Technology of embedded inner lining plastic steel pipe

With the popularization of people's environmental awareness and health awareness, new types of environmentally friendly water supply pipes have sprung up, and many varieties are difficult to enumerate. As a domestic patented technology product, the embedded lining plastic steel pipe has been favored by users since its launch in 2001, and its sales have doubled year after year. It inherits the respective advantages of steel pipes and plastic pipes, while at the same time abandoning their respective shortcomings. One of the most important aspects of pipe design is to reasonably determine the wall thickness of the pipe according to the conditions of use and requirements, and this parameter directly affects the cost performance of the product. The unique wall thickness design of the inner rib embedded plastic pipe includes the inner layer plastic pipe wall thickness and the outer pipe wall thickness, which determines a series of technical features of the inner rib embedded plastic pipe.

First, the scope of application is wide, the specifications are complete

At present, in the building water supply industry, the long-term use pressure of the water supply pipe and fire-fighting pipe of the high-rise building is about 1.6 MPa. Therefore, the design pressure of the inner-reinforced embedded plastic-lined steel pipe is determined to meet the pressure requirement of the building water supply at 2.0 MPa. At the same time, this parameter is also an important parameter for wall thickness design. The temperature of use is also an important parameter in the design of the pipe, which determines the allowable stress of the material. In the industry, the temperature of the conveying water is divided into cold water and hot water. The temperature of the cold water is generally 0 °C ~ 25 °C, but the medium temperature in the exposed pipeline is affected by the atmospheric temperature. The summer temperature in southern China can be as high as 40 °C, while the north The temperature can be lower than -40 ° C in winter, but the water will solidify into ice below 0 ° C, thus not achieving the purpose of water. Therefore, there are some specifications for insulation in the industry, so that the temperature of the water in the pipeline is kept above 0 °C to maintain the fluidity of the fluid. Hot water is generally used for heating and showering. The water temperature is usually below 75 °C, and the instantaneous temperature can reach about 95 °C. Between the above investigations, the embedded lining plastic steel pipes are divided into two types: cold water type and hot water type. The long-term use temperature of cold water type is 0 °C ~ 55 °C, and the long-term use temperature of hot water type pipe is 0 °C ~ 75. °C, the instantaneous temperature can reach 95 °C. According to the standardization of pipeline diameter, the specifications are 14 varieties of DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN80, DN100, DN125, DN150, DN200, DN250 and DN300.

Second, the production process is unique

What kind of process is used to produce after the product structure is determined is of vital importance in current economic activities. It directly relates to the production cost and production efficiency of the product, and at the same time, the process design and material selection of the product are proposed. Claim. The inner rib embedded plastic lining steel pipe adopts a unique mechanical drawing composite process, which compresses the inner plastic pipe by reducing the diameter of the metal pipe, so that the two kinds of hardware materials have permanent and reasonable interference, and the inner surface of the welded pipe is uniquely designed. The embedding effect of the rib on the outer surface of the plastic pipe and the physical and chemical modification of the plastic pipe before the composite pipe make the inner rib embedded plastic pipe have the characteristics of no delamination, no shrinkage, and long-term use. And in 2001 won the national utility model patent. This unique process has high production efficiency, easy process control and high composite quality.

Third, the connection method is reliable and fast

The connection between pipelines is the most important problem in the building materials industry. The connection strength can be unreliable, it is not easy to install and maintain, and it can adapt to harsh natural conditions. These problems are the most concerned issues for users, design, construction and other units. . The inner rib embedded plastic-lined steel pipe is formed by a cold extrusion principle at a certain distance from the end face of the pipe to form a small circular arc groove, and then the circlip type stainless steel snap ring is placed in the groove, and the nut or the interface is put on, and the new enamel pipe fitting is put on the sleeve. And its accessories, can be tightened and installed quickly. Thanks to the tapered self-locking design of the snap ring fittings and the end-to-end and radial two-way sealing design, it has reliable joint strength and leakage resistance. At the same time, due to the detachable structure of all the pipe joints, combined with the use of special joint pipe fittings, it is extremely convenient to repair.

Fourth, the outer surface of the anti-corrosion measures perfect

As we all know, the corrosion of steel is very common, and the economic losses caused by it are enormous. We know that the corrosion of steel is mainly due to electrochemical corrosion. The corrosion aging of plastics is mainly caused by chemical corrosion and ultraviolet radiation. The internal reinforced plastic-lined steel pipe completely eliminates the plastic because the inner plastic pipe is sheltered by the outer metal pipe. The cause of corrosion aging makes the plastic tube durable. The protection of the outer metal tube is much more difficult. The outer surface of the inner reinforced plastic-lined steel pipe adopts three layers of anti-corrosion measures: the first layer is a galvanized layer, and the steel tube forms a cathode for protection against rust. The second layer: epoxy primer, forming a dense polymer protective film on the outer surface of the galvanized layer to isolate it from air and water, slowing down the oxidation corrosion of the zinc layer, thereby increasing the service life of the pipe. The third layer: topcoat, strengthen the protective effect of the film and improve the aesthetics of the product. When used in the buried area, appropriate anti-corrosion measures shall be taken to improve the service life of the system; it may also be used in the case of a plastic-lined steel pipe as the base pipe, and the outer surface is covered with a plastic pipe. PE pipe + carbon steel pipe + PP pipe) series products are directly buried in the ground. These products were granted national utility model patents in 2004 and applied to the West-East Gas Pipeline-Kela 2 gas field construction project.

Fifth, the welded pipe wall thickness is reasonable

Wall thickness is an important parameter. The design formula for the wall thickness of the pipe given in the Mechanical Design Manual, Volume 3: S=PD/(2[δ]ψ)+C where: S: wall thickness (mm) P: medium pressure in the pipe (MPa); D: outer diameter of the pipe (mm); [δ]: allowable stress of the pipe at the working temperature (MPa); j: longitudinal weld coefficient of the pipe, seamless steel pipe j = 1; Welded steel pipe j = 0.8; C: additional value of pipe wall thickness (mm); including manufacturing negative deviation C1; corrosion margin C2; thread depth C3; C = C1 + C2 + C3. The inner rib embedded plastic-lined steel pipe determines the wall thickness of the welded pipe according to the above theory. The allowable stress [δ] of the pipe 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 pipe material. At the same time, because the inner rib embedded plastic-lined steel pipe adopts the snap ring connection, the cold extrusion deformation groove does not need to consider the added value of the pipe wall thickness C3. Therefore, compared with the traditional galvanized steel pipe, the wall thickness is more reasonable and the economy has obvious potential.

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Tag: lining plastic steel pipe, embedded pipe, PP pipe, water isolation

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