Murcia321 stainless steel coiled plateDoes the application improve work efficiency?

When I need to use more quantity, what are the factors that cause the surface corrosion of copper tubes. Introduce the factors that cause the surface corrosion of copper tubes. Surface pollution: The oil, dust, acid, alkali, salt, etc. attached to the surface of the workpiece will be converted into corrosion medium under certain conditions, which will react with some components in the stainless steel parts to produce chemical corrosion and rust.

Use the medical copper tube table to eat. Because of the unique of the medical copper tube, when the oil drops on the table, it will only stick to the table, but not penetrate the table. Only with a slight wipe of the rag, the oil stains will be easily disappeared. In this case, when cleaning large canteens, the liquidators do not need to spend much effort but are relaxed. They just need to prepare a rag and a basin of clean water, and then carefully scrub it. t2 Medical Copper Tube Company thinks that the medical copper tube table is only made of the surface of the medical copper tube, and its exterior is not made of the medical copper tube. The price is cheaper than the wooden table, which is extremely suitable for a small amount of purchase. The medical copper tube has a natural bright and beautiful feeling. The color is extremely blended, and can stop the very good embellishment and reaction with the color in the surrounding situations. Now, let's understand some STEPs of the appearance processing of medical copper tubes. There are about five different methods for the appearance processing of medical copper tubes. Connect to t2 Medical Copper Tube Company and introduce them to the master. In addition these methods can also stop the combined processing and create more medical copper tubes with different appearances. No matter which method is used, the following STEPs should be followed. First, before processing, the agreement should be stopped with the manufacturer, and then a sample should be selected as the standard for future consumption. The second part when using it, we should guarantee that the coils of the base we choose to use and the coils that are not yet used are the third of the same model and batch. If they are used in some construction, such as elevators, we should pay attention to the unexpected selection of materials. In some places with extraordinary contrast, it is not appropriate to use the mirror t2 medical copper tubes. When processing, it is necessary to select the appropriate manufacturing process, such as weld grinding, how to restore the appearance. Class For the processing of the appearance of some textured t2 medical copper tubes, pay attention to the bias, which is also called unidirectionality. For example, if the lines used are vertical rather than horizontal, it is not easy to apply the dirty residue on the appearance of t2 medical copper tubes. It is extremely easy when they are clean. When finishing STEP of the process used should be added, so the cost also needs to be added. Therefore, when selecting the appearance of the processing, t2 Medical Copper Tube Company revealed that Panbo consumers should carefully select according to the situation, they should have a full understanding of the appearance of t2 Medical Copper Tube. Since the birth of medical copper tube, it has been widely used in food, crude oil, machine manufacturing and other industries for its superior . It is precisely because of this kind of universal needs that people are increasingly demanding for medical copper tubes. Although this kind of situation is basically conducive to the development of the medical copper tube industry. Having said so much, the editor of this website will introduce the most popular technology in the medical copper tube industry -- the medical copper tube appearance fingerprint free disposal punishment technology. Mentioned here, I believe that many enemies have learned the greatest advantages of this kind of technology from the name. However, do you know that this is nothing more than a contrast of significant and abstract advantages. The most one-sided introduction is also my face. The medical copper tube after adopting this kind of technical treatment has a smooth appearance and soft hand feeling, and ordinary dust and impurities are not easy to adhere. Therefore, it is also extremely easy to clean. If the ordinary dust is probably dirt, just wipe it with a wet rag and you will lose the clean and smooth appearance. Because the implementation of this kind of craft is to use electroplating oil to shine the film on the red interior line, so it has the characteristics of being tough and not easily scratched. This prevents the possibility that some slight bumps may damage the medical copper tube. It also allows the medical copper tube to be used twice as quickly. Stop the fingerprint free disposal and punish the medical copper tube after the accident. It also loses great promotion in appearance. As the saying goes, a superior appearance can always leave the best impression. Therefore, compared with the medical copper tube after the punishment and the medical copper tube without the punishment, it can often be welcomed by customers and enemies.Hot rolling and hot expansion. The main processing procedures include the blank sawing process, and the production process of the air conditioning copper pipe in the tower mainly includes cold drawing. Ring furnace heating process, piercing process, pipe rolling process, sizing process, cooling bed process, straightening process, pipe cutting soot blowing process, magnetic flux leakage detection process, surface inspection, length measurement and weighing to packaging and warehousing. Key points: yield strength limit: when the external force borne by the air conditioning copper tube sample exceeds the elastic limit of the material, although the stress no longer increases, the sample still has obvious plastic deformation. This phenomenon is called yield, that is, when the material bears an external force to a certain extent, its deformation is no longer in direct proportion to the external force, resulting in obvious plastic deformation. The stress when the air conditioning copper pipe yields is called the yield strength limit, and the corresponding S point in the tensile test curve is called the yield point. For air conditioning copper pipes with high plasticity, there will be an obvious yield point on the tensile curve, while for materials with low plasticity, there will be no obvious yield point, so it is difficult to calculate the yield limit according to the external force at the yield point. Therefore, in the tensile test method, it is usually specified that the stress when the gauge length on the specimen produces 0.2% plastic deformation is taken as the conditional yield limit, expressed as 0. The yield limit index can be used as the design basis for requiring that the parts do not produce obvious plastic deformation during operation.

