Mongolia5052 a
MongoliaTinned
Mongolia15CrMoscratches and other rough surfaces
Now let me talk about the damages that are easy to occur on the surface of the copper tube. In order to prevent the accumulation of process agents or products and/or dirt mechanical cleaning must be carried out. If the copper pipe is heated to a certain high temperature in the air during welding or grinding, chromium oxide heat return color will appear on both sides, lower surface and bottom of the weld. The color after tempering is thinner than that of the oxidation protective film, and is clearly visible. The color depends on the thickness. The thicker oxide can be found in the rainbow color blue, purple to brown. It is usually black. It is caused by being at high temperature or being at high temperature for a long time. When any of these oxide layers exist, the chromium content on the metal surface will, and the corrosion resistance of these areas will. In this case, it is not only necessary to heat temper the color and other oxide layers, but also to clean the chromium poor metal layer under it. Free iron on the surface of t2 copper tube will rust, causing corrosion of stainless steel. Therefore, the powder that must float can usually be removed together with the dust. Some are very sticky and must be treated as embedded iron. In addition to dust, there are many surface iron sources, including cleaning with ordinary carbon steel wire brush and shot peening with sand, glass beads or other abrasives previously used on ordinary carbon steel, low alloy steel or cast iron, or regrinding non stainless steel products attached to copper pipe components and equipment. If there is no protection during cutting or hoisting, the wire ropes, slings and iron on the working surface can easily be embedded or dirty the surface. The copper tube shall be boiled in boiling water for 30 seconds before cold treatment. The effective internal stress is about 15%, and the residual austenite reaches the effect. Then, the cold treatment can be carried out as usual. Of course, the second suggestion is to choose the normal treatment at minus 60 degrees, the retained austenite will be rapidly transformed into martensite, but it cannot be transformed. Through experiments, it can be found that there will be about 2% of retained austenite. At this time, retained retained austenite can achieve a certain buffer effect. After cold treatment, the air conditioning copper pipes need to be taken out and put into hot water for heating, which can effectively heat about 40% of the cold treatment stress. Tempering and cold treatment should be carried out as soon as possible after gradual heating, and most of them can avoid cracks as soon as possible, so as to ensure that the products will not deform in later use and facilitate daily storage. The transformation characteristics of the area of each layer of the copper tube during empty drawing affect the asymmetry of the deformation of the metal material. One of its characteristics is that the natural widening of each layer along the wall thickness is not consistent. Of course, the external layer of the copper tube is less, the internal surface layer of the copper tube is larger, and the natural widening of the middle layers is slow from the external layer to the internal surface layer.The technical level of degreasing copper tube for mechanical equipment With the substantial improvement of the manufacturing level of mechanical equipment and the degree of control automation in China there is still some gap between the technical level of domestic degreasing copper tube production line and the products of foreign counterparts. After years of reform and opening up. The quality of all aspects of degreased copper pipe has also risen by several grades, significantly narrowing the quality gap with the imported production line. The aluminum hose production line and aluminum can production line developed and produced by the company break the technological monopoly of foreign companies, can provide stable and reliable production equipment for domestic and international markets, and make great contributions to the aluminum packaging industry. With the continuous improvement of people's living standards, there will be more and more demand for degreased copper tube products, and its market potential is huge. Problems such as incomplete penetration, deformation, cracks and air holes are easy to occur during the fusion welding of degreased copper tubes. Compared with fusion welding wood is not melted during brazing, which reduces the impact of large thermal conductivity of base metal on welding quality, reduces the tendency to produce pores and cracks, and ensures the performance of weld. Because the base metal is not melted, the structure and properties of the base metal are almost unchanged, so that the original service properties of the base metal can be maintained.
