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When welding thin wall stainless steel, the technical level requirements are very high, because in the welding of this kind of material, will face many problems, such as construction site problems, heat treatment problems, thermal expansion and cold contraction problems, the following to tell the solution to these problems. First of all, the construction capacity, welding is a relatively strong professional activities, generally after welding can not be demolished, in the actual construction site for a long time, because it is necessary to change, resulting in very inconvenient. Because of the need for specialized equipment and argon arc welding of thin wall stainless steel tube, the thickness is very thin, there must be a high level of welders operation, but in the actual construction site personnel mobility, if no welding operation certificate of personnel of electric welding, argon flow, the adjustment will not be reasonable, and the influence of construction site space and human factors, often produce weld and weld welding pipe even wear phenomenon, although Water Leakage problem does not appear in the pressure test, but there is a great risk in construction, after a certain period of time, because of the effect of thermal expansion and contraction and other factors, will lead to future Water Leakage. The second is the problem of heat treatment, as for thin wall stainless steel pipe and socket fittings to place for welding solution treatment at the factory, but in the construction site, restricted construction site welding pipes and pipe fittings, is unlikely to do solid solution treatment of austenitic stainless steel, due to slow after 450~800 degrees. The carbon precipitation generated by the precipitation of chromium carbide in grain boundary material, chromium content in the vicinity and therefore lower generation lack of chromium, lead to corrosion resistance drop. Long time use is usually late, will produce in the weld of stainless steel materials most worried about intergranular corrosion, if the high carbon content of stainless steel materials, in the weld will lead to failure of stainless steel pipe in advance, and this is certainly flawed will appear in the use of a certain period of time after the test is not on the spot. The third point is the expansion and contraction of the problem, the stainless steel plate material with the change of temperature and the formation of destructive force is very strong, so the expansion and contraction of stainless steel material is critical. The influence of thermal expansion is not simply in the products produced by pulling force to determine the value, such as the original thread connection with much more easily affected by thermal expansion and contraction, because the stainless steel pipes and pipe fittings have no way to extend or shorten the occurrence of fatigue and often burst, if the temperature the greater the damage the greater the. So the connection of thin wall stainless steel pipes and pipe fittings if buried installation, must fully consider the material thermal properties, and by argon arc welding of the socket type pipe, is difficult to achieve the parent pipe and pipe fittings and welding, to eliminate stress, especially in the north of the buried pipeline is mostly in the summer season, resulting in water and when the maximum buried negative temperature difference of 35 degrees, especially when the temperature drops sharply, the pipeline expansion joint is not installed under the condition of axial tension will cause the pipe and pipe welding crack, once the treatment is not good, there are pores, weld damage is thermal expansion and contraction of the defect, with the passage of time will be completely unmasked, so we must pay attention to the use of the installation process is reasonable in the case of buried. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In order to enhance the performance of the stainless steel pipe, usually use some cold processing technology, such as cold drawing, cold rolling, cold rolling, cold, cold, cold expansion distortion, but finally achieve effect, also will inevitably suffer some damage, these cold working process and welding processing, will damage the performance of the stainless steel pipe, especially corrosion or heat resistance. There are five main reasons for the damage of stainless steel pipes. First of all, it will increase the micro defects and surface roughness of the lattice dislocation of the pipe material, and also induce martensite transformation and precipitation of carbides. For example, austenitic stainless steel presents a magnetic increasing phenomenon after cold working. Secondly, the lattice dislocation or phase transition of stainless steel pipe will occur on the surface, and it will also become the starting position of pitting corrosion. This phenomenon will produce a direct adverse effect when the deformation degree reaches 20% reduction section rate. The residual stress in the stainless steel pipe will be left after the cold working, and the residual stress is very unfavorable to the stress corrosion cracking of the pipe. Any degree of cold processing will lead to a great increase in the sensitivity of the material to stress corrosion cracking. The cold working degree also has an adverse effect on the high temperature endurance strength of austenitic stainless steel. The higher the general working temperature or the higher the fracture life requirement, the lower the cold working degree can be. For stainless steel pipes subjected to alternating loads, cold processing will cause cracking and expansion rates to increase due to the decrease of elongation and residual elongation. In order to solve the above problems, there are several solutions. First of all, the stainless steel standards in most countries, especially the European unified stainless steel pipe standard, stipulate that all seamless stainless steel pipes must be supplied in solid solution or annealed