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Stainless steel has the ability to resist atmospheric oxidation — that is, stainless steel, but also in the acid, alkali, salt medium is the ability to corrosion – that is, corrosion resistance. But its corrosion resistance is the size of its steel chemical composition, plus the state, the use of conditions and environmental media type and change. Such as 304 stainless steel pipe fittings, in the dry and clean atmosphere, there is absolutely excellent resistance to corrosion, but it moved to the beach area, in a large amount of salt containing sea fog, will soon rust; and 316 steel performance good. Therefore, not any kind of stainless steel, in any environment can be resistant to corrosion, no rust. Stainless steel is the surface of the formation of a thin layer of thin and strong and stable stable chromium oxide film (protective film), to prevent the continued infiltration of oxygen atoms, continue to oxidize, and the ability to obtain corrosion resistance. Once for some reason, the film has been constantly destroyed, the air or liquid oxygen atoms will continue to infiltrate or metal iron atoms continue to precipitate out to form loose iron oxide, metal surface will continue to rust. But does not mean that no rust, stainless steel pipe fittings is not easy to rust and the composition of stainless steel has a great relationship. Stainless steel components in addition to iron, there are chromium, nickel, aluminum, silicon and so on. General stainless steel chromium content is generally not less than 12%, high or even up to 18%. Steel added chromium and other elements, you can change the performance of steel, such as steel, such as the molecular structure is more uniform in the steel surface is more likely to generate a layer of dense oxide protective film, etc., thereby greatly improving the ability of stainless steel corrosion resistance. So stainless steel can resist fire, water, acid, alkali and a variety of solutions to its corrosion, no rust. Scientists have found that the more uniform the internal structure of steel, the more closely connected components, the more difficult the corrosive invasion, coupled with the surface and attached a layer of oxide protective film, like steel to wear armor, natural It is not easy to rust. The optimum temperature for stainless steel pipe fittings is 1050-1080 ° C. The temperature quickly rose to this degree, according to the thickness of stainless steel pipe fittings to stay 1-3 minutes, and then quickly cooled to 100 ℃ below, remember to be rapid cooling, because 500-800 degrees Celsius are stainless steel sensitization temperature, stay in this range Too long will affect the molecular structure of stainless steel, leading to material changes. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Oil and gas are important energy and chemical raw materials. The International Energy Agency (IEA) predicts that by 2030, the global oil and gas industry will invest $about 200000000000 per year to meet market demand, of which 80% of the investment will be spent outside the middle east. In the oil and gas exploration, drilling, transportation, refining and long-distance transportation to the user’s entire process, seamless pipes can not be separated from the oil and gas drilling and drilling is the largest professional users of seamless steel pipe. The most expensive oil casing is made of carbon manganese steel and low-alloy steel with a yield strength of 400 ~ 800MPa. But for the acid gas (C02, C02+H2S) and chloride (CL-) oil and gas corrosion, requires the use of corrosion resistant stainless steel even with nickel alloy casing and oil pipe, the stainless steel has wide application prospect in the oil and gas development areas. In the process of oil and gas production, the corrosion of CO2 has appeared in 1950s, and it was alleviated by adding preservatives. However, there has been a series of problems, such as unstable effect of corrosion inhibitor, worse effect at high temperature, pollution to environment and higher life cycle cost than stainless steel. As the oil and gas resources, to have the corrosion environment of oil and gas wells had abandoned re exploitation, especially from the beginning of 70s at the beginning of last century since the oil crisis, with the offshore oil and gas (accounted for 44% of global oil and gas reserves) comprehensive development, C02 corrosion problem is more prominent, has become a key topic in recent 20 years of corrosion in oil and gas development in the. It was not until 1980s, especially in the development of Beihai oil field, that duplex stainless steel was adopted to solve the problems of C02 corrosion oil and gas well production. But because of the high price of dual phase steel, the use is limited. Developed countries in Europe and America began to study the materials of substitute duplex steel. First of all, in Europe, the study of using martensitic steel S13Cr instead of dual phase steel has been carried out. But a lot of practical and extensive study and forms the industrial production to occupy the market and not the developed countries, but the Japanese catch up from behind. Japan’s 4 largest stainless steel seamless pipe production plant from the beginning of 1980s, have developed their own characteristics of the series. Source: China Stainless Steel Seamless Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The petrochemical industry including chemical fertilizer industry, the great demand for stainless steel pipe industry, the main use of stainless steel seamless pipe, specifications include: 304, 321, 316, 347, 316L, 317L, 18- in diameter Phi Phi 610, the wall thickness is about 6mm-50mm (usually in low pressure pipeline with a diameter of more than 159mm in size the specific application fields:), furnace tube, material conveying pipe, heat exchanger tube etc.. Such as: Heat-resistant stainless steel pipe, mainly used for heat exchange and fluid transport, the domestic market capacity of about 160 thousand tons per year, due to strict requirements related, mainly by import. Duplex stainless steel pipe is mainly used in chemical, fertilizer heat exchangers and fluid tube markets. Because of its high strength, stress resistance, corrosion resistance and economy, its annual consumption is about 4000-5000 tons. Stainless steel casing, the use of oil