Corrosion-resistant seamless steel pipe for chemical industry

Abstract

The utility model discloses a kind of corrosion-resistant seamless steel pipes for chemical industry, it includes base pipe, composite protective layer and reinforcing bar. Composite protective layer is made of corrosion-resistant coating, fiber reinforced layer and wear-resistant outer layer, corrosion-resistant coating is made by mixing epoxy resin and nano oxide, fiber reinforced layer is cross-woven glass fiber cloth, and wear-resistant outer layer is polyurethane material. Reinforcing bar is helical stainless steel wire, embedded in fiber reinforced layer. Base pipe inner surface is provided with microporous ceramic coating, and both ends are provided with flange connecting piece with sealing groove and positioning pin hole. The application can significantly improve the corrosion resistance and mechanical strength of the pipeline, prolong the service life, ensure the reliability and efficiency of the connection, and is suitable for chemical strong corrosion environment.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment and materials technology, and in particular to a corrosion-resistant seamless steel pipe for chemical use. Background Technology

[0002] In the chemical industry, many equipment and pipelines are exposed to highly corrosive media for extended periods, placing high demands on the corrosion resistance of materials. Seamless steel pipes, as a crucial basic material in the chemical industry, are widely used in scenarios involving the transport of high-temperature, high-pressure, or corrosive fluids. However, in actual use, ordinary seamless steel pipes are susceptible to corrosion from the media, leading to thinning of the pipe wall and even perforation, thus affecting the safety and service life of equipment. To address this issue, corrosion resistance is typically improved by increasing the pipe wall thickness or applying an anti-corrosion coating to the surface, but this increases costs and process complexity. Furthermore, the coating is easily damaged during transportation and installation, further weakening its anti-corrosion effect. Therefore, there is an urgent need for a seamless steel pipe that combines excellent corrosion resistance and structural strength to meet the specific needs of the chemical industry. Utility Model Content

[0003] The purpose of this utility model is to provide a corrosion-resistant seamless steel pipe for chemical applications, which solves the problems mentioned in the background art.

[0004] This invention is achieved as follows: a corrosion-resistant seamless steel pipe for chemical applications. The seamless steel pipe is mainly composed of: a base pipe, a composite protective layer set on the outer surface of the base pipe, and reinforcing ribs embedded in the composite protective layer. The base pipe is the main structure, and the composite protective layer and reinforcing ribs are arranged around the base pipe and combined into one piece in a specific way.

[0005] A further technical solution of this utility model is: the composite protective layer includes, from the inside out, a corrosion-resistant coating, a fiber reinforcement layer and an anti-wear outer layer. The corrosion-resistant coating is directly coated on the outer surface of the base tube. The fiber reinforcement layer is bonded to the corrosion-resistant coating by a resin adhesive. The anti-wear outer layer covers the outside of the fiber reinforcement layer and is fixed by a hot-pressing molding process.

[0006] A further technical solution of this utility model is: the corrosion-resistant coating is made by mixing epoxy resin and nano-oxide particles, and the nano-oxide particles are uniformly dispersed in the epoxy resin matrix to form a dense protective network to prevent corrosive media from penetrating to the surface of the base pipe.

[0007] A further technical solution of this utility model is: the fiber reinforcement layer is composed of multiple layers of cross-woven glass fiber cloth, and the weaving directions of adjacent two layers of glass fiber cloth are staggered at 90° to improve the tensile strength and shear resistance of the overall structure.

[0008] A further technical solution of this utility model is: the wear-resistant outer layer is made of polyurethane material with a thickness of 1.5mm to 2.5mm. The surface of the wear-resistant outer layer is provided with a number of grooves distributed along the axial direction. The cross-section of the grooves is semi-circular, which is used to reduce the impact force of the fluid on the pipe wall and improve the fluid transport efficiency.

[0009] A further technical solution of this utility model is: the reinforcing rib has a spiral structure and is embedded in the fiber reinforcement layer of the composite protective layer. The reinforcing rib is made of stainless steel wire with a diameter of 2mm to 3mm and a pitch of 50mm to 80mm. The reinforcing rib is fixed by being embedded in the fiber reinforcement layer and then bonded to the resin adhesive.