state, so as to remove the damage caused by cold processing and welding. Secondly, three key parameters should be paid attention to in solution treatment, i. e. heating temperature, rapid cooling method and high temperature residence time. Excessive solution treatment temperature or residence time will be detrimental to the corrosion resistance of stainless steel. Determine whether the solution is in place, hardness determination, expansion, curling, flattening, tensile data can be determined, in which hardness is the most simple. The solid solution or by high temperature heating annealing and pickling treatment, it significantly increased the manufacturing cost and production cycle, with acid mist and other waste gas and waste water emissions plus, some enterprises omit this process, the use of this product, easy to cause the production and personal accident after use. Finally, for some stainless steel pipes which may be difficult to implement solid solution or annealing, it is necessary to control the degree of cold processing and local annealing at low temperature, which can effectively reduce the harmful effects. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel plate can be used to make a lot of daily necessities, stainless steel processing technology is perse, such as stamping, bending, shear folding, etc., this paper focuses on stamping process. The common stamping forming processes of stainless steel sheet include drawing process, bulging process, flanging process (including reaming) and bending process. The corresponding material properties are bulging forming performance, flanging formability, reaming formability and bending formability. But before talking about the stamping process of stainless steel plate, the two factors that will affect the mechanical properties of stainless steel are also discussed. They are internal cause and external cause respectively. Internal causes are more important, that is, different chemical elements in stainless steel tissue, mainly metal elements, different types of stainless steel because the chemical composition is different, so the strength is also different. There are generally three factors, the first is the deformation temperature, and under normal conditions, the strength is increased when the temperature is lower. For austenitic stainless steel, the decrease of temperature will make the plasticity decrease little, so it has better impact toughness at low temperature. For ferritic stainless steel, the temperature drop will greatly reduce the plasticity, so there is a low temperature brittleness. It’s just ordinary. When the temperature drops, the internal structure of stainless steel will be changed, and the abnormal phenomenon will also occur. A large number of stacking faults occur in the CrMnN stainless steel under low temperature impact, so there is a significant ductile brittle transition phenomenon. For example, 304 stainless steel bars with low carbon, chromium and nickel content will form martensite at low temperature, which will also reduce impact toughness. The second is the deformation velocity. Generally speaking, increasing the deformation rate will reduce the toughness. For example, the temper brittleness that can not be reflected by tensile properties can be shown by impact toughness. Ferrite at the pulse speed causes ferrite free phase transformation and twinning, which will decrease the toughness of ferrite. The third is the state of stress, the sample with notch, crack and sample thickness will change the stress state and stress concentration, thus affecting the toughness of stainless steel material. It is because of the above mechanical properties of stainless steel material, so the processing is based on the actual needs and material properties to do targeted programs. The stamping process of stainless steel plate is introduced as follows. Drawing process, which is a kind of stamping process method using the special mold to cut or cut the flat blank to open hollow parts. Its characteristic is that the stainless steel sheet can flow into the die under the driving of the punch, that is to say, the material is formed by the fluidity and elongation of the material. Bulging forming process is to use the mold to force the thickness of the blank thinning and surface area increase, so as to get the geometry of the workpiece stamping method. It is characterized by that the blank is crushed by the blank holder and can not flow into the die. It is completely dependent on the extension of the material itself. Flanging forming process is a stamping process which uses the mold to turn the hole edge or the outer edge of the blank into the vertical edge. In the middle stage of the round hole flanging, that is, the material under the punch has not been transferred to the side. If the deformation is stopped, the forming method will be shown on the right. This forming method is called reaming and is widely used in production. The last bending forming process is actually a forming process for bending the stainless steel sheet, bar, tube or profile into fixed shape and angle parts. Source: China Stainless Steel Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Generally speaking, stainless steel bellows in the application may encounter internal leakage or leakage phenomenon, resulting in a lot of reasons, usually due to liquid medium containing solid impurities damage the sealing surface caused by. The causes of valve stem leakage are mainly related to valve structure, working environment and service mode. The structural stem uses stainless steel bellows and packing double seal structure, bellows lining ring and outer lining ring welded into bellows components, and then with the stem and guide body welding, so as to block the medium through the valve stem leakage. The distance between the upper and lower of the valve rod moves upwards until the upper end of the flat key is contacted with the lower end of the lower packing. Because the lower packing is made of PTFE material, once the valve is over