drilling in stainless steel super magnetic drill collar, high resistance to CO, CO2 and Cl- corrosion of ferritic stainless steel Cr13 and Cr25 oil casing, according to rough statistics analysis in the amount of more than 10 thousand tons, year after year 3~5 will take approximately 4~5 million tons, while the stainless steel tube at most still rely on imports. In addition, the petrochemical industry is the potential market for transporting oil pipe and the low-temperature cracking furnace of large diameter, heat and corrosion resistance because of its special requirements and equipment installation and maintenance inconvenience, and requirements of equipment life cycle is long, through the material properties and performance optimization control of material composition and special heat treatment. Another potential market for the chemical fertilizer industry (urea, phosphate) dedicated steel pipe, the main steel grades are 316Lmod and 2re69. At present, the above stainless steel pipes mainly rely on imports. As an important component of the chemical industry, the petrochemical industry covers many production sectors, such as pesticides, chemical fertilizers, rubber, synthetic materials and other industries. The petrochemical industry is the basic industry of economic development, involving many aspects of the real economy. A wide range of international oil prices fell in 2008 and stirring the spread of financial crisis, brought hitherto unknown challenge to the petrochemical industry, the first 8 months of September to maintain two digit growth, the growth rate fell sharply in November, growth is close to zero, the negative growth in December, the whole industry boom cycle by high growth in 10 years into the downstream channel. An average of nearly of all oil and chemicals prices fell by nearly 10% in August, according to a ranking of the departments concerned. If you count after July, the whole industry product prices fell by up to 30-40%, not only in the first half of this year accumulated most of the bubble squeezed, even the price of some varieties has been returned to the level of 2007, 2006. At the same time, according to the China petroleum and Chemical Industry Association released data, November to 2008, China petrochemical industry losses of 4360 enterprises, the loss of 14.9%, an expansion of 0.4%; business losses amounted to 160 billion 595 million yuan, an increase of 605.6%. Therefore, the Sinopec in 2008 industry application of consumption of stainless steel tube is relatively weak, statistics show that about 213 thousand and 700 tons, is mainly used for construction, maintenance and repair related equipment as required for the replacement of a poly phenol plant overhaul of the stainless steel tube is 99.1 tons, of which 108630mm with large diameter stainless steel pipe accounted for 53.79%. Again, a set of 520 thousand tons of urea and 300 thousand tons of synthetic ammonia, large urea plant required process pipelines, heat exchanger tubes, “urea grade” dedicated tubes, duplex stainless steel pipes and other types of steel pipes totaling 2018.5 tons. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel head in the process of heating and cooling, the cooling speed of the stainless steel head due to the surface and center and time inconsistency, formation temperature, will lead to uneven volume expansion and contraction stress, thermal stress. Under the action of thermal stress, as surface temperature is lower than the core, and make the heart of contraction is greater than the core department in tension, when at the end of the cooling, due to the heart of the final cooling volume shrinkage can’t free and make the surface tension of compression of the core. That is, under the action of thermal stress, the surface of the workpiece is subjected to pressure and the heart is pulled. This phenomenon is affected by factors such as cooling speed, material composition and heat treatment process. When the cooling rate is faster, the carbon content and the alloy composition are higher. The greater the non-uniform plastic deformation under thermal stress in the cooling process, the more the residual stress will be formed. Steel in the process of heat treatment on the other hand due to the change of organization of austenite to martensite transformation, due to the increase of the volume will be accompanied by the expansion of the size of workpiece, workpiece parts successively phase transition, grew up volume caused by inconsistent and organization stress generation. The ultimate result of stress change of stainless steel seal head is tensile stress at the surface and stress in the core, which is the opposite of thermal stress. The size of tissue stress is related to the cooling speed, shape and chemical composition of the material in martensite phase transition. Only the thermal stress in the organization transformation had produced stainless steel head, and organizational stress is produced in the process of organizational change, in the cooling process, a result of the combined action of thermal stress and organization stress, is the real stress in the workpiece. The results of these two kinds of stress synthesis are very complicated and are influenced by many factors, such as composition, shape, heat treatment, etc. In terms of the development process, there are only two types, namely thermal stress and organizational stress, which cancel out when the direction of action is opposite. Whether it is offsetting or overlapping, the two stresses should have a dominant factor. The result of the thermal stress is the tension of the part of the workpiece and the surface under pressure. The result of the dominant stress is the tension surface of the workpiece core. Source: China Stainless Steel Head Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Industrial stainless steel pipe is widely used in various industries, different industries and applications for the quality of steel, performance requirements there is a big difference. Low-end market access to the lower threshold, and some applications in high temperature, high pressure, deep cold, high vacuum, strong corrosion, flammable and explosive and other complex conditions of high-end industrial stainless steel pipe market, especially used in petroleum, chemical , Natural gas, power equipment manufacturing industries such as industrial