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Production process of seamless steel pipe The production process of the general seamless steel pipe can be pided into two kinds of cold drawing and hot rolling. The production process of cold rolled seamless steel tube is generally more complicated than hot rolling. The tube billet must be three rolls in continuous rolling. After the extrusion, the diameter of the pipe must be tested. If the surface has no response to the crack, the pipe must be cut through the cutting machine and the cutting growth is about one meter. The blank. Then enter the annealing process, annealing to use acid liquid for acid washing, acid washing should pay attention to the surface is a large number of bubbles, if there is a large number of bubbles, the quality of the steel pipe can not reach the standard of response. The appearance of the cold rolled seamless steel tube is shorter than the hot rolled seamless steel pipe, the wall thickness of the cold rolled seamless steel tube is generally smaller than the hot rolled seamless steel pipe, but the surface looks brighter than the thick wall seamless steel tube, the surface is not too rough, and the diameter is not too much burr. The delivery status of hot-rolled seamless steel tubes is generally delivered after hot rolling. After quality inspection, the hot rolled seamless steel tube must be carefully selected by the staff after quality inspection. After the quality inspection, the surface oil should be applied to the surface. Then the cold drawing experiment is followed by many experiments. After hot rolling, the experiment of perforation should be carried out. If the perforated expansion is too large, straightening and correction will be needed. After straightening, the transmission device is then transmitted to the flaw detecting machine to carry out the flaw detection experiment. Finally, the label is attached and the specification is arranged to be placed in the warehouse. Hot rolling (extruded seamless steel pipe) Pipe billet, heating, perforation, three roll skew rolling, continuous rolling or extrusion, depipe, diameter (or reducing diameter), cooling, straightening, water pressure test (or flaw detection), mark to warehouse seamless steel pipe is made of steel ingot or solid pipe through perforation, and then hot rolled, cold rolled or cold dialed. The specification of seamless steel pipe is expressed by outer diameter * millimeter of wall thickness. Two types of seamless steel tubes are pided into hot-rolled and cold rolled (seamless) steel tubes. The hot rolled seamless steel tubes are pided into steel tubes, low and medium pressure boiler tubes, high pressure boiler tubes, alloy tubes, stainless steel pipes, oil cracking pipes, geological pipes and other steel pipes. The cold rolled (dialing) seamless steel tubes are pided into ordinary steel tubes, low medium pressure boiler tubes, high pressure boiler tubes, alloy steel tubes, stainless steel pipes, oil cracking tubes and other steel pipes, including carbon thin-walled steel tubes, alloy thin-walled steel tubes, stainless steel tubes and special-shaped steel tubes. The outer diameter of hot rolled seamless tube is generally greater than 32mm, the wall thickness is 2.5-200mm, the cold rolled seamless steel pipe can reach 6mm, the wall thickness can be 0.25mm, the outer diameter of the thin-walled tube can be less than 0.25mm, and the cold rolling mill has a higher precision than the hot rolling. The seamless steel tubes are made of hot rolled or cold rolled steel with low alloy structural steels such as 10, 20, 30, 35, 45 and other high quality carbon steel 16Mn, 5MnV, or 40Cr, 30CrMnSi, 45Mn2, 40MnB, etc. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipe for manufacturing mechanical parts, such as cars and tractors of the force parts. Generally, the strength and flattening test of seamless steel pipe should be ensured. Hot rolled steel pipes are delivered in hot rolling or heat treatment; cold rolling is delivered in heat and heat treatment. Hot rolling, as the name suggests, the temperature of the rolled piece is high, so the deformation resistance is small, and large deformation can be achieved. Taking the rolling of steel plate as an example, the thickness of continuous casting billets is about 230mm, and after rough rolling and finishing rolling, the final thickness is 1~20mm. At the same time, because of the small width to thickness ratio of steel plate, the requirement of dimensional accuracy is relatively low, and the shape problem is not easy to appear. For the organization that is required, it is generally realized through controlled rolling and controlled cooling, that is to control the rolling temperature and finishing rolling temperature of the finishing rolling, the round tube billet, the heating, the piercing, the punch, the annealing, the acid washing, the oil (copper plating), the multi pass cold drawing (cold rolling), the billet tube, the heat treatment, the straightening, the water pressure test (inspection), the marking, and the warehouse. Two. The production process of spiral steel pipe Spiral steel pipe is made of rolled steel strip as raw material, often warm extruded and welded by automatic double wire submerged arc welding technology. (1) raw materials are steel coil, wire and flux. Strict physical and chemical tests should be carried out before the input. (2) butt welding of steel head and tail, single wire or double wire submerged arc welding, and automatic submerged arc welding repair after rolling into steel pipe. (3) before forming, strip is leveled, trimming, planing, surface cleaning, transportation and bending. (4) the electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor so as to ensure the smooth conveying of the strip. (5) use external or internal control roll forming. (6) the weld gap control device is adopted to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld clearance are strictly controlled. (7) internal and external welding uses Lincoln Electric Welder to carry out single wire or double wire submerged arc welding so as to achieve stable welding quality. (8) the welded seam after welding is checked by on-line continuous ultrasonic automatic injury detector, which ensures the non-destructive detection coverage of 100% spiral weld. If defective, automatic alarm and spray marking, production workers adjust the process parameters at any time, eliminate defects in time. (9) use air plasma cutting machine to cut the steel pipe into single root. (10) after cutting into single steel pipe, each steel pipe must be strictly first inspected, to check the mechanical properties of the weld, the chemical composition, the condition of dissolution, the quality of the surface of the steel tube and the inspection of nondestructive testing, so as to ensure that the production of the pipe is qualified. (11) There are continuous sonic detection marks on the weld, through manual ultrasonic and X ray review, such as defects, after repair, again after nondestructive testing, until the defect has been confirmed. (12) all the butt welds of the strip and the joint of the butt joint with the spiral weld are all examined by X ray television or film. (13) each steel pipe is hydrostatic test and the pressure