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Stainless steel refers to the resistance of air, steam, water and other corrosive medium and weak acid, alkali, salt and other corrosive medium corrosion of steel, also known as stainless acid resistant steel. In practical applications, the corrosion resistance of steel is often referred to as corrosion resistant stainless steel, and the chemical resistance of the medium corrosion of steel called acid resistant steel. Due to the difference in chemical composition of the two, the former is not necessarily resistant to chemical medium corrosion, while the latter are generally non rust. The corrosion resistance of stainless steel depends on the alloy elements contained in the steel. The basic elements of stainless steel, nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., in order to meet the needs of various applications of stainless steel structure and performance requirements. Stainless steel is easy to chloride corrosion, because chromium nickel chloride is collocated elements, elements will be collocated to form stainless steel corrosion exchange assimilation. Stainless steel pipe rust, may have the following reasons: 1, the use of chloride ions in the environment There is a wide range of chloride ions, such as salt / sweat / sea / sea breeze / soil, etc.. Stainless steel pipe in the presence of chloride ion environment, corrosion quickly, even more than ordinary low carbon steel. Therefore, the use of stainless steel pipe has the requirements of the environment, but also the need for regular cleaning, remove dust, clean and dry. This will give him a “improper use” The United States is an example: an enterprise solution with a container containing a chlorine ion of the oak, the container has been used for nearly 100 years, the 90s plan of last century replacement, due to insufficient material using modern oak, leakage due to corrosion of stainless steel container for 16 days after the replacement. 2, no solid solution treatment The alloying elements did not dissolve into the matrix, resulting in low alloy content and poor corrosion resistance. 3, inherent intergranular corrosion This kind of material without titanium and niobium has the tendency of intergranular corrosion. The addition of titanium and niobium can be reduced to intergranular corrosion. From the point of view of metallography, a thin chromium film is formed on the surface of the stainless steel tube containing chromium, which is separated from the oxygen in the steel from corrosion. In order to maintain the corrosion resistance of stainless steel pipe, steel must contain more than 12% chromium. Used for welding occasion, low carbon content makes precipitation near the weld heat affected zone of carbide minimized, and carbide precipitation may lead to intergranular corrosion of stainless steel pipe in some environments (weldingerosion). Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In the production and processing of stainless steel flanges, no matter what kind of processing methods will be used in some defects, although the defects can not be 100% to eliminate points, but as long as carefully grasp the method, or as much as possible to avoid these defects. The following is a brief introduction. 1, weld defects: stainless steel flange weld defects are more serious, if it is to use manual mechanical polishing method to make up, then produce grinding marks, resulting in uneven surface, will affect the appearance; 2, polished and passivated passivation uneven: hand-polished after pickling passivation treatment, the larger area of the workpiece, it is difficult to achieve uniform uniform treatment effect, can not be ideal for uniform surface. There are shortcomings of its working hours costs, accessories are also higher costs; 3, scratches difficult to remove: the overall pickling passivation, corrosion of the media in the presence of chemical corrosion or electrochemical corrosion and rust, can not be removed due to scratches, welding splash and adhere to the stainless steel surface of carbon steel , Splash and other impurities; So how to solve the problem of stainless steel flange processing? 1, choose blanking, after the completion of the next process, stainless steel different parts according to the processing requirements into the corresponding process; 2, the first time to bend according to the size of the drawings, stainless steel thickness to determine the use of bending when the knife and knife slot, to avoid collision with the product caused by deformation of the mold is the key to the selection (in the same product, may Will use different models of the model), the choice of the next model according to the thickness of the plate to determine; 3, in order to weld firmly, in the workpiece to be bumped on the bump, you can make the bumps in the welding before welding with the flat uniform contact to ensure that the same point of heating, but also to determine the welding position, the need for welding, Good preload time, holding time, maintenance time, rest time, to ensure that the workpiece can be spot welding solid. Source: China Flange Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