stainless steel pipe, there is a high industry barriers. ​ (1) Production license Due to the important role of industrial stainless steel pipe in the safe production and operation of special industries, China has set up a production license system for the production of stainless steel pipes for oil and gas industry, stainless steel pipes for boilers and pressure vessels, and stainless steel pipes for civil nuclear safety facilities. For enterprises that do not have the corresponding production license, it is not allowed to carry out the production and sales activities of related products. According to the “Special Equipment Safety Supervision Regulations” and “on the oil and gas industry with welded steel pipe and other types of industrial products to implement special equipment manufacturing license management notice” and other provisions, the State Administration of Quality Supervision, Inspection and Quarantine by the professional category to develop a special equipment Licensing rules and related technical specifications, provisions of the pressure pipeline components of industrial stainless steel pipe enterprises must obtain the appropriate special equipment manufacturing license. According to the Regulations on the Supervision and Administration of Civil Nuclear Safety Equipment and the Detailed Rules for the Design and Installation of Civil Nuclear Pressure Equipment Design and Installation License, the enterprises engaged in the design, manufacture and sale of stainless steel pipes for nuclear facilities must obtain the design of civil nuclear safety equipment / Manufacturing license, the State Council nuclear safety supervision departments of the applicant to apply for a higher application conditions, and conduct a rigorous review. (2) Qualified supplier qualification Industrial stainless steel pipe as the basic equipment in the system engineering, safety production is of great significance, almost all of the large industrial customers will be as a key equipment management, industrial stainless steel pipe suppliers to implement strict screening procedures, Qualified supplier qualification system, and only from the qualified supplier of qualified enterprises to select suppliers. The system of industrial stainless steel pipe manufacturing enterprises in the industrial scale, credit, product quality, production capacity, after-sales service and many other areas of extensive and rigorous assessment, only through the assessment and long-term meet the conditions of industrial stainless steel pipe production enterprises Obtain qualified supplier qualification. (3) product safety record Large industrial users in addition to the establishment of qualified supplier qualification system, but also the supplier of related products before the safe use of performance assessment. In the field of oil and gas, power equipment, nuclear power and other fields, large industrial users out of product quality and durability considerations, the relevant industrial use of stainless steel pipe to make clear the performance requirements, usually will not choose no The use of recorded products, so for the emerging industrial stainless steel pipe enterprises to enter the market set up a higher access barriers. (4) technical and equipment requirements Industrial stainless steel pipe industry is technology-intensive. On the one hand, with the development of new materials such as super duplex steel, nickel base alloy, corrosion resistant and high temperature resistant alloy, stainless steel deep processing is facing increasingly high technical requirements; on the other hand, oil, chemical, natural gas, power equipment and other downstream Industry for industrial stainless steel pipe material, length, diameter, wall thickness, quality, corrosion resistance and other requirements tend to persify, making the application of stainless steel pipe more and more obvious. Industrial stainless steel pipe enterprises need to maintain a high level of technology and research and development capabilities, improve the application of new technologies, new materials and new technology. At the same time in order to meet the needs of differentiated products to meet the safety requirements of high-end products and quality standards, enterprises need to invest more advanced production, testing equipment and facilities. Industrial stainless steel pipe production enterprises need people, technology and equipment, and so has a profound experience of accumulation. (5) capital requirements Industrial stainless steel pipe is also a capital-intensive industry, on the one hand, stainless steel round steel, sheet and other raw materials in the production of a large proportion of the production costs, enterprises need to invest a lot of money for the procurement of raw materials to meet production requirements; , The production of industrial stainless steel pipe with expensive production equipment and testing equipment, enterprises in the preparation and production process into a huge, high capital requirements of the enterprise. 1, favorable factors (1) national industrial policy to promote the development of the industry As the basic material of industrial field, industrial stainless steel pipe is widely used in China’s equipment manufacturing industry, equipment manufacturing industry is the national economy to provide technical and equipment industry, strategic industries, and other industries associated with high technology-intensive, industry Upgrading, an important guarantee for technological progress and a concentrated expression of national comprehensive strength. The National Development and Reform Commission promulgated the “industrial structure adjustment guide directory (2011 this)” clearly “stand-alone 600,000 kilowatts and above supercritical, ultra supercritical unit power plant construction”, “nuclear power plant construction”, “crude oil, natural gas, liquefied natural gas, Refined oil storage and transportation and pipeline transportation facilities and network construction “and other large areas of industrial use of stainless steel pipe as a encouraged category. Ministry of Industry and Information Technology issued by the “major technology and equipment independent innovation guide directory (2012 edition)” will “nuclear power unit”, “million kilowatt-class ultra-supercritical thermal power units”, “million tons of ethylene