is radial sealed. The test pressure and time are strictly controlled by the microcomputer inspection device for steel pipe water pressure. The test parameters are automatically printed and recorded. (14) machining the end of the pipe, making the verticality of the end face, the slope angle and the blunt edge accurately controlled. Three. Production process of welded pipe Welded pipe The longitudinal welded pipe has the advantages of simple production process, high production efficiency, low cost and rapid development. The strength of a spiral welded pipe is generally higher than that of a straight welded pipe. It can produce a larger pipe with a narrow blank, and the same width of the blank can be used to produce a pipe with different diameters. However, compared with the straight seam pipe of the same length, the weld length is increased by 30~100% and the production speed is low. Large diameter or thicker welded pipes are usually made directly from steel billets, while small welded pipe can only be welded directly through steel strips. Then after a simple polishing, the wire can be pulled. Therefore, small diameter welded pipes are mostly welded longitudinally, while large diameter welded pipes are mostly spiral welded. Four. The production process of bearing steel Bearing steel 50 tons UHP electric furnace smelting, 60 tons LF furnace refining, 60 ton VD furnace vacuum treatment, alloy steel rectangular billet continuous casting (260mm x 300mm, 180mm x 220mm), slow cooling or hot delivery, rolling material, finishing and inspection into the warehouse. Five. The production process of galvanized pipe (galvanized pipe) Inspection of black parts, hanging material, degreasing, rinsing, pickling, cleaning, washing, dipping and helping plating agent, hot air drying, hot dip galvanizing, internal and external, cooling, passivation and rinsing, unloading, discharging, testing, dressing, marking, packing, transportation and transportation Six. Forming process of straight welded pipe Main production process of large diameter longitudinal welded pipe: large diameter longitudinal welded pipe) 1., plate inspection: after the steel plate used for manufacturing large diameter submerged arc welded straight steel pipe has entered the production line, ultrasonic inspection of the whole board is carried out first. 2. milling edge: through the edge milling machine, double side milling on the edge of the steel plate two, so as to achieve the required width, edge parallelism and groove shape. 3. preflanging: pre bending machine is used to pre bend the edge of the plate, so that the edges of the board meet the required curvature. 4. molding: in the JCO molding machine, the first half of the plate after the pre bending is stepped into the form of “J”, then the other half of the steel plate is bending to form a “C” shape, and finally the “O” shape of the opening is formed. 5. pre welding: make the formed longitudinal welded steel pipe seams and use gas shielded welding (MAG) for continuous welding. 6. internal welding: using longitudinal multi wire submerged arc welding (up to four wire) to weld the inner side of the straight seam pipe. 7. external welding: longitudinal multi wire submerged arc welding is carried out on the outside of the longitudinal submerged arc welded pipe. 8. ultrasonic test I. inspection of the inside and outside weld of the longitudinal welded pipe and the base metal on both sides of the weld seam 100%. 9. X ray examination I: 100% X – ray industrial TV inspection of internal and external welds. Image processing system is adopted to ensure the sensitivity of flaw detection. 10. expanding diameter: expanding the length of submerged arc welded straight steel pipe to improve the dimensional accuracy of the steel pipe and improving the distribution state of the internal stress of the steel pipe. 11. water pressure test: on the water pressure test machine, the steel pipe after the expansion is tested by the root by root to ensure the test pressure of the steel pipe to meet the standard requirements. The machine has the function of automatic recording and storage. 12. chamfering: the steel pipe after inspection is processed to meet the required pipe end groove dimensions. 13. ultrasonic testing II: ultrasonic inspection is carried out again and again to check the possible defects of longitudinal welded pipe after expanding and water pressure. 14. X ray examination II: X – ray industrial TV inspection and pipe end fillet shooting for steel pipe after expanding and hydraulic test; 15. tube end magnetic particle inspection: carry out this inspection to find pipe end defects; 16. anticorrosion and coating: qualified steel pipe shall be anticorrosive and coated according to user requirements. Source: China Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Straight seam high frequency welded steel pipe has the characteristics of relatively simple process and fast continuous production, and is widely used in civil buildings, petrochemical industry, light industry and other departments. It is used for conveying low pressure fluid or making various engineering components and light industrial products. 1. Production process of straight seam high frequency welded steel pipe The longitudinal welded steel pipe is rolled into a round tube by a high-frequency welding unit and welded by a straight seam. The shape of the steel pipe can be round or square or irregular. It depends on the sizing rolling after welding. The materials for welded steel pipe are mainly low alloy steel and low alloy steel or other steel products withσs≤300N/mm2、σs≤500N/mm2.  2. high frequency welding High frequency welding is based on the principle of electromagnetic induction and the skin effect, proximity effect and eddy heat effect of AC charge in the conductor, so that the steel at the edge of the weld is partially heated to the melting state. The intergranular joint is realized by the extrusion of the roller, thus the purpose of welding welding is achieved. High frequency welding (HF) is a kind of induction welding (or pressure contact welding). It is widely used in the production of steel pipe without the need of weld filling material, no welding spatter, narrow welding heat affected zone, beautiful welding molding, good mechanical properties and so on. The high frequency welding of the steel tube is using the skin effect and the proximity effect of alternating current. After rolling, the steel (strip) is rolled and formed, forming a circular tube blank with a cross section, rotating near the center of the induction coil near the center of the induction coil, or a group of impedance devices (magnetic rods). The impedance device forms an electromagnetic induction back at the opening of the tube billet. Road, under the effect of skin effect and proximity effect, the edge of the opening of the tube produces a strong and concentrated heat effect, which makes the weld edge quickly heated to the temperature required by the pressure roller to be extruded. The metal of the molten state realizes intercrystalline joint and forms a solid butt weld after cooling. 