① Nominal size and actual size A, nominal size of steel pipe: is the standard size specified in the standard, the user and the manufacturer want to get the desired size, but also the contract specified in the size of the order. B, the actual size: the actual size of the production process, the size is often greater than or less than the nominal size. This phenomenon is greater or less than the nominal size of the phenomenon known as the deviation. ② deviation and tolerance A, Deviation: In the production process, because the actual size is difficult to achieve nominal size requirements, that is often greater than or less than the nominal size, so the standard specifies the actual size and nominal size allows a difference between. The difference is positive for the positive deviation, the difference is negative for the negative deviation. B, tolerance: the provisions of the standard positive and negative values of the sum of the absolute value is called tolerance, also known as “tolerance zone.” The deviation is directional, that is, “positive” or “negative”; tolerance is no direction, therefore, the deviation of the value of “positive tolerance” or “negative tolerance” is wrong. ③ delivery length Delivery length, also known as the length of the user requirements or contract length. There are several rules for the length of the delivery: A, usually length (also known as non-length length): Where the length of the standard length of the provisions of the length and no fixed length requirements, are called the usual length. For example, the structure of the pipe standard: hot (extrusion, expansion) steel pipe 3000mm ~ 12000mm; cold drawn (rolled) steel pipe 2000mmm ~ 10500mm. B, length of length: length should be in the normal length of the length of the contract is required in a fixed length size. But the actual operation are cut out the absolute length of the length is not possible, so the standard length of the length of the provisions of the allowable positive deviation. The structural pipe standard is: Production length of the length of the tube than the average length of the pipe into the rate of decline is greater, the production enterprises to raise the price requirements are reasonable. Increase the rate of the enterprise is not consistent, generally based on the base price increase of about 10%. C, the length of the length: the length of the length should be within the normal length range, the contract should be marked with a single length and the length of the total length of the composition (for example, 3000mm × 3, that is, 3000mm 3 times the total length of 9000mm). In practice, should be based on the total length of the allowable positive deviation of 20mm, plus the length of each monogon should stay incision margin. To structural tube, for example, the provisions of the incision margin: diameter ≤ 159mm for the 5 ~ 10mm; diameter> 159mm for 10 ~ 15mm. If there is no deviation in the length of the standard deviation and cutting allowance, the supply and demand sides should be negotiated and specified in the contract. Times the length of the same length with the length of the production will bring a significant reduction in production rate, so the production enterprises to raise the price is reasonable, the increase in the rate of increase with the length of the same length of the same. D, the length of the range: the length of the range in the normal length range, when the user requires a fixed range of length, the need to specify in the contract. For example: usually length of 3000 ~ 12000mm, and the length of the length of 6000 ~ 8000mm or 8000 ~ 10000mm. It can be seen that the length of the length is longer than the length and length of the length, but it is much more severe than the usual length, and the production rate is reduced. Therefore, the production enterprises to raise the price is justified, the increase in the price increase in the base price of about 4%. ④ uneven wall thickness Steel pipe wall thickness can not be the same everywhere, in its cross-section and longitudinal pipe body on the objective of the existence of wall thickness, that is, uneven wall thickness. In order to control this non-uniformity, in some steel pipe standards in the provisions of the wall thickness of the allowable indicators, the general provisions of not more than 80% of wall thickness tolerance (after consultation between the supply and demand sides). ⑤ ellipticity In the cross section of the circular steel pipe there is a phenomenon in which the outer diameter is not equal, that is, there is not necessarily perpendicular to each other, the maximum outer diameter and the minimum outer diameter, the difference between the maximum outer diameter and the minimum outer diameter is ellipticity Roundness). In order to control the ellipticity, some steel pipe standard provides the allowable index of ellipticity, the general provisions of not more than 80% of the outer diameter tolerance (after consultation between the supply and demand sides). ⑥ curvature The steel pipe is curved in the length direction, and the curve is expressed by the number of curvature. The curvature specified in the standard is generally pided into the following two types: A, local bending degree: with a meter long ruler by the maximum bending in the steel pipe, measured the chord height (mm), that is, local bending value, the unit is mm / m, that method such as 2.5mm / m The This method also applies to the bending of the pipe end. B, the total length of the total curvature: with a string, from the tube at both ends of tension, measuring the maximum bending height of steel pipe (mm), and then converted into length (in meters) percentage, The length of the curvature. For example: steel pipe length of 8m, measured the maximum string height 30mm, then the tube full length of curvature should be: 0.03 ÷ 8 m x 100% = 0.375% ⑦ size tolerance Size tolerance or size of the standard deviation beyond the standard. Here the “size” mainly refers to the outer diameter of the steel pipe and wall thickness. Often it is called the size of the tolerance is called “tolerance outrageous”, this deviation and tolerance is equivalent to the name is not tight, should be called “deviation”. The deviation here may be “positive”, it may be “negative”, rarely in the same batch of steel pipe in the “positive, negative” deviation are out of the phenomenon. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