plant”, ” Pipeline equipment “and” large-scale natural gas liquefaction equipment “as the focus of the development of independent innovation technology and equipment, will promote the development of industrial stainless steel pipe industry. (2) equipment localization policy to provide development opportunities To promote China’s equipment manufacturing industry independent innovation and industrial upgrading, China’s “equipment manufacturing industry restructuring and revitalization plan” clearly put forward the domestic equipment to meet the domestic market satisfaction rate of about 70% of the planning objectives, the relevant state departments in accordance with the above objectives Development and deployment of major areas of major industrial equipment with stainless steel pipe localization program, PetroChina, Sinopec and other large enterprise groups have also set up a domestic equipment steering group to promote the application of domestic industries related to the process of industrial stainless steel pipe for industrial use The stainless steel pipe industry provides an opportunity for development. (3) infrastructure construction to promote the industry demand Infrastructure construction is one of the main driving forces of China’s economic growth. With the development of China’s urbanization and industrialization process, the investment in fixed assets will continue to be an important force to promote China’s economic development. , Power and energy industries, key projects and key projects started construction, by the 2008 financial crisis and 11 years of European debt crisis is not affected. Steady growth in fixed asset investment in these sectors has led to a sustained increase in the demand for industrial stainless steel pipes. 2, unfavorable factors (1) low-end market competition, irrational industrial structure Domestic stainless steel pipe manufacturing enterprises, large, medium and small enterprises coexist, currently have the ability to produce used in petrochemical, natural gas and power equipment industry, high corrosion-resistant oil and gas pipe, LNG pipe, ultra supercritical power plant boiler, nuclear equipment Pipe and other high-end industrial stainless steel pipe business less, most of the products concentrated in the low-end market, industry competition, production and operation of extensive, low level of profits, anti-market risk ability is weak. The above structural problems are not conducive to the overall competitiveness of the industry continue to improve. (2) high-end market foreign enterprises have a certain competitive advantage Although China’s industrial stainless steel pipe enterprises in the high-end market output, technology, improve the quality of the rapid, but with some international outstanding enterprises still exist a certain gap. Foreign outstanding enterprises after a long period of accumulation in the application of materials, production technology, equipment and testing has certain advantages, these companies monopoly of some special conditions under the high-end industrial stainless steel pipe market segments. With the rise of domestic enterprises, these international manufacturers to use their own cost and technological advantages, establish a high competitive barriers, resulting in domestic enterprises to enter the high-end market is more difficult, making the domestic enterprises can not share high-end market high profits, With the stainless steel pipe industry to enhance the technical level and product quality, improve profitability had a negative impact. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

1, the removal of stainless steel pipeline, the first use of plasma cutting machine stainless steel pipeline cut and then manually removed the stainless steel pipeline, if the diameter is greater than DN200 stainless steel pipeline, hand chain hoist can be used to assist lifting. 2, the demolition of the stainless steel pipeline, it should be promptly cleaned up, otherwise, the new stainless steel pipeline will be no prefabricated work. 3, the new stainless steel pipeline prefabricated, the stainless steel pipeline in the ground according to the original line to lined up, prefabricated, should be based on the actual situation of the site positioning. 4, for the installation of stainless steel pipeline and pipeline fittings should have the manufacturer’s certificate of competency, chemical composition and mechanical properties and other information, and heat treatment and intergranular corrosion experiments. pipeline and pipeline fittings in the use of visual inspection before the surface shall not have cracks, heavy skin and other defects. 5, the pipeline should be installed before the general cleaning, remove the oil and other dirt. 6, stainless steel pipeline is strictly prohibited the use of oxygen – acetylene cutter, should be used sawing, hand saw, wheel cutting machine, plasma cutting machine for stainless steel pipeline cutting, grinding wheel should be used for special wheel. 7, 18-8 stainless steel pipeline with welded connection, accessories using pressed parts, as 18-8 stainless steel for the austenitic stainless steel, the use of welding methods for manual welding. Selection of the electrode and wire specifications: electrode grade A132, wire steel H0Cr20Ni10Ti 8, stainless steel pipeline should be fixed after the installation of the bracket, the tube shall not be in direct contact with the carbon steel bracket, stainless steel pipeline and bracket should be padded between the stainless steel, non-chloride ion plastic sheet and rubber sheet. 9, according to the different transmission medium and operating temperature, flange gasket should be required to use non-metallic gasket or metal gasket, non-metallic gasket chloride content of not more than 50 * 10-6. 10, stainless steel pipeline line is longer or the transmission medium temperature is high, the pipeline should be set compensator. 11, stainless steel pipeline installation is completed, according to the design or specification requirements for pressure test, take water pressure test water chloride content should not exceed 25 * 10-6. Source: China Stainless Steel Pipeline Manufacturer – wilsonpipeline pipeline Industry Co., Limited (www.wilsonpipeline.com)