3. high frequency welded pipe unit The high frequency welding process of the longitudinal steel pipe is completed in the high frequency welded pipe mill. The high frequency welded pipe unit is usually composed of rolling molding, high frequency welding, extrusion, cooling, sizing, flying saw cutting and other components. The front end of the unit is equipped with a storage sleeve, and the back end of the unit is equipped with a steel tube rollover frame, and the electrical part mainly consists of high frequency generator, DC excitation generator and instrument automatic control device. Taking the 165mm high frequency welded pipe mill as an example, the main technical parameters are as follows: 3.1 welded pipe finished products Diameter of circular tube: [Phi] 111~165mm Square tube: 50 x 50~125 x 125mm Rectangular tube: 90 x 50~160 x 60~180 x 80mm Tube wall thickness of finished product: 2~6mm 3.2 molding speed: 20~70 M / min 3.3 high frequency inductor: Thermal power: 600KW Output frequency: 200~250KHz Power: three phase 380V 50Hz Cooling: water cooling Excitation voltage: 750~1500V 4. High frequency excitation circuit High frequency excitation circuit (also called high frequency oscillating circuit) is composed of large electronic tubes and oscillating channels installed in the high frequency generator. It uses the amplification of the electronic tube to feed the anode output signal to the gate and form a self excited oscillation circuit when the tube is connected to the filament and anode. The frequency of excitation depends on the electrical parameters of the oscillating channel (voltage, current, capacitance and inductance). 5. High frequency welding technology for straight seam steel pipe 5.1 Control of weld gap The strip is sent to the welded pipe unit. Through the roll rolling, the strip is rolled up gradually, forming a circular tube with open gap, adjusting the pressing amount of the extrusion roll so that the weld gap is controlled in 1~3mm, and the two ends of the weld are flat. If the clearance is too large, the proximity effect will be reduced, the eddy heat is insufficient, and the intercrystalline bonding between the welds is poor, resulting in unfusion or cracking. If the gap is too small, the adjacent effect increases, the welding heat is too large and the weld is burned, or the weld is squeezed and rolled to form a deep pit, which affects the quality of the weld surface. 5.2 temperature control of welding The welding temperature is mainly influenced by the high frequency eddy thermal power. According to the formula (2), it is known that the high frequency eddy thermal power is mainly influenced by the current frequency. The thermal power of the eddy current is proportional to the square of the current excitation frequency, and the current excitation frequency is influenced by the excitation voltage, current and capacitance and inductance. The excitation frequency formula is as follows: F=1/[2 PI (CL) 1/2]… (1) Type: f- excitation frequency (Hz); capacitance in the C- excitation loop (F), capacitance = power / voltage; inductance in L- excitation circuit = inductance / flux / current. It is known that the excitation frequency is inversely proportional to the square root of the capacitance and inductance in the excitation loop, or is proportional to the square root of the voltage and current. As long as the capacitance, inductance, or voltage and current in the loop are changed, the excitation frequency can be changed to control the welding temperature. For low carbon steel, the welding temperature is controlled at 1250~1460 C, which can meet the requirement of 3~5mm penetration. In addition, the welding temperature can also be achieved by adjusting the welding speed. When the input heat is insufficient, the weld edge of the welded seam can not reach the welding temperature, and the metal structure remains solid to form the non fusion or non weld penetration. When the input heat is insufficient, the heated weld edge exceeds the welding temperature, resulting in overheating or droplets to make the weld formation melting hole. Control of 5.3 extrusion pressure After the two edges of the tube are heated to the welding temperature, the common metal grains are formed to penetrate and crystallize under the extrusion of the extrusion rollers, and finally a solid weld is formed. If the pressure is too small, the number of the common crystal is small, the strength of the weld metal decreases and the force will crack. If the extrusion pressure is too large, the molten metal will be squeezed out of the weld, which not only reduces the strength of the weld, but also produces a large number of internal and external burrs, so as to cause welding joints and other defects. 5.4 control of the position of high frequency induction coil The high frequency induction coil should be as close as possible to the position of the extrusion roll. If the induction coil is far away from the extrusion roll, the effective heating time is longer, the heat affected zone is wider and the weld strength decreases; on the contrary, the weld edge is not heated and the forming is bad after extrusion. The 5.5 impedance is a special magnetic rod for a welded pipe. The section area of the impedance is usually not less than 70% of the section area of the inner diameter of the pipe. The effect is to make the induction coil, the weld edge of the tube billet and the magnetic rod to form an electromagnetic induction circuit, which produces the adjacent effect. The heat of the eddy current is concentrated near the edge of the weld seam, so that the edge of the tube is heated. To the welding temperature. The impedance device is driven by a steel wire in the tube blank, and its central position should be relatively fixed near the center of the extrusion roller. Because of the rapid movement of the tube blank, the impedance of the impedance tube is greatly damaged by the friction of the inner wall of the tube and needs to be replaced frequently. 5.6 weld seam will be welded and pressed to produce weld scar and need to be removed. The cleaning method is to fix the tool on the rack and scrape the weld scar by the fast movement of the welded pipe. The burrs inside the welded pipe are generally not cleared. 5.7 process examples Taking the welded 32 2mm welded pipe as an example, the process parameters are briefly described. Strip specification: 2 * 98mm bandwidth expanded according to medium diameter and small amount of molding allowance. Steel material: Q235A Input excitation voltage: 150V excitation current: 1.5A frequency: 50Hz Output DC voltage: 11.5kV DC current: 4A frequency: 120000Hz Welding speed: 50 m / min Parameter adjustment: adjust the output voltage and welding speed according to the change of welding line energy. When the parameters are fixed, it is generally not to be adjusted. 