1. Overview Angle bar is a kind of carbon structural steel used in construction, which is a simple section steel. It is required to have good weldability, plastic deformation and mechanical strength. The raw material for the production of angle bar billet is low carbon steel billet, finished angle bar for hot rolling, normalizing or hot-rolled state delivery. 2. types and specifications It can be pided into two types: equilateral angle bar and non equilateral angle bar, of which the unequal angle bar can be pided into unequal thickness and unequal thickness of the same kind of two kinds. The specification of angle bar with the length and thickness of the edge. At present, the domestic steel specifications for 2 – 20 cm, to length number number, the same horn steel often have 2 – 7 different edge thickness. The imported angle bar shall be marked on both sides of the actual size and thickness and indicate the relevant standards. Generally more than 12.5cm side of the large angle, 12.5cm – 5cm between the medium angle, the side length of 5cm for the small angle. Inlet and outlet angle bar orders to use commonly required in the specification, the steel is carbon steel steel corresponding. That is, in addition to the specifications of the angle, there is no specific composition and performance series. The length of the angle of the length of the fixed length, two times the size of the domestic angle of the fixed length of the choice of different sizes according to the specifications of the different – 9m, 4 – 12M, – 19m, 6 – 19m range of four -. The length of Japanese steel angle is 6 – 15m. The cross section of unequal angle bar is calculated by the long side width of unequal angle bar. 3. import and export situation China’s imports and exports have a certain amount of angle, mainly from Japan, Western Europe imports. Exports to the region mainly for Hong Kong, Macao, Southeast Asia, Latin America and Arabia countries. Export production enterprises mainly in Liaoning, Hebei, Beijing, Shanghai, Tianjin and other provinces and cities of the iron and steel plant (rolling mill). Most of the imported angle bars are large and small angle bar and special shape angle bar, and most of them are medium angle bar, such as No. 6 and No. 7. 4. appearance quality requirements The surface quality of the angle bar is stipulated in the standard, and the general requirements for the use of harmful defects such as delamination, scarring, cracks, etc.. The allowable range of the geometric deviation of angle bar is also stipulated in the standard, including the bending degree, the width, the thickness, the vertex angle, the theoretical weight and so on. 5. chemical composition test (1) composition index: the chemical composition of angle bar is a series of rolled steel series for general structure, and the main indexes are C, Mn, P, S and four. According to the different grades, the content of each difference, the approximate range of C 0.22%, Mn:0.30 – 0.65%, P < 0.060%, S < 0.060%. (2) test method: detection of the chemical composition, test methods commonly used standard GB223, JISG1211, BS1837, BS – 1215, 19 F C, manual is 22536. 6. commonly used products, specifications and standards GB/T2101 – 89 (General requirements of steel acceptance, packing, marking and quality certification); GB9787 – 88/GB9788 – 88 (hot rolled / unequal angle size, shape, weight and tolerances); JISG3192 94 (shape, size, and weight of hot rolled steel tolerance; DIN17100 – 80 (mass) standard steel structure; it is common), 535 – 88 f (technical conditions of ordinary carbon steel). According to the standard requirements, the angle should be a bundle of delivery, the bundle passes, bundle length should be specified. Angle is generally a bare delivery, transportation and storage should pay attention to moisture. 7. mechanical properties test (1) inspection methods: Tensile test method. Method for inspection of commonly used standard GB/T228-87, JISZ2201, JISZ2241, ASTMA370, BS18, C, f is 1497 and DIN50145; bending test method. Method for inspection of commonly used standard GB/T232-88, JISZ2204, JISZ2248, ASTME290, F, C and DIN50111 is 14019. (2) performance indicators: the inspection of the performance of the angle of the main tensile test and bending test. The indexes include yield point, tensile strength, elongation and bending compliance. Source: China Angle Bar Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Duplex stainless steel with its excellent corrosion resistance, high strength and easy processing and other excellent performance, in many areas to replace austenitic stainless steel, the market prospect is very broad. The annual output of duplex stainless steel in the world is only about 1% of the total output of stainless steel. Since 1990, the annual growth rate of duplex stainless steel is close to 17%, the annual output increased from 24,000 tons in 1990 to 11 million tons in 1999. Its products are distributed as hot-rolled plates (71% of the total output) for the manufacture of duplex stainless steel tubes (6% of the duplex stainless steel) containers; cold rolled plates accounted for 14%, duplex stainless steel seamless pipe accounted for 8%. Modern duplex stainless steel in the low-grade duplex stainless steel (2304 type), is a low alloyed duplex stainless steel. It has excellent mechanical and physical properties, excellent resistance to stress corrosion cracking and other forms of corrosion performance and good weldability, can replace the standard Austrian stainless steel 304/306; standard duplex stainless steel (2205 type), is a medium alloy The duplex duplex stainless steel. Due to the excellent corrosion resistance, suitable for the production of chloride and hydrogen sulfide media under the conditions of the equipment, especially suitable for use with chloride water or brackish water to do the cooling medium heat exchanger, also applies to dilute sulfuric acid solution and storage Equipment for organic acids. At the same time, 2205 duplex stainless steel due to its high strength in the heavy load of structural applications become austenitic stainless steel ideal alternative material. Due to the good mechanical properties and corrosion resistance of 