Stainless Steel Pipe
Stainless steel pipe is a hollow long circular steel, mainly used in petroleum, chemical, medical, food, light industry, mechanical instruments and other industrial pipelines and mechanical structural components. In addition, the bending, torsion strength of the same, the lighter weight, it is also widely used in the manufacture of mechanical parts and engineering structure. Also used for the production of conventional weapons, barrels, shells and so on.
Where both ends of the opening and has a hollow section, and its length and length of the cross-section of the larger steel, can be called steel pipe. When the length and length of the cross-section is relatively small, can be called pipe or pipe fittings, they belong to the category of pipe products.
For more than sixty years, architects have been using stainless steel to build cost-effective permanent buildings. Many of the existing buildings fully illustrate the correctness of this option. Some are very ornamental, such as Chrysler Building in New York City. But in many other applications, the role of stainless steel is not so compelling, but in the building’s aesthetic and performance has played an important role. For example, since stainless steel is more wear resistant and resistant to stamping than other metals of the same thickness, it is the preferred material for designers when building sidewalks where the flow of people is large.
Stainless steel has been used for the construction of new buildings and structural materials used to repair historic sites for more than 70 years. The early design was calculated on the basis of the basic principles. Today, the design specifications, for example, the American Society of Civil Engineers ANSI / ASCE-8-90 “cold-formed stainless steel structural parts design specifications” and NiDI and Euro Inox jointly published “structural stainless steel design manual” has simplified the long service life, The design of structural parts with good integrity.
Stainless steel export is an important part of China’s export economy, it has an important role in stimulating China’s economic growth, but from the current situation of China’s stainless steel trade, China’s stainless steel exports encountered greater resistance.
Since last year, foreign frequently came to China’s stainless steel casting products, “double reverse” message, which China’s stainless steel casting industry has a great impact, exports of stainless steel industry in China is a large part of the development of its industry The development of a huge market share in the face of economic downturn, the slow pace of development, China’s stainless steel industry development should continue to improve product quality, better development of overseas trade and trade protectionism to suppress, Will be products and environmental protection, energy resources, human environment together to enhance the competitiveness of stainless steel products, the only way to obtain an unbeaten position in foreign trade.
- Surface resistance is less than 1000 megabytes
- Wear protection
- Excellent chemical resistance
- Good alkali resistance and acid properties
- Toughness strong
- Flame retardant
The production process of stainless steel seamless pipe a. Round steel ready; b. Heating; c. Hot rolling perforation; d. Cut the head; Pickling; f. Grinding; g. Lubrication; Cold rolling; i. Degreasing Solution heat treatment; k. Straightening Cut; Pickling; Product testing.
Strength refers to the metal in the external force, resistance to plastic deformation and fracture capacity
When the metal sample is stretched, the ratio of the maximum load to the original cross-sectional area of the specimen before drawing is called the tensile strength
Well, Pb——The maximum load before the specimen is pulled off（N）
Fo——The original cross-sectional area of the specimen（mm ）
The maximum positive pressure at which the cross section is subjected to the breaking of the specimen, when it is broken under a concentrated load located between the two supports
On the round sample：σbb=——
On a rectangular specimen：σbb=——
Well, P——The maximum concentrated load of the specimen（N）
L——The span between the two points(mm)
d——Outside diameter of circular cross section(mm)
b——Width of rectangular cross-section specimen(mm)
h——Width of rectangular cross-section specimen(mm)
Stainless steel pipe is divided into ordinary carbon steel pipe, high-quality carbon structural steel pipe, alloy structure pipe, alloy steel pipe, bearing steel pipe, stainless steel pipe and precious metals to meet the special requirements and meet the special requirements of the double metal composite pipe, The A wide range of stainless steel tube, use different, its technical requirements vary, the production method is also different. The current production of steel pipe diameter range of 0.1-4500mm, wall thickness range of 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 two categories of seamless pipe and pipe, seamless steel pipe can be divided into hot-rolled tube, cold-rolled tube, cold-drawn tube and extrusion pipe, cold drawing, cold rolling is the second Processing; welded pipe is divided into straight seam welded pipe and spiral welded pipe.
Stainless steel pipe according to the cross-sectional shape can be divided into tube and shaped tube. Shaped tube with rectangular tube, diamond-shaped tube, oval tube, hexagonal tube, all directions and a variety of cross-section asymmetric tube. The profiled tube is widely used in various structural parts, tools and mechanical parts. Compared with the tube, shaped tube generally have a larger moment of inertia and cross-section modulus, a greater bending, torsion ability, can greatly reduce the weight of the structure, saving steel.
Stainless steel pipe according to the longitudinal section can be divided into equal section tube and variable cross-section tube. The cross-section tube has a conical tube, a stepped tube and a periodic section tube.
Tube end shape
Stainless steel pipe according to the pipe end state can be divided into light pipe and wire tube (with threaded steel pipe). Car wire can be divided into ordinary wire (transport water, gas and other low-pressure pipe, the use of ordinary cylindrical or tapered pipe thread connection) and special thread pipe (oil, geological drilling pipe, for important car wire, Special thread connection), for some special tube, in order to compensate for the impact of the thread on the strength of the tube, usually in front of the wire before the tube thickening (thickening, thickening or thickening inside and outside).
According to the use can be divided into oil pipe (casing, tubing and drill pipe, etc.), pipeline, boiler tubes, mechanical structure pipe, hydraulic prop pipe, cylinder tube, geological pipe, chemical pipe (high pressure fertilizer pipe, ) And ship management.
Wenzhou stainless steel industry
Wenzhou stainless steel industry is a new industry, originated in the early 80s of the 20th century, after 20 years of pioneering and exploration in the domestic market has been quite well-known and certain influence.
The current production enterprises amounted to more than 130, with a good development, the expansion of the momentum. The entire industry perforation equipment 38. Cold rolling, cold drawing equipment more than 500 Taiwan, smelting equipment 6, all used outside the furnace refining, other equipment more complete. The company’s production capacity and scale are constantly expanding and strengthening. In 2001, the output value of over a hundred million enterprises have five, more than 10 enterprises were rated as city, district star enterprises. In order to ensure product quality, water pressure, eddy current and ultrasonic testing, direct reading spectrometer and other analytical testing equipment are constantly increasing and perfect. 2001 by the higher technical supervision departments sampling test, the pass rate of 80% or more. With all kinds of high and mid-level titles of the technology, management staff of more than 300 people, enterprises are gradually embarked on a standardized production, management track. Wenzhou stainless steel industry is mainly the production of stainless steel pipe and stainless steel rods, varieties, specifications, models have reached more than 400 kinds. 2001 stainless steel sales of 1.715 billion yuan, production reached 106,000 tons. Stainless steel bar 222 million yuan, the output of 21.1 million tons, turned over to the national tax amounted to more than 100 million yuan. Steel pipe exports also increased year by year, in 2001 to 5000T, is expected this year’s export volume of 8000 ~ 10000T, 10 companies have made self-import and export rights. Stainless steel pipe exported to Southeast Asia, the European Union dozens of countries and regions, by foreign businessmen and users of appreciation.
