Dusseldorf60SI2MN alloy round steelThe scientific method of how to resist in life

The plastic coated copper pipe is pollution-free, so the GRP sand pipe can be used to transport domestic water, and it is not easy to have the odor generated by the pipe itself.As we all know, 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, and the thickness of glass fiber filament winding. The production and manufacturing of plastic coated copper pipe in China has a fast development trend, 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,Dusseldorf310s stainless steel welded pipe, 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.

Xiao Bian would like to talk about the production of a copper tube for automotive air conditioners to help you better understand this product. During the production of automotive air conditioning copper tubes, bending deformation and torsion deformation are very easy to occur. Therefore, attention should be paid to the use of straighteners in production, and the tubes should be straightened to meet the requirements of automobiles for automotive air conditioning copper tubes. The air conditioner copper pipe straightener uses vertical and horizontal rubber rollers to straighten it, so that the air conditioner copper pipe can be used by users to a certain extent.Nowadays, most straighteners can only straighten some copper pipes for automobile air conditioners with low accuracy, while most straighteners with high accuracy can only straighten some copper pipes for automobile air conditioners with small defects. Therefore, the straightening equipment used for rectangular pipes with different bending degrees is different, which brings a lot of inconvenience to the production of copper pipes for automobile air conditioners. Therefore, some other construction processes should be used, To solve some problems arising from the above production. For example, in the preliminary manufacturing of medical copper tubes for automobiles, the air conditioner copper tube materials can be selected according to the actual size required by the user, and then the air conditioner copper tubes for automobiles can be manufactured, followed by pickling, putting the produced air conditioner copper tube materials into the pickling tank for pickling, and then stretching, and then stretching the pickled air conditioner copper tubes according to their size requirements. The warehouse shall not be mixed with acid Alkali, salt, cement and other materials that are corrosive to steel are stacked together. Air conditioning copper pipe is based on carbon structural steel. The phenomenon of torsional deformation of 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. The automobile air conditioner copper tube is also called the air conditioner copper tube. In fact, it refers to a kind of air conditioner copper tube with equal side length. The automobile air conditioner copper tube is made of strip steel as raw material, and then processed and rolled by relevant processes. It is generally made into a circle after the strip rod is unpacked, straightened, curled and welded. Among them, hardness is an index to measure the degree of hardness and softness of automotive air conditioner copper tubes. At present, the commonly used hardness method for measuring product hardness in production refers to the use of an indenter with a certain geometric shape to measure the hardness value of the metal surface being tested under a certain load according to its degree of coverage. The air conditioner copper pipe in the automobile air conditioner copper pipe is also divided into weld and seamless. Seamless air conditioner copper pipe is a metal material formed by directly using seamless round pipe. The plasticity of the air conditioner copper pipe refers to the ability to deform under a certain load without its original performance. The copper pipe for automobile air conditioner is a hollow and square section. The light thin-walled copper pipe for air conditioner is also known as steel cold-formed profile. It is a square section steel made of strip or coiled plate after processing in the cold bending area and high-frequency welding. In addition to being used in the automobile industry, the air conditioning copper pipes are used in construction, machinery manufacturing, steel construction and other projects, solar power generation support, steel structure engineering, electric power engineering, power plants, boiler construction glass curtain walls, highway railings, housing construction, oil tanks, bridges, power station equipment, lifting and transportation machinery and other high load welding structures. In addition to the thickening of the wall, the size and external straightness of the extra thick wall air conditioning copper tube can both exceed the water content of the resistance welded cold formed air conditioning copper tube. Therefore, this kind of automobile air conditioning copper tube has better comprehensive mechanical properties and has the advantages of hot processing, weldability and corrosion resistance.

Dusseldorf.When installing, the copper pipe has the advantages of low transportation cost, easy maintenance and small space occupation.