6. Technical requirements and quality inspection of high frequency welded pipe According to the standard of GB3092 “welded pipe for low pressure fluid transportation”, the nominal diameter of the welded pipe is 6~150mm, the nominal wall thickness is 2.0~6.0mm, the length of the welded pipe is usually 4~10 meters, and the length of the pipe can be made at the length or the length of the ruler. The surface quality of the steel pipe should be smooth, and there are no defects such as folding, cracking, delamination, lap welding and so on. There are minor defects such as scratches, scratches, weld mismatches, burns and scarring, which are not more than negative wall thickness. Allow thickening of weld thickness and internal seam welds. Welded steel pipes should be tested in mechanical properties, flattening tests and flaring tests, and meet the standard requirements. The steel pipe should be able to bear certain internal pressure. If necessary, carry out the 2.5Mpa pressure test, and maintain no leakage for one minute. Eddy current testing is allowed instead of hydraulic pressure test. Eddy current inspection is carried out according to the GB7735 “eddy current inspection method for steel pipe” standard. The method of eddy current flaw detection is to fix the probe on the frame, to keep the distance between the flaw detection and the weld 3~5mm, to scan the weld by the fast motion of the steel tube, and to achieve the purpose of the flaw detection by the automatic treatment and the automatic separation of the eddy current flaw detector. After welding, the welded pipe is cut off according to the required length, and the bottom line is turned off. The ends of the steel pipes should be chamfered, printed and marked, and the finished products can be packed with hexagonal bundled packages and left the factory. 7. Summary The technology of straight seam high frequency welded pipe has the characteristics of simple process and high efficiency. It has wide application prospects in civil buildings, petrochemical industry, light industry and other departments. Source: China Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

A variety of surface processing of stainless steel has widened its application field. Different surface processing makes the surface of stainless steel different, so that it is unique in its application. In the field of building applications, there are many reasons for the importance of surface processing of stainless steel. One, the basic types of surface processing There are basically five kinds of surface processes that can be used for stainless steel. They can be combined and used to transform more and more final products. The five species are: Rolling surface processing Mechanical surface processing Chemical surface processing Reticulated surface processing Color surface processing There are some special surface treatments, but no matter which surface is specified, the following steps should be followed: 1, with manufacturers to agree on the necessary surface processing, it is best to prepare a sample for future volume production standards. 2. When large areas are used, such as composite boards, the same base must be used to ensure that the base rolls or rolls are used in the same batch. 3, the manufacturing process should be taken into consideration when selecting surface processing. For example, in order to remove the bead, it is possible to repair the weld and restore the original surface processing. The pattern board is hard to even meet this requirement. 4, for some surface processing, grinding or polishing texture is directional, is called unidirectional. If it is used vertically and not horizontally, dirt is not easily attached to it, and it is easy to clean. Two. Rolling surface processing There are three basic rolling surface processes for sheet and strip, which are represented by plate and village production processes. No.1: hot rolling, annealing, pickling and descaling. The surface of the treated steel sheet is a dull surface and a bit rough. No.2D: the surface is better than N0.1, and it is also a bleak surface. After cold rolling, annealing, descaling, and finally rolling with the wool surface roller. No.2B: This is the most commonly used in architectural applications. Except for the last mild cold rolling of the polishing roll after the annealing and the descaling, the other processes are the same as the 2D, and the surface is slightly light and can be polished. No.2B bright annealing: This is a reflective surface that is rolled through a polishing roller and annealed in a controlled atmosphere. Bright annealing still keeps its reflective surface and does not produce oxide scales. Because no oxidation reaction occurs in the process of bright annealing, no pickling and passivation treatment is necessary. Three, polishing surface processing No.3: expressed by 3A and 3B. 3A: the surface is evenly grind and the abrasive particle size is 80~100. 3B: the wool surface is polished with uniform straight lines on the surface. It is usually made by grinding and polishing the abrasive belt with a size of 180~200 on the 2A or 2B board. No.4: unidirectional surface processing, not strong reflectivity, this surface processing may be the most widely used in building applications. The process is first polished with coarse abrasives, and then grinded with a particle size of 180. No.6: it is a further improvement to No.4, which is to polish the No.4 surface with tampo brush in abrasive and oil medium. There is no surface processing in British standard 1449, but it can be found in the US standard. No.7: known as bright polishing, it is polishing the surface that has been finely worn but still worn. 2A or 2B boards are usually used, with fiber or cloth polishing wheels and corresponding polishing paste. No.8: mirror polished surface, high reflectivity, usually referred to as mirror surface processing, because it reflects the image very clear. The stainless steel is continuously polished with fine abrasives and then polished with very fine polishing paste. What should be noted in building applications is that such a surface will leave a fingerprint if it is used in areas where the flow of personnel is large or where people often touch. The handprints can be erased, but sometimes they are beautiful. Four, surface roughness The classification of rolling surface finishing and polishing surface machining is a description of the extent to which it can be achieved. Another effective method is to measure surface roughness. The standard method of measurement is called CLA (mean value of the center line). The measuring instrument moves horizontally on the surface of the steel plate to record the change range of the peak valley. The smaller the CLA’s number, the smoothed the surface. The final results of different grades can be seen from the surface processing and CLA numbering in the following table. Five. Mechanical polishing Note: we should remember that grinding with sandpaper or sand belt in grinding operation is basically a polishing operation, leaving a fine line on the surface of the steel plate. We have encountered trouble when using alumina as abrasive, partly due to pressure. Any abrasive parts of the equipment, such as abrasive belts and grinding wheels, must not be used before other stainless steel materials. Because this will pollute the surface of the stainless steel. Six. Electrolytic polishing This is a metal removal process. In this process, stainless steel is used as the anode in the electrolyte, and the metal is removed from the surface after electrified. The process is usually used for parts processing because their shape is difficult to be polished by traditional methods. The process is often used on the surface of cold-rolled steel sheet because its surface is smoother than that of hot-rolled steel sheet. However, electrolytic