Stainless steel pipe industry in Wenzhou was blank, rapid development, the scale continues to expand, but there is a certain gap in production capacity, still can not meet the needs of the domestic market. Wenzhou stainless steel industry in the future development ideas and specific practices are:
⒈ to improve product production as the center, to strengthen internal management, improve the scale of enterprises, grade as the goal, to further improve the visibility of stainless steel pipe and Wenzhou enterprises to encourage enterprises to the Group of development, strengthen technical personnel, management personnel introduction and training, Strengthen the production equipment construction, ensure and improve product quality.
⒉ to the brand development of the road, the number of Wenzhou stainless steel industry and entrepreneurial credit, shaping the Chinese brand awareness.
⒊ the establishment of Wenzhou stainless steel pipe production park, gathered stainless steel production enterprises, so that the scale, on the grade, a leading, a brand name, the formation of group production; through mergers, anchors, equity, joint, etc., to achieve the Zhejiang Provincial Economic and Trade Office ” Focus on the development of “planning objectives.
⒋ run Wenzhou stainless steel professional market. Stainless steel industry is developing rapidly, but because there is no certain size of the professional market, can not attract all corners of the globe, so the production enterprises can only set up operations throughout the country, both to increase the cost of enterprises, but also hindered the development of enterprises. If the completion of a professional market, production, sales and service in one, will enable manufacturers to truly foothold, to the country, out of the country.
This type of steel pipe can be divided into stainless steel seamless steel pipe and stainless steel welded pipe (with pipe) two categories, according to the different manufacturing process.
For the hot rolling, extrusion, cold drawing and cold rolling of these basic types, according to the cross-section shape can be divided into tube and shaped tube, widely used is a circular steel pipe, but there are some square, rectangular, semi-circular , Hexagonal, equilateral triangle, octagonal and other profiled stainless steel pipe.
For the pressure of the steel pipe to be carried out by the hydraulic test to test its pressure capacity and quality, under the provisions of the pressure does not occur leakage, wetting or expansion of qualified, and some steel pipe according to the requirements of the standard or demand side of the curling test , Flaring test, flattening test.
Seamless stainless steel pipe, also known as stainless steel seamless pipe, is made of steel ingot or solid tube through the perforated tube, and then made by hot rolling, cold or cold. The specifications of the seamless steel pipe are indicated by the outer diameter * wall thickness mm.
201 stainless steel tube – S20100 (AISI.ASTM)
304 stainless steel pipe full name SUS304 stainless steel tube
SUS304 stainless steel tube is the United States grade material of stainless steel tube, the domestic brand is equivalent to 0Cr19Ni9 stainless steel tube, usually replaced with 0Cr18Ni9.
The mechanism of stainless steel rust is the formation of positive alloy alloy elements, no longer have the ability to transport electrons to oxidants.
304 material rust phenomenon, there may be the following reasons:
⒈ use of the environment in the presence of chloride ions.
Chloride is 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 low carbon steel, chloride ions and alloying elements in the formation of complex Fe, the Fe positive potential decreased, and then by the oxidant took electrons and was oxidized.
So the use of stainless steel environment requirements, and the need to often wipe, remove the dust, keep clean and dry.
316 and 317 stainless steel are molybdenum-containing stainless steel. 317 stainless steel in the molybdenum content is slightly higher than the 316 stainless steel due to 316 stainless steel molybdenum, the steel’s overall performance is better than 310 and 304 stainless steel, high temperature conditions, when the sulfuric acid concentration of less 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.
Stainless steel pipe with the socio-economic development, its application has also been more and more widely popular. Will bring new changes in various fields.
The theoretical weight of stainless steel pipe formula: W = (outside diameter – wall thickness) x wall thickness x0.02491x length, where W unit is kg, outer diameter, wall thickness units are mm, the length of the unit is meters (m).
Stainless steel pipe production process:
Raw materials – slitting – welding pipe – repair – polishing – inspection (printing) – packaging – shipping (warehousing) (decorative pipe)
Raw materials – slitting – welding pipe – heat treatment – correction – straightening – repair – pickling – water pressure test – inspection (printing) – packaging – shipping (warehousing) (Pipe for piping industrial pipe)
Stainless steel pipe commonly used Brinell, Rockwell, Vickers three hardness indicators to measure the hardness.
In the stainless steel pipe standard, Brinell hardness is the most widely used, often with indentation diameter to represent the hardness of the material, both intuitive and convenient. But not for harder or thinner steel pipes.
Stainless steel tube Rockwell hardness test with the Brinell hardness test, are indentation test method. The difference is that it is the depth of the indentation measured. Rockwell hardness test is currently widely used method, which HRC in the steel pipe standard used after Brinell hardness HB. Rockwell hardness can be applied to the determination of very soft to very hard metal material, which makes up for the Buchner method is not, than the Brinell method is simple, can be directly from the hardness of the dial read out the hardness value. However, due to its indentation is small, so the hardness value is not as accurate as the Brinell method.
Stainless steel tube Vickers hardness test is also an indentation test method, can be used to determine the thin metal materials and surface layer hardness. It has the main advantages of the Brinell and Rockwell methods, and overcomes their basic shortcomings, but not as easy as the Rockwell method, Vickers method is rarely used in the steel pipe standard.
Stainless steel pipe diameter of 6.0mm or more, the wall thickness of 13mm below the annealing of stainless steel pipe, you can use W-B75-type Wechsler hardness tester, it is very fast and simple test, suitable for stainless steel pipe to do fast and qualified test. Stainless steel tube diameter greater than 30mm, wall thickness greater than 1.2mm stainless steel tube, using Rockwell hardness tester, test HRB, HRC hardness. Stainless steel tube diameter greater than 30mm, wall thickness of less than 1.2mm stainless steel tube, using the surface Rockwell hardness tester, test HRT or HRN hardness. Diameter less than 0mm, greater than 4.8mm stainless steel tube, the use of pipe dedicated Rockwell hardness tester, test HR15T hardness. When the stainless steel tube diameter greater than 26mm, you can also Rockwell or surface Rockwell hardness tester wall hardness test.