Copper tube has good bearing capacity. For example in large cities, road bridges and undersea bridges often appear. Most road bridges are built with plastic coated copper pipes. With plastic coated copper pipes, engineering construction in large cities will become stronger and stronger. The actual operator shall carry out the actual operation of the heating furnace, yze the materials of the heating furnace determine the cleaning, and select the type and concentration of cleaning solution. Pay attention to the cleaning time and temperature to develop more effective solutions, and also develop some safety protection measures. An obvious feature of plastic coated copper pipe is heat resistance, because this kind of seamless steel pipe for heating furnace is mainly used for machining parts. Because the seamless steel pipe must be heated at high temperature during production and processing. What are the plastic coated copper tubes to prevent wear. What are the plastic coated copper tubes to prevent wear. We all know that all objects will wear in application, so how to prevent the wear of oil cracked pipes. Now let's introduce it to you. The packaging of petroleum cracking tubes shall be able to prevent and damage during normal loading, unloading, transportation and storage. If the Demander has special requirements for packaging materials and packages of petroleum cracking tubes, it shall be indicated in the contract; If it is not marked, the supplier shall select packaging materials and packaging. Packaging materials shall comply with relevant requirements. If the material is not packaged, it should be suitable for the intended use and avoid obvious and natural purification. If the customer stipulates that the surface layer of the cracked tubing should not be damaged by bumps it can be considered to repair and install the cracked tubing in the middle. Rubber sleeves, tree trunks, straw ropes, fiber cloth, plastics, pipe caps, etc. can be used for maintenance and installation. The thick wall petroleum cracking pipe can choose the internal fulcrum or external structure. Because thick walled tubes are thin. The supporting frame and frame are made of steel, which is inconsistent with the plastic coated copper pipe. If the customer needs a packer, the petroleum cracking tube can be weighed in a decentralized way. However, the specification must be 159MM500MM.

.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.

Air conditioning copper pipe is a common metal material in daily work of industrial production. The conductivity, heat conduction and corrosion resistance are excellent, and the W shape trend of air conditioning copper pipe is depressed due to the high copper content. Good machinability, the cutting machine should carry out calibration and other operations. You can try to use scrap metal first to prevent machine problems from causing me to cut off defective products.

In addition, brass has a unique sound so the gongs, cymbals, bells, horns and other instruments in the East, as well as the western brass instruments, are all made of brass, which is a kind of non-ferrous metal processing bar, with good processing performance and high conductivity. It is mainly divided into copper tube (copper zinc alloy, cheaper). The manufacturing principle of copper tube: All elements without exception reduce the conductivity and thermal conductivity of the copper bar. All elements are dissolved in the copper bar, causing lattice distortion of the copper bar, causing wave dispersion when free electrons flow in a directional direction, increasing the resistivity. On the contrary, there are no or few elements with solid solution in the copper bar, which has little impact on the conductivity and thermal conductivity of the copper bar, Special attention should be paid to the fact that the solid solubility of some elements in the copper bar decreases sharply with the decrease of temperature. The precipitation of simple substances and metal compounds can not only strengthen the copper bar alloy by solid solution and dispersion, but also reduce the conductivity slightly. This is an important alloying principle for the study of high-strength and high conductivity alloys. Here, it should be pointed out that the alloy composed of iron, silicon, chromium and copper bar is a very important high-strength and high conductivity alloy; As the influence of alloy elements on the properties of copper bars is superposition, CoCrZr series alloys are * high-strength and high conductivity alloys; It is not easy to heat. Semi continuous casting copper tube has excellent conductivity. Copper tube has excellent conductivity. Alloy copper to ensure safety and fatigue resistance. Tin phosphor bronze jack adopts hard wire electrical structure without rivet joint or conflict contact, which can ensure excellent touch, good elasticity and smooth dial. Phosphor bronze has high corrosion resistance, wear resistance, and will not produce sparks when stamping. It is used for medium speed and heavy load bearings. The working temperature is up to 250 ° C, and the bearing capacity is high. It can withstand radial load and self lubrication without protection. The company is a manufacturer specializing in the production of various bronze tubes, bronze plates and profiled bronze profiles. Technical advantages: The maximum diameter of bronze bars and pipes can reach 300mm, while that of plates can reach 600mm. The wall thickness of bronze tube can be as small as 4mm. The copper tube is a common bronze material. The aluminum content of copper tube generally does not exceed 5%. Sometimes, an appropriate amount of iron, nickel, the aluminum content is 5%, and the 7% copper tube has good plasticity and is suitable for cold working.