polishing will cause more obvious impurities on the surface, especially titanium and niobium stabilized materials will cause differences in the weld area due to granular impurities. Small welding scar and sharp edge can be removed by this process. The process focuses on the surface protrusions, giving priority to dissolving them. The electrolytic polishing process is to immerse stainless steel in heated liquid, and the ratio of liquid involves many proprietary technology and patented technology. The effect of electrolytic polishing of austenitic stainless steel is very good. Seven. Reticulated surface processing There are many kinds of patterns that can be used in stainless steel. The advantages of making steel plates with textured or textured surfaces are as follows: 1) reduce “oil can-ning”, a term used to describe the surface of a bright material, which looks inhomogeneous from an optical angle. For example, a large area of decorative panels, even after stretching straightening or tension leveling, is difficult to make the surface completely flat, resulting in metal roof material shrinkage. 2) netted patterns can reduce glare in the sun. 3) if the pattern board has slight scratches and small area indentation, it is not very obvious. 4) increase the strength of the steel plate. 5) the choice is provided for the architect. Patented designs include cloth patterns (used for Ed building in London), mosaic designs, pearls and leather stripes. Ripple and linear patterns can also be used. The pattern surface is especially suitable for interior decoration, such as elevator panels, counters, panels and entrance. The external application should be taken into consideration to make the stainless steel clean the surface through rain and artificial scour, and avoid the dead angle which is easy to gather dirt and air impurities, so as to avoid the beauty of corrosion. Eight. Surface processing of wool surface Surface finishing is one of the most commonly used surface processes. It is polished or annealed on the surface of steel plate with nylon abrasive belt or brush. Source: China Alloy Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The latest process of removing burr for stainless steel plate is electrolytic polishing, which requires a complete set of electrolytic polishing equipment for production, such as power supply, rectifier, polishing tank, workpiece hanger, heating facility, cathode and anode materials, several rinse frames, and stainless steel electrolytic polishing liquid. Let’s talk about burr related knowledge of stainless steel products. The stainless steel electrolytic polishing equipment with good quality is basically suitable for electrolytic polishing of all stainless steel and stainless steel. It has strong versatility, high polishing brightness and long gloss (stainless steel material can throw out the mirror effect). The electrolytic polishing machine (power supply series) can be pided into the air cooling series and the water cooling series. The product structure is designed reasonably, the quality is reliable, the energy saving, the corrosion resistance is strong, the heat dissipation is fast, the electrolysis effect is good, the current and voltage are adjustable, the steady current, the steady pressure, the overheat, the over current protection, the buffering start function, the use of special integrated board circuit, and It has been treated with antisepsis, completely sealed, the output voltage range is 0-300V, and the output current range is 10A – 10000A. The advantage is that electrolytic polishing is not restricted by the size and shape of the workpiece, and electrochemical polishing is suitable for the workpiece which is not suitable for mechanical polishing. For example, slender tube inner wall, elbow, bolt, nut and container inside and outside wall, polishing efficiency is high, good quality, in a few minutes can be thrown to mirror bright. Stainless steel electrolytic polishing liquid is suitable for polishing all stainless steel and stainless steel. It is versatile and versatile (stainless steel material can be used to throw out mirror effect. It is widely used in mechanical manufacturing, electronic parts, instrument instruments, light industry and watch parts, military and aerospace, textile equipment, automobile zero parts, bearing industry, medical equipment and precision. Parts, powder metallurgy, metal stamping, handicrafts, tools and other industrial fields. The operation process is to rinse the water after removing oil and heat the electrolysis polishing liquid to 55-75 degrees (using quartz rod or titanium heating rod) to stop heating after the requirement of temperature. Fix the hanger on the anode rod, open the power rectifier switch and adjust the voltage to 5-12 volts. The polishing time is from 30 seconds to 10 minutes (the fastest 30 second is to save the mirror effect). Source: China Stainless Steel Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Millions of miles of pipelines are used to transmit drinking water around the world. These pipelines must have good corrosion resistance to water itself, soil chemicals and treatment chemicals, so as to ensure adequate service life and provide sanitary drinking water. Type 316 (2-3%Mo) stainless steel has been proven to provide adequate corrosion resistance in most applications, and is more competitive than other piping materials. If additional corrosion protection is required, for example, in the installation of coastline, duplex stainless steel (3.0-3.5%Mo) can be used to achieve the required sanitary conditions and service life. As for the reasons, I have learned the following summary of the beneficial properties of molybdenum bearing stainless steel below. The first is excellent corrosion resistance. Stainless steel is more resistant to oxidation of water and biocide than carbon steel and cast iron or ductile iron. This leads to longer service life of stainless steel water pipelines. Followed by corrosion protection, stainless steel does not require internal and external coatings, nor does it require cathodic protection. This will reduce the cost of the system and make the stainless steel more compatible with the environment. The third is hygienic material. Because of its very high oxide film stability, stainless steel water pipelines are basically inert in water. The leaching of alloying elements (Cr and Ni) is within the safety limits. Therefore, stainless steel pipelines can provide better drinking water quality. The fourth is friction coefficient. Compared with cement lined carbon steel pipeline or corroded carbon steel, the friction loss of stainless steel pipeline leads to smaller hydraulic pressure along the pipeline. This provides the opportunity to reduce the inner diameter of the pipeline and save capital costs. This is also the reason for lower sediment adhesion and lower bacterial colonization. They can also provide higher traffic. The fifth is good strength and ductility. Stainless steel pipelines, especially duplex stainless steel, have higher mechanical properties compared with carbon steel and cast iron pipelines. This can reduce the wall thickness of the water pipeline (no need for any corrosion allowance), thereby saving investment costs. Better ductility is also