With the continuous development of process technology, the quality of stainless steel pipe is constantly improving, making it more and more recognized in the process of using. And people in its recognition at the same time, but also put forward higher requirements, hope that in the quality of continuously improve, in performance can continue to break through. Therefore, the development and application of new steel pipe is very necessary. ​ Ferritic stainless steel has been very hot in recent years. As it usually does not contain nickel alloy elements, the price of the product is much lower than that of austenitic stainless steel. Therefore, ferritic stainless steel is becoming more and more popular in some application fields. But in the production process of stainless steel seamless pipe, the ferritic stainless steel plasticity, toughness and formability are relatively poor, difficult to meet by the pipe to the process of pulling or rolling, seamless pipe, therefore, in the process of production of stainless steel seamless pipe, application of ferritic stainless steel has not been recognized. In contrast, duplex stainless steel seems to be much better. The so-called duplex stainless steel is in its solid quenched structure, ferrite and austenite phase each half, the general minimum phase content may reach 30%. Compared with ordinary austenitic stainless steel, duplex stainless steel yield strength is higher, and the forming need sufficient plasticity and toughness, its performance can fully meet the various techniques from pipe seamless process requirements. In some special environments, the amount of duplex stainless steel can be reduced by 30-50% by using the amount of austenitic stainless steel, which is helpful to reduce the production cost. The dual advantages of duplex stainless steel pipe have been greatly recognized in terms of performance and cost, and the development prospect of duplex stainless steel pipe is also getting better and better. Compared with austenitic stainless steel, the nickel content of duplex stainless steel is lower than that of austenitic stainless steel, the price is higher, and the price of nickel austenitic stainless steel is lower. To some extent, the impact of nickel prices is relatively small. Because the price of duplex stainless steel is less affected by the price of nickel, when the price of nickel fluctuates greatly, the risk of enterprises producing dual phase stainless steel is relatively small. In foreign countries, duplex stainless steel is widely used in the pulp and paper industry, oil and gas industry, transportation and construction industry. In order to expand its scope of application, enterprises continue to strive to further expand the specifications of duplex stainless steel pipe, improve production capacity. Sandvik developed SAF 2205 duplex stainless steel pipe has been widely used in offshore oil and natural gas, heat exchanger and processing industry of material demanding field. In China, although dual phase stainless steel pipes have been applied in some industries, the actual use of domestic varieties is relatively small, and due to technical and technological problems, many times can only rely on imported products. The domestic duplex stainless steel pipe has been applied to some cooling pipes at sea, as well as condensed pipes, decomposition pipes and conveying pipes of chemical products, and the effect is better. In the chemical and petrochemical industries, dual phase stainless steel pipes used in many devices are manufactured abroad. Duplex stainless steel has dual advantages of austenite and ferrite, and has even been used in some areas instead of 316L. At present, the import of duplex stainless steel pipe occupies a considerable market share in china. With the full understanding of the application fields of duplex stainless steel pipes and the continuous progress of process technology, the development of duplex stainless steel pipes will surely cause great attention of Chinese steel pipe enterprises. Source: China Duplex Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The definition of stainless steel seamless pipe Stainless steel seamless steel pipe is a kind of steel strip with hollow section and without seams. The characteristics of stainless steel seamless pipe First, the product of the wall is thicker, it is more economical and practical, the wall thickness of the thinner, processing costs will be substantially increased it; secondly, the product process to determine its performance limitations, generally low precision seamless steel pipe: uneven thickness, inner and outer surface of light low brightness, high cost of fixed length, and the inner surface pitting and black spots difficult to remove; the detection and plastic third, must be processed offline. Therefore, it has its advantages in high pressure, high strength, mechanical structure and timber. The stainless steel seamless pipe type The hot rolling, hot extrusion and cold drawing (rolling) stainless steel pipes are used for rolling. According to the stainless steel metallographic structure, it is pided into half ferrite half martensite system, stainless steel tube, martensitic stainless steel tube, austenitic stainless steel tube, austenitic iron ferritic stainless steel tube, etc.. Finally, stainless steel seamless pipe specifications and appearance quality A, according to GB14975-94 “stainless steel seamless steel pipe” stipulates that the length of the pipe is usually (variable length) hot-rolled steel pipe 1.5 ~ 10m, hot extrusion steel pipe is equal to and greater than 1m. Cold drawn (rolled) steel tube wall thickness of 0.5 to 1.0mm, 1 to 7m; wall thickness greater than 1.0mm, 1.5 ~ 8m. The diameter of B and hot rolled (hot extruded) steel tubes ranged from 54 to 480mm, 45 to 36, and 4.5 to 45mm in thickness. The diameter of cold drawn (rolled) steel pipe is 6 to 200mm in total, 65 to 39 in thickness and 0.5 to 21mm in wall thickness. C, stainless steel seamless pipe inside and outside surface shall not have cracks, folding, cracking, crack, rolling reduction, separation and scarring and defects, these defects should be completely removed (except for machining tube), after the removal of the outer wall thickness and shall not exceed the negative deviation. Other minor surface defects that do not exceed the allowed deviation shall not be removed. D, straight allowing depth. Hot rolled, hot extruded steel pipe, diameter less than and equal to 140mm is not greater than the nominal wall thickness of 5%, the maximum depth is not greater than 0.5mm; cold drawn (rolled) steel pipe is not greater than 4% of the nominal wall thickness, the maximum depth is not greater than 0.3mm. E, stainless steel seamless pipe at both ends should be cut into the right angle, and remove burrs. Source: China Stainless Steel Seamless Pipe Manufacturer – wilsonpipeline pipeline Industry Co., Limited (www.wilsonpipeline.com)