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 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.

Finished products must be stored indoors. During storage, they should be protected from direct sunlight to the copper tubes. During the transfer transportation and loading and unloading of copper tubes, rain should be avoided; In summer, pay attention to the principle of first in first out to reduce no loss; The copper pipe loading process is better carried out indoors to avoid the copper pipe being exposed to the sun and the speed of copper pipe surface is accelerated. When storing copper pipe, so as to accelerate the speed of the outer wall of the copper pipe. After the loading is completed, at least two layers of canvas shall be used to tightly wrap the whole vehicle materials; After loading, if the truck can not depart in time, the truck shall be driven to the back of the sun to prevent the goods from being exposed to the sun for a long time to absorb heat.

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,DusseldorfAluminum plate, widely used in aviation, automobile, tractor and other industrial sectors; Pipe for petroleum industry mainly used for oil and gas exploitation, such as casing, drill pipe and tubing, which is used to manufacture the race of ball bearing, 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, 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.

equipment maintenance .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.

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 ℃.

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,Dusseldorfcopper Stick, acid, alkali, salt, which will react with some components in the stainless steel parts to produce chemical corrosion and rust.

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 sheet metal shall be first opened in the sheet metal workshop according to the dimensions shown in the drawings, which is commonly referred to as opening. Then cut the corners of these open sheets according to the height of the edge, and then use the bending machine to form the edge according to the drawing forming diagram. The shaped copper pipe shall also be installed with reinforcing ribs as required, and the four corners of the shaped plate shall be welded well. The welded parts shall be sent to the grinding workshop, the surface of the sculpted copper pipe shall be chrome treated and the process hole shall be drilled so as to ensure that the sculpted copper pipe can be hung on the spraying line well, and the painting can be smooth without flow marks, and the color is consistent without color difference. After that, according to customer demand, the qualified products are pasted with protective film and bound with bubble film or wooden box.

Copper pipe has the characteristics of firmness and corrosion resistance, and is the choice for the installation of water pipe, heating pipe and refrigeration pipe.

Generally speaking, professional t2 copper tube manufacturers will adopt an integrated molding process to improve the yield and reduce production costs while packaging products with superior performance. As long as the above t2 copper tube quality identification method is used, it is basically guaranteed to purchase t2 copper tubes with reliable quality. If long-term and large-scale procurement is required, it is recommended to go to the manufacturer for field inspection to determine the basic performance and quality of t2 copper tubes before large-scale mold procurement. The position of grid accessories plays a very important role in the whole construction process. The products with high cost performance and good performance certainly have a great assistance effect for the implementation of the project. In addition, it is also beneficial to the application of the middle and later stage of the forming project. There are high regulations for the performance of the grid. How about the corrosion resistance of the grid accessories? The performance of durable products such as grid and grid accessories needs to meet certain technical standards. The anti-corrosion performance of grid production and processing must be good. For manufacturers, it is necessary to improve technology and consider the performance requirements of today's construction projects. In fact, the anti-corrosion performance of accessories is not very good. It is necessary to take protective measures in the production and application process to reduce product erosion, Only by maintaining the overall reasonable layout of the grid products can we ensure the long-term performance advantages. Many technologies are required in the whole process of production and manufacturing of space truss accessories. The production and manufacturing staff should ensure the performance advantages when carrying out production and manufacturing of products. The production and processing of space truss should improve its corrosion resistance, compression resistance and strength to ensure that qualified products are produced by the original factory.

Dusseldorf.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.

It is applicable to the removal of thin liquid oil stain and light rust and the generation of phosphating film with certain corrosion resistance. See Table 3 for example of formula and operating conditions. Table 3 Degreasing, rust removal, phosphating and passivation

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, 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 ℃.