Stainless steel pipe is an economical section steel, is an important product in the steel industry, can be widely used in life decoration and industry, many people on the market for the production of staircase handrails, window protection, railings, furniture and so on. Common are 201 and 304 two kinds of materials.
Accounting for the total amount of steel 8% to 16% of the total, it is widely used in the national economy. As the steel pipe has a hollow section, which is most suitable for liquid, gas and solid pipelines; at the same time with the same weight of the round steel, steel pipe section coefficient, bending and torsional strength, it has become a variety of machinery and building structure On the important material. The structure and parts made of stainless steel pipes have a larger cross-sectional modulus than the solid parts in the case of equal weights. Therefore, the stainless steel tube itself is a kind of economical steel section of steel, which is an important part of efficient steel, especially in oil drilling, smelting and transportation industry demand, followed by geological drilling, chemical, construction industry, machinery Industrial, aircraft and automobile manufacturing as well as boilers, medical equipment, furniture and bicycle manufacturing also need a lot of a variety of steel pipe. With the development of new technologies such as atomic energy, rocket, missile and aerospace industries, the status of stainless steel pipes in defense industry, science and technology and economic construction is becoming more and more important.
Stainless steel pipe is safe and reliable, hygienic and environmental protection, economical application, thin wall of pipeline and new reliable, simple and convenient method of connecting the development of success, it has more advantages of other pipe irreplaceable, the application of the project will be more and more , The use will be more and more popular, promising.
Since stainless steel has the many desirable properties required for building materials, it can be said to be unique in metals, and its development continues. In order to make stainless steel better in traditional applications, has been improving the existing type, and, in order to meet the stringent requirements of advanced building applications, is developing new stainless steel. As the production efficiency continues to improve, the quality of continuous improvement, stainless steel has become the architects choose one of the most cost-effective materials.
Stainless steel sets performance, appearance and use characteristics in one, so stainless steel will remain one of the world’s best building materials.
With the implementation of China’s reform and opening up policy, the rapid growth of the national economy, urban housing, public buildings and large-scale construction of tourist facilities, hot water supply and domestic water supply put forward new requirements. In particular, water quality problems, people pay more and more attention, the requirements are also rising. Galvanized steel pipe This commonly used pipe because of its perishable, under the influence of relevant national policies, will gradually withdraw from the stage of history, plastic pipe, composite pipe and copper pipe has become a common pipe system pipe. However, in many cases, stainless steel pipe is more superior, especially the wall thickness of only 0.6 ~ 1.2mm thin-walled stainless steel pipe in the quality of drinking water systems, hot water systems and safety, health first water supply system, with Safe and reliable, health and environmental protection, economic and other characteristics. Has been domestic and foreign engineering practice proved to be the best performance of the water supply system, the new, energy saving and environment-friendly pipe is one of the very competitive water supply pipe, will improve the water quality, improve people’s living standards play Comparable effect.
In the construction of water supply pipe system, galvanized steel pipe has ended a century of glorious history, a variety of new plastic pipe and composite pipe has been rapid development, but the various pipe also varying degrees of some deficiencies, far from fully adapt to the water supply pipe The need for the state and the requirements for drinking water and related water quality. Therefore, the experts predict that: building water supply pipe will eventually return to the era of metal pipe. According to foreign application experience, in the metal tube identified thin-walled stainless steel pipe for the comprehensive performance of one of the best pipe.
Thin-walled stainless steel pipe, the domestic production began in the late 90s of the 20th century, the use of today’s pipe field is emerging as a new generation, has been widely used in building water supply and direct drinking water pipeline.
Thin-walled stainless steel tube durable, has been recognized by the engineering sector, and the parties concerned are from reducing the wall thickness, lower prices in order to facilitate further promotion. Especially the small diameter of the stainless steel tube, the price is not high, so supporting the connection method, the reliability and price of the pipe is to determine its development of the main factors. China in Sichuan, Guangdong, Zhejiang, Jiangsu and other places have developed the independent development of the connection technology and fittings, is a very promising pipe. The Ministry of Construction and the relevant departments also attach great importance to this new type of pipe, according to the China Technology Market Management Promotion Center, State Key words  No. 71 document on the promotion of “high diameter wall than high precision stainless steel, high pressure water supply pipe and supporting Pipe and special technology, “the notice was informed that thin-walled stainless steel tube technology and product promotion and application to improve the quality of modern Chinese architecture, improve and protect the water quality is of great significance.
At the same time, the Ministry of Construction attaches great importance to the promotion and application of thin-walled stainless steel pipe. “Thin-walled stainless steel water pipe,” the industry standard was released in 2001. Related pipeline engineering technical regulations and installation Atlas, the Ministry of Construction has issued a document, is being prepared by the Tongji University. At present, Sichuan, Guangdong, Zhejiang, Jiangsu and other places have professional manufacturers of thin-walled stainless steel pipe production, the product has matured, therefore, to promote the application of the time has come.
Domestic prospects are good
① building water supply pipe demand
According to the “construction business” Ninth Five-Year Plan and the 2010 vision of the Outline, “from 2001 to 2010, the annual demand for pipe 50 to 60 million km, of which residential construction area hot and cold water demand of 400,000 km. Some people think that the development of stainless steel water pipes, to improve the quality of modern city buildings, of great significance.
② direct drinking water pipeline development
With the development of the national economy, the pipeline straight drinking water in the domestic Beijing, Shenzhen, Shanghai, Chongqing and other cities in the rapid development of economically developed medium-sized cities are also actively planning to catch up. In the direct drinking water, stainless steel pipe system is undoubtedly second to none. The current domestic grade hotels, public places have been configured or in the configuration of direct drinking water pipes.
③ domestic alternative import a broad future
In order to promote the stainless steel pipe, China from the 20th century, 90 years since the reduction of wall thickness, reduce costs, to solve the “high diameter wall than high precision” thin-walled stainless steel pipe technical problems, so that stainless steel tube to promote the application, The A pipeline to be able to fully promote the application, and ultimately domestic. When the country has a part of the manufacturers have the production and further development of thin-walled stainless steel pipe and pipe fittings capacity.
Stainless steel pipe connection in a variety of ways, the common types of pipe compression, compression, live, push, push thread, socket welding, live flange connection, welding and welding with the traditional connection phase Combined with a derived series of connections. These connections, according to their different principles, its scope of application is also different, but most are easy to install, solid and reliable. Connection using the sealing ring or gasket material, most of the selection of meet the national standards of silicone rubber, nitrile rubber and EPDM rubber, eliminating the user’s worries.