opened, the flat key I is inserted into the packing so that the valve can no longer be opened and closed, and the components of the bellows are also killed, leading to the leakage of the dielectric along the valve stem. The length and compression amount of the stainless steel bellows are determined according to the distance of the valve. Once it exceeds the limit tension or compression, it may destroy the bellows, resulting in the failure of the small tube and the sealing failure. Therefore, it is necessary to increase the valve opening and closing of the limit device, so that the valve opening and closing process, bellows has been in the design range of expansion. Here’s an example. The stop valve of stainless steel bellow is installed on the pipeline of the power plant of the ship. During the use of the valve, there are some problems, such as the leakage of the valve stem and the rust of the valve stem. But the problems will happen again and again. By analyzing the causes of the failure, using appropriate solutions to remove the fault, thereby protecting the performance of the valve. Through the analysis of the valve problems, the structure, operation and environment were improved. The first is to increase the limited welfare cost of flat key I, and ask the lower filler of PTFE material to ask for a thick 3mm stainless steel filler pad, so as to avoid the contamination of the filler and the valve stem limit. When the valve is closed, if the valve can not be stopped, do not force forcibly shut down, but to open the valve, flush with fluid for a period of time after closing again, again and again, if not yet closed, check the grinding sealing surface. When the valve is opened, when the valve opens to a certain height, the valve stem meets small resistance, try not to continue to force open, thereby extending the life of the valve stem and its sealing components. Valve with thrust ball bearing on the upper part of the valve, in the installation, we should try to avoid condensation water directly drop in the valve account, resulting in corrosion of the stem position. In addition, the bellows stop valve working environment is bad, but also cause one of the reasons for its easy failure. Because the body is installed on the corrugated pipe valve for long-term work in the salt spray environment, and is also often condensate dripping water, lead to corrosion of the upper thrust ball bearings, it will lead to more serious stem contact corrosion, operation in use if excessive open or closed bellows globe valve, may the valve can not meet the relevant performance requirements. Over close the valve, it may crush the sealing surface, resulting in seal failure when the valve again. When the valve is opened excessively, the stainless steel bellows assembly may be operated to make the valve leak out. Source: China Stainless Steel Bellows Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

There are more than 10 kinds of common elements in stainless steel plate. In addition to the basic element iron, the most important elements affecting the performance and microstructure of stainless steel plates are carbon, chromium, nickel, manganese, silicon, molybdenum, titanium, niobium, titanium, manganese, nitrogen, copper, cobalt and so on. When some elements coexist in the whole stainless steel, the influence of far is much more complex than when they exist independently, because not only to consider the elements of its function, but also pay attention to their effects caused by each other, so the performance of stainless steel is the sum of various elements affect the decision by the. Chromium plays a decisive role in stainless steel, as long as the stainless steel contains a certain amount of chromium. This is because the addition of chromium to the steel will result in the movement of stainless steel inside the contradiction to the resistance to corrosion damage. The main reason is to increase the electrode potential of Fe based solid solution, in addition, chromium also absorbs the iron electron to make iron passivation. In addition, carbon is one of the main elements of industrial steel. The properties and structure of steel are largely determined by the content and distribution of carbon in steel, and the effect of carbon in stainless steel is more obvious. The effect of carbon on the microstructure of stainless steel is mainly manifested in two aspects, one of which is stable austenite elements, and the degree of action is great, is 30 times the effect of nickel, and the other is because of the great affinity of carbon and chromium, and chromium formation of a series of complex carbide. Therefore, from the two aspects of strength and corrosion resistance candle, the role of carbon in stainless steel is contradictory. The role of nickel in stainless steel is to play with chromium to play out, nickel is an excellent corrosion resistant material, but also an important alloying elements of alloy steel. Nickel in stainless steel is austenite formation elements, but the low carbon nickel steel to obtain pure austenite, nickel content must be as high as 24%. Only when the content of nickel is 27%, can the corrosion resistance of stainless steel change obviously in some media. Therefore, nickel can not be made into stainless steel alone. However, nickel and chromium exist in stainless steel at the same time, nickel containing stainless steel has a lot of valuable properties. Nickel as alloying element in stainless steel, is the high chrome organization changes, so as to improve the corrosion resistance of stainless steel materials and process performance. In addition of manganese and nitrogen can replace nickel chromium nickel stainless steel, chromium nickel austenitic stainless steel has the advantages of many, but over the years because refractoloy and heat resistant steel containing nickel below 20% a large number of development and application, and the chemical industry development needs more and more and the stainless steel, nickel deposits the relatively small and