a large section coefficient and a large flexural and torsional strength, so it has also become an important material in various machinery and building structures. Structures and components made of stainless steel tubes have a larger cross-sectional modulus than solid parts under the condition of equal weight. Therefore, stainless steel pipe itself is a kind of economical section steel that saves metal. It is an important part of high-efficiency steel, especially in petroleum drilling, smelting and transportation industries. Secondly, geological drilling, chemical industry, construction industry, machinery industry, aircraft and automobile manufacturing, boiler, medical equipment, furniture and bicycle manufacturing also need a large number of various steel pipes. With the development of new technologies such as atomic energy, rocket, missile and aerospace industries, stainless steel tubes play an increasingly important role in national defense industry, science and technology and economic construction.

Stainless steel pipes are safe, reliable, sanitary, environmental friendly, economical and applicable. The thin wall of pipes and the successful development of new reliable, simple and convenient connection methods make them have more advantages that can not be replaced by other pipes. They will be used more and more in projects, and will be used more and more widely. The prospect is promising.

Because stainless steel has many desirable properties required by building materials, it can be said to be unique among metals, and its development is still continuing. In order to make stainless steel better in traditional applications, the existing types have been improved all the time, and new stainless steel is being developed to meet the strict requirements of advanced building applications. Due to the continuous improvement of production efficiency and quality, stainless steel has become one of the most cost-effective materials selected by architects.

Stainless steel combines performance, appearance and use characteristics, so stainless steel will still be one of the best building materials in the world.

With the implementation of China's reform and opening-up policy, the national economy has achieved rapid growth, and a large number of urban houses, public buildings and tourist facilities have been built, which puts forward new requirements for hot water supply and domestic water supply. In particular, people pay more and more attention to the water quality problem, and the requirements are also constantly improving. Galvanized steel pipe, a common pipe, will gradually withdraw from the historical stage under the influence of relevant national policies due to its easy corrosion. Plastic pipe, composite pipe and copper pipe have become common pipes in the pipeline system. However, in many cases, stainless steel pipes have more advantages, especially the thin-walled stainless steel pipes with a wall thickness of only 0.6 ~ 1.2mm, which are safe, reliable, sanitary, environmental friendly and economical in high-quality drinking water systems, hot water systems and water supply systems that put safety and hygiene first. It has been proved by engineering practice at home and abroad that it is one of the new, energy-saving and environmentally friendly pipes with the best comprehensive performance in the water supply system. It is also a very competitive water supply pipe and will play an incomparable role in improving water quality and improving people's living standards.

In the building water supply pipeline system, galvanized steel pipe has ended its glorious history of one hundred years, and various new plastic pipes and composite pipes have developed rapidly. However, various pipes still have some shortcomings in varying degrees, which are far from fully meeting the needs of the water supply pipeline system and the national requirements for drinking water and related water quality. Therefore, relevant experts predict that building water supply pipes will eventually return to the era of metal pipes. According to the application experience of foreign countries, thin-walled stainless steel pipe is recognized as one of the best pipes with comprehensive performance among metal pipes.