Murcia.Dissolved oxygen in water is a major factor in copper pipe corrosion.

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,Murcia304L stainless steel plate, 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 integrates cone die tube expansion, low energy consumption, less infrastructure construction, good products, wide application fields of raw materials and 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, 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, 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.

.No heating and plating bath is required. The process is simple and easy to operate. The cold drawn degreased copper tube bright tin plating is one of the anti discoloration mirror bright brush tin plating and degreased copper tube tin plating mean copper bar partial or overall tin plating.

However, 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, mainly used for oil and gas exploitation, 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%, while when using a square cone piercer, the T/D limit can be 2%. Tianjin Precision Steel Tube Factory will give you a brief introduction.

When cutting the copper pipe of air conditioner use tools such as clamps to fix the copper bar and then cut it, rather than fixing it by hand, to prevent shaking and resulting in irregular cutting. 3 After the cutting of the air conditioner copper pipe is completed, the cut parts need to be placed in a dry place, and then processed again after cooling, otherwise oxidation will occur due to high temperature. Liu Shuchen, the mining super cycle driven by China's demand has not changed, especially the growth rate of the country's economy. After the global economy may improve in the second half of the year the global mining industry will rise again, and the W-shaped trend will fully emerge. In the second half of the year, there were signs of stabilizing and rebounding. In terms of the macro factors affecting the bulk commodities, the factors affecting the European market of tinned copper bars have gradually weakened, and the economic conditions of China and the United States have become the key factors affecting the bulk commodities. The European economic recession is a foregone conclusion, and the possibility of a crisis in the next period of time is also reduced. In recent years, the American market economy has shown the characteristics of better than expected in the first quarter and weaker than expected in the second quarter. Since January, the global price of medical copper tubes has gradually got rid of the main tone of this year's shock and decline. &Air conditioning copper tubes show signs of stabilizing and rebounding. The three-month copper on the London Metal Exchange once rebounded nearly 7% from the year's low point, and the market price has rebounded to around 7600 dollars per ton. Driven by this, products including aluminum, zinc and other products have also rebounded. Only nickel, a basic metal product has remained weak.

The utility model relates to a connecting structure, in particular to a connecting structure of a copper tube and an aluminum row. At present, most of the copper aluminum transition joints have not been effectively protected. In this way, under the condition of long-time electrification and heating and affected by the water vapor or corrosive gas in the air, the parts at the connection point are more likely to be oxidized, resulting in the reduction of the effective contact area of the connection point, the increase of the contact resistance, and the excessive heating or even burning of the connection point.

The hard copper tube is not artificially treated after being drawn or extruded, so that it can be naturally formed. At this time, the organizational form in the copper tube is full. This kind of copper tube is more likely to crack and is not suitable for bending. Therefore, the hard copper tube is generally straight.

No heating and plating bath is required. The process is simple and easy to operate. The cold drawn degreased copper tube bright tin plating is one of the anti discoloration mirror bright brush tin plating and degreased copper tube tin plating mean copper bar partial or overall tin plating.

Where is it.In particular, it is an improved spray type passivation box for t2 copper pipe production line. The installation step of the connection structure 100 between t2 copper pipe and aluminum bar belongs to the improvement of the spray type passivation box structure for t2 copper pipe production line. The passivation solution spray box is set above the side of the passivation solution box,Murcia316L stainless steel coiled plate, the passivation solution spray box with downward sloping bottom is connected with the inlet of the passivation solution box by the outlet set on the box wall at the bottom of the inclined bottom, the inlet of the passivation solution box is located on the box wall above the passivation solution box, the upper side of the passivation solution box is installed with a passivation pump, and the inlet pipe of the passivation pump is connected with the passivation solution box, The outlet pipe of the passivation pump is connected with the upper port of the passivation liquid spray box. With reasonable structure and convenient operation, it is convenient for operators to add passivation liquid to the passivation box, clean colloidal crystals at the bottom of the passivation box, avoid equipment blockage, avoid crystals adhering to the zinc layer on the surface of galvanized pipe, and improve the surface quality of galvanized steel pipe.