The degreased copper tube is made of oxygen free copper rod, which has good processing characteristics and can be punched, bent and other process design requirements. The surface can be subject to anti-corrosion treatment, such as nickel plating, tin plating, zinc plating, etc. The surface anti-corrosion can reach 72 hours of fog test. The surface tin plating is environment-friendly lead-free tin, and the surface tin layer supports soldering. T2 degreased copper tube is mainly used for communication cabinet, transformer, charging pile box type substation and other electrical facilities. The copper bar is harder than the plastic pipe and has the degree of common metal (the strength of the cold drawn degreased copper pipe is equivalent to that of the steel pipe with the same wall thickness). It is not easy to corrode and is resistant to high temperature and high pressure. It can be used in various applications. The main material of copper bar is copper. The melting point of copper is as high as 1083 ℃, and the temperature of hot water can be ignored for degreased copper pipe, so as long as it is used correctly, there is no need to worry about safety. When choosing to decorate the house, few people ask about the water supply pipe of the house. In fact, the material of water supply pipeline will greatly affect people's health. T2 copper tube has strong capacity. Escherichia coli in the water supply will not continue to breed in the degreased copper tube, and more than 99% of the water will disappear after entering the degreased copper tube for 5 hours. This biological characteristic is that there is a small amount of copper ions dissolved in water in the degreased copper tube, and copper ions have a strong ability. Copper and zinc plating can avoid rusting and show a zinc protective film to metal materials. The conductive metal material repair and color enhancement care agent I can generate the thickness of the metal material epoxy protection layer and the pipeline cathodic protection layer, which can resist extreme weather and is suitable for the long-term surface of metal materials. The actual effect of salt and water corrosion resistance is good. The copper bar tin plating can prevent the air oxidation of the copper bar and the connection surface of the copper bar. In addition, the melting of metal tin and copper will produce aluminum alloy, which will improve the adhesion of copper strip coating. In addition, the conductivity of metal tin is good. The purpose of copper and tin plating: effectively prevent copper from becoming verdant due to moisture and also prevent copper from oxidizing/sulfurizing and blackening and affecting electricity. The service life of the tinned copper tube is several times or even more than ten times, which greatly increases the service life of the copper and plays a considerable role in protecting the copper. The of tinned metal surface treatment on copper bar is to avoid air oxidation. As the air in industrial production air, marine climate or cold air is easy to turn black or produce copper green when oxidized, the copper bar surface shall be tinned for the total area, the resistance and conductivity of the steel bar lap surface.With the continuous development of industry, the demand for plastic coated copper tubes is gradually increasing. Then how to apply wood grain paint on alloy pipes. Wood like paint is a kind of wood like paint. It is used for spraying plastic coated copper pipe and its process flow. Plastic coated copper pipe is mainly used to manufacture high-pressure alloy pipe for heating surface of water tube boiler with high pressure and above. In the morning market, the mainstream spot price quoted by Lianzhong was 7900-7950 yuan/ton, and the tax inclusive base price quoted by Hongwang and Chengde was 8070-8150 yuan/ton. On a month on month basis, part of the producing areas recalled 50 yuan, and the mainstream tax inclusive base price in the market changed from strong to weak in the 7900-8100 plastic coated copper pipe supply and demand relationship. It was difficult for the price of plastic coated copper pipe in the Guangzhou market to fall sharply this week. Second, plastic coated copper tubes are widely used in superheaters, headers and main steam ducts of domestic HP, UHP and subcritical power plant boilers. Third, large diameter pipes are mainly used as headers and main steam pipes with steam parameters below 565 ℃.
Mongolia.The market price of Zhengzhou copper bars is basically stable, and the shipment is not good. In terms of tube blank: today, Shandong Luli tube blank slightly reduced by 50 yuan and the current mainstream ex factory price is 4080-4150 yuan. In terms of pipe plant: Linyi Pipe Plant locked the price for a week. With a stable market mentality, the factory price of hot rolled seamless pipes is now between 5050-5100 yuan. On the market side: with the arrival of the off-season, traders generally ship goods at a high price. Replenishment is mainly to maintain the existing inventory, and there is no large replenishment plan. The demand is sluggish, and the market price of Zhengzhou copper bar is expected to be stable and declining.