important in terms of safety, such as in the case of earthquakes. The sixth is erosion corrosion performance. Duplex stainless steel is more resistant to corrosion and corrosion than carbon steel, especially if there is sand in the surrounding environment. Seventh is easy to make. Stainless steel is an adaptable material. It is easy to form, machine and weld. It is easy to install and modify the pipeline with its good ductility. They also have a variety of product forms. In addition, the stainless steel pipelines are easy to maintain, with high corrosion resistance and easily weldability, the probability of water leakage will be reduced greatly, and it may be reduced from 25% to less than 5%, which will further reduce the cost. This argument is becoming more and more important because of the increasing cost of water and water treatment. There is also good durability, because SS can resist crevice corrosion, cavitation and wear in pure and polluted waters, as well as in the atmosphere (and even pollutants). It is cost-effective for long-term use and will not cause environmental pollution. The last one is recyclable, stainless steel is 100% recyclable, and part of its initial cost may be recovered during recycling. Source: China Stainless Steel Water Pipeline Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

There are hundreds of different types of stainless steel flanges on the market, which may be difficult to find the perfect metal for your application. In many purchasing processes, the cost of metals is the first consideration rather than the performance of metals, but this is wrong. In some cases, additional costs are required for different high-performance alloys. But the common use is mainly made of 304 stainless steel and 316 stainless steel. They are high performance in tensile strength, durability and corrosion resistance. 304 stainless steel can withstand various environments, and the tolerance of 316 stainless steel to chloride and other corrosive agents is improved. However, some processes involve extreme working conditions which require higher performance properties than these alloys, such as better grade 317L stainless steel. What makes grade 317L SS different from 304 and 316 stainless steel? 304, 316 and 317L stainless steel are considered to be austenitic stainless steel alloys. All these alloys have some similar properties, such as high strength, corrosion resistance and high concentration of chromium and nickel. The difference between 316 and 317L stainless steel and 304 stainless steel is that these high amounts of alloy add molybdenum in its formula grade 316, with a content of about 2-3%, and 317L stainless steel with more than 3% molybdenum. This addition of molybdenum greatly enhances the corrosion resistance of stainless steel to chloride, which is why 316 stainless steel is often used in chemical processing and marine industry. However, the added molybdenum content also affects the cost of the two alloys. 317L stainless steel is usually more expensive than 316 stainless steel. 316 is more expensive than 304. For the most corrosive applications, 316 stainless steel should be sufficient to withstand frequent exposure. But 317L to 304 or 316 has better resistance to certain specific corrosive resistance. As stated in the ATI Metals publication, the corrosion rate of 317L stainless steel in the boiling test solution of 1% hydrochloric acid is 54.2 mil / year, and the corrosion rate of 316 stainless steel is 226 million cubic meters per year. 317L in sulfuric acid and sodium hydroxide test, it is obviously better than 316. Therefore, if it is involved in the use of very diluted (less than 3-4%) hydrochloric acid, mild concentration (10%) or sodium hydroxide (also called caustic sodium), it is more appropriate to use 317L grade stainless steel. In addition, it should be noted that any concentration of hydrochloric acid above 5% will easily corrode all austenitic stainless steel alloys. Source: China Stainless Steel Flanges Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The seamless stainless steel pipe is a long steel bar with a hollow section and seamless joints. The thicker the wall thickness of a stainless steel pipe is, the higher its economical efficiency and practicality, and the thinner the wall thickness, the greater the production and processing costs. The process of the seamless stainless steel tube determines its limited performance. Usually, the accuracy of the seamless stainless steel tube is low, there are uneven wall thickness, low brightness inside and outside the tube, high cut-in cost, and pits and black spots on the inside and outside surfaces are not easily removed. Disadvantages, seamless stainless steel tube inspection and shaping must also be handled offline. However, seamless stainless steel tubes also exhibit their advantages in terms of high-pressure, high-strength, mechanical structural materials. However, there are many problems with poor quality stainless steel seamless tubes, and some may even cause serious problems in practical applications. Here is a list of the common phenomena of inferior seamless stainless steel tubes for reference. One is that the surface of the inferior seamless stainless steel tube is likely to form scars. That is because of the non-uniformity of the material of the material and the fact that it contains more impurities. The equipment made is very simple and easy to stick to steel. High-quality stainless steel seamless pipes do not have such problems and phenomena. The second reason is that the surface of the inferior seamless stainless steel pipe is very easy to form cracks because the billet is adobe, and the billets have many holes, and the adobe will be cracked quickly due to thermal stress during the cooling process. There will be cracks afterwards. The third is that the inferior seamless stainless steel pipe has an elliptical cross-section. The reason is that in order to save the material cost, the amount of reduction in the front roller of the finished roller is too large, and the strength of the stainless steel pipe will be greatly reduced, and Nor will it meet the pipe’s dimensions. The fourth reason is that the inner diameter of inferior seamless stainless steel pipe fluctuates greatly because the temperature of the stainless steel plate is unstable and there is a yin and yang face, and the composition of the steel is also uneven, because the equipment is simple, the foundation strength is low, and the mill bouncing is large. . There will be a larger change in the inner diameter in the same week, so that the stainless steel tube is also very easy to form fractures due to uneven force. The longitudinal bars of stainless steel seamless pipes for counterfeit structures are often wavy. Source: China Seamless Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The welded stainless steel pipe has two main features, one is that the small diameter welded stainless steel pipe is continuously produced online. The thicker the wall thickness of the pipe, the larger the investment scale of the unit and welding equipment, the worse the economy and practicality of this kind of welded stainless steel pipe. The thinner the wall thickness, the input-output ratio of the stainless steel pipe will decrease