concentrated in a few areas in the world, so there is a contradiction in the supply and demand of nickel. Therefore in many other fields of stainless steel and alloy forging steel, tool steel, heat resistant steel etc., especially nickel less resources, widely carried out section of nickel and nickel with other elements of the generation of scientific research and production practice, the research in this aspect and is widely applied to manganese and nitrogen instead of nickel in stainless steel and heat resistant steel. The effect of manganese on austenite is similar to that of nickel. More precisely, the effect of manganese is not on the formation of austenite, but because it can reduce the critical quenching rate of stainless steel, increase the stability of austenite in cooling, inhibit the decomposition of austenite, so that the austenitic structure at high temperature can be maintained at room temperature. The corrosion resistance of stainless steel increased, little effect of manganese, nickel manganese austenite is about half the stability in the role of low nickel stainless steel, stainless steel and nickel free CrMnN Stainless steel has been used in the industry, some areas have been successfully used to replace 18-8 chromium nickel stainless steel. Source: China Stainless Steel Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Nitric acid is a strong oxidizing acid, strong oxidative corrosion, a lot of chemical fiber used in chemical fertilizers, dyes and other chemical industries. Stainless steel acid-resistant steel is developed from the application of nitric acid industry. Cr13 stainless steel has a certain corrosion resistance in dilute nitric acid at room temperature. Cr18 stainless steel has a very good corrosion resistance to dilute nitric acid at various temperatures. However, nitric acid industry is relatively large amount of application or better overall performance of Cr18Ni9 type stainless steel. Since molybdenum has a negative effect on the corrosion resistance of acid-resistant steels in nitric acid, it is not usual to select molybdenum-containing stainless steels in the nitric acid industry. Also in the production of concentrated nitric acid, but also the need to use a specific stainless steel. When nitric acid with chlorine, chromium plasma, its corrosion will be strengthened. Chlorine ion in nitric acid easily causes pitting corrosion of stainless steel acid-resistant steel. Intergranular corrosion of nitric acid is also very strong, easy to weld heat affected zone knife-like corrosion. Boiling nitric acid at a concentration of 65% is not only sensitive to the tendency of intergranular corrosion caused by precipitation of chromium carbide, but also to the tendency of intergranular corrosion caused by precipitation of d phase. Industrial nitric acid concentrated nitric acid (96% ~ 98%) and dilute nitric acid (<65%) two. Next, a brief introduction of stainless steel materials in dilute nitric acid, concentrated nitric acid production equipment. Application of stainless steel in dilute nitric acid production 18-8 type alone – nickel austenitic stainless steel is excellent resistance to dilute nitric acid, it is widely used in dilute nitric acid concentrations below 65%, the same is true of duplex stainless steel 022Cr2lNi5Ti, 022Cr25Ni6M02N. The mechanical properties of the castings are usually less demanding, even less welding, can be replaced by more economical Cr17 ferritic stainless steel. When required corrosion resistance and high strength, but also the use of martensitic stainless steel 12Cr13 (403), 14Cr17Ni2 steel, used in the quenched and tempered state. Application of stainless steel in concentrated nitric acid production When the nitric acid concentration is greater than 68%, ordinary 18-8 chrome-nickel stainless steel has been unable to meet the requirements. Concentration ≤ 85%, the general use of Cr25Ni20-type stainless steel. If the nitric acid concentration is too high, the corrosion resistance of Cr25Ni20 stainless steel will drop sharply due to nitric acid peroxidation and will be severely corroded. Therefore, it is necessary to use stainless steel with 4% to 6% silicon content, such as 14Cr18NiIISi4AITi, 06Cr18Ni13Si4 and 022Cr20N. When the nitric acid concentration ≥ 97%, you can use the chromium content of 5% to 6% of chromium-nickel stainless steel. Stainless steel in sulfuric acid equipment applications Sulfuric acid is also a very important basic chemical raw material, used to produce and put sulfuric acid equipment or containers generally use stainless acid steel. Although sulfuric acid is an oxyacid, dilute sulfuric acid and moderate concentrations of sulfuric acid are not very oxidizing and are reducing acids. The concentrated sulfuric acid, especially hot concentrated sulfuric acid oxidation is very strong, is an oxidizing acid. Because of this characteristic of sulfuric acid, the choice of sulfuric acid-resistant stainless steel, with sulfuric acid concentration, temperature of the different grades selected. Dilute sulfuric acid, medium concentration of sulfuric acid can choose 06Cr17Ni12M02 (316), 022Cr17 Ni12 M02 (316 1), 06Cr17Ni12M02Ti (316Ti) and other molybdenum content is 2% -3% stainless steel. Molybdenum-free stainless steel 18-8 chrome-nickel austenitic stainless steel, due to intolerance of dilute sulfuric acid, medium-grade sulfuric acid corrosion, it can not be used in the case of sulfuric acid corrosion. When high molybdenum content, this stainless steel corrosion will be enhanced again. Stainless steel containing molybdenum, Cu, Si (3% to 4%) of Cr-Ni austenitic stainless steel and duplex stainless steel better sulfuric acid resistance. In the concentration of 90% -98% of the high-temperature concentrated sulfuric acid, according to the use of temperature and concentration, the use of silicon content of about 6% of stainless steel works well. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipe according to the material points are mainly ordinary carbon steel pipe, high-quality carbon structural steel pipe, alloy structural pipe, alloy steel pipe, bearing steel pipe, stainless steel pipe and bimetallic composite pipe, coating and coating pipe. Stainless steel tube of many varieties, uses are also different, their technical requirements are not the same, the production methods are also different. Divided by the mode of production, there are two seamless stainless steel pipe and welded pipe, seamless steel pipe can be pided into hot-rolled pipe, cold-rolled tubes, cold drawn tubes and extruded tubes, cold drawn, cold rolled stainless steel tube Secondary processing, welded pipe has a longitudinal welded pipe and spiral welded pipe. Divided by the cross-sectional shape, stainless steel tube with a round tube and shaped tube. Shaped pipe and rectangular tube, diamond-shaped tube, oval tube, the six-tube, P Plus and a variety of sections of asymmetric steel. Shaped pipe is mainly used in a variety of structural parts, tools and mechanical parts. Compared with the round tube, shaped stainless steel tube generally has larger moment of inertia and section modulus, stronger bending resistance and torsion resistance, which can greatly reduce the weight of the structure and save the stainless steel. Stainless steel pipe according to vertical section shape can also be pided into sections such as cross-section pipe and variable cross-section tube. Variable cross-section pipe, including tapered pipe, stepped pipe and periodic cross-section pipe. Divided by the tube end shape, stainless steel tube light pipe and tube two. Tube can also be pided into ordinary car wire and thread pipe and special. Divided by purpose, stainless steel pipe can be pided into oil well pipe, pipe line, boiler tube, mechanical pipe, hydraulic prop tube, cylinder tube, geological tube, chemical tube and marine tube. Stainless steel pipe is used in a wide range of applications more areas of the automotive industry, petrochemical industry, and fluid transport. Which used in the automotive industry is the main exhaust pipe stainless steel tube system, and most of the ferritic stainless steel. Exhaust gases from the car engine pass through the exhaust gas intake pipe, the front pipe, the hose, the converter, and the center pipe finally flow out of the muffler. Exhaust system commonly used steel 409L, 436L and so on. Automotive mufflers mainly use stainless steel welded pipe. In the petrochemical industry, including fertilizer industry, the demand for stainless steel pipe is very large, commonly used stainless steel seamless pipe, made of 304,321,316,316 L, 347,317 L, etc., outside diameter ¢ 18- ¢ 610 or so, wall thickness In 6mm-50mm or so. In addition water and gas and other fluid delivery is also commonly used stainless steel tube, this tube corrosion resistance than other pipe materials are stronger. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Duplex stainless steel pipe has better corrosion resistance than austenitic stainless steel pipe, and its practicability is wider. Because of ferrite structure in duplex stainless steel pipe, it has both the properties of ferrite and austenitic stainless steel pipe. The advantages of duplex stainless steel pipes are many. First, the yield strength is much higher than that of ordinary austenitic stainless steel pipes, and there is enough plastic and toughness for forming dual phase stainless steel pipes. The wall thickness of a dual phase stainless steel pipe or pressure vessel is reduced by 30%~50% than that of austenitic stainless steel, which reduces most of the cost. The duplex stainless steel pipe resistance to stress corrosion cracking ability is outstanding, especially in chloride environment, even if the resistance to stress corrosion cracking ability is stronger than the austenitic stainless steel pipe alloy containing the lowest amount of duplex stainless steel, and stress corrosion can be said to be very difficult to solve the problems of ordinary austenitic stainless steel pipe. In some media, such as acetic acid and formic acid, the corrosion resistance of duplex stainless steel pipes can even replace high alloy austenitic stainless steel pipes, or even part of corrosion resistant alloy pipes. The double phase stainless steel pipe also has excellent resistance to localized corrosion and similar alloy content of austenitic stainless steel pipe as compared to duplex stainless steel pipe with high strength and good corrosion resistance, wear resistance corrosion and corrosion fatigue properties are more excellent than the austenitic stainless steel pipe. The coefficient of linear expansion of dual phase stainless steel pipe is lower than that of austenitic stainless steel pipe, close to carbon steel pipe, and suitable for joining with carbon steel pipe. Engineering significance is very important, for example, producing composite panels or linings. In addition, the energy absorption capacity of the dual phase stainless steel pipe is better than the austenitic stainless steel pipe, regardless of the dynamic load or the static load. This is of obvious advantage to the duplex stainless steel pipe, such as collision and explosion, and its practical application value is higher. But the duplex stainless steel pipes also have some disadvantages. For example, the universality and multifaceted nature of the duplex stainless steel pipes are not as good as those of the austenitic stainless steel pipes. For example, the application temperature of the duplex stainless steel pipes must be controlled below 250 degrees. Secondly, the ductility of the dual phase stainless steel pipe is lower than the austenitic stainless steel pipe, and the cold, hot processing technology and the molding performance are inferior to the austenitic stainless steel pipe. Moreover, the duplex stainless steel pipe has moderate temperature brittle area. We must strictly control the heat treatment and welding process system to prevent the occurrence of harmful phase and damage the performance of duplex stainless steel pipe. Source: China Duplex Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

