topper
Functions of Steel Plastic Compound Pipes And Plastic Lined Pipes
Jan 22, 2022
da***********01
On this page
As the replacement products of drinking water pipeline, steel plastic compound pipes and galvanized plastic lined compound pipes completely solve the secondary pollution problem caused by galvanized pipes, which is a revolution of the pipeline industry. Both of them have the characteristics of high mechanical strength, stable pressure bearing performance and long service life, but they have essential differences.
The steel plastic compound pipe is a compound pipe with five layers structure, and its inner pipe is an HDPE pipe continuously extruded by extruders. The inner layer is sanitary and non-toxic, pollution-free. The inner wall is smooth with no scaling and no bacteria breeding. The fluid resistance and head loss are small. The outer PE layer has excellent anti-corrosion, anti-aging and decoration effects. We here introduce to everyone the related knowledge of steel plastic compound pipes and plastic lined steel pipes.
Steel plastic compound pipes
The steel plastic compound pipe is based on seamless steel pipes and welded steel pipes, and the inner wall is coated with polyethylene powder coating or epoxy resin coating with high adhesion, anti-corrosion and food grade hygiene. The galvanized steel pipe with plastic coating for water supply is made by pretreatment, preheating, internal coating, leveling and post-treatment processes. This is an upgraded product of traditional galvanized pipes, and the steel plastic compound pipe is generally connected with threads.
The structure of steel plastic compound pipes is a new type of compound pipes, which are called steel plastic pipes in many places. Steel is a kind of iron material. The plastic material of steel plastic compound pipe is generally high-density polyethylene (HDPE).
There are many classifications of steel plastic compound pipes, which can be classified into steel belt reinforced steel plastic compound pipes, seamless steel pipes reinforced steel plastic compound pipes, hole mesh steel strip steel plastic compound pipes and steel plastic compound pipes with steel mesh framework. At present, the most popular steel belt reinforced steel plastic compound pipes is the steel plastic compound pressure pipe we call.
It is often said to have a middle layer of high carbon steel strip welded by crimping and butt welding, and the inner and outer layers are high density polyethylene (HDPE). The middle layer of the pipe is a steel belt, so the pressure bearing performance of the pipe is very good. Different from the aluminum strip, the maximum diameter of the pipe can only be 63 mm, and the maximum diameter of the steel plastic pipe can be 200 mm or even larger. Because the steel belt in the middle layer of the pipe is closed, the steel plastic pipe has the oxygen resistance function at the same time, and it can be directly used in direct drinking water engineering, and the inner and outer layers are plastic material. It has very good corrosion resistance. Such excellent performance makes the steel plastic compound pipes widely used, such as oil and natural gas transportation, industrial and mining pipes, drinking water pipes, drainage pipes and other fields.
Plastic lined steel pipes
The plastic lined steel pipe is based on galvanized seamless steel pipes and welded steel pipes. After removing the welding rib on the inner wall, it is lined with the food grade polyethylene (PE) pipe with the same diameter as the galvanized pipe. The thickness of the polyethylene lining layer should meet the CJ/T136-2007 standard. Finally, it will be formed after heating under pressure for a certain time. It is an upgraded product of traditional galvanized pipes.
Advantages and disadvantages of plastic lined steel pipes
Advantages
1. Wide range of applications and complete specifications and varieties
As of June 19, 2013, the long-term service pressure of water supply pipes and fire-fighting pipes for high-rise buildings is about 1.6Mpa in the building water supply industry.
Therefore, the design pressure of embedded plastic lined steel pipes with internal reinforcement at 2.0MPa can basically meet the pressure requirements of building water supply, and this parameter is also an important parameter for wall thickness design. The service temperature is also an important parameter in pipe design, which determines the allowable stress of material. According to the temperature of water transported in the industry, it is divided into cold water and hot water. The temperature of cold water is generally 0 ℃-25 ℃. However, the medium temperature in the surface mounted pipeline is affected by the atmospheric temperature. The temperature in the south of China can be as high as 40 ℃ in summer, while the temperature in the north can be lower than - 40 ℃ in winter. The water will solidify into ice below 0 ℃, so the purpose of water use can not be achieved. Therefore, there are some specifications for insulation in the industry, so that the temperature of water in the pipeline has been kept above 0 ℃ to maintain the fluidity of the fluid. Hot water is generally used for heating and showers. The water temperature is usually below 75 ℃ and the instantaneous temperature can reach about 95 ℃. Based on the above investigation, the embedded plastic lined steel pipe with inner reinforcement is divided into cold water type and hot water type. It is determined that the long-term service temperature of cold water type is 0 ℃-55 ℃. The long-term service temperature of hot-water pipe is 0 ℃-75 ℃, and the instantaneous temperature can reach 95 ℃.
