Corrosion-resistant and compression-resistant steel-plastic composite pipe for drainage pipe network and manufacturing method thereof

Abstract

The invention belongs to the technical field of pipes, and particularly discloses a corrosion-resistant and compression-resistant steel-plastic composite pipe for a drainage pipe network and a manufacturing method thereof.The corrosion-resistant and compression-resistant steel-plastic composite pipe comprises a steel pipe, and the inner wall and the outer wall of the steel pipe are both provided with high-density polyethylene, so that an inner plastic layer and an outer plastic layer are formed on the inner wall and the outer wall of the steel pipe; and the thicknesses of the inner plastic layer and the outer plastic layer are 0.4-1mm. The composite pipe disclosed by the invention has high corrosion resistance and high compression resistance, so that the composite pipe can meet higher requirements of a modern urban drainage pipe network on safety and durability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pipe materials, and relates to a composite pipe for drainage pipe network, in particular to a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe network and a manufacturing method thereof. BACKGROUND

[0002] At present, the pipe materials widely used in municipal drainage pipe network systems include concrete pipes, cast iron pipes, PVC pipes, HDPE pipes and various composite pipes. Although these pipe materials have certain applicability in specific environments, there are still the following significant problems: Insufficient corrosion resistance: Traditional metal pipe materials (such as cast iron pipes and steel pipes) are prone to chemical corrosion and electrochemical corrosion when in long-term contact with sewage, acidic soil or humid environments, resulting in pipe wall thinning, strength reduction, and even leakage, which seriously affects the service life of the pipe and the safety of the system.

[0003] Limited pressure resistance: Especially in areas with deep burial or heavy vehicle load, ordinary plastic pipes (such as PVC and HDPE) are corrosion-resistant but weak in external pressure resistance, prone to deformation or crushing, while concrete pipes are heavy, inconvenient to construct, and prone to leakage at the interface.

[0004] Therefore, there is an urgent need for a composite pipe material that has high corrosion resistance and high pressure resistance to meet the higher requirements of modern urban drainage pipe networks for safety and durability. SUMMARY

[0005] In view of the above deficiencies in the prior art, the purpose of the present application is to provide a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe network and a manufacturing method thereof. The composite pipe of the present application has high corrosion resistance and high pressure resistance, thereby meeting the higher requirements of modern urban drainage pipe networks for safety and durability.

[0006] The technical solution of the present application is as follows: A corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe network, comprising a steel pipe, the inner wall and outer wall of the steel pipe are provided with high-density polyethylene, thereby forming an inner plastic layer and an outer plastic layer on the inner wall and outer wall of the steel pipe, the thickness of the inner plastic layer and the outer plastic layer is 0.4-1mm.

[0007] Further, polyethylene is provided between the steel pipe and the inner plastic layer to form a first hot melt adhesive layer; polyethylene is provided between the steel pipe and the outer plastic layer to form a second hot melt adhesive layer, the second hot melt adhesive layer is in a net-like structure and is spirally wound on the outer wall of the steel pipe.

[0008] Further, the thickness of the first hot melt adhesive layer and the second hot melt adhesive layer is 0.35-3mm.

[0009] Further, the inner plastic layer contains a nano-silver antibacterial agent.

[0010] The method for manufacturing the corrosion-resistant and pressure-resistant steel-plastic composite pipe for a sewer network comprises the following steps: (1) pretreating the steel pipe to increase the roughness of the steel pipe surface; (2) heating the pretreated steel pipe as a whole to 230-280℃, and uniformly spraying the polyethylene-based thermoplastic powder coating on the inner wall of the steel pipe by using the electrostatic spraying method; the polyethylene-based thermoplastic powder coating forms a first hot melt adhesive layer on the inner wall of the steel pipe after being heated, leveled and cooled; (3) heating the high-density polyethylene material to a molten state, and then uniformly coating the high-density polyethylene material on the surface of the first hot melt adhesive layer, so as to obtain an inner plastic layer; (4) processing the mesh-shaped reinforcing structure by using the polyethylene-based thermoplastic powder coating, spirally winding the mesh-shaped reinforcing structure on the outer wall of the steel pipe processed in step (3), and then heating the steel pipe, so that the temperature of the outer wall of the steel pipe reaches 180-220℃, so that the polyethylene-based thermoplastic powder coating in the mesh-shaped reinforcing structure is molten, and then a second hot melt adhesive layer is formed on the outer wall of the steel pipe; (5) heating the high-density polyethylene material to a molten state, and then uniformly coating the high-density polyethylene material on the surface of the second hot melt adhesive layer, so as to obtain an outer plastic layer; (6) performing a heating and curing treatment on the composite pipe processed in step (5), and then naturally cooling and forming the composite pipe, so that the layers are tightly combined into a whole, so as to obtain the corrosion-resistant and pressure-resistant steel-plastic composite pipe.