304 stainless steel plate is more durable than ordinary steel, its surface is beautiful and the application of various forms, excellent corrosion resistance, but also high temperature oxidation, high strength, can be fire-resistant, so the production of stainless steel plate More likely. In addition, the stainless steel plate can be plasticized and processed at room temperature without surface treatment. 316 and 304 compared to the main difference between stainless steel chemical composition, including 316 stainless steel containing molybdenum, stainless steel in general 316 stainless steel corrosion resistance is better, better corrosion resistance in high temperature 304 stainless steel. Therefore, in high temperature environment, engineers usually choose 316 stainless steel for production. But not necessarily, in the case of concentrated sulfuric acid, the temperature is too high can not use 316, because in order to avoid the threads at high temperatures bite, to apply a dark solid lubricant. 304 stainless steel because of its high yield point, the hardness is high, cold hardening effect is obvious, 304 stainless steel bending process is characterized by poor thermal conductivity due to ordinary low carbon steel, the elongation is low, resulting in deformable board required Compared with carbon steel, the large and stainless steel sheets tend to rebound strongly compared with carbon steel during bending, and their elongation relative to carbon steel is also low. Therefore, the bending angle R of the stainless steel workpiece during bending is higher than that of carbon steel, Otherwise there will be cracks may occur. Because of the high hardness of 304 stainless steel, cold work hardening effect is significant, so choose the bending tool should choose the heat treatment up to 60HRC hardness of the tool steel, and its surface roughness than carbon steel bending tool an order of magnitude higher. According to the above characteristics, generally speaking, the unit size, the thicker the stainless steel plate, the greater the required bending force, and as the thickness increases in the choice of bending equipment, the bending force margin should be stronger, In the unit size, the higher the tensile strength of the board, the lower the elongation, the greater the required bending force, the greater the bending angle. According to the actual situation, the unfolding dimension of a bent workpiece is the addition and subtraction of two thickness at right angle, which can fully meet the design precision requirements. Based on experience and formula, the calculation of unfolding quantity can simplify the calculation process and greatly improve the production efficiency. The greater the yield strength of the material, the greater the elastic recovery, in order to get the angle of 90 degrees of the bending piece, the angle of the required pressure knife should be designed smaller. Relative to the same thickness of 304 stainless steel plate bending angle, which requires great attention, will generate bending cracks, which will affect the strength of stainless steel workpiece. Source: China Stainless Steel Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pneumatic flange butterfly valve, with pneumatic actuators in application, because pneumatic actuators perform very fast and do not need to be done by workers themselves, it can save manpower and time cost. Working principle of stainless steel pneumatic flange butterfly valve The advantages of stainless steel pneumatic butterfly valve flange mainly has simple structure, small volume and light weight, cheap price, usually installed in the upper passage, after two position five way solenoid valve control easy to operate, but also can adjust the flow of medium. The fluid resistance is low, medium and large caliber pneumatic butterfly valve fully open when the larger effective flow, quick opening and closing and pulling rotation angle of 90 degrees to the butterfly can be opened and closed, because the shaft on both sides of the disc hand medium is approximately equal to the force, torque and the opposite direction, so the opening and closing torque is small, but also under low pressure good sealing butterfly valve sealing material is mainly butadiene acrylonitrile rubber, fluorine rubber, edible rubber, PTFE, so the sealing performance should be relatively good, which is soft and hard sealing butterfly valve has the advantages of laminated sheet metal, metal seal and elastic sealing, even under low temperature sealing performance is also very good. Application of stainless steel pneumatic butterfly valve is used to rotate with the valve orange do open and close, thus enable the action of the pneumatic valve main shut-off valve used to do, can be designed to have a section of the valve or adjust the function and regulation, is now very much application of butterfly valve in the low pressure large size pipelines. The structure of the pneumatic flange butterfly valve of stainless steel The butterfly plate of the butterfly valve is installed in the direction of the diameter of the pipe. In the cylindrical channel of pneumatic flange valve body, the disc shaped butterfly plate revolves around the axis, the rotation angle is between 0 degrees -90 degrees, when the rotation is 90 degrees, the valve is in the full open state. The butterfly valve is usually made up of only a few small parts. And as long as the rotation of 90 degrees can be completed fast opening and closing, easy operation, and the electric valve of the fluid control performance is very good. When the pneumatic flange butterfly valve is fully open, the thickness of the butterfly plate is the only resistance of the medium flowing through the valve body, so the pressure generated by the valve will be very low, so it has relatively good flow control characteristics. The seal form of pneumatic flange butterfly valve has two kinds of elastic seal and metal seal. Elastic sealing valve, sealing ring can