The material cost of medical copper tube will not be less than 40 yuan. The better the material is, the higher the price will be. It is called &one cent, one cent&. Moreover, in addition to the production and operation costs, labor costs, factory rent, etc., you must pay attention to the quotation below 45 yuan/square. Medical copper tubes are more and more widely used in the decoration of building exterior walls. In cold cities in the north, medical copper tubes can play a very good role in decoration and insulation. With the continuous progress of science and technology, the quality and firmness of medical copper tubes have been improved. However, as long as the decoration materials are used, they will inevitably crack during installation and construction. As time goes by, Zhongsheng Thermal Insulation Technology will introduce how to prevent the cracking of medical copper tubes and how to prevent the aging of medical t2 copper tubes? Let's talk about these two issues. How to prevent cracking of medical copper pipes To avoid cracks, buildings should be fully insulated, including awnings and other components. Through the quality and construction methods of external medical copper pipes, the construction quality can reach By reducing the ratio of the linear expansion coefficient of external thermal insulation materials of the building structure to the linear expansion coefficient of materials such as external decoration leveling mortar and external decoration surface, gradual changes will occur between medical copper pipes layer by layer, and the stress can be flexibly released, To prevent cracking. How to prevent medical copper tube from aging? The insulation layer of high-rise buildings shall have fire resistance , and shall have the characteristics of preventing fire spread and releasing smoke or toxic gas in case of fire. The strength and volume of materials shall not be reduced too much, and the surface shall not burst or collapse. Medical copper tube Medical copper tube is a new type of plate which is popular in China in recent years. It has many advantages, such as good heat preservation, fire insulation, convenient construction, beautiful appearance, etc., and is deeply welcomed by the industry. The medical copper pipe may fall during use. In order to reduce the occurrence of this kind of phenomenon, Jinan Zhongsheng Thermal Insulation Technology made a detailed ysis. Next, we will introduce the reasons for the fall of the external wall of the medical copper pipe and how to protect the medical copper pipe during installation. Reasons for the fall of the external wall of the medical copper pipe The medical copper pipe was not firmly fixed and moved, forming a push-pull effect, and long-term water seepage after cracks, leading to the fall of the insulation layer. 3 At the connection between the concrete beam column and the masonry, the medical copper pipe is easy to fall off due to the deformation of the masonry. 4 Scaffold holes are not solid, forming insulation layer, and local base course is not firm and damaged. 5 The surface load of the medical copper tube is too large, or the anti negative wind pressure measures are unreasonable.
.The demand for t2 copper tubes is increasing. At the same time in the market, the quality identification method of t2 copper tube for grid fittings is currently accompanied by rapid economic development. There are many kinds of sales, different types, different purposes, and different quality. Therefore, when purchasing, you should be clear and have certain selection skills. Here we introduce the quality identification method of t2 copper tube. The color of t2 copper tube depends on the color of t2 copper tube. Although the external color is a visible factor, the color of the product is closely related to its production process and quality control. If the product is bright in color and high in glossiness, it is generally superior to the product with poor color. The t2 copper tube with uniform thickness should be selected. Because some small manufacturers are limited in technology and process, it is difficult to ensure that the product thickness is uniform and neat. Therefore, the thickness is also an important factor to test the quality of the pattern plate. Later, the casting process of t2 copper tube.
The selection of medical copper tube table, these problems are natural.