2005 duplex stainless steel, the service life of the equipment can be reduced. Therefore, in many applications, 2205 stainless steel is an economical choice. At present, it is the main force of duplex stainless steel series, accounting for 80% of the world’s total output of duplex stainless steel; super duplex stainless steel (2507 type), widely used in harsh corrosive environment, the market share of about 13%. Duplex stainless steel is widely used in various fields for its unique advantages: pulp and paper industry: pulp and paper industry is the first use of duplex stainless steel processing industry. Sulfuric acid and sulfuric acid cookers made of 304 and 316 austenitic stainless steels are often scrapped by stress corrosion cracking and sometimes live for just two months. At the same time, with low-carbon steel cooking pot, the wall thickness of up to 43mm, making the total weight of the steamer is high. And the use of duplex stainless steel, that is, corrosion resistance, high strength, wall thickness also reduced a lot. Since 1998, abroad in the pulp and paper factory with duplex stainless steel containers more and more, greatly enhance the service life, the effect is very good. Chemical processing industry: chemical processing industry is involved in a very wide range of conditions are more complex. Preservation of industrial wet-process phosphoric acid storage tanks, usually 316L or 317L Austenitic stainless steel to manufacture, but the wall is very thick. Using duplex stainless steel 2205, the strength is almost higher than the 316L and 317L times, and can reduce the wall thickness, thereby reducing the important and cost of the tank. At the same time, in the industrial sulfuric acid environment, especially in the presence of chloride ions in the case, 2205 resistance to local corrosion better than the austenitic stainless steel. Food and beverage industry: Food and beverage industry production is generally processed in hot solutions containing chloride ions. Duplex stainless steel has a unique advantage in resistance to stress corrosion cracking. Therefore, depending on the use of different environments, can choose different duplex stainless steel, but the total cost of austenitic stainless steel than the dominant. Which SAF2304 the most cheap. At present, some foreign sugar mills, breweries and other equipment used in duplex stainless steel. Transportation: Due to the high strength and excellent corrosion resistance of duplex stainless steel, it has a great advantage when used in the production of chemical tankers. Reducing the importance of the ship, reducing the consumption of fuel, in this regard, the use of the most is 22% chromium duplex stainless steel. At the same time to meet the needs of the goods contained in the corrosion resistance of materials. Construction: In the coastal areas, the air is filled with gas (sea atmosphere) evaporated from sea water. The concentration of chloride in this oceanic atmosphere is much higher than that of inland air, and therefore requires a “seawater” material. The corrosion resistance of duplex stainless steel is with this advantage, while its high strength can also reduce the weight. At present, there are many offshore oil platforms are used duplex stainless steel to create explosion-proof walls. Some of the foreign bridge, the floor of the building also uses a duplex stainless steel. Petrochemical industry: petrochemical and chemical industry Corrosive environment is characterized by high reaction temperature, the medium often contains high concentration or medium concentration of chloride, easy to induce stress corrosion cracking of stainless steel. Therefore, this area requires not only duplex stainless steel, but also more use of super duplex stainless steel. Refining industry is the use of duplex stainless steel one of the more areas, mainly used in atmospheric and vacuum distillation, catalytic cracking hydrodesulfurization and other devices, both at home and abroad have used. In addition, duplex stainless steel in acid gas and oil production in the amount of gradually increased, mainly for the production of pipe lining, shore and offshore piping systems and heat exchangers. In addition, duplex stainless steel has also been successfully used in wastewater treatment heat exchangers, hot water pipes, water heaters. At present, China has developed five kinds of duplex stainless steel, are the second generation of steel, only 0Cr18Ni5Mo3Si2 steel into the international and mass production, the other by the standard production, production is not. According to the development level of China’s duplex stainless steel and the production conditions and technical level of special steel mills, some domestic duplex stainless steel can replace imports, such as involving large and medium-sized chemical fertilizer plant technological transformation, new, expansion of the required ammonia pump Materials can be made of domestic duplex stainless steel instead of imports of 316L, 329 steel, to achieve the ammonium pump pump material replacement and localization. TISCO, Pu Gang is the main domestic production of duplex stainless steel business. Three Gorges project used in the 2205 duplex stainless steel is TISCO and other enterprises. However, the duplex stainless steel market still needs a large number of imported foreign products. Such as duplex stainless steel applications of the most areas – the chemical industry, most of the equipment is imported, the equipment used in the duplex stainless steel also introduced. At present, some special equipment in the thinner duplex stainless steel can be produced in China, and thicker duplex stainless steel still need to import. The main use of duplex stainless steel has the following aspects: Neutral chloride environment Refining industry Often decompression device Catalytic cracking unit Hydrocracking, hydrotreating unit Petrochemical and chemical industries PVC (PVC) stripping tower