[0011] Further, the pretreatment step in step (1) is that the inner wall and the outer wall of the steel pipe are subjected to oil removal, pickling, polishing, polishing and sand blasting rust removal treatment in sequence.

[0012] Further, in step (2), the speed of the electrostatic spraying is controlled to be 0.8-1.5 m / min.

[0013] Further, in step (3), the high-density polyethylene material is added with a nano-silver antibacterial agent.

[0014] Further, in step (6), the curing temperature is 150-200℃, and the curing time is 25-40 min.

[0015] Compared with the prior art, the method has the following beneficial effects: 1. Both the inner and outer plastic layers of this invention are made of high-density polyethylene, which has excellent corrosion resistance and can adapt to buried and humid environments ranging from -30 to 120℃, further extending the service life of the composite pipe. The inner plastic layer is applied to the inner wall of the steel pipe via a first hot-melt adhesive layer, effectively preventing sewage from contacting the steel pipe and avoiding corrosion. Simultaneously, the smooth inner surface of the inner plastic layer facilitates drainage. The outer plastic layer is applied to the outer wall of the steel pipe via a second hot-melt adhesive layer, which is spirally wound around the outer wall. This effectively disperses external pressure, improves the compressive strength of the composite pipe, prevents excessive local stress from causing deformation or damage, and enhances the adhesion between the outer plastic layer and the steel pipe, preventing the outer plastic layer from peeling off during long-term use. Furthermore, the outer plastic layer has good corrosion resistance and UV resistance, protecting the steel pipe from external environmental factors such as damp soil and air oxidation, thus extending the service life of the composite pipe.

[0016] 2. The composite pipe of the present invention has high corrosion resistance and high pressure resistance, thus meeting the higher requirements of modern urban drainage pipe networks for safety and durability. Attached Figure Description

[0017] Figure 1 - A schematic diagram of the structure of the present invention.

[0018] Wherein: 1-steel pipe; 2-inner plastic layer; 3-outer plastic layer; 4-first hot melt adhesive layer; 5-second hot melt adhesive layer. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] Existing drainage pipe networks use pipes with insufficient corrosion resistance and limited compressive strength. These pipes are constantly in contact with sewage, acidic soil, or humid environments, making metal pipes susceptible to chemical and electrochemical corrosion. This leads to thinning of the pipe wall, affecting the pipeline's service life and safety. Meanwhile, plastic pipes, especially in areas with deep burial or heavy vehicle loads, have weak compressive strength and are prone to deformation or crushing. Therefore, this invention provides a corrosion-resistant and compressive-resistant steel-plastic composite pipe for drainage networks, exhibiting excellent corrosion resistance and compressive strength.

[0021] See Figure 1 A corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe network includes a steel pipe 1. The inner and outer walls of the steel pipe 1 are provided with high-density polyethylene, thereby forming an inner plastic layer 2 and an outer plastic layer 3 on the inner and outer walls of the steel pipe. The thickness of the inner plastic layer 2 and the outer plastic layer 3 is 0.4-1mm.

[0022] Meanwhile, polyethylene is arranged between the steel pipe 1 and the inner plastic layer 2, thereby forming a first hot melt adhesive layer 4; and polyethylene is arranged between the steel pipe 1 and the outer plastic layer 3, thereby forming a second hot melt adhesive layer 5, which is in a net structure and is spirally arranged on the outer wall of the steel pipe 1. The thickness of the first hot melt adhesive layer 4 and the second hot melt adhesive layer 5 is 0.35-3mm.

[0023] The steel pipe herein is made of high-strength alloy steel, which has a yield strength greater than 235MPa, so that it can withstand a large external pressure. The inner plastic layer is arranged on the inner wall of the steel pipe through the first hot melt adhesive layer, which can effectively prevent the sewage in the pipe from contacting the steel pipe and avoid corrosion of the steel pipe. Meanwhile, the inner surface of the inner plastic layer is smooth, which is beneficial to drainage.