In future work, try to protect the surface of the copper tube.

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, 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, 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, and then conduct deep cooling at minus 120 degrees. The lower the treatment temperature is, 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, 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, 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, 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.

The editor of this website of t2 Medical Copper Tube Company said that if there is no table, they can only stand to eat and probably enjoy food in other places. In the catering industry, there are various kinds of tables, and all kinds of tables are available. There are wooden tables and medical copper controlled tables. This table controlled by red copper in Chinese medicine is most common in large canteens such as schools, while wooden tables can often be found in small restaurants as one of the steel products of medical copper tubes. As his name is common, medical copper tubes have the ability to prevent rust. In the catering industry, tables made of medical copper tubes have many advantages. Next, Ltd. will introduce you to the master. The medical copper tube table is easy to see in the large canteen. This kind of canteen is extremely large, and the number of tables is amazing, it will cost a lot of money, 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, 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, and then conduct deep cooling at minus 120 degrees. The lower the treatment temperature is, 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, 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, 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, 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.

{2} The excellent performance of copper pipe The welded copper pipe has the characteristics of firmness and corrosion resistance, which makes it a suitable choice for modern contractors to install the water pipe, heating pipe and refrigeration pipe in all residential commercial houses.

In addition,MurciaAluminum row of cold storage, the stress corrosion cracking inside the stainless steel plate will cause the transition film on the surface of the stainless steel plate. Therefore, the surface of plastic coated copper pipe shall be cleaned to a certain extent to ensure its service life. The oil cracking tube circuit breaker must be selected. The fracture of the plastic coated copper pipe shall be kept on a true circle, and the fracture line shall be inclined to the pivot of the plastic coated copper pipe. Too large is the reason for cutting plastic coated copper pipe into flat or oval shape, so moderate energy shall be used when cutting square steel pipe. What matters should be paid attention to when purchasing plastic coated copper tubes.

Murcia.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, the stress at the crack tip first increases and then decreases. With the increase of the pipe internal pressure, 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, corrosion defects and other factors, 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.

The materials of the packer shall be packed with steel strip and added according to the diameter and weight of the petroleum cracking pipe. The degreased copper pipe from the pipe can be packed without a packer. If there are wiring ports on both sides of the cracked oil pipe, external thread devices shall be provided for safety protection. Brush the nozzle with clean oil or anti rust oil. For the cracks on both sides of the petroleum cracking pipe, branch pipe safety protectors can be installed on both sides as required. If the oil cracking pipe is installed in the container, the container shall be lined with waterproof devices, such as woven cloth and straw mats. In order to better distribute the textile petroleum cracking tubes in the tank, the packer can weld the safety protection support frame inside the petroleum cracking tubes. Previous page: How to clean plastic coated copper tubes. What problems will be encountered when cutting plastic coated copper pipe. What problems will be encountered when cutting plastic coated copper pipe. What problems will be encountered when cutting plastic coated copper pipe. When plastic coated copper pipe is cut, the wound is uneven and cracked. Then I will introduce how to solve these problems. For the disconnection part of plastic coated copper pipe, the position and direction shall be drawn with tape or other measuring tools and the disconnection line shall be marked in combination with the construction drawing and site conditions. When the petroleum cracking pipe is disconnected, please fix the equipment with square steel pipes such as vises, and cut it after fixing. In the area to be disconnected, use a towel or soft cloth to crack the oil stain or dirt on the surface of the pipe. As we all know, if steel pipes are exposed outdoors for a long time, or there are some, they will damage the air oxide layer on the surface of the stainless steel plate, plastic coated copper tube has incomparable advantages, because its surface is not easy to be oxidized, which is the key to constitute the raw material of plastic coated copper tube. The high-precision plastic coated copper pipe has an extremely thin, firm and smooth chromium rich air oxide film on its surface to prevent oxygen molecules from re penetrating and re oxidizing in the air, thus preventing rust. The description of the plastic coated copper pipe shows that the part with weak corrosion resistance of the transition film will produce pitting corrosion reaction due to the self-excited reaction, and the small holes will form highly corrosive aqueous solution. The chloride ion content will accelerate the corrosion rate.

The surface coating of medical copper tube is very important. Observe its thickness, how to prevent the aging of medical copper tube? How to select the foam density of medical copper tube Good medical copper tube and foam density are very high and hard. Check the quality of aluminum zinc coated color steel plate on the surface. As exterior wall thermal insulation decorative plate. Then use your hand to break it up and down to see if it is easy to deform. If you break it with force, it will deform, which is not good. 3 See the price.