and heat exchanger Vinyl chloride production plant Methanol synthesis reactor Carbonyl alcohol synthesis reactor Acetic acid and other organic acid production equipment Chemical industry pipelines Oil and gas industry Pulp and paper industry Continuous sulfuric acid cooking device Intermittent digester Chlorine dioxide bleach cartridge Paper pressure roller machine Fertilizer industry Urea industry Phosphate fertilizer industry Seawater environment Energy and environmental protection industry Light industry and food industry Salt chemical plant Food and pharmaceutical industry equipment High strength structural parts Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The reliability of several non-destructive testing methods, such as magnetic flux leakage, eddy current, ultrasonic and electromagnetic ultrasonic, is discussed. By comparing the reliability of the above methods, it can be seen that the electromagnetic ultrasonic method has the advantages of other non-destructive testing methods. And broad application prospects. 1. Introduction Steel is the most widely used steel variety. Its quality directly affects the economic benefits and the safety of personnel. Countries around the world have paid great attention to the quality of steel pipe inspection, using a variety of non-destructive testing (NDT) method of steel pipe for a rigorous testing. For example, Mannesmann of Germany and Sumitomo Metals of Japan have adopted the field (UT) and magnetic flux leakage (MFL) methods in the detection of large diameter steel tubes. The detection of small diameter steel tubes by means of overtravel and eddy current (ET) A more mature detection program. China’s steel pipe inspection using a large number of ultrasonic and eddy current methods, more and more use of magnetic flux leakage method. However, due to the natural defects in the production of steel pipe produced by NDT method can not detect the phenomenon. Therefore, how to improve the NDT detection reliability, it becomes an increasingly urgent issue. In this paper, combined with some defects in the detection of natural defects in steel pipe inspection, in-depth analysis of the principle and the performance of the testing equipment provides a reference for the development of the best detection scheme. 2. MFL (MagneticFluxLeakage) method reliability MFL because of its surface condition on the pipe is not high, the detection depth is also large, in the foreign steel pipe detection in a large number of domestic and more and more use, especially in the steel pipe inspection has been widely used The United States manufactured by Tubescope MFL flaw detection equipment. In the use of MFL, due to management and technical reasons, there have been some missed problems. One of them is a defect that is at an angle of 45 degrees to the tube axis. Such as the MFL device in the longitudinal probe and horizontal probe at the same time, may reduce the missed rate, otherwise it is difficult to ensure reliable detection of such inclinations. Another important factor influencing the reliability in the MFL method is the angle between the natural defect and the tube surface. Theoretical calculations and experimental studies have shown that when the orientation of the artificial groove along the wall thickness direction is 30 degrees from the outer surface of the tube, it is impossible to detect the defects parallel to the surface, such as delamination defects, by MFL. Some, such as steel pipe in the process of forming a larger deformation, and sometimes the natural defects will be rolled. At this time, the defect generated by the magnetic flux leakage is very small, resulting in difficult to use MFL method out. In the production of detection, there have been used MFL method can not detect the phenomenon of large holes in the pipe through the wall. Aside management and personnel factors, the technology should also be into the sub-board and to guard against. For the MFL method can detect the surface of the deep defects, there has been no clear conclusion. This is related to instrument and probe performance and defect size and so on. 3. ET (EddyCurrentTesting) method of reliability Due to the high detection speed, the through-coil ET method has been widely used for testing the quality of steel tubes over the years, especially its compactness. In use, it is difficult to detect cracks in the ferromagnetic steel pipe defects, so in the high standard ET, the use of probe coil ET method. In addition, for the ET method can be pulled out of the surface of the deep lack of such a simple question, it seems that has not yet formed a clear consensus. For the steel pipe often produce “outside the fold” class defects, many eddy current instruments and probes are often found. Often appear outside the eye is clearly visible, but can not use the instrument with the alarm of the embarrassing phenomenon. This has been fundamentally changed since the vortex device with sector-type phase alarms has emerged. But choosing the right instrument and probe and adjusting it properly is still an important issue that can not be ignored 4. UT (UltrasonicTesting) method of reliability UT method in the steel pipe inspection and thickness measurement in the most widely used. However, as a detection method, its reliability is affected by various factors. Such as the analysis of the study is not enough, or even a serious missed, false positive phenomenon. Here are just a few of the possible factors that may exist in UT to reduce the reliability of UT. (1) the effect of natural defect orientation on UT reliability In the steel pipe rolling process, the occurrence of high frequency is the axial (longitudinal) defects. However, with the steel pipe axis is an extension of the angle of the defect is not uncommon. Vertical (transverse) defects perpendicular to the tube axis also occur from time to time. NDT’s task is to these different orientations of the defects are stuck out. Similarly, in