correspondingly. Secondly, the process of welding stainless steel pipe determines its advantages and disadvantages, usually the precision of the welded stainless steel pipe is higher, the wall thickness is more uniform, the surface light of the inner wall of the pipe is high (the surface grade of the stainless steel plate determines the surface brightness of the stainless steel pipe) and can be arbitrarily fixed. Therefore, the welded stainless steel pipe is in high precision and middle low pressure flow. The application of body shows good economy and beauty. Material and use of stainless steel welded pipe The welded stainless steel pipes are pided into 6 types according to their materials and uses. The first kind is GB/T3092-1993 (galvanized steel pipe for low pressure fluid delivery). This kind of stainless steel pipe is mainly used for transporting water, gas, air, oil and heating hot water or steam and other general low pressure fluid and other use pipes. The representative material is Q235 a grade steel. The second is GB/T3091-1993 (galvanized steel pipe for low pressure fluid delivery). This kind of steel pipe is mainly used for transporting water, gas, air, oil, heating hot water or steam and other general low pressure fluids and other use pipes. The third is GB/T12770-1991 (stainless steel welded pipe for mechanical structure), which is mainly used for mechanical, automobile, bicycle, furniture, hotel and hotel decoration and other mechanical parts and structural parts. Its representative material is 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb and so on. The fourth one is GB/T14291-1992 (mining fluid conveying welded steel pipe), which is mainly used for longitudinal welded steel pipe for mine ventilation, drainage and gas. The fifth one is GB/T12771-1991 (stainless steel welded pipe for fluid transportation), which is mainly used for conveying low pressure corrosive medium. The representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc. The last kind is GB/T14980-1994 (large diameter welding steel pipe for low pressure fluid delivery), which is mainly used for the low pressure fluid and other uses such as water, sewage, gas, air, heating steam and so on. Source: China Stainless Steel Welded Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The stainless steel pipe is a kind of pipe with hollow cross section and complete weld. Compared with solid steel and other solid steel, stainless steel pipe products are a kind of economic section steel when the bending and torsion resistance is the same, it is a kind of economic section steel. It is used in the manufacture of structural parts and mechanical parts, such as oil drilling rod, automobile drive shaft, bicycle frame, and steel scaffold used in construction. Using stainless steel pipe to make ring parts, it can improve the utilization of material, simplify the manufacturing process and save the length of material and processing, such as rolling bearing rings and Jack sleeves, all of which are made of stainless steel pipes. Because of its wide use and precision components, the finished products are basically smooth and no burr on the surface, so if you want to have better quality, the stainless steel electrolytic polishing process can be used to make the surface clean, no burr, and maintain a lasting light. Manufacturing method of stainless steel pipe for fluid In general, the temperature of the boiler pipes is below 450 C, and the domestic pipes are mainly made of 10 or 20 carbon steel hot-rolled pipes or cold drawn pipes. High pressure boiler pipes are often used at high temperature and high pressure, and their pipes will oxidize and corrode under the action of high temperature flue gas and steam. Therefore, it is necessary to make stainless steel pipe products have higher endurance strength, higher corrosion resistance and better stability. The use of electrolytic polishing of stainless steel pipes is widely used. Generally, the boiler pipes are mainly used to make water wall pipes, boiling water pipes, superheated steam pipes, superheated steam pipes for locomotive boilers, large, small smoke pipes and arch pipes, and high pressure boiler pipes are mainly used to make superheater pipes and reheater pipes for high pressure and ultra-high pressure boilers. The trachea, main steam pipe and so on. However, the stainless steel pipe also has some limitations, for example, under the condition of plane bending, the round pipe is not as strong as square and rectangular pipe, and some farm machinery skeleton, steel and wood furniture, etc. are commonly used and rectangular pipe. According to different uses, there are other special-shaped stainless steel pipes with different cross-section shapes. No matter what kind of stainless steel pipe, as long as the stainless steel electrolytic polishing treatment, its advantages are not successful, such as removing burr, can make the stainless steel surface to reach the 8K mirror effect, suitable for special shaped pipe fittings, such as high polishing efficiency, low production cost and long gloss. Corrosion resistance and antioxidation. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When stainless steel plates are welded, defects often occur. The causes of these defects are different. This article describes some of the defect classification and avoidance methods. Stoma The pores formed by the stainless steel plate weld can be pided into internal pores, surface pores, and joint pores. There are two types of internal pores, one is that the spherical pores are mostly generated in the middle of the weld. The reasons for the formation are excessive welding current, long arc, too fast moving rod, unclean welding area, and moisture in the welding rod. . The above causes the pore causes to be solved if appropriate adjustments and pay attention to the welding process and operation method. There are several reasons for the formation of surface pores. For example, if the base metal contains carbon, sulfur, and silicon, high content of the pores is likely to occur. The solution is either replacement of the base metal or the use of a low-hydrogen slag-based electrode. The welding site is also unclean and prone to blow holes. Therefore, the welding site requires welding. Before the removal of oil, rust and other dirt, the use of low-hydrogen welding rod welding requirements are more stringent; In addition, excessive welding current can also lead to surface pores, so that the second half of the electrode coating red, but also prone to air holes, so require the appropriate The welding specification, welding current to the maximum end of the electrode is not red is appropriate; low hydrogen electrode easy to absorb moisture, so before use are required to be baked at a temperature of 350 °C 1h or so, otherwise prone to air holes. There are species of solder wave joint pores, the use of low hydrogen electrode is often easy to appear at the weld joint surface and internal porosity, the solution is in the solder wave joint, should be in the direction of the weld from the arc 9-10mm Start the arc, after the arc burns, first reverse the rod back to the crater position, fully melt forward and then advance, or arc at the weld to avoid this type of pore generation. Crack There are