Snap connection step
1, broken tube: cut off the required length of the pipe, broken tube, the force can not be too large to prevent the pipe rounded.
2, remove the burr: pipe cut off, the burr should be removed to avoid cutting the seal ring.
3, crossed mark: In order to completely insert the pipe pipe fittings, the length of the insertion must be marked at the end of the line.
4, assembly: the ring should be installed correctly in the U-slot tube, the tube inserted into the pipe fittings, waiting for crimping.
5, crimping: crimping, the tube protruding parts placed in the mold concave groove, jaw and tube axis to maintain vertical.
6, check: crimp is completed, the use of special gauge to check the size of crimping.
① with the international chemical elements and symbols of the country to represent the chemical composition, with Arabic letters to represent the content of ingredients:
Such as: China, Russia 12CrNi3A
② with a fixed number of digits to represent the steel series or figures; such as: the United States, Japan, 300 series, 400 series, 200 series;
③ use the Latin alphabet and order to form the serial number, only that use.
① using element symbols
② use, Chinese Pinyin, flat furnace steel: P, boiling steel: F, sedative steel: B, a class steel: A, T8: special 8,
◆ composite steel, spring steel, such as: 20CrMnTi 60SiMn, (with a few points that C content)
◆ stainless steel, alloy tool steel (with thousands of points that C content), such as: 1Cr18Ni9 one thousand (ie
0.1% C), stainless steel C ≤ 0.08% such as 0Cr18Ni9, ultra-low carbon C ≤ 0.03% such as 0Cr17Ni13Mo
The American Society of Iron and Steel is using three digits to mark a variety of standard grade wrought stainless steel. among them:
① austenitic stainless steel with 200 and 300 series of digital signs, for example, some of the more common austenitic stainless steel
Is labeled 201, 304, 316 and 310,
② ferrite and martensitic stainless steel with 400 series figures. Ferritic stainless steel is marked with 430 and 446, martensitic stainless steel is 410,420 and 440C as the mark, biphasic (austenite – ferrite),
③ stainless steel, precipitation hardening stainless steel and iron content of less than 50% of the high alloy is usually a patent name or trademark name.
① national standard GB ② industry standard YB ③ local standard ④ enterprise standard Q / CB
① product standards ② packaging standards ③ method standards ④ basic standards
4-3 standard level (in three levels):
Y level: the international advanced level I level: the international level of general level H: the domestic advanced level
GB1220-84 stainless steel bar (grade I) GB4241-84 stainless steel welding plate (H)
GB4356-84 stainless steel welding plate (Class I) GB1270-80 stainless steel pipe (Class I)
GB12771-91 stainless steel pipe (Y grade) GB3280-84 stainless steel plate (Class I)
GB4237-84 stainless steel hot plate (grade I) GB4239-91 stainless steel cold (I)
200 Series D7S
Product Description: D7S nickel content of about 2.5%, slightly lower than the D11 nickel content, the price is relatively low. 1% nickel content of stainless steel to a certain extent will be the key to the D7S market supply, so in the competitive, high quality stainless steel high utilization rate will also be an important part of the sales plan.
Application areas: the target market for new products such as stainless steel kitchen appliances and other areas of stainless steel pipe market sales plan.
Product Description: The tensile strength of the material is 980 ~ 1180MPa, the maximum working temperature up to 90 ℃.
Application areas: Pipeline tubes for harsh seabed environments
Product Description: Super (super) critical unit is the basis of modern power generation and energy saving. Among the important compression parts of super (super) critical boilers, the most demanding working parts are the superheater and the reheater. Previously, China’s domestic use of all kinds of materials imported from abroad, and only 10 international steel material manufacturers limited capacity, such materials gap is large, the import price is expensive, and procurement difficulties, in short supply, seriously affected the Chinese super Production of supercritical boilers and development of electric energy. China’s current demand for power plant boilers is about 30,000 tons per year, and with the continuous improvement of super (super) critical power generation technology, demand has expanded year by year. Several large domestic enterprises have invested a lot of manpower, financial resources, commitment to such products R & D, production, and achieved considerable results. On the one hand for the country’s power industry has made its own contribution, but also to the enterprise has brought considerable economic benefits.
Application areas: power plant boiler industry, mainly superheater and reheater high temperature section and other key parts.
Air conditioning use
Product Description: The product has a high processing performance, weight can be reduced by 60% than copper, the price is lower than the copper, copper can be used as a substitute.
Application areas: air conditioning industry
Duplex stainless steel
Product Description: This stainless steel in the urea – carbamate solution has good corrosion resistance, in the chloride environment has a high resistance to stress corrosion cracking ability. At the same time, the duplex stainless steel mechanical properties, can be applied to the safety requirements of the higher plant construction.
Application areas: chemical industry, construction industry.
Steel pipe size and allowable deviation
Stainless steel features
Resistant to air, steam, water and other weak corrosive media and acid, alkali, salt and other chemical corrosive media corrosion of steel. Also known as stainless acid resistant steel. Practical applications, often weak corrosive medium corrosion of steel known as stainless steel, and corrosion resistance of chemical corrosion of steel known as acid-resistant steel. Due to the difference in the chemical composition of the two, the former is not necessarily resistant to chemical corrosion, while the latter are generally have a stainless. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel. Chromium is the basic element to obtain corrosion resistance of stainless steel, when the chromium content of steel to about 1.2%, chromium and corrosive media in the role of oxygen in the steel surface to form a thin layer of oxide film (self-passivation film) , Which can prevent further corrosion of the steel substrate. In addition to chromium, the commonly used alloying elements are nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the various uses of stainless steel structure and performance requirements.
Stainless steel classification
Stainless steel is usually divided into the matrix:
⒈ ferritic stainless steel. Contains 12% to 30% chromium. Its corrosion resistance, toughness and weldability with the increase in chromium content increased resistance to chloride stress corrosion resistance is better than other types of stainless steel.
⒉ austenitic stainless steel. Containing more than 18% chromium, also contains about 8% of nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Comprehensive performance is good, can withstand a variety of media corrosion.
⒊ austenitic – ferrite duplex stainless steel. Both the advantages of austenitic and ferritic stainless steel, and has a superplasticity.
⒋ martensitic stainless steel. High strength, but poor plasticity and weldability.
⒌ precipitation hardening stainless steel. Has a good forming performance and good weldability, can be used as ultra-high strength materials in the nuclear industry, aviation and aerospace industry applications.
(SUS400), Cr-Ni (SUS300), Cr-Mn-Ni (SUS200) and precipitation hardening (SUS600) can be classified into Cr.