order to reliably detect the folding defects with the steel pipe surface, two sets of probes which are incident in the opposite direction of the tube circumference must be provided. (2) the impact of acoustic coupling on UT reliability Water intrusion UT, the sound waves in the wall of the attenuation is very serious. Because the acoustic characteristic impedance of the water is much smaller than that of the steel, the reciprocating transmittance of the sound wave from the water to the water from the steel to the water is very small. Second, the sound waves in the wall of each reflection are accompanied by wave conversion. And the transverse wave to the water transmission when it is completely absorbed by the water, it is significantly increased water intrusion UT ultrasonic attenuation. This leads to the propagation of ultrasound along the wall is very small, even a quarter of a week can not reach. The calculated value T (LS) of the reciprocating transmittance of the sound pressure of the steel pipe is measured by the oblique contact method of the plexiglass wedge when the transverse wave refraction angle is 45 degrees without considering the wave mode conversion during the acoustic propagation process, About equal to 25%. And T (LS) is about 15% when immersed in water on the outside of the pipe and the inside is still air. The The latter 4dB lower than the former. If the bore of the pipe is also filled with water (for example, water is immersed in the hole from the hole), the defect echo signal is reduced by at least 6 dB compared to the contact method or the water film method. If the defective echo signal is not strong due to the influence of unfavorable factors such as defect shape or orientation, the defect is likely to be missed. A better solution to this problem is to water film method instead of immersion method for coupling. 5. Electromagnetic Magnetic EMAT (ElectronmagneticAcousticTransducer) Flaw Detection Technology In order to solve the various difficulties brought by the acoustic coupling to the UT, there was an electromagnetic ultrasonic transducer (EMAT) that did not need the acoustic coupling in the 20th century to stimulate and receive the sound waves in the metal. After 30 years of research, Development, now has entered the engineering, commercialization stage. The United States, Germany, Russia, Japan and other countries have been selling goods and equipment. I began from the early 70s MEAT research and development, at present, the development of EMAT equipment has a number of domestic steel pipe, steel production and use of units should be successful. EMAT is produced by three ways to produce Lorentz force, magnetostrictive force and magnetic force to stimulate and receive ultrasound, directly in the metal to stimulate and receive ultrasound, no acoustic coupling, so the rough surface of the workpiece and high temperature, high speed Motion of the workpiece for ultrasonic testing. It can easily select the desired ultrasonic mode, in particular, can be very simply excited with the receiving SH-wave, which is difficult to do in piezoelectric ultrasonic transducers. It is excited in the steel tube of the ultrasound, can spread around the workpiece for several weeks or even a dozen hit, which is used to detect the defect by the wave size to lay a good foundation. As mentioned earlier, if the defect is not completely perpendicular to the sound beam in the UT, the reflected wave is greatly reduced if it is more than 10 degrees. Skewed 45 degrees defects will be missed. 6. MEL, ET, UT and EMAT method reliability comparison MEL, ET, UT and EMAT methods were compared with a large number of natural defects. The measurement of the depth of defects of each method is calibrated with various artificial standard defects of a given depth. And then scan these natural defects. When the depth of the defect is large, the dispersion of the measurement result is the smallest, but when the depth of the defect is 2mm, the dispersion is quite large. The MFL and ET method of the greater dispersion, measured in many parts of the depth of 0, can not detect. this might be. As a result of the defects in the site was rolled. EMAT does not have this missed test, in our EMAT equipment also confirmed the use of this advantage, regardless of artificial defects or natural defects, EMAT equipment has a high detection rate. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

According to the requirements of different manufacturers, the length of steel pipe measurement methods, mainly in the following categories: 1, grating length measurementa The basic principle is: the steel pipe at both ends of the outer side were set up two fixed-length grating, the use of rodless cylinder driven grating near the ends of the pipe, the use of light interference to achieve the length of the measurement of steel pipe. Characterized by high accuracy. But the grating is expensive and difficult to maintain, the dust and the impact of vibration is very sensitive. 2, the camera length measurement. Camera length measurement is the use of image processing to achieve the length of steel pipe measurement, the principle is in the steel conveyor roller on a section of the installation of equidistant range of photoelectric switch, in another section plus light source and camera. When the steel pipe through this area, you can according to a photoelectric switch through the camera to capture the image on the screen position to determine the length of the pipe. Features can be achieved on-line measurement, the length of the pipe through the length of the area can be obtained when the length of data, no interval. Inadequate is: If you do not use special light source, the steel pipe will be subject to external light interference, and the use of special light source after the steel pipe in the inverted edge of the tube after the high brightness and reflection of the light is very strong, likely to cause reading error. 