What problems should we pay attention to in each production. It is a key process to weld copper pipe with correct process. Welding materials welding speed of t2 copper pipe, welding current, welding voltage, wire arrangement, spacing, inclination and other process parameters will affect the performance of the weld. The residual stress of final welded pipe affected by forming is divided into anti-corrosion performance of copper pipe. Copper pipe is a kind of production of pipe material, which is processed into seamless square pipe. The physical properties of copper tubes are slightly weaker than those of hot-rolled steel tubes. The copper tube adopts a two-step push tube expanding machine, which integrates cone die tube expansion, data medium frequency induction heating and hydraulic press. With effective processing technology, low energy consumption, less infrastructure construction, good products, and what are the production batches suitable for copper tube testing. When purchasing copper tubes, we pay more attention to their general possibilities and observations but this is effective for a few customers, but it is time-consuming and labor-intensive for many customers, and may not be able to accurately distinguish between them. For such problems, it is recommended to conduct a large number of inspections within a small scope of procurement, and then the following is how to conduct inspections. The dimension tolerance of the cleanliness and wall thickness of the inner cavity of the copper tube is strict. However, in the whole process of electric welding due to the role of the molten metal material of the air conditioning copper pipe, the thickness of the pipe at the welding point will be uneven, and the inside and outside of the welding will be uneven. This will cause energy consumption of the conveyor. At this time, the internal welding ground must be used for leveling. Next, we will take you to the production process of copper pipe - internal welding and calibration. At present, many materials are also used in the life of red copper pipes. Be as judgmental as possible when buying. In fact there are many things to pay attention to when purchasing copper tubes. Want to keep high when buying. What should we pay attention to when buying copper tubes next. The daily use and market are calculated according to the weight, so you should decide how much to use before buying.
Now let me talk about the damages that are easy to occur on the surface of the copper tube. In order to prevent the accumulation of process agents or products and/or dirt, scratches and other rough surfaces, mechanical cleaning must be carried out. If the copper pipe is heated to a certain high temperature in the air during welding or grinding, chromium oxide heat return color will appear on both sides, lower surface and bottom of the weld. The color after tempering is thinner than that of the oxidation protective film and is clearly visible. The color depends on the thickness. The thicker oxide can be found in the rainbow color, purple to brown. It is usually black. It is caused by being at high temperature or being at high temperature for a long time. When any of these oxide layers exist, the chromium content on the metal surface will, and the corrosion resistance of these areas will. In this case, it is not only necessary to heat temper the color and other oxide layers, but also to clean the chromium poor metal layer under it. Free iron on the surface of t2 copper tube will rust, causing corrosion of stainless steel. Therefore, the powder that must float can usually be removed together with the dust. Some are very sticky and must be treated as embedded iron. In addition to dust, there are many surface iron sources, including cleaning with ordinary carbon steel wire brush and shot peening with sand, glass beads or other abrasives previously used on ordinary carbon steel low alloy steel or cast iron, the wire ropes, slings and iron on the working surface can easily be embedded or dirty the surface. The copper tube shall be boiled in boiling water for 30 seconds before cold treatment. The effective internal stress is about 15%, and the residual austenite reaches the effect. Then, the cold treatment can be carried out as usual. Of course, the second suggestion is to choose the normal treatment at minus 60 degrees, the retained austenite will be rapidly transformed into martensite, but it cannot be transformed. Through experiments, it can be found that there will be about 2% of retained austenite. At this time, retained retained austenite can achieve a certain buffer effect. After cold treatment, the air conditioning copper pipes need to be taken out and put into hot water for heating, which can effectively heat about 40% of the cold treatment stress. Tempering and cold treatment should be carried out as soon as possible after gradual heating, so as to ensure that the products will not deform in later use and facilitate daily storage. The transformation characteristics of the area of each layer of the copper tube during empty drawing affect the asymmetry of the deformation of the metal material. One of its characteristics is that the natural widening of each layer along the wall thickness is not consistent. Of course, the external layer of the copper tube is less, the internal surface layer of the copper tube is larger, and the natural widening of the middle layers is slow from the external layer to the internal surface layer.The technical level of degreasing copper tube for mechanical equipment With the substantial improvement of the manufacturing level of mechanical equipment and the degree of control automation in China, there is still some gap between the technical level of domestic degreasing copper tube production line and the products of foreign counterparts. After years of reform and opening up. The quality of all aspects of degreased copper pipe has also risen by several grades, significantly narrowing the quality gap with the imported production line. The aluminum hose production line and aluminum can production line developed and produced by the company break the technological monopoly of foreign companies, can provide stable and reliable production equipment for domestic and international markets, and make great contributions to the aluminum packaging industry. With the continuous improvement of people's living standards, there will be more and more demand for degreased copper tube products, and its market potential is huge. Problems such as incomplete penetration, deformation, wood is not melted during brazing, which reduces the impact of large thermal conductivity of base metal on welding quality, prevents the formation of incomplete penetration, reduces the tendency to produce pores and cracks, and ensures the performance of weld. Because the base metal is not melted, the structure and properties of the base metal are almost unchanged, so that the original service properties of the base metal can be maintained.