[0010] A further technical solution of this utility model is: the inner surface of the base tube is provided with a microporous ceramic coating, the thickness of the microporous ceramic coating is 0.2mm to 0.5mm, and the surface of the microporous ceramic coating has a honeycomb microporous structure. The honeycomb microporous structure can adsorb impurities in the fluid and form a dynamic protective film, thereby further improving the corrosion resistance of the base tube.

[0011] A further technical solution of this utility model is: the two ends of the base pipe are provided with flange connectors, the flange connectors are fixed to the base pipe by welding, the contact surface of the flange connectors is provided with an annular sealing groove, and a rubber sealing ring is embedded in the annular sealing groove to achieve a sealing effect when the pipe is connected.

[0012] A further technical solution of this utility model is: the outer side of the flange connector is provided with positioning pin holes, the number of positioning pin holes is two and they are symmetrically distributed on both sides of the flange connector. The positioning pin holes are used to insert positioning pins to ensure the coaxiality of the two pipe sections when connected.

[0013] The beneficial effects of this utility model are as follows: This utility model provides a corrosion-resistant seamless steel pipe for chemical applications. Through a multi-layer composite protective layer design, it significantly improves corrosion resistance. The corrosion-resistant coating effectively blocks the penetration of corrosive media, the fiber reinforcement layer provides excellent mechanical strength, and the wear-resistant outer layer reduces fluid abrasion on the pipe wall. The spiral structure of the reinforcing ribs further enhances the overall rigidity and deformation resistance of the pipe. Simultaneously, the introduction of a microporous ceramic coating not only improves the corrosion resistance of the base pipe but also extends the pipe's service life by adsorbing impurities and forming a dynamic protective film. Furthermore, the sealing design of the flange connections and the application of locating pin holes ensure the reliability and convenience of pipe connections, making this utility model more widely and efficiently applied in the chemical industry. Attached Figure Description Figure 1 This is a schematic diagram of the overall structure of the present invention, showing the arrangement of the base pipe, composite protective layer, reinforcing ribs and flange connectors. The composite protective layer wraps around the outer surface of the base pipe, the reinforcing ribs are embedded in the composite protective layer in a spiral shape, and the flange connectors are set at both ends of the base pipe.

[0014] Figure 2 This utility model Figure 1 Enlarged view of the flange connection.

[0015] Figure 3 This is a schematic diagram of the layered structure of the composite protective layer of this utility model.

[0016] The attached diagram is labeled as follows: 1. Base pipe; 2. Composite protective layer; 3. Reinforcing rib; 4. Corrosion-resistant coating; 5. Fiber reinforcement layer; 6. Wear-resistant outer layer; 7. Flange connector; 8. Annular sealing groove; 9. Rubber sealing ring; 10. Locating pin hole. Detailed Implementation The specific implementation method of this utility model of a corrosion-resistant seamless steel pipe for chemical industry is described in conjunction with the appendix. Figure 1 To be continued Figure 3 Detailed explanation follows. (Attached) Figure 1 The overall structure of this utility model is shown, in which the base pipe 1 serves as the main structure, the composite protective layer 2 wraps around the outer surface of the base pipe 1, the reinforcing ribs 3 are spirally embedded in the composite protective layer 2, and the flange connectors 7 are located at both ends of the base pipe 1. (Attached) Figure 2 This is a schematic diagram of the layered structure of the composite protective layer 2, which, from the inside out, includes a corrosion-resistant coating 4, a fiber reinforcement layer 5, and an anti-wear outer layer 6. Figure 3 This is a partially enlarged schematic diagram of the flange connector 7, showing the specific arrangement of the annular sealing groove 8, the rubber sealing ring 9, and the locating pin hole 10 on the flange connector 7. The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0017] The base tube 1 is the core structure of this invention. It is made of carbon steel or alloy steel and manufactured using seamless steel pipe production processes. The inner surface of the base tube 1 is coated with a microporous ceramic coating, with a thickness of 0.2 mm to 0.5 mm, applied using a spraying process. The surface of the microporous ceramic coating has a honeycomb-like microporous structure, with pores ranging in diameter from 10 μm to 50 μm. These pores can adsorb impurities in the fluid and form a dynamic protective film, thereby further improving the corrosion resistance of the base tube 1. In practical applications, when fluid passes through the base tube 1, the microporous ceramic coating gradually adsorbs particulate matter in the fluid. This particulate matter, combined with the coating, forms a physical barrier, further isolating the corrosive medium from contact with the inner wall of the base tube 1.