[0024] The outer plastic layer is arranged on the outer wall of the steel pipe through the second hot melt adhesive layer, which is spirally arranged on the outer wall of the steel pipe herein, can effectively disperse the external pressure, improve the pressure resistance of the composite pipe, prevent the steel pipe from being deformed or damaged due to excessive local stress, and meanwhile, can enhance the adhesion between the outer plastic layer and the steel pipe, avoid the outer plastic layer from falling off in the long-term use, and meanwhile, the outer plastic layer has good corrosion resistance and ultraviolet resistance, which can protect the steel pipe from being eroded by external environmental factors such as humid soil and air oxidation, and prolong the service life of the composite pipe.

[0025] In addition, the inner plastic layer and the outer plastic layer are both made of high-density polyethylene, which has good corrosion resistance and can adapt to a buried and humid environment of-30-120℃, further prolonging the service life of the composite pipe.

[0026] In specific implementation, the inner plastic layer 2 contains a nano-silver antibacterial agent. The nano-silver antibacterial agent has a sterilization function, which can effectively inhibit the growth of bacteria in the pipe and prevent microorganisms in the sewage from damaging the pipe, thereby ensuring the sanitary safety of the pipe.

[0027] The manufacturing method of the corrosion-resistant and pressure-resistant steel-plastic composite pipe for a drainage pipe network described above comprises the following steps: (1) The steel pipe is pretreated to increase the surface roughness of the steel pipe, which is beneficial to the adhesion of the first hot melt adhesive layer and the second hot melt adhesive layer, improves the bonding force between the inner plastic layer and the outer plastic layer and the steel pipe, and ensures the bonding strength of each layer of the composite pipe.

[0028] The pretreatment step specifically comprises: ① oil removal treatment: the steel pipe is put into a degreasing agent solution (5% sodium hydroxide solution) and soaked at room temperature for 30min, through the chemical reaction between the degreasing agent and the oil, the oil stains on the surface of the steel pipe are removed. Then the steel pipe is taken out and washed with clean water.

[0029] ② Pickling treatment: Put the steel pipe treated by degreasing into a pickling tank, use 15% hydrochloric acid or 10% sulfuric acid solution for pickling, soak for 1-2 hours at room temperature to remove the oxide scale and rust on the surface of the steel pipe. After pickling, take out the steel pipe and rinse with clean water until neutral.

[0030] ③ Polishing treatment: Use mechanical polishing method, use sandpaper or grinding wheel to polish the surface of the steel pipe, and then polish to further remove the impurities and burrs on the surface and increase the roughness of the surface of the steel pipe.

[0031] ④ Sand blasting rust removal treatment: Use compressed air to spray quartz sand or steel sand at high speed to the inner wall and outer wall of the steel pipe to completely remove the remaining rust and oxide scale, so that the surface of the steel pipe reaches Sa3 level. After treatment, the steel pipe is placed in a clean environment for standby.

[0032] (2) The pretreated steel pipe is heated to 230-280°C as a whole, and polyethylene-based thermoplastic powder coating is uniformly sprayed on the inner wall of the steel pipe by electrostatic spraying method; after heating, leveling and cooling, the polyethylene-based thermoplastic powder coating will be tightly adsorbed on the inner wall of the steel pipe, thereby forming a first hot melt adhesive layer on the inner wall of the steel pipe; the speed of electrostatic spraying is controlled at 0.8-1.5 m / min.

[0033] (3) The high-density polyethylene material (and nano-silver antibacterial agent is added therein) is heated to a molten state, and then uniformly coated on the surface of the first hot melt adhesive layer, thereby obtaining an inner plastic layer.

[0034] (4) Use polyethylene-based thermoplastic powder coating to process a mesh reinforcing structure, and then wrap the mesh reinforcing structure on the outer wall of the steel pipe treated in step (3), and then heat the steel pipe so that the temperature of the outer wall of the steel pipe reaches 180-220°C, so that the polyethylene-based thermoplastic powder coating in the mesh reinforcing structure melts, and then a second hot melt adhesive layer is formed on the outer wall of the steel pipe.