2. Unique production process
After the product structure is determined, that which process is used for production is crucial in economic activities as of June 19, 2013.
It is directly related to the production cost and efficiency of the product, and on the other hand, it puts forward the technological requirements for the structural design and material selection of the product. The plastic lined steel pipes with inner reinforcement adopt a unique mechanical drawing composite process. The inner plastic pipe is compressed by reducing the diameter of the metal pipe, so that the two materials have permanent reasonable interference. In addition, the unique design of the inner surface of the welded pipe has the embedding effect on the outer surface of the plastic pipe, as well as the physical and chemical modification before the plastic pipe is the compounded layer, non shrink pipes, long-term use of guaranteed technical features. In 2001, it obtained the national utility model patent. This unique process has high production efficiency, easy process control and high composite quality.
3. Reliable and fast connection mode
The connection mode between pipelines is the most important problem in the building materials industry. The connection strength can not be reliable, which is not convenient for installation and maintenance, and whether it can adapt to harsh natural conditions. These problems are the most concerning problems of users, design, construction and other units. Using the principle of cold extrusion, the embedded plastic lined steel pipe with inner reinforcement forms a small circular arc groove by drawing at a certain distance from the end face of the pipe. Then, the stainless steel clasp of the snap spring type is placed in the groove, and the nut or sexual expansion interface, new enamel pipe fittings and accessories are sheathed, and the installation is fast. Because of the self-locking cone surface design of the mating part of the snap ring and the use of the end and radial two-way seal design, it has reliable connection strength and anti leakage performance. It is easy to use because of the special structure of the union and the use of the union is extremely convenient.
4. Perfect corrosion prevention measures for the outer surface
As we all know, the corrosion of steel is very common, and the economic loss is huge.
We know that the corrosion of steel is mainly due to electrochemical corrosion, and the corrosion aging of plastics is mainly caused by chemical corrosion and ultraviolet radiation. As the inner plastic pipe is protected by the outer metal pipe, the causes of plastic corrosion aging are completely eliminated, and the plastic pipe has durable performance. The protection of the outer metal tube is much more difficult. Three anti-corrosion measures are adopted on the outer surface of the embedded plastic lined steel pipe with inner reinforcement: the first layer is the galvanized layer, and the steel pipe forms a cathode for protection and rust prevention. The second layer is the epoxy primer, which forms a dense polymer protective film on the surface of zinc coating to isolate it from air and water, slow down the oxidation and corrosion of zinc layer, so as to improve the service life of pipes. The third layer is the topcoat, which can strengthen the protection of the film and improve the beauty of the product. When it is used in the underground, appropriate anti-corrosion measures should be taken to improve the service life of the system. It can also be used in the "embedded double-sided plastic lined steel pipes" (PE pipes + carbon steel pipes + PP pipes series products) with plastic lined steel pipes as the base pipe and a layer of plastic pipes on the outer surface.
5. Reasonable wall thickness of welded pipes
The wall thickness is an important parameter. The design formula of pipe wall thickness given in volume 3 of Mechanical Design Manual: S=PD/(2[δ]ψ)+C ( marks: S: wall thickness (mm); P: medium pressure in pipes (MPA); D: outer diameter of pipes (mm); [δ]: allowable stress of pipes under working temperature (MPA); J: longitudinal weld coefficient of pipes, j = 1; butt welded steel pipe J = 0.8; C: The additional value of pipe wall thickness (mm); including manufacturing negative deviation C1; corrosion allowance C2; thread depth C3; C = C1 + C2 + C3. The wall thickness of the welded pipe is determined according to the above theory. The allowable stress [δ] of pipeline material is generally divided by the corresponding safety factor according to the strength of the material, and the minimum value is taken as the allowable stress of the material, which is the allowable stress of the pipeline material. At the same time, due to the internal reinforcement embedded plastic lined steel pipe adopting snap ring connection and cold extrusion deformation grooving, it is not necessary to consider the additional value of pipe wall thickness C3. Therefore, compared with the traditional galvanized steel pipe, the wall thickness is more reasonable and the economy has obvious potential.