be inlaid on the valve body or attached to the circumference of the butterfly plate. The life of a valve using a metal seal is generally better than a flexible sealing valve, but it is also difficult to complete a complete seal. Metal seals can adapt to higher working temperatures, and elastic seals have a temperature limitation. If the stainless steel pneumatic flange butterfly valve is used as the flow control, it is generally to choose the size and type of the valve. The structural principle of the butterfly valve is especially suitable for making large caliber valves. The butterfly valve is not only widely used in oil, gas, chemical, water treatment and other common industries, but also used in the cooling water system of the thermal power station. Source: China Butterfly Valve Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In general, the process of manufacturing stainless steel pipe fittings in accordance with the order including cutting, forming, heat treatment, surface treatment, cutting, nondestructive testing, surface protection and the logo, the following step by step under the details. The first is the cutting, the production of stainless steel pipe fittings used in the material is usually pipe, stainless steel plate and stainless steel bar, according to the characteristics of the material and the shape of the product to choose blanks blanking method. Blank shape, size and other requirements are also based on different product specifications. For stainless steel pipe, the commonly used methods of cutting the band sawing machine or bow saw cutting, gas cutting, plasma cutting. For stainless steel sheet, often used cutting method is gas cutting, plasma cutting, punching punch. For stainless steel bars, frequently used blanking methods include band sawing or bow sawing, blanking and cutting. The second step is forming, also known as welding, all stainless steel pipe production and forming processes are inseparable from this process. This article describes the heating and welding in the next part of the forming process. The heating refers to the requirement of deformation of the stainless steel material in the forming process and heating of the billet during forming. The heating temperature is generally determined by the material and the process needs. Hot elbow or hot elbow forming, the general use of IF or high frequency induction heating method, but also the use of flame heating method. This type of heating process is a continuous heating of the elbow or elbow forming process, the tube is heated during the movement and complete the forming process. Hot elbow, hot tee or forging forming, the general use of reflective furnace heating, flame heating, induction heating or electric furnace heating and other methods. Such heating process is to first heat the stainless steel tube to the required temperature, and then into the mold or forging forming. The welding, there are two cases, one is the use of pipe production of pipe, the use of pipe forming process and the use of seamless pipe forming process is basically the same, the pipe forming process does not include the welding process, the other is from the pipe factory To complete the pipe forming the welding process required, and then welded into the tube after the stainless steel plate tube and then pressed the tee and so on. The third step is heat treatment, this process is an important part of stainless steel pipe production. After heating, heat preservation and cooling heat treatment step, to remove forming hardening, residual stress, deformation of metal defects and so on, so that after the formation of stainless steel pipe fittings of the metal structure, performance changes, return to the pre-deformation state or to make its performance Be improved and improved. Often used heat treatment equipment is the reflection furnace, electric furnace, etc., the control method is the thermocouple inside the furnace through the sensor connected to the temperature – time automatic recorder control device. Different pipe products in the standard heat treatment requirements are not the same. Not all of the deformed pipe must be heat treated, in general, for the low-carbon steel pipe fittings the final forming temperature of not less than 723 ℃, no longer need to heat treatment, due to the temperature under the conditions of its final organization Usually normalized, below this temperature or higher than 980 ℃ to be heat treatment, alloy steel or stainless steel tube regardless of the use of cold forming or thermoforming, should be heat treatment. Routine inspection The effect of heat treatment is usually to see the hardness test situation. The fourth step is the surface treatment, the method is basically sandblasting, shot blasting, grinding, pickling, etc., so as to remove the surface rust, scratches, etc., to improve the surface smoothness, to follow-up processing, testing needs. After the shot blasting stainless steel pipe fittings, the surface hardness will be slightly increased. The fifth step is cutting, it is to complete the welding of stainless steel pipe ends, the size of the structure, shape and position tolerance process. For some pipe products, cutting and processing, including internal and external diameter of the processing. Cutting is usually done by a dedicated machine or general-purpose machine tool. For oversized pipe fittings, when existing machine tools can not meet the machining requirements, they can be finished by other processes, such as gas cutting and sanding after large-diameter elbows . Stainless steel pipe usually appearance, size inspection after cutting. The sixth step is non-destructive testing, non-destructive testing is to detect stainless steel materials and pipe processing process may produce defects in an important process. Most stainless steel pipe product standards for non-destructive testing requirements have some provisions, but the requirements are not the same. In addition to the non-destructive testing of stainless steel standards and ordering requirements, some