Copper pipe has the characteristics of, and is the choice for the installation of water pipe, quartz sand is used as sand intercalation layer on the long distance uniform pavement in the middle of chemical fiber. Its wall thickness and structure are reasonable, and the plastic coated copper pipe laying process stipulates that the plastic coated copper pipe is a non-metallic material pipe with light quality, high strength and corrosion resistance. The glass fiber with epoxy resin based weight relief is coiled on the rotating hollow floor step by step according to the processing technology. It can make full use of the efficacy of raw materials, achieve the goal of applying compressive strength, improve the strength and stiffness, and ensure the reliability and stability of t2 copper tube. FRP sand pipe is accepted by many customers because of its excellent resistance to solvent erosion, light weight, high strength, non fouling, strong durability, long service life compared with ordinary seamless steel pipe, low comprehensive project cost, convenient installation, reliability and other advantages. Plastic coated copper pipe is used in: gray and black metallurgy industry nonferrous plate metallurgy industry, power industry, coal engineering, petroleum industry, chemical industry, electromechanical engineering industry, vehicle and motorcycle processing and manufacturing industry, railway line for industrial production, engineering construction, light industry, food industry, electronic industry, power, culture and art, sports culture and game entertainment, agriculture and animal husbandry, commercial services, Diagnosis, treatment and health and its national defense and civilian industries.
Quotation sheet.The operation is very convenient. The forward and reverse switches are set on the front panel and can be toggled up and down. The advantage is power saving (efficiency 90%, time saving (only two thirds of the time of the original rectifier, or even shorter), material saving (at the same time, raw materials can be saved 30%, and efficiency is high (more than one third of the output value of each savings). The degreased copper tube has less deformation resistance and is easier to form. The original color of copper should be orange or rose, but it is easy to oxidize into purple in the air, so it is also called degreasing copper tube. In terms of conductivity and thermal conductivity, brass rod has no hardness of copper rod, and degreased copper tube is inferior to copper wire. The defatted copper tube Huangtong brand has its own advantages and disadvantages,Mongolia304 stainless steel plate, but the differences are also luminous points. Can affect people's lives, because it can be applied to different aspects. As the conductivity of copper is better than aluminum, copper bus is widely used in electrical equipment, especially in complete power distribution equipment. The UVW phase bus and PE bus in the general distribution cabinet are copper bus; In use, for some important parts it is also considered that the yield ratio should be smaller to improve their safety and reliability. However, at this time, the utilization rate of materials is also low. Common sense: copper pipes for air conditioners are mainly used for conveying liquid, gas and steam; Boiler pipes and steam transmission pipes are used for the piping, structure and steam transmission of steam boilers, including the transmission of high-temperature and high-pressure steam; Structural pipe, widely used in aviation, automobile, tractor and other industrial sectors; Pipe for petroleum industry, such as casing, drill pipe and tubing, and pipe for petroleum refining and processing; Pipe for mechanical manufacturing, which is used to manufacture the race of ball bearing, the plunger, rotating shaft and body of air pump and hydraulic pump; High pressure vessel, used for manufacturing bottles, boilers, shells, etc. At present, copper pipes for air conditioners are mainly used in three aspects in practical applications. First, medical copper pipes are widely used in industrial plants, high-rise civil buildings, municipal engineering, oil platforms, bridges, railway vehicles and other fields. Because of their good plasticity, high structural stability and strong resistance to natural disasters, they are particularly suitable for building structures in earthquake prone areas. Second, the air conditioning copper pipe has high tensile strength and toughness, high buildings, bridges and other steel structures have good cold bending performance and welding performance, and the section size and surface quality are well controlled, so it is widely used in vehicle manufacturing, large bridge construction, mechanical manufacturing industrial plant components and many other industries. Third, air conditioning copper pipes are mainly used to make transmission line towers, microwave transfer station towers, construction crane towers, elevator supports, etc. The idea is to use weather resistant steel when making iron towers to meet the service conditions of both normal temperature and low temperature. PPM pressure roll piercer used for air conditioning copper pipe tapping rolling is not replaced by inclined roll piercer used for square steel billet. The advantage of the conical piercer is that it has the consequence of rotary euphemism casting and the of restraining the shear deformation of the square circumference and the square back. Therefore, it can prevent the defects outside the steel pipe. It can be used for the perforation of agricultural materials, especially not for the reaming and fat wall perforation. When using a general piercer, the wall thickness/pitch diameter ratio (T/D limit is about 6%, the T/D limit can be 2%. Tianjin Precision Steel Tube Factory will give you a brief introduction.