Corrosion resistance of stainless steel
All metals react with oxygen in the atmosphere to form an oxide film on the surface. Unfortunately, the formation of iron oxide on ordinary carbon steel continues to oxidize, so that corrosion continues to expand, and ultimately the formation of holes. The surface of the carbon steel can be secured by painting with paint or oxidation resistant metals (eg zinc, nickel and chromium), but, as is known, this protection is only a film. If the protective layer is damaged, the following steel will begin to rust.
The corrosion resistance of stainless steel depends on chromium, but because chromium is one of the components of steel, so the protection method is not the same.
When the chromium content is 10.5%, the atmospheric corrosion resistance of the steel is significantly increased, but the chromium content is higher, although the corrosion resistance can be improved, but not obvious. The reason is that when the steel is alloyed with chromium, the type of surface oxide is changed to a surface oxide similar to that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface from further oxidation. This oxide layer is extremely thin, through which it can see the natural gloss of the steel surface, so that stainless steel has a unique surface. Moreover, if the surface damage, the exposed steel surface and the atmosphere will be self-repair, re-formation of this “passive film”, continue to play a protective role.
Therefore, all the stainless steel has a common characteristic, that is, chromium content of 10.5% or more.
There are usually six types of steel associated with the construction of the building. They all contain 17 to 22% chrome, and the better grades contain nickel. The addition of molybdenum can further improve atmospheric corrosivity, especially corrosion resistance to chloride-containing atmospheres.
Stainless steel resistant to atmospheric corrosion
Experience has shown that the degree of atmospheric corrosion varies from region to region. For ease of explanation, it is recommended that the area be divided into four categories, namely, rural, urban, industrial and coastal areas.
The village is essentially pollution-free areas. The population density is low, only pollution-free industry.
The city is a typical residential, commercial and light industrial area with mild pollution, such as traffic pollution.
Industrial areas for heavy industry caused by air pollution in the region. Pollution may be due to the formation of fuel gas, such as sulfur and nitrogen oxides, or chemical plants or processing plants to release other gases. Suspended particles in the air, such as the production of dust or iron oxide produced in the steel production process will increase the corrosion.
Coastal areas usually refer to areas within a mile of the sea. However, the ocean atmosphere can spread to the depth of the inland, the island is even more so, the prevalence of wind from the ocean, and the weather is bad. For example, the British climate conditions are so, so the whole country belongs to the coastal area. If the wind is mixed with ocean fog, especially due to evaporation caused by salt deposition, coupled with less rain, not often washed by rain, coastal areas of the conditions even more unfavorable. If there is industrial pollution, then corrosive even greater.
The research work carried out by the United States, Britain, France, Italy, Sweden and Australia has identified the impact of these areas on the atmospheric corrosion resistance of various stainless steels. The contents of the book in the NiIDI published “Architects” made a brief introduction, the table can help designers to choose the best cost for the various regions of stainless steel.
When making a selection, it is important to determine if there are local factors that affect the use of the site environment. For example, stainless steel used in the factory chimney below, used in the air conditioning exhaust baffle near or near the scrap steel field, there will be non-general conditions.
Repair and cleaning of stainless steel
As with other materials exposed to the atmosphere, stainless steel is also dirty. Future lectures will analyze the design factors that affect maintenance and cleanup costs. However, there is a relationship between rain erosion, manual flushing and dirty surfaces.
The effect of rainwater scuffing was determined by placing the same slats in the atmosphere directly and on the shelter. The effect of manual flushing is determined by manually scrubbing the right side of each slab every six months with a sponge stained with soapy water. It was found that dust and siltation on the surface by rainwater scrubbing and manual scrubbing had a good effect on the surface condition compared to the slats placed in the shed and not flushed. But also found that the surface processing of the situation also has an impact on the surface of the slab than the surface of the rough effect is better.
So the interval between the scrubbing by a variety of factors, the main factor is the required aesthetic standards. Although many stainless steel curtain walls are only flushed when wiping the glass, in general, the stainless steel used for external scrubbing twice a year.
Typical use of stainless steel
Most of the use requirements are long-term to maintain the original appearance of the building. In determining the type of stainless steel to be selected, the main consideration is the required aesthetic standards, the corrosiveness of the atmosphere and the clean-up system to be used.
However, other applications are increasingly seeking structural integrity or impermeability. For example, the roof and side walls of industrial buildings. In these applications, the owner of the construction costs may be more important than the aesthetic, the surface is not very clean can.
In the dry indoor environment using 430 stainless steel effect is quite good. However, in rural areas and cities in order to keep its appearance outdoors, you need to regularly clean. In heavily polluted industrial areas and coastal areas, the surface will be very dirty, and even rust. But to get the aesthetic effect of outdoor environment, you need to use nickel-containing stainless steel. Therefore, 304 stainless steel is widely used in curtain walls, side walls, roofs and other construction purposes, but in the serious erosion of industrial or marine atmosphere, the best use of 316 stainless steel.
The advantages of using stainless steel in structural applications have been fully recognized. Several design guidelines include 304 and 316 stainless steel. Because the “two-phase” stainless steel 2205 has a good resistance to atmospheric corrosion and high tensile strength and elastic strength of the integration, so the European guidelines also include this steel.
Stainless steel product shape
In fact, stainless steel is manufactured in a fully standard metal shape and size, and there are many special shapes. The most commonly used products are made of sheet and strip, and are also produced with plates for special products such as hot rolled structural steels and extruded structural steels. But also round, oval, square, rectangular and hexagonal welded pipe or seamless steel pipe and other forms of products, including profiles, bars, wire and castings.
As will be discussed later, in order to meet the aesthetic requirements of architects, has developed a variety of different commercial surface processing. For example, the surface may be highly reflective or dull; it may be glossy, polished or embossed; it may be colored, colored, electroplated or etched on a stainless steel surface to meet the designer’s appearance The various requirements.
It is easy to keep the surface state. You can remove dust by occasional rinsing. Due to good corrosion resistance, it is also possible to easily remove surface contamination or other similar surface contamination.
Pressure test formula for hydraulic test of stainless steel pipe for fluid (GB / T1277-2008)
P = 2RS / D
Where: P – test pressure, MPa;
R-stress, take yield point 50%, MPa;
S-pipe nominal wall thickness, mm;
D-pipe nominal diameter, mm.
W = (outer diameter – wall thickness) × wall thickness × 0.02491 = KG / M (weight per meter)
Application and maintenance of stainless steel pipe:
Stainless steel pipes should be used when used to avoid contact with higher corrosive water and gas.