[0035] Here, in order to avoid the influence of heating on the first hot melt adhesive layer and the inner plastic layer on the inner wall of the steel pipe, a medium-frequency induction heating method can be used to locally heat the steel pipe, and a cooling medium is conveyed in the inner wall of the steel pipe to protect the temperature of the inner plastic layer below the softening point of high-density polyethylene. Other methods of the prior art can also be used.

[0036] (5) The high-density polyethylene material is heated to a molten state, and then uniformly coated on the surface of the second hot melt adhesive layer, thereby obtaining an outer plastic layer.

[0037] (6) The composite pipe treated in step (5) is heated and cured at 150-200°C for 25-40 min, so that the layers are tightly combined as a whole, thereby obtaining the corrosion-resistant and pressure-resistant steel-plastic composite pipe.

[0038] Finally, it should be noted that the above-described embodiments of the present application are merely given as an example of the application but are not a limitation of the present application. It will be obvious to a person skilled in the art that, based on the above description of the embodiments, other changes in the form and details can be made to the application. Here, it is not possible to describe all of the embodiments of the application. Any changes or modifications of the present application that are obvious to a person skilled in the art are still within the scope of the present application.

Claims

1. A corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks, comprising a steel pipe, characterized in that, The inner and outer walls of the steel pipe are both lined with high-density polyethylene, thereby forming an inner plastic layer and an outer plastic layer on the inner and outer walls of the steel pipe. The thickness of the inner plastic layer and the outer plastic layer is 0.4-1mm.

2. The corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks according to claim 1, characterized in that, A polyethylene layer is provided between the steel pipe and the inner plastic layer to form a first hot melt adhesive layer; a polyethylene layer is provided between the steel pipe and the outer plastic layer to form a second hot melt adhesive layer, the second hot melt adhesive layer having a mesh structure and being spirally wound around the outer wall of the steel pipe.

3. The corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks according to claim 2, characterized in that, The thickness of the first hot melt adhesive layer and the second hot melt adhesive layer is 0.35-3mm.

4. The corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks according to claim 2, characterized in that, The inner plastic layer contains a nano-silver antibacterial agent.

5. The method for manufacturing a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks as described in claim 2, characterized in that, Includes the following steps: (1) Pre-treat the steel pipe to increase the surface roughness of the steel pipe; (2) The pretreated steel pipe is heated to 230-280℃, and the polyethylene-based thermoplastic powder coating is uniformly sprayed onto the inner wall of the steel pipe using electrostatic spraying. After the polyethylene-based thermoplastic powder coating is heated, melted, leveled and cooled, it forms a first hot melt adhesive layer on the inner wall of the steel pipe. (3) Heat the high-density polyethylene material to a molten state, and then uniformly coat it on the surface of the first hot melt adhesive layer to obtain the inner plastic layer; (4) Use polyethylene thermoplastic powder coating to process the mesh reinforcement structure. The mesh reinforcement structure is spirally wound on the outer wall of the steel pipe after step (3). Then the steel pipe is heated so that the temperature of the outer wall of the steel pipe reaches 180-220℃, thereby melting the polyethylene thermoplastic powder coating in the mesh reinforcement structure and forming a second hot melt adhesive layer on the outer wall of the steel pipe. (5) Heat the high-density polyethylene material to a molten state, and then uniformly coat it on the surface of the second hot melt adhesive layer to obtain the outer plastic layer; (6) The composite pipe after step (5) is heated and cured, and then naturally cooled and shaped to make the layers tightly bonded into a whole, thereby obtaining the corrosion-resistant and pressure-resistant steel-plastic composite pipe.

6. The method for manufacturing a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks as described in claim 5, characterized in that, The pretreatment steps in step (1) are as follows: the inner and outer walls of the steel pipe are degreased, pickled, ground, polished and sandblasted to remove rust.

7. The method for manufacturing a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks as described in claim 5, characterized in that, In step (2), the electrostatic spraying speed is controlled at 0.8-1.5 m / min.

8. The method for manufacturing a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks as described in claim 5, characterized in that, In step (3), nano-silver antibacterial agent is added to the high-density polyethylene material.

9. The method for manufacturing a corrosion-resistant and pressure-resistant steel-plastic composite pipe for drainage pipe networks as described in claim 5, characterized in that, In step (6), the curing temperature is 150-200℃ and the curing time is 25-40min.

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