Disadvantages: high cost and time-consuming installation. It can not solve the problem of water pollution.
The steel plastic compound pipe is a compound pipe with five layers structure, and its inner pipe is an HDPE pipe continuously extruded by extruders. The inner layer is sanitary and non-toxic, pollution-free. The inner wall is smooth with no scaling and no bacteria breeding. The fluid resistance and head loss are small. The outer PE layer has excellent anti-corrosion, anti-aging and decoration effects. We here introduce to everyone the related knowledge of steel plastic compound pipes and plastic lined steel pipes.
Steel plastic compound pipes
The steel plastic compound pipe is based on seamless steel pipes and welded steel pipes, and the inner wall is coated with polyethylene powder coating or epoxy resin coating with high adhesion, anti-corrosion and food grade hygiene. The galvanized steel pipe with plastic coating for water supply is made by pretreatment, preheating, internal coating, leveling and post-treatment processes. This is an upgraded product of traditional galvanized pipes, and the steel plastic compound pipe is generally connected with threads.
The structure of steel plastic compound pipes is a new type of compound pipes, which are called steel plastic pipes in many places. Steel is a kind of iron material. The plastic material of steel plastic compound pipe is generally high-density polyethylene (HDPE).
There are many classifications of steel plastic compound pipes, which can be classified into steel belt reinforced steel plastic compound pipes, seamless steel pipes reinforced steel plastic compound pipes, hole mesh steel strip steel plastic compound pipes and steel plastic compound pipes with steel mesh framework. At present, the most popular steel belt reinforced steel plastic compound pipes is the steel plastic compound pressure pipe we call.
It is often said to have a middle layer of high carbon steel strip welded by crimping and butt welding, and the inner and outer layers are high density polyethylene (HDPE). The middle layer of the pipe is a steel belt, so the pressure bearing performance of the pipe is very good. Different from the aluminum strip, the maximum diameter of the pipe can only be 63 mm, and the maximum diameter of the steel plastic pipe can be 200 mm or even larger. Because the steel belt in the middle layer of the pipe is closed, the steel plastic pipe has the oxygen resistance function at the same time, and it can be directly used in direct drinking water engineering, and the inner and outer layers are plastic material. It has very good corrosion resistance. Such excellent performance makes the steel plastic compound pipes widely used, such as oil and natural gas transportation, industrial and mining pipes, drinking water pipes, drainage pipes and other fields.
Plastic lined steel pipes
The plastic lined steel pipe is based on galvanized seamless steel pipes and welded steel pipes. After removing the welding rib on the inner wall, it is lined with the food grade polyethylene (PE) pipe with the same diameter as the galvanized pipe. The thickness of the polyethylene lining layer should meet the CJ/T136-2007 standard. Finally, it will be formed after heating under pressure for a certain time. It is an upgraded product of traditional galvanized pipes.
Advantages and disadvantages of plastic lined steel pipes
Advantages
1. Wide range of applications and complete specifications and varieties
As of June 19, 2013, the long-term service pressure of water supply pipes and fire-fighting pipes for high-rise buildings is about 1.6Mpa in the building water supply industry.
Therefore, the design pressure of embedded plastic lined steel pipes with internal reinforcement at 2.0MPa can basically meet the pressure requirements of building water supply, and this parameter is also an important parameter for wall thickness design. The service temperature is also an important parameter in pipe design, which determines the allowable stress of material. According to the temperature of water transported in the industry, it is divided into cold water and hot water. The temperature of cold water is generally 0 ℃-25 ℃. However, the medium temperature in the surface mounted pipeline is affected by the atmospheric temperature. The temperature in the south of China can be as high as 40 ℃ in summer, while the temperature in the north can be lower than - 40 ℃ in winter. The water will solidify into ice below 0 ℃, so the purpose of water use can not be achieved. Therefore, there are some specifications for insulation in the industry, so that the temperature of water in the pipeline has been kept above 0 ℃ to maintain the fluidity of the fluid. Hot water is generally used for heating and showers. The water temperature is usually below 75 ℃ and the instantaneous temperature can reach about 95 ℃. Based on the above investigation, the embedded plastic lined steel pipe with inner reinforcement is divided into cold water type and hot water type. It is determined that the long-term service temperature of cold water type is 0 ℃-55 ℃. The long-term service temperature of hot-water pipe is 0 ℃-75 ℃, and the instantaneous temperature can reach 95 ℃.