of the more stringent quality control manufacturers also make non-destructive testing requirements based on materials, processing techniques, and internal quality controls to ensure the quality of the final product. The actual work of non-destructive testing of stainless steel pipe to determine the level of acceptance should be based on the order requirements or standards of the specific provisions. As the stainless steel pipe is usually the original surface of the original pipe, plate or forgings, stainless steel pipe surface quality of the non-destructive testing, if there is no clear grade requirements can be Ⅱ grade, for mezzanine and crack such defects are not easy to determine the depth of As unqualified. For non-destructive testing of internal quality of pipe fittings, if there is no clear grade requirement, ray inspection should be carried out in grade Ⅱ and ultrasonic inspection should be grade Ⅰ. In order to avoid the stainless steel tube during heat treatment may have a defect situation, the final non-destructive testing of stainless steel pipe fittings to be carried out after the heat treatment. The seventh step is the surface protection, the use of pickling stainless steel pipe passivation approach. The main purpose of stainless steel pipe surface protection is anti-corrosion, but also to achieve beautiful appearance of the product results. In general, the order surface protection put forward specific requirements, the manufacturer according to the requirements of the order to complete the stainless steel pipe surface protection. The last is marked on the stainless steel tube, the mark is an integral part of the product is to achieve the basis of traceability requirements. In general, the standard stainless steel pipe on the logo content and methods to do some provisions. Stainless steel pipe signs usually include the manufacturer’s trademark, name, material grade, specifications and other requirements of the order. Signs are mainly permanent signs, such as stamping, sculpture, galvanic corrosion, there are also non-permanent signs, such as jet printing, labels and so on. In addition, in addition to some of the above conventional production processes, in order to control the quality of raw materials, the production plant to complete the inspection of raw and auxiliary materials to ensure the accuracy of the use of materials to meet some special requirements, but also for example, microstructure , Intergranular corrosion, ferrite and other tests and tests to ensure that the final product quality in line with the needs of use. Source: China Pipe Fittings Manufacturer – wilsonpipeline pipe fitting Industry Co., Limited (www.wilsonpipeline.com)

We all know that when the outer surface of stainless steel pipe fitting with dirt, directly rinse dry naturally after clean with a dry cloth wipe oil leaching solvent, then the open air dry. This is relatively easy, but if the inner surface of stainless steel pipe fitting is rust or dirt? What to do again? There is rust and dirt such as the inner surface of stainless steel pipe fitting, can be the first to use circular wire brush and cloth binding in thick wire or thin steel rope, pull the brush back and forth into the pipe fitting, if the large diameter pipe fitting, can also use the winch drag brush back and forth, and then use steam or water into the washing, and then use compression air or exhaust air drying pipe fitting, then can skim the. After degreasing, first plug end of the pipe fitting blocked, 15-20% volume poured into the pipe fitting to the degreasing solvent, if the band bending of stainless steel pipe fitting, to increase the amount of degreasing solvent, then the other end is blocked, flat on the flat clean place or placed in the table on the sleeper for 1-1.5 hours, and every 15 minutes, turning once stainless steel pipe fittings, successive to need to soak parts, can also shoot long pipe fitting filled with closed immersion degreasing solvent in solvent degreasing, put the pipe fitting out with exhaust fan blowing pipe fitting, or oil-free compressed air, nitrogen dry, can also choose natural ventilation in general, we must fully dry. After degreasing, it is necessary to check whether the degreasing condition of each stainless steel pipe fitting is qualified. The inspection method is made to use absorbent gauze clean plug, tied to the wire through the needle, pull to see if there are clean, grease, also need to test if necessary. The defatted pipe fittings need to be sealed with a skimmed old cloth or plastic film to avoid re contamination of the inner surface of the stainless steel pipe fitting. When the installed stainless steel pipe fitting is skimmed, it is best to disassemble into a pipe fitting with no dead end, and then degrease. The stainless steel pipe fitting, which is not detachable after installation, must be degreased before installation, but it is necessary to ensure the installation process and not be contaminated after installation. The concentrated nitric acid pipe fittingline and equipment in the concentrated nitric acid unit can be pumped directly with 98% concentrated nitric acid after the installation of the concentrated nitric acid pipe fittingline to carry out acid pickling. But before pickling, we should do a good pickling scheme. In the acid washing, we should pide the system according to the process flow, rinse first with water and recycle the acid for 2-4 hours. Only after the analysis is qualified, the acid is guided to the other system. When the acid contains more than 0.03% organic matter, or the concentration of the acid is less than 90%, the new acid solution is changed and the waste acid is discharged to the underground trough. After the pickling is qualified, it is necessary to deliver the material in time to prevent the dilution of the concentrated nitric acid from the corrosion of the aluminum equipment and pipe fittings. Source: China Pipe Fitting Manufacturer – wilsonpipeline pipe fitting Industry Co., Limited (www.wilsonpipeline.com)