The process flow of plastic coated copper pipe: the settlement price of 904l stainless steel plate is on the high side, and the price is stable. 904l stainless steel plate: last Friday, the steel plant made all the orders. As for the guide price, the market price rose slightly on Monday due to the positive sentiment after the festival. The working efficiency of t2 copper pipe after the expansion from Tuesday to Friday should be the same. Between the upper and lower clamping groove bodies of the alloy pipe to be flared, the end of the alloy pipe to be flared faces the flaring die, extends a certain length (depending on the flaring length), and then drives the upper clamping groove body to move down through the oil cylinder. Then, the flaring hydraulic cylinder drives the flaring die to the alloy pipe, so that the t2 copper pipe flaring die will stretch the alloy pipe port to expand its inner diameter in the alloy pipe port at the front end. The length of flared section can be 20200 mm. How to solve the crack of plastic coated copper pipe? How to solve the common fault of crack in case of improper operation during the construction of plastic coated copper pipe project? If it is not handled in time, there is a serious risk. Therefore, I will carry out practical operations in strict accordance with the engineering construction specifications and requirements related to immediacy, find more practical welding processes and then ensure the welding quality of electric welding. If we continue to develop plastic coated copper pipe materials under such circumstances, we will find that the price difference of plastic coated copper pipe with low-grade anti rust materials is different, and there are many reasons for the price difference. First, there are significant differences in production. Although it is made of stainless steel, the plastic coated copper pipe can be compared with the plastic coated copper pipe on the market.
The process flow of plastic coated copper pipe: the settlement price of 904l stainless steel plate is on the high side, and the price is stable. 904l stainless steel plate: last Friday, the steel plant made all the orders. As for the guide price, the market price rose slightly on Monday due to the positive sentiment after the festival. The working efficiency of t2 copper pipe after the expansion from Tuesday to Friday should be the same. Between the upper and lower clamping groove bodies of the alloy pipe to be flared, the end of the alloy pipe to be flared faces the flaring die, extends a certain length (depending on the flaring length) and then drives the upper clamping groove body to move down through the oil cylinder. Then, the flaring hydraulic cylinder drives the flaring die to the alloy pipe, so that the t2 copper pipe flaring die will stretch the alloy pipe port to expand its inner diameter in the alloy pipe port at the front end. The length of flared section can be 20200 mm. How to solve the crack of plastic coated copper pipe? How to solve the common fault of crack in case of improper operation during the construction of plastic coated copper pipe project? If it is not handled in time,MongoliaSquare aluminum tube, there is a serious risk. Therefore, I will carry out practical operations in strict accordance with the engineering construction specifications and requirements related to immediacy, find more practical welding processes and then ensure the welding quality of electric welding. If we continue to develop plastic coated copper pipe materials under such circumstances, we will find that the price difference of plastic coated copper pipe with low-grade anti rust materials is different, and there are many reasons for the price difference. First, there are significant differences in production. Although it is made of stainless steel, the plastic coated copper pipe can be compared with the plastic coated copper pipe on the market.