[0018] The composite protective layer 2 is applied to the outer surface of the base pipe 1, and consists of a corrosion-resistant coating 4, a fiber reinforcement layer 5, and an anti-wear outer layer 6, arranged sequentially from the inside out. The corrosion-resistant coating 4 is directly applied to the outer surface of the base pipe 1, and its material is a mixture of epoxy resin and nano-oxide particles. The nano-oxide particles are uniformly dispersed in the epoxy resin matrix, forming a dense protective network. The particle size of the nano-oxide particles ranges from 20 nm to 50 nm, and their mass fraction in the epoxy resin is 5% to 10%. The thickness of the corrosion-resistant coating 4 is 0.1 mm to 0.3 mm. The coating process is completed using electrostatic spraying technology, and after spraying, it undergoes a high-temperature curing treatment at 180℃ to 200℃ to ensure the adhesion and density of the coating.

[0019] The fiber reinforcement layer 5, located outside the corrosion-resistant coating 4, is composed of multiple layers of cross-woven fiberglass cloth. The weaving directions of adjacent fiberglass cloth layers are staggered at 90° to enhance the tensile strength and shear resistance of the overall structure. The thickness of a single fiberglass cloth layer is 0.15 mm to 0.25 mm, and the total thickness of the fiber reinforcement layer 5 is 0.6 mm to 1.0 mm. The fiberglass cloth is bonded to the corrosion-resistant coating 4 using a resin adhesive. The adhesive is made of unsaturated polyester resin with a mass fraction of 30% to 40%, and the adhesive application amount is controlled between 200 g and 300 g per square meter. After bonding, a hot-pressing process is performed at a temperature of 120°C to 150°C and a pressure of 0.5 MPa to 1.0 MPa to ensure a tight bond between the fiber reinforcement layer 5 and the corrosion-resistant coating 4.

[0020] The wear-resistant outer layer 6 covers the outside of the fiber-reinforced layer 5 and is made of polyurethane with a thickness of 1.5 mm to 2.5 mm. The surface of the wear-resistant outer layer 6 has several axially distributed grooves. The grooves have a semi-circular cross-section, a depth of 0.5 mm to 1.0 mm, and a width of 2 mm to 3 mm. These grooves reduce the impact force of the fluid on the pipe wall and improve fluid transport efficiency. The wear-resistant outer layer 6 is formed by hot pressing at a temperature of 80°C to 100°C and a pressure of 0.3 MPa to 0.6 MPa. After molding, the surface of the wear-resistant outer layer 6 is polished to ensure its smoothness.

[0021] The reinforcing rib 3 has a spiral structure and is embedded in the fiber reinforcement layer 5 of the composite protective layer 2. The reinforcing rib 3 is made of stainless steel wire with a diameter of 2mm to 3mm and a pitch of 50mm to 80mm. The embedding process of the reinforcing rib 3 is completed during the laying of the fiber reinforcement layer 5. The stainless steel wire is evenly embedded into the fiber reinforcement layer 5 using a mechanical winding device and fixed with resin adhesive. The spiral structure of the reinforcing rib 3 not only enhances the overall rigidity of the pipeline but also improves its resistance to deformation, effectively resisting the impact of external loads on the pipeline in practical applications.