several types of cracks. The first is a rigid crack, which is usually the longitudinal crack in the weld where the weld joint is found, mainly due to the stress generated during welding. In the following cases, the welding stress is large, the rigidity of the welded structure is large, the welding current is large, the welding speed is fast, and the cooling rate of the weld metal is too fast. So it is very easy to form longitudinal cracks in the above situation. The solution is to use a reasonable welding sequence or preheat the workpiece where possible to reduce the rigidity of the structure. Special thick plates and rigid structures should use low hydrogen electrodes with appropriate current and welding speed. The second is the crack caused by carbon and sulfur elements. When the carbon and sulfur of the base metal being welded are high or segregated, cracks are likely to occur. The solution is to preheat the weldment or use a low hydrogen electrode. The third is a gap crack, which occurs inside the weld metal and does not develop external hairy micro cracks. Considering that the weld metal is subject to rapid cooling and embrittlement, local stress and hydrogen gas influence. The prevention method for this is to make the cooling rate of the weldment slower, to preheat the weldment under possible conditions, or to use a low hydrogen electrode to achieve a satisfactory solution. Arc blow When the welding is performed on a DC welding machine using a low-hydrogen electrode, blow-off occurs frequently. The solution is that the ground wire is placed in the direction of the arc blow; the ground wire is pided into two or more; welding is performed in the direction of the partial blow of the arc; and the welding is performed using the short arc operation. Source: China Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Salt spray corrosion will destroy the passivation film on the surface of the stainless steel plate, so that the decorative nature of the plate will be lost, and the mechanical strength of the material will be reduced. Some electronic components and electrical wiring will cause the power line to be interrupted due to corrosion, especially in vibration. In the environment, it is particularly serious; whenever the salt spray falls onto the surface of the insulator, the surface resistance of the stainless steel plate will be reduced; after the insulator absorbs the salt solution, the volume resistance will also be reduced by four orders of magnitude; the movement of mechanical parts or moving parts Due to the formation of corrosive substances, the friction of the material is increased so that the moving parts are jammed. Let’s look at the mechanism of salt spray corrosion. Salt spray corrosion of stainless steel and other metal materials, mainly conductive salt solution infiltrated into the stainless steel plate to generate electrochemical reactions, generate low-potential metal – electrolyte solution – high potential impurity micro-battery system, resulting in electron transfer, metal as the anode Dissolution occurs and new compounds, ie corrosion products, form. The same applies to the metal protective layer and the organic material protective layer. After the salt solution as an electrolyte penetrates into the interior, a micro-battery with a metal as an electrode and a metal protective layer or an organic material as another electrode is formed. Chloride ions play a major role in the salt fog corrosion damage process. It has a very strong penetrating power and easily penetrates the passivation layer on the surface of the stainless steel plate and enters the interior of the stainless steel plate while destroying the passivation state of the metal. And chloride ion has a very small hydration energy and is easily adsorbed on the surface of the stainless steel plate, thereby replacing the oxygen in the oxide layer on the surface of the stainless steel plate, so that the metal surface such as stainless steel is damaged. In addition to chloride ions, the salt spray corrosion mechanism is also affected by oxygen dissolved in the salt solution (essentially the salt solution that dissolves on the surface of the sample). Oxygen can lead to the depolarization process of stainless steel and other metal surfaces, speed up the dissolution of the anode metal, because the salt spray process continues to spray, the salt liquid film continuously settles on the surface of the sample, so that the oxygen content will always remain near saturation . The formation of corrosion products, so that the volume of the salt solution infiltrated into the metal defect expansion, so it also increases the internal stress of the stainless steel plate, the formation of stress corrosion, resulting in the surface of the passive layer of the stainless steel plate bulging. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When the surface of the stainless steel plate is not annealed (for example, the surface after welding), drilling mud residue, rust-proof film, or ferrite impregnated with stainless steel after the molding process, the corrosion resistance of the stainless steel material will be directly affected. At this point you need to use acidic oil cleaning agent to do the appropriate cleaning and maintenance operations on the stainless steel surface. Stainless steel pickling passivation can completely remove impurities and promote the formation of a new passivation layer, which is a complete chemical reaction process. It can not only clean the surface of the stainless steel plate, but also can form a completely uniform silver white on the surface of the treated stainless steel plate. According to actual tasks, stainless steel plates with different structures and surface sizes can use different pickling products. First look at the stainless steel pickling passivation paste, this product is used to deal with the surface of the larger stainless steel plate or surface weld around the weld spot, oxide layer color, as long as the uniform smear on the surface of the stainless steel plate, wait until The surface of the stainless steel plate is completely uniform and white. Followed by the stainless steel pickling passivation solution, which is mainly used for the pickling of small serial parts, such products are easy to immerse, usually using plastic containers soaked at room temperature, and even can achieve high efficiency pickling and passivation done synchronously, such as stainless steel After the surface of the board has been pickled and passivated, the maximum salt spray resistance can reach about 500 hours. In addition to the pickling spray, this process is suitable for pickling large stainless steel surfaces (including wall panels, containers) as well as non-removable structures or difficult-to-access structures such as bridge components. Pickling sprays can increase application control. There is also ablation pickling. This technique can remove the surface tension and internal stress of the stainless steel plate material by specifically removing the 3-5 micron surface, and also remove surface microcracking. However, no matter which process is used, the treated surface acid must be completely cleaned. It is best to use high-pressure cleaning. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)