Standard for the implementation of stainless steel tubes
stainless steel pipe
Stainless steel tube (2 sheets)
GB2270-80 stainless steel seamless steel pipe GB / T14976-94 stainless steel pipe for fluid delivery
Stainless steel tubes for structural use GB / T14975-2002
Stainless steel tubes for conveying fluids GB / T14976-2002
GB13296-91 boiler tubes, stainless steel tubes for heat exchangers
(GJB2608-96) (YB676-73) Air structural pipe, thick-walled seamless steel pipe
(GJB2296-95) (YB678-71) aviation with stainless steel tube
(YB / T679-97) (YB679-71) Air with 18A hollow rivet thin-walled seamless steel pipe
(GJB2609-96) (YB680-71) Aeronautical structural pipe, thin-walled seamless steel pipe
(YB / T681-97) (YB681-71) Air duct 20A Thin wall seamless steel pipe
GB3090-82 small diameter stainless steel pipe
Seamless steel tubes for high pressure boilers GB5310-2008
Low and medium pressure boiler tubes GB3087-2008
GB3089-92 stainless steel acid resistant thin wall seamless steel pipe
Petroleum cracking tubes GB9948-2006
ASTM A213 boiler, ferrite and austenitic alloy tubes for heat exchangers
ASTM A269 general purpose austenitic stainless steel pipe and welded pipe
ASTM A312 Austenitic Stainless Steel Seamless Steel Tube Welding Pipe
ASTM A450 carbon steel, ferrite and austenitic alloy steel pipe of the general requirements
ASTM A530 general purpose ferritic steel and alloy steel general requirements
ASTM A789 generally requires austenitic stainless steel seamless steel tubes and welded steel tubes
Standard Specification for Stainless Steel Tubes for Mechanical Structures JIS G3456-88
Standard Specification for Stainless Steel Tubes for Common Pipes JIS G3448-88
Standard Specification for Stainless Steel Pipe for Pipes JIS G3459-88
Standard Specification for Stainless Steel Tubes for Boilers and Heat Exchangers JIS G3463-88
Seamless Steel Tube for Q / HYAD Chemical Industry
(0Cr18NI11T) Q / HYAD Cr18Ni5MO3Si2 duplex stainless steel seamless steel pipe
The main use of stainless steel exhaust system, accounting for the total amount of automotive stainless steel more than 1/2, 80% of ferritic stainless steel. The exhaust gas generated by the automobile engine passes through the exhaust gas intake pipe, the front pipe, the hose, the converter, and the center tube finally flows out of the muffler. Exhaust system commonly used steel has 409L, 436L and so on. The car muffler mainly uses stainless steel pipe. It is estimated that the car used stainless steel pipe accounted for the entire downstream of the amount of stainless steel pipe about 1.5%, while the use of stainless steel seamless pipe and pipe ratio of about 2: 1
Petrochemical industry, including fertilizer industry
The demand for stainless steel pipe is very large, the industry mainly uses stainless steel seamless pipe, specifications include: 304,321,316,316 L, 347,317 L, etc., the diameter of ¢ 18- ¢ 610 or so, wall thickness of 6mm-50mm (Generally selected specifications in the Φ159mm above the low-pressure pipeline), the specific application areas: furnace tube, material delivery pipe, heat exchanger tube.
Water and gas and other fluid delivery
Stainless steel pipe and its water supply equipment, is the world’s most advanced basic water purification materials, its anti-corrosion performance, cast iron pipe, carbon steel pipe, plastic pipe, etc., can not be compared with it.
Water preparation, storage, transportation, purification, regeneration, desalination and other water industry best choice. The annual demand is about 25,000 tons.
Equipment manufacturing and maintenance
Annual consumption of more than 20,000 tons of stainless steel pipe. This type of industry mainly uses sanitary or antibacterial grade stainless steel tube. The use of imported SUS304, 316L production of sanitary seamless pipe, to meet the food, bio-pharmaceutical field of the special requirements of various media. Antimicrobial stainless steel has the advantages of stainless steel and good antibacterial properties, in the kitchen equipment, food industry workstations and utensils, medical equipment, daily life tableware and towel stents, refrigerators and other areas of the demand for increasing.
Suction tube, especially for
Used for solids such as powders, debris and granular objects
Used for gaseous media
For industrial dust and suction equipment, air conditioning and ventilation systems
Used as a durable protective tube
Used in the manufacture of mechanical parts and engineering structures
For a variety of conventional weapons, barrels, shells
If the human living space than the human body, the living space laying a variety of pipes like blood vessels and nerves. The choice of conveying high quality drinking water and pipe fittings is essential. In this regard, the author recently visited the China Special Steel Association of stainless steel branch of the relevant experts.
Experts believe that most of today’s construction water pipes are hidden projects and pipeline wells project, if the pipe selection is not appropriate, according to expert estimates, will give investors the value of water pipe material itself 10 to 20 times the economic losses. In addition, the selection of pipe is also a barometer of water industry development and progress. Water supply pipe five principles: safety and reliability, economy, health, energy saving, sustainable development, which is the green pipe several major features, only to be able to meet these principles of the pipe is really good pipe.
The most commonly used stainless steel in the water industry is 304 and 316 stainless steel, which meet the vast majority of water treatment and delivery conditions.
Features & Performance
Product development history
China used arc furnace mass production of stainless steel in 1949 after the early production of Cr13 martensitic stainless steel, master production technology, the mass production of 18-8 Cr-Ni austenitic steel, such as 1Cr18Ni9Ti, began in 1952 The Subsequently, in order to meet the needs of the development of the domestic chemical industry, began to produce containing Mo2% -3% 1Cr18Ni12Mo2Ti and 1Cr18Ni12Mo3Ti and so on. In order to save valuable elemental nickel, 1Cr18Mn10Ni5Mo3N (204 + Mo) was prepared by adding Mo2% -3% to AISI 204 steel in 1958 to 1Cr17Mn6Ni5N and 1Cr18Mn8Ni5N with Mn and N on behalf of Ni, and for the whole cycle Method urea production device to replace 1Cr18Ni12Mo2Ti. From the late 1950s to the early 1960s, the industrial trial of 1Cr17Ti, 1Cr17Mo2Ti and 1Cr25Mo3Ti and other non-ferritic stainless steel were started and the high-silicon stainless steel 1Cr17Ni14Si4ALTi (equivalent to the Soviet grade ЭИ654), which was resistant to nitric acid corrosion, Is a kind of α + γ duplex stainless steel. 60 years, due to the domestic chemical industry, aerospace, aviation, atomic energy and other industrial development needs and the use of electric furnace oxygen steel technology, a large number of new steel, such as 17-4PH, 17-7PH, PH15-7Mo precipitation hardening stainless steel, C? 0.03% of the ultra-low carbon stainless steel 00Cr18Ni10,00Cr18Ni14Mo2, 00Cr18Ni14Mo3 and Ni-free Cr-Mn-N stainless steel 1Cr18Mn14Mo2N (A4) have been successfully developed and put into production. In the 1970s, some α + γCr-Ni duplex stainless steels have been developed and formally produced and applied in order to solve the problem of chloride stress corrosion of 18-8 Cr-Ni steel in chemical industry and atomic energy industry. There are 1Cr21Ni5Ti, 00Cr26Ni6Ti, 00Cr26Ni7Mo2Ti, 00Cr18Ni5Mo3Si2 (3RE60) and 00Cr18Ni6Mo3Si2Nb and so on.