Project scope.The plastic coated copper pipe is pollution-free, so the GRP sand pipe can be used to transport domestic water, the pipeline leakage problem is a problem that I can not always ignore. The area where GRP sand pipe is very easy to leak is leakproofness. The pH value of slurry in the desulfurization tower must be controlled within the range. If it is too low, the slurry will lose its absorption; On the other hand, if it is too high, the system software will cause relatively serious adverse effects of scale blocking, and the PH value will be adjusted according to the dynamic characteristics of dolomite feeding line. Relative density of desulfurization tower slurry. The thickness of plastic coated copper pipe is mainly determined by the four difficult problems: the number of layers of cloth, resin, cloth quality, the total number is gradually rising, and the application scope and units are also increasingly wide. Plastic coated copper pipe is a kind of non-metallic material pipeline with light weight, high strength and corrosion resistance. The glass fiber with resin based weight relief shall be wound on the rotating hollow floor step by step according to the processing technology regulations, and the stone sand shall be used as the intermediate weathering layer on the long distance uniform pavement in the middle of the chemical fiber.
Corrosion caused by impure copper materials.
The copper tube warehouse of automobile air conditioner shall not be stacked with acid, alkali, salt, cement and other materials that are corrosive to steel. The air conditioning copper pipe is based on carbon structural steel. The phenomenon of torsional deformation of the air conditioning copper pipe requires weeds and all sundries on the site. One or more alloy elements shall be added appropriately to improve the mechanical properties, toughness and hardenability of the annealing steel.
Mongolia.Attention shall be paid to the purchase of red copper pipe in order to study the distribution law of pipeline crack stress field under internal pressure. The simulation ysis and experimental verification are carried out for pipes with cracks of different shapes, different directions, different internal pressures and different sizes. The results show that the stress at the crack tip is much greater than that at the crack center. The crack shape has little effect on the stress. With the increase of the included angle between the crack direction and the pipe axis, crack depth, and crack length, the stress at the crack tip increases linearly. Among them the effect of crack length on the stress at the crack tip is smaller than that of internal pressure and crack depth. During the construction and operation of long-distance pipeline, due to the influence of pipe manufacturing defects, welding defects, internal and external loads, stress concentration, the pipeline will produce cracks and expand cracks, which is the most dangerous defect of long-distance pipeline and the main reason for pipeline failure. At present, pipeline cracks are mainly determined by internal testing and non-destructive testing after excavation. Among them, ultrasonic internal testing has a good identification rate for cracks with a length of more than 25 mm, a depth of more than 1 mm in the base metal or a depth of more than 2 mm in the weld; Magnetic flux leakage internal detection has a certain detection rate for cracks with opening more than 0.25mm, but it is difficult to identify and quantify. In NDT, magnetic particle, penetration, eddy current and radiographic methods have high detection and identification rate. The generation and propagation of cracks will cause local stress concentration in the pipeline, which is prone to brittle fracture, fatigue damage, corrosion damage and other failure phenomena, seriously affecting the service performance and reliability of long-distance pipeline. In this paper, the influence of crack shape, direction and size on the stress at the crack tip is yzed by studying the stress field distribution law of copper pipe cracks, which provides a reference for the prevention and control of pipe cracks. What problems will be encountered in the production of copper tubes. The production of copper pipe includes four steps: welding, forming, inspection and pipe expansion.
Some problems. For example, in the preliminary manufacturing of copper tubes for air conditioners for automobiles, the materials for air conditioners can be selected according to the actual size required by users, and then the copper tubes for air conditioners for automobiles can be manufactured, followed by pickling. The produced copper tubes for air conditioners are put into the pickling tank for pickling, and then stretched. Then the pickled copper tubes for air conditioners are stretched according to their size requirements.
The selection of medical copper tube table, these problems are natural.