2. Unique production process
After the product structure is determined, that which process is used for production is crucial in economic activities as of June 19, 2013.
It is directly related to the production cost and efficiency of the product, and on the other hand, it puts forward the technological requirements for the structural design and material selection of the product. The plastic lined steel pipes with inner reinforcement adopt a unique mechanical drawing composite process. The inner plastic pipe is compressed by reducing the diameter of the metal pipe, so that the two materials have permanent reasonable interference. In addition, the unique design of the inner surface of the welded pipe has the embedding effect on the outer surface of the plastic pipe, as well as the physical and chemical modification before the plastic pipe is the compounded layer, non shrink pipes, long-term use of guaranteed technical features. In 2001, it obtained the national utility model patent. This unique process has high production efficiency, easy process control and high composite quality.
3. Reliable and fast connection mode
The connection mode between pipelines is the most important problem in the building materials industry. The connection strength can not be reliable, which is not convenient for installation and maintenance, and whether it can adapt to harsh natural conditions. These problems are the most concerning problems of users, design, construction and other units. Using the principle of cold extrusion, the embedded plastic lined steel pipe with inner reinforcement forms a small circular arc groove by drawing at a certain distance from the end face of the pipe. Then, the stainless steel clasp of the snap spring type is placed in the groove, and the nut or sexual expansion interface, new enamel pipe fittings and accessories are sheathed, and the installation is fast. Because of the self-locking cone surface design of the mating part of the snap ring and the use of the end and radial two-way seal design, it has reliable connection strength and anti leakage performance. It is easy to use because of the special structure of the union and the use of the union is extremely convenient.
4. Perfect corrosion prevention measures for the outer surface
As we all know, the corrosion of steel is very common, and the economic loss is huge.
We know that the corrosion of steel is mainly due to electrochemical corrosion, and the corrosion aging of plastics is mainly caused by chemical corrosion and ultraviolet radiation. As the inner plastic pipe is protected by the outer metal pipe, the causes of plastic corrosion aging are completely eliminated, and the plastic pipe has durable performance. The protection of the outer metal tube is much more difficult. Three anti-corrosion measures are adopted on the outer surface of the embedded plastic lined steel pipe with inner reinforcement: the first layer is the galvanized layer, and the steel pipe forms a cathode for protection and rust prevention. The second layer is the epoxy primer, which forms a dense polymer protective film on the surface of zinc coating to isolate it from air and water, slow down the oxidation and corrosion of zinc layer, so as to improve the service life of pipes. The third layer is the topcoat, which can strengthen the protection of the film and improve the beauty of the product. When it is used in the underground, appropriate anti-corrosion measures should be taken to improve the service life of the system. It can also be used in the "embedded double-sided plastic lined steel pipes" (PE pipes + carbon steel pipes + PP pipes series products) with plastic lined steel pipes as the base pipe and a layer of plastic pipes on the outer surface.
5. Reasonable wall thickness of welded pipes
The wall thickness is an important parameter. The design formula of pipe wall thickness given in volume 3 of Mechanical Design Manual: S=PD/(2[δ]ψ)+C ( marks: S: wall thickness (mm); P: medium pressure in pipes (MPA); D: outer diameter of pipes (mm); [δ]: allowable stress of pipes under working temperature (MPA); J: longitudinal weld coefficient of pipes, j = 1; butt welded steel pipe J = 0.8; C: The additional value of pipe wall thickness (mm); including manufacturing negative deviation C1; corrosion allowance C2; thread depth C3; C = C1 + C2 + C3. The wall thickness of the welded pipe is determined according to the above theory. The allowable stress [δ] of pipeline material is generally divided by the corresponding safety factor according to the strength of the material, and the minimum value is taken as the allowable stress of the material, which is the allowable stress of the pipeline material. At the same time, due to the internal reinforcement embedded plastic lined steel pipe adopting snap ring connection and cold extrusion deformation grooving, it is not necessary to consider the additional value of pipe wall thickness C3. Therefore, compared with the traditional galvanized steel pipe, the wall thickness is more reasonable and the economy has obvious potential.
Disadvantages: high cost and time-consuming installation. It can not solve the problem of water pollution.