00Cr18Ni6Mo3Si2Nb is to solve the Swedish grade 3RE60 easy to appear after the single-phase ferrite structure, resulting in corrosion resistance and toughness of the development of N, Nb containing α + γ duplex stainless steel. In the 1980s, the second generation α + γ duplex stainless steel containing N, such as 00Cr22Ni5Mo2N, 00Cr25Ni6Mo3N and 00Cr25Ni7Mo3WCuN, was developed and imitated to solve the local corrosion corrosion of chlorinated pitting and crevice corrosion. Stainless steel to form a series, but also in-depth study of their organization and performance and N in the dual-phase stainless steel mechanism of action. Since the 1970s, other important developments in the research work of stainless steel materials in China have been: developed high strength and ultra-high strength martensitic stainless steel and put into industrial trial and application; vacuum induction furnace, vacuum electron beam furnace and vacuum furnace Smelting and mass production of high purity ferrite stainless steel 00Cr18Mo2, 00Cr26Mo1 and 00Cr30Mo2 with C + N≤150-250ppm; high Mo and high Mo containing Cr-Ni austenitic stainless steel with Mo content ≥ 4.5%, for example, successfully developed 00Cr20Ni25Mo4 .5Cu, 00Cr18Ni18Mo5 (N), 00Cr25Ni25Mo5N and so on in the chemical, petrochemical and marine development has been applied in the solution of concentrated nitric acid corrosion and solid solution intergranular corrosion, developed 00Cr25Ni20Nb and several ultra-low carbon high silicon stainless steel, Since the 1980s, ultra-low carbon and steel phosphorus content and α-phase control of urea-grade stainless steel 00Cr18Ni14Mo2 and 00Cr25Ni22Mo2N two grades developed, their plates, tubes, bars, forgings and welding materials are in large and medium Urea industry has been applied, and achieved satisfactory results; due to some special steel mills have been built smelting stainless steel furnace refining equipment, such as AOD (argon oxygen refining furnace), VOD (vacuum oxygen refining furnace) and so on, China Stainless steel smelting technology on a new level. It not only makes low-carbon, ultra-low carbon stainless steel production becomes easy, but also to improve the inherent quality of stainless steel, the cost is reduced. As a result of Ti 18-8 type Cr-Ni austenitic steel there are a series of shortcomings, the United States, Japan and other industrial advanced countries as early as the 60’s has been achieved from the Ti-containing stainless steel to the general use of low-carbon, ultra-low carbon stainless steel China and China have made great progress in the development, production and application of low-carbon, ultra-low carbon stainless steel from 1985 to 1990. For example, at the end of 1988, China’s low-carbon, ultra-low carbon 18-8 stainless steel production Accounting for about 10% of China’s stainless steel production. However, compared with stainless steel production and application of advanced countries (such as Japan, the United States and other countries containing Ti 18-8 Cr-Ni steel only about 1.5% of stainless steel production), there is still a big gap. 80 years, China also carried out nitrogen (N 0.05% -0.10%) and nitrogen alloying (N> 0.10%) Cr-Ni austenitic stainless steel development work. Experiments show that nitrogen is an invaluable and very beneficial alloying element in Cr-Ni austenitic stainless steels and duplex stainless steels. The strengthening of nitrogen, reducing the intergranular corrosion susceptibility of steel, improving the corrosion resistance of steel, especially the mechanism of improving pitting resistance of steel, is in-depth research work. Several nitrogen and nitrogen alloyed Cr-Ni austenitic stainless steels have been combined with the need for mass production and application.
Usually stainless steel pipe has three characteristics: weldability, corrosion resistance, polishing performance (BQ)
The use of different products on the welding performance requirements are also different. A class of utensils on the welding performance is generally not required, and even part of the pot business. But the vast majority of products require good raw material welding performance, like two types of tableware, insulation Cup, steel, water heaters, drinking fountains and so on.
Most of the stainless steel products require good corrosion resistance, stainless steel tube like one, two types of tableware, kitchen utensils, water heaters, drinking fountains, etc., some foreign businessmen also do corrosion resistance test products: NACL aqueous solution heated to boiling, (Note: when the product is polished, due to emery or sandpaper contains Fe composition, will lead to the test surface rust), the amount of corrosion,
Polishing performance (BQ)
Stainless steel products in the production are generally polished after this process, only a few products such as water heaters, water dispenser liner and so do not need to polish. So this requires a good polishing performance of raw materials. Factors affecting the performance of the main polishing are the following:
① raw material surface defects. Such as scratches, pitting, pickling and so on.
② stainless steel pipe material quality problems. Hardness is too low, it is not easy to polish when polished (BQ is not good), and the hardness is too low, in the deep drawing surface prone to orange peel phenomenon, thus affecting the BQ. High hardness of the BQ is relatively good.
③ After deep drawing of the product, the deformation of a large area of the surface will be a small black spots and RIDGING, thus affecting the BQ.
Stainless steel can be divided into Cr (400 series), Cr-Ni (300 series), Cr-Mn-Ni (200 series) and precipitation hardening (600 series) according to the composition. 200 series – chromium – nickel – manganese austenitic stainless steel 300 series – chromium – nickel austenitic stainless steel.
301 —– good ductility, for molding products. It can also be hardened by mechanical processing. Good weldability. Abrasion resistance and fatigue strength is better than 304 stainless steel.
302 —– corrosion resistance with the 304, because the carbon is relatively high and thus better strength.
303 —– by adding a small amount of sulfur, phosphorus to make it more than 304 more cutting.
304 —– that is 18/8 stainless steel. GB grade 0Cr18Ni9. 309 – has a better temperature resistance than 304.
316 —– Following 304, the second most widely used steel, mainly for the food industry, pharmaceutical industry and surgical equipment, add molybdenum elements to obtain a special anti-corrosion structure. Due to 304 stainless steel pipe with its better resistance to chloride corrosion and therefore also for the “marine steel” to use. SS316 is usually used for nuclear fuel recovery devices. 18/10 grade stainless steel pipe is also usually in line with this application level.