3, the encoder length measurement The principle is to install the encoder at the cylinder, the use of cylinder to promote the movement of the steel pipe in the roller, on the other side of the installation of a series of equidistant photoelectric switch, when the pipe is pushed by the cylinder tube to the photoelectric switch, from the recorded encoder reading , Calculate the stroke of the cylinder, so you can calculate the length of the pipe. The characteristic is that the pipe needs to rise when the length is measured. In addition, the photoelectric switch detection there are some errors, may need to be fully measured. 4, improved encoder length measurement This method is an indirect measurement method, by measuring the two ends of the steel pipe and the distance between the respective reference points, indirectly measured the length of steel pipe. In the steel pipe at both ends of the set of a trolley car, the initial position of zero, the spacing of L. And then move the editor length to the respective pipe end of the walking distance (L2, L3), L-L2-L3, is the length of the steel pipe. This measurement method to overcome the huge volume of steel, the production site environment is complex, the measurement mechanism can not cross the lower part of the steel pipe support and other difficulties. This method is easy to operate, measuring accuracy within ± 10mm, repeat the accuracy of ≤ 5mm. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Austenitic stainless steel in acetic acid usually have good corrosion resistant force, but cannot be used in martensite and ferrite stainless steel containing acetic acid, in most cases the austenitic stainless steel is completely at room temperature for hangzhou all the concentration of acetic acid corrosion. At higher temperatures, 316L stainless steel, 317L stainless steel is more resistant to acid corrosion than other austenitic stainless steel. 304 stainless steel and 347 stainless steel are used for equipment such as acetators, pipes, pumps, valves, etc., but the fractionating tower material is the best use of 316L stainless steel, which is also used for cold treatment of glacial acetic acid. No stainless steel can adWP Clean Upapt to the corrosion of ice acetic acid at the boiling temperature and the temperature of the superheated steam. The reductant, such as the formic acid, occurs in the form of impurities in acetic acid, causing further corrosion of stainless steel, especially in high temperature. On these occasions, the use of molybdenum stainless steel is the most widely used. The presence of ionized halogens in acetic acid is also harmful. The formic acid is a good reducing agent, and it is very serious at any temperature against martensitic and ferrite stainless steel. At room temperature, any austenitic stainless steel container can safely store the formic acid. At higher temperatures usually need to use 316 stainless steel and 316l stainless steel, these two kinds of stainless steel has been used for fast curing device and a separate formic acid distillation unit or formic acid distillation unit of mixed with other organic substances. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Austenitic stainless steel on weak base, such as hydroxide and organic compounds such as ammonia, which the organism and aliphatic amine aniline with excellent corrosion resistance, 304 stainless steel can be used in the ammonia distillation apparatus and some types of amination reaction. By sodium hydroxide solution corrosion test, the stainless steel in the performance of alkali solution, 302 and 304 stainless steel in concentration below 50% NaOH solution, under the temperature 104 ℃, generally only mild corrosion. At higher temperatures and concentrations, erosion tends to be severe. Under various stress effects, the corrosion cracking of the stress can occur in the solution of the hot hydroxide solution or the potassium nitrogen oxide solution. When a hot metal surface is eroded by a dilute solution, it can also be corroded by the vaporization of hydroxide. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Martensitic and ferrite stainless steel in lactic acid are usually very poor, and austenitic stainless steel is widely used in the food industry and dairy industry. 18-8 steel can be used for the processing work, 304 steel under 38 ℃ for storage of lactic acid is the best. Concentrated hot lactic acid solution may cause serious corrosion of non-molybdenum austenitic stainless steel, so 316L stainless steel and 317L stainless steel are the most suitable materials at high temperatures. In the treatment of the organic acids such as oxalic acid, carbonic acid, citric acid, naphthenic acid, tartaric acid, oleic acid, stearic acid, palmitic acid, benzene dicarboxylic acid and malic acid and handling these acid mixture of austenitic stainless steel is the most commonly used. Generally speaking, 302 and 304 steel are suitable for use at room temperature and are used as storage and processing equipment for these acids. At higher temperatures austenitic stainless steel is durable in such as citric acid and oleic acid, and in some acids, such as malic acid and naphthenic acid, require the use of molybdenum steel 316L or 317L. They are used to make oil and acid distillers and malic acid and benzoate evaporator. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Austenitic stainless steel on weak base, such as hydroxide and organic compounds such as ammonia, which the organism and aliphatic amine aniline with excellent corrosion resistance, 304 stainless steel can be used in the ammonia distillation apparatus and some types of amination reaction. By sodium hydroxide solution corrosion test, the stainless steel in the performance of alkali solution, 302 and 304 stainless steel in concentration below 50% NaOH solution, under the temperature 104 ℃, generally only mild corrosion. At higher temperatures and concentrations, erosion tends to be severe. Under various stress effects, the corrosion cracking of the stress can occur in the solution of the hot hydroxide solution or the potassium nitrogen oxide solution. When a hot metal surface is eroded by a dilute solution, it can also be corroded by the vaporization of hydroxide. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Surface finishing grades, characteristics and uses ​ Original surface: NO.1 after hot rolling with heat treatment and acid treatment of the surface. Generally used in cold rolling materials, industrial tanks, chemical equipment, etc., the thickness is thicker than 2.0MM-8.0MM. Blunt surface: NO.2D cold rolling, after heat treatment and pickling, the material is soft, the surface of silver white luster, used for deep stamping processing, such as automotive components, pipes and so on. Fog: NO.2B after cold rolling by heat treatment and pickling, and then finishing processing to make the surface of moderate brightness. As the surface is smooth, easy to re grinding, make the surface more bright, wide range of uses, such as tableware, building materials, etc.. Surface treatment with improved mechanical properties almost meets all uses. Coarse sand NO.3 products made from abrasive No. 100-120. Having better gloss; having discontinuous coarse lines. Used for building interior and exterior decoration materials, electrical appliances and kitchen equipment, etc.. Fine sand: NO.4 abrasive products with abrasive grit No. 150-180. Having better gloss, discontinuous coarse lines, and thinner stripes than NO.3. It is used for bath, building interior and exterior decoration materials, electrical appliances, kitchen equipment and food equipment, etc.. #320 grinding products with No. 320 abrasive belt. Having better gloss, discontinuous coarse lines, and thinner stripes than NO.4. It is used for bath, building interior and exterior decoration materials, electrical appliances, kitchen equipment and food equipment, etc.. Continuous grinding surface by NO.4 HAIRLINE:HL filament proper size generating grinding polishing abrasive pattern of the products (subpision No. 150-320). Mainly used for building decoration, elevators, building doors, panels and so on. Bright surface: BA after cold rolling, with bright annealing, and after the smooth products. Excellent surface gloss and high reflectivity. Like the surface of a mirror. For household electrical appliances, mirrors, kitchen equipment, decorative materials, etc.. Product characteristics and Applications SUS304: has good corrosion resistance, heat resistance, low temperature strength and mechanical properties, stamping, bending and other hot workability, no heat treatment hardening phenomenon, no magnetism. Widely used in household appliances (1, 2 types of tableware), cabinets, indoor pipelines, water heaters, boilers, bathtubs, auto parts, medical equipment, building materials, chemicals, food industry, agriculture, marine components. SUS304L: the basic austenitic steel, the most widely used; corrosion resistance and excellent heat resistance; low temperature strength and excellent mechanical properties; single phase austenite non hardening heat treatment (non magnetic, temperature -196–800 C). SUS304Cu: using 17Cr-7Ni-2Cu as the basic composition of austenitic stainless steel; excellent formability, especially drawing and anti aging crack and good corrosion resistance; – the same as 304. SUS316: corrosion resistance and high temperature strength is particularly good, can be used in harsh conditions, work hardening good, without magnetism. Suitable for marine equipment, chemicals, dyes, paper making, oxalic acid, fertilizer production equipment, photography, food industry, coastal facilities SUS316L: Mo (2-3%) is added in steel, so the corrosion resistance and high temperature strength are good; SUS316L carbon content is lower than SUS316; therefore, intergranular corrosion resistance is better than SUS316; high temperature creep strength is high. Can be used in harsh conditions, work hardening good, without magnetism. Suitable for marine equipment, chemicals, dyes, paper making, oxalic acid, fertilizer production equipment, photography, food industry, coastal facilities SUS321: Ti is added to 304 steel, so it has good intergranular corrosion resistance, high temperature strength and high temperature resistance to oxygen, high cost and poor processability than SUS304. Heat resistant materials, automobiles, aircraft exhaust pipes, boilers, furnace covers, pipes, chemical installations, heat exchangers SUH409H: good processability, good weldability, good oxidation resistance at high temperature, able to withstand the temperature range from room temperature to 575 degrees. Widely used in automobile exhaust gas exhaust system. SUS409L: control C and N content in steel, the weldability, forming excellent resistance and corrosion resistance; with 11%Cr, high temperature and normal temperature with a structure of BCC ferritic stainless steel; due to fill in the Ti, 750 DEG C air oxidation and corrosion resistance. SUS410: martensite represents steel, high strength, high hardness (magnetic), poor corrosion resistance, not suitable for severe corrosive environment, low C content, good processability, surface hardening by heat treatment. SUS420J2: martensite represents steel, high strength, high hardness (magnetic), poor corrosion resistance, poor processing, good wear resistance, heat treatment, mechanical performance improvement. Widely used in cutting tools, nozzles, valves, plates, rulers, tableware. SUS430: low thermal expansion rate, molding and oxidation resistance, suitable for heat resistant appliances, burners, household appliances, 2 types of tableware, kitchen sink. Low price and good processability are ideal alternatives to SUS304. They are good against mile corrosion, and are typically non heat treated hardened ferritic stainless steels. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)