1, the yield strength of duplex stainless steel is twice as tall as austenitic stainless steel, small deformation, than the latter should be adopted when cold rolled must choose appropriate speed and sent to the amount, try to reduce the longitudinal uneven wall thickness and rolling fold. When cold drawing, the steel pipe reduction ratio should not be too large. 2, duplex stainless steel pipe‘s middle softening and finished products by continuous roller hearth heat treatment furnace with water cooling device (the exit), prohibit using electrical contact heating, which is not easy to control temperature, heating up fast, easy to overtemperature, make the ferritic phase quantity to exceed bid, especially when rolling thin wall pipe, once the control is not good, easy to produce bamboo-like uneven thickness, although this kind of wall thickness is not mean not (generally not more than 0.1 mm). In electrical contact when heated, thin wall parts rapidly warming, caused by local over temperature, make the ferrite quantity increase greatly, appear even single-phase organization, coarse grained ferrite reduces the corrosion resistance, acid pickling, then this will produce local pickling, make steel scrap. 3. Solid solution treatment of two phase stainless steel pipes is very critical, not only to eliminate the residual stress of the cold machining of the double-phase stainless steel pipe, but also to ensure the proper two phase ratio and the surface quality of the finished pipe. The uniformity of heat treatment need to pay attention to the material temperature and enough time of heat preservation, avoid the insufficient solution of duplex stainless surface residual stress is too high, resulting in some medium caused by stress corrosion. 4. For the biphase stainless steel, which is mainly used for the stress corrosion, it is necessary to make the delivery of the solid solution pickling and avoid the abrasive delivery. When the surface distribution of steel pipe has small cracks, folding and other defects, it needs to be cleaned by the whole pipe. After the grinding, the double – phase stainless steel pipe needs to be reprocessed by the resolvent. The shear stress in residual stresses generated by grinding is the main stress that produces SCC damage. Source: China Duplex Stainless Steel Pipe Manufacturer – wilsonpipeline pipeline Industry Co., Limited (www.wilsonpipeline.com)

Heat treatment of stainless steel welded pipe widely used abroad there is no oxidation continuous heat treatment furnace with protective gas, the intermediate heat treatment in the process of production and the final finished heat treatment, because of lack of oxidation of the surface of the light can get, and cancel the traditional pickling process. The adoption of this heat treatment process has improved the quality of the steel pipes and the pollution of the environment. According to the current trend of world development, the light continuous furnace is pided into three types: (1) roller bottom bright heat treatment furnace. This type of furnace is suitable for heat treatment of large and large steel tubes. The protective gas can be used for high purity hydrogen, decomposing ammonia and other protective gases. It can be equipped with convection cooling system to cool the steel pipe faster. (2) mesh belt bright heat treatment furnace. This type of furnace is suitable for small diameter thin wall precision steel tube, the output of the hour is about 0.3 to 1.0 tons, the length of the steel tube can reach 40 meters, and can also be processed into the capillaries. (3) maffer light heat treatment furnace. The steel tube is mounted on a continuous rack, which can be heated in the maf tube, which can handle the small diameter thin-walled steel tube with low cost, and the output is about 0.3 tons per hour. Technology of stainless steel welded pipe – argon arc welding Penetration depth of molten stainless steel welded pipe requirements, do not contain oxide inclusions, heat affected zone as small as possible, argon arc welding of tungsten inert gas protection has good adaptability, high welding quality and good penetration performance, its products in the chemical industry, nuclear industry and food industry widely used. The lack of welding speed is the disadvantage of argon arc welding. In order to improve the welding speed, many methods have been developed abroad. The welding method of single electrode welding torch is used in production. In the 1970s Germany first used the welding torch to line in line in the direction of the welding line, forming a long heat flow distribution, obviously improving the speed of welding. It is generally used for argon arc welding of three electrode welding torch, welding steel tube wall thickness S is greater than 2mm, welding speed is 3 to 4 times higher than single welding torch, and welding quality can be improved. Argon arc welding and plasma welding can weld a larger steel tube, in addition, 5-10% of the hydrogen in argon, then high frequency pulse welding power, can also improve the welding speed. Argon arc welding is suitable for welding of austenitic and ferritic stainless steel welded pipe. Technology of stainless steel welded pipe – high frequency welding High frequency welding is used for the production of carbon steel welded pipe for more than 40 years, but it is a new technology for welding stainless steel welded pipe. The economy of its production makes its products more widely used in architectural decoration, household appliances and mechanical structure. The high frequency welding has the power of the power, and the steel tube with different materials and the thickness of the outer wall can reach the high welding speed. Compared with argon arc welding, it is more than 10 times the maximum welding speed. As a result, the stainless steel welded pipe that produces general-purpose USES has high productivity. Because the high frequency welding speed is