Model 321 – In addition to the addition of titanium to reduce the risk of material weld corrosion other than the performance of similar 304.
400 series – ferrite and martensitic stainless steel.
408 – good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.
409 – the cheapest model (Anglo-American), usually used as a car exhaust pipe, is a ferritic stainless steel (chrome steel).
410 – martensite (high strength chrome steel), good wear resistance, poor corrosion resistance.
416 – Added sulfur improves the processability of the material.
420 – “cutting edge” martensitic steel, similar to Brinell high chrome steel this first stainless steel. Also used for surgical instruments, can be done very bright.
430-ferrite stainless steel, decorative, for example for car accessories. Good formability, but poor in temperature and corrosion resistance.
440 – high strength cutting tool steel, slightly higher carbon, after a proper heat treatment can get a higher yield strength, hardness can reach 58HRC, are the hardest stainless steel column. The most common application example is the “shaving blade”. There are three commonly used models: 440A, 440B, 440C, in addition to 440F (easy to type).
500 series – heat-resistant chrome alloy steel.
600 series – martensitic precipitation hardening stainless steel tube.
Strategy market development
The development of stainless steel pipe industry to experience the import period, growth period, maturity and recession. The law of the same market development, stainless steel pipe industry should be spotted the opportunity, waiting for an opportunity to move. Stainless steel market has entered the stage of brand competition, market competition is increasing. Stainless steel tube in order to share market share, must be based on market conditions to develop new strategies to develop market segments. China’s stainless steel market has been from the product, channel competition, into the brand, marketing competition in the development stage. Brand, marketing competition stage, do a good job market segment has become the key to winning the competition of stainless steel tube. Many well-made stainless steel pipe enterprises are focused on doing a good job market segments. Stainless steel tube focused on the introduction of ecological, environmentally friendly products, open up new market segments. With the continuous maturity of the stainless steel pipe market and market competition continues to intensify, the future industry is “the market must be subdivided.” The market segment will become a new wrestling field for stainless steel pipes. The following is a brief description of the use of stainless steel pipe under the outline and manufacturing methods.
Overview of stainless steel pipes for fluids
The stainless steel tube for the fluid is a hollow section with no welds from beginning to end. Stainless steel pipe products and round steel and other solid steel compared to the same bending strength, the weight is light, is an economic section of steel, widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, , Bicycle frame and steel scaffold used in construction. With stainless steel tube manufacturing ring parts, can improve the utilization of materials, simplify the manufacturing process, saving materials and processing time, such as rolling bearing rings, jack sets, etc., widely made of stainless steel pipe.
Stainless steel pipe or a variety of conventional weapons indispensable materials, barrels, barrels and so on to stainless steel tube to manufacture. Stainless steel pipe products according to the cross-sectional shape of the different shapes can be divided into tube and shaped tube. In addition, the ring cross section in the internal or external radial stainless steel tube pressure, the force is more uniform, so the vast majority of stainless steel tube is a tube.
Method for manufacturing stainless steel tubes for fluids
① general use of the boiler tube temperature below 450 ℃, domestic tube mainly with 10, 20 carbon steel hot-rolled tube or cold-drawn tube manufacturing.
② high-pressure boiler tubes are often used in high temperature and high pressure conditions, the tube in the role of high temperature flue gas and water vapor, oxidation and corrosion. Requires stainless steel tube products with high durability, high oxidation resistance, and good organizational stability.
The following are the same as the ”
① general boiler tube is mainly used to make water wall tube, boiling water pipe, superheated steam pipe, locomotive boiler with superheated steam pipe, large, small pipe and arch pipe.
② high-pressure boiler tube is mainly used to manufacture high-pressure and ultra-high pressure boiler superheater tube, reheater tube, air pipe, the main steam pipe.
However, the tube also has some limitations, such as in the plane under the conditions of bending, the tube is not as good as the square tube bending strength, some agricultural machinery skeleton, steel and wood furniture on the commonly used side, rectangular tube. According to different purposes also need to have other cross-shaped shaped stainless steel tube.
Common: Material 201/304 / 304L / (diameter – wall thickness) x Wall thickness x0.02491x Length = Weight (kg)
Material 316 / 316L (Diameter – Wall Thickness) x Wall Thickness x0.02513x Length = Weight (kg)
Unit: kg / m
Sulfuric acid equipment applications
Sulfuric acid is an important basic chemical raw material, its production is often a measure of a country’s industrial development level of the mark. Used in the production of acid equipment and acid-filled tanks, containers and other commonly selected acid-resistant stainless steel tube. Although sulfuric acid is an oxo acid, but dilute sulfuric acid and moderate concentrations of sulfuric acid oxidation is weak, so they belong to the reductive acid. And concentrated sulfuric acid, especially hot concentrated sulfuric acid is a strong oxidizing, and therefore belongs to the oxidizing acid. As a result of sulfuric acid in this feature, in the selection of sulfuric acid resistant stainless steel tube, with the sulfuric acid concentration, temperature difference, the selected grades are different.
Dilute sulfuric acid, medium concentration of sulfuric acid is reduced, can choose 316 stainless steel tube, 316L stainless steel tube, 316Ti stainless steel tube and other molybdenum in 2% to 3% of the stainless steel tube. Stainless steel pipe without molybdenum 18-8 Cr-N austenitic stainless steel, can not be used for sulfuric acid corrosion due to insoluble sulfuric acid and medium sulfuric acid corrosion. When the high molybdenum content (Mo ≥ 4%), the corrosion resistance of the stainless steel pipe will be further improved. Steel containing molybdenum, copper, silicon (3% to 4%) of chromium-nickel austenitic stainless steel and duplex stainless steel tube better resistance to sulfuric acid.
In the concentration of 90% to 98% of the high temperature concentrated sulfuric acid, according to the use of temperature and concentration, the choice of silicon about 6% of stainless steel can achieve satisfactory results, such as 022Cr17Ni17Si6,022Cr18Ni20Si6MoCu.
In the manufacture of pickling, synthetic rubber, rayon bath and sulfuric acid contact with the equipment, optional 06Cr18Ni18Mo2Cu2Ti stainless steel tube. In the manufacture of sulfuric acid corrosion resistant pipes, pumps, valves, towers and containers and other equipment and components, can choose 06Cr12Ni25Mo3Cu3Si2N stainless steel tube.
For Carbon Steel Pipe, you can refer to: https://cnflanges.com/service/carbon-steel-pipe/