high, it is difficult to remove the burr in the pipe. At present, high frequency welding stainless steel pipe is not acceptable for chemical industry and nuclear industry, which is one of the reasons. From welding materials, high frequency welding can weld various types of austenitic stainless steel welded pipes. At the same time, the development of new steel and the progress of forming welding methods have also successfully welded the steel types of ferritic stainless steel AISI409. Technology of stainless steel welded pipe – welding technology All welding methods of stainless steel welded pipe have their own advantages and disadvantages. How to foster strengths and circumvent weaknesses, several welding methods will be combined to form a new welding technology, meet the demand for stainless steel welded pipe quality and production efficiency, is the new trend of the current stainless steel welded pipe technology development. After several years of research, the process of composite welding has been made, and the production of stainless steel welding tube in Japan, France and other countries has obtained some combination welding technique. The combined welding method is: argon arc welding, plasma welding, high frequency welding and plasma welding, high frequency preheating + 3 welding torch argon arc welding, high frequency preheating + plasma + argon arc welding. Combined welding speed is very obvious. To adopt the combination of high frequency preheating welded steel pipe weld quality and conventional argon arc welding, plasma welding, the welding operation is simple, easy to implement the whole welding system automation, this combination is easy to interface with the existing high frequency welding equipment, low investment cost, the benefit is good. Influence of TIG welding surfactant on weld forming (1) TIG welding has been widely used in production, and it can obtain high quality welds, commonly used to weld nonferrous metals, stainless steel, ultra-high strength steel and other materials. However, TIG welding has the defects of depth (less than 3mm) and low welding efficiency. The increase of welding current can increase the depth of melt, but the volume of melt width and molten pool will increase much more than the depth of the melting depth. Effect of TIG welding surfactant on weld forming (2) The active TIG welding method has attracted worldwide attention in recent years. This technique is prior to welding the weld surface coating on a layer of active flux (surfactant), under the same welding specification, compared with the conventional TIG welding, can dramatically improve penetration (up to 300%). For the 8mm thick plate welding, it can not open the groove and obtain a large depth or one solder at a time. For the thin plate, the welding heat input can be reduced without changing the welding speed. At present, a-tig welding can be used for welding stainless steel, carbon steel, nickel base alloy and titanium alloys. Compared with traditional TIG welding, a-tig welding can greatly improve productivity, reduce production cost, and reduce welding deformation, which has A very important application prospect. The key factor of a-tig welding is the selection of active ingredients. The active ingredients commonly used are oxides, chlorides and fluorides, different materials, and the active ingredients are different. But due to the importance of this technology, the active ingredients and formulations have patent restrictions in both PWI and EWI, which are rarely reported in public publications. At present, the research on a-tig welding mainly focuses on the research on the mechanism of active agent and the research on the application of activated welding technology. Effect of TIG welding active agent on weld shaping (3) There are three main types of active agents developed and used at home and abroad: oxide, fluoride and chloride. The active agents developed by PWI for titanium alloy welding are mainly oxides and chlorides, but the toxicity of chlorides is not conducive to promotion and application. At present, the active agent used for welding stainless steel and carbon steel in foreign countries is mainly oxide, while the welding of titanium alloy material contains a certain fluoride component. Effect of TIG welding surfactant on weld forming (4) Effect of single component active agent on weld forming of stainless steel: (1) with the application of the weld of SiO2, the width of the weld passes gradually narrowed with the increase of the amount of SiO2 coating, and the arc pit lengthened and narrowed. At the end of the weld bead, the height of the weld is high, and at the junction of the coated active agent and the uncoated active agent, the weld metal piles up. In all the active agents, SiO2 has the greatest effect on weld forming.  (2) surfactant NaF, Cr2O3 welds forming effect is not obvious. With the increase of the application, the width of the weld is not changed greatly, and there is no obvious change in the arc pit. There is no significant change in the width of the weld line compared with the welding seam of the surfactant, but the arc pit is larger than the surfactant.  (3) with the increase of amount of TiO2 coating, bead appearance change is not big, there is no obvious change of arc crater, similar to the absence of surfactant. However, the formation of the weld surface is relatively flat, no bite phenomenon, better than the soldering path of the surfactant.  (4) surfactant CaF2 influence on forming welds. With the increase of the amount of CaF2 coating, the weld deformation is poor, the arc pit is not changing, and the weld width is not much changed. But with the increase of CaF2, there are some defects such as nibbling.  (5) the impact on the penetration, compared with no surfactant, the above five kinds of surfactant can increase the weld penetration, and with the increase of amount of coating, penetration also increased accordingly. However, when the applied amount reaches a certain value, the melting depth increases to reach saturation, and then the depth of penetration decreases. Effect of TIG welding surfactant on weld forming (5) Advanced TANDEM high efficiency MIG/MAG double wire welding technology This process can weld carbon steel, low alloy steel, stainless steel, aluminum and other metal materials, it is a high speed and high efficiency, widely used in the advanced welding technology. High speed welding and high deposition rate welding is the development direction of welding technology in the future, and MIG/MAG double wire high speed and high efficiency welding is one of the hot spots. It will be widely used in industrial production TANDEM double wire welding principle The TANDEM double wire welding system consists of two welding machines, two wire feeding machines and one welding gun, which can be used with the automatic special machine or welding robot. Two wire feeding machines are used to feed two electrodes into the welding gun and two separate electrically conductive mouths, which are melted in the double arc to form a molten pool. The process characteristics of TANDEM double wire welding 1. High performance welder, the welding current of 100% transient load is 1000A, pulse current 1500A; 2. Digital dual pulse power supply, programmable, connect PC and printer; 3. The specification parameters of each wire can be set independently, and the material and diameter can be different. 4. The feeding speed of each wire can reach 30m/min; 5. Greatly improve the efficiency of deposition and welding speed; 6. Maintain low thermal input while the deposition efficiency is increased; 7. Stability of arc, controlled droplet transition; 8. Small welding deformation; 9, flying small; Welding data monitoring and management; 11. Use standard gas and consume less gas; 12. Wide range and high productivity. Source: China Stainless Steel Welded Pipe Manufacturer – wilsonpipeline pipeline Industry Co., Limited (www.wilsonpipeline.com)

The manufacturing process of butt welded seamless elbow is pided into two kinds: hot rolling (extrusion) seamless elbow and cold drawing (rolling). Cold drawing pipe is pided into two types: circular pipe and heteroid pipe. A brief introduction to welding seamless bend process is as follows: Cold drawing (rolling) : seamless elbow pipe billet and heating to punch to heading, annealing, pickling and oil (copper) and multichannel time cold drawing (cold rolled) to the pipe billet – heat treatment – straightening, hydrostatic test (NDT) – > tag to put in storage. Hot rolled seamless elbow (extrusion) : the circular pipe billet – heat – perforated – three-roll skew rolling, rolling or extrusion – pipe – sizing (or reducing) – cooling – straightening to hydrostatic test or inspection – > tag, put in storage Rolling seamless elbow materials are tubular billet, round pipe embryo through cutting machine cutting the growth degree of billet is about one meter, and the conveyor belt to the heating furnace. Billet heating are fed into the furnace, the temperature is about 1200 degrees Celsius. Fuel for hydrogen or acetylene. Furnace temperature control is a crucial problem. Circular pipe billet after going through pressure punch wear empty. General is one of the more common punch is tapered roller puncher, this kind of punch high production efficiency, product quality is good, large amount of perforated hole enlargement, can wear a variety of pipe fittings. After perforation, circular pipe billet has been three-roll skew rolling, rolling, or pressing. To take off the pipe sizing. After extruding sizing mill by taper drill bits high-speed steel into embryo punching and forming pipe. Pipe diameter by sizing mill bit length to determine the diameter. Pipe after sizing, into the cooling tower, by water spray cooling, pipe after cooling will be straightening. Pipe fittings by the conveyor belt to the metal detection after straightening machine (or water pressure experiment) for internal inspection. If the steel pipe internal crack, air bubble, will be detected. Seamless elbow after also through strict in quality control manual pick. Seamless elbow after quality inspection, spray paint on the serial number, specification, batch number, etc. Seamless elbow and by crane into the warehouse. Cold drawing (rolling) seamless steel pipe rolling method is more complicated than the hot-rolled seamless elbow (extrusion). They are in the same production process flow of the first three steps. The difference from the fourth step, circular pipe billet after punch to heading, annealing. After annealing to use special acid pickling liquid. After acid pickling, oil. Then followed by cold drawing through multi-channel time (cold) and billet pipe, special heat treatment. After heat treatment, will be straightening. Steel pipe by the conveyor belt to the metal detection after straightening machine (or water pressure experiment) for internal inspection. If the steel pipe internal crack, air bubble, will be detected. After the quality inspection, the steel pipe shall be selected by hand after the quality inspection. After the quality inspection, the steel pipe shall be sprayed with the number, specification and batch number of the paint and shall be hoisted into the warehouse by crane. Source: China Seamless Elbow Manufacturer – wilsonpipeline pipeline Industry Co., Limited (www.wilsonpipeline.com)

The pipe reducer is also one of the chemical pipe fittings used for the connection of two different pipe diameters. It is pided into concentric pipe reducer and eccentric pipe reducer. pipe reducer for diameter specification does not accord with the inner diameter of the process piping, should undertake the corresponding reducing or expanding process, if the shrink tube, pipe pressure loss caused by this should be considered whether will affect the process. In order to prevent the installation of pipe reducer influence the distribution of velocity field, pressure loss, and reduce the measurement accuracy of electromagnetic flowmeter, the requirements of the central Angle alpha is not more than 15 °, as small as possible. There are pided into two concentric and eccentric, concentric pipe reducer is generally used in vertical pipe; The eccentric pipe reducer is used for the horizontal pipe, and it should be noted that the top level or the bottom level. There are several main places: 1. When the flow of fluid in the pipe changes, such as increase or decrease, the flow rate of the flow will not change very much. 2. Pump inlet to prevent cavitation. 3. Contact with the instrument, such as flowmeter and regulating valve, in order to cooperate with the instrument’s joint, the pipe reducer should also be used Source: China pipe reducer Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)