[0022] Flange connector 7 is fixed to both ends of base pipe 1 by welding. The material of flange connector 7 is the same as that of base pipe 1. The welding process uses argon arc welding with a welding current of 100A to 150A and a welding voltage of 18V to 22V. After welding, the weld is ground to ensure flatness. The contact surface of flange connector 7 has an annular sealing groove 8, with a width of 3mm to 5mm and a depth of 1.5mm to 2.5mm. A rubber sealing ring 9 is embedded in the annular sealing groove 8. The rubber sealing ring 9 is made of nitrile rubber with a hardness of 70 Shore A and a compression ratio of 20% to 30%. During pipe connection, the rubber sealing ring 9 achieves a sealing effect through compression deformation. Two locating pin holes 10 are provided on the outer side of flange connector 7, symmetrically distributed on both sides. The diameter of the locating pin holes 10 is 6mm to 8mm, and the depth is 10mm to 15mm. The locating pin hole 10 is used to insert a locating pin to ensure the coaxiality of the two pipe sections when connected. The locating pin is made of stainless steel and its diameter matches that of the locating pin hole 10.

[0023] In practical applications, the corrosion-resistant seamless steel pipe for chemical use of this invention is mainly used to transport highly corrosive media, such as acid and alkali solutions, and salt solutions. During use, the inner surface of the base pipe 1 adsorbs impurities in the fluid through a microporous ceramic coating, forming a dynamic protective film to prevent corrosive media from directly contacting the inner wall of the base pipe 1. The corrosion-resistant coating 4 of the composite protective layer 2 blocks the penetration of external corrosive media, the fiber reinforcement layer 5 provides excellent mechanical strength, and the wear-resistant outer layer 6 reduces fluid wear on the pipe wall. The spiral structure of the reinforcing ribs 3 enhances the overall rigidity and deformation resistance of the pipe, ensuring the stability of the pipe under high pressure or complex working conditions. The sealing design of the flange connector 7 and the application of the locating pin hole 10 ensure the reliability and convenience of the pipe connection, making the application of this invention more widespread and efficient in the chemical field.

[0024] The above content describes in detail the various components of this utility model and their connection relationships, positional relationships, and mutual cooperation relationships. The dimensions, materials, and process parameters of all components have been optimized to ensure that this utility model can achieve the expected technical effect in practical applications. In order to enable those skilled in the art to fully understand and implement this utility model, the following supplementary explanation of the specific implementation principle of this utility model is given in conjunction with a specific application scenario.

[0025] In a chemical plant, a pipeline system transporting a highly corrosive hydrochloric acid solution needs to be upgraded to address the problems of existing pipelines being susceptible to corrosion and having a short service life. This application utilizes a corrosion-resistant seamless steel pipe for chemical applications, as described in this invention. The installation and operation process is as follows: First, during the pipeline manufacturing stage, the base pipe 1 is processed using seamless steel pipe manufacturing technology, and a microporous ceramic coating is sprayed onto its inner surface. During the spraying process, thermal spraying equipment is used to uniformly cover the inner wall of the base pipe 1 with ceramic powder, forming a coating with a thickness of 0.2 mm to 0.5 mm. Subsequently, a high-temperature sintering process is used to solidify the coating, ensuring the formation of a honeycomb-like microporous structure on its surface. The diameter of these micropores is controlled between 10 μm and 50 μm, effectively adsorbing impurity particles in the fluid. When hydrochloric acid solution flows through the base pipe 1, the microporous ceramic coating gradually adsorbs solid particles in the solution. These particles combine with the coating to form a dynamic protective film, further isolating the hydrochloric acid from direct contact with the inner wall of the base pipe 1, thereby improving the corrosion resistance of the base pipe 1.

[0026] Next, a composite protective layer 2 is constructed sequentially on the outer surface of the base pipe 1. The corrosion-resistant coating 4 is applied using electrostatic spraying technology, with the spraying material being a mixture of epoxy resin and nano-oxide particles. After spraying, the base pipe 1 is placed in a high-temperature oven for curing at a temperature set to 180°C to 200°C to ensure the adhesion and density of the coating. Subsequently, a fiber reinforcement layer 5 is laid on the outside of the corrosion-resistant coating 4. The fiber reinforcement layer 5 consists of multiple layers of fiberglass cloth, with the weaving directions of adjacent layers staggered at 90° to enhance tensile strength and shear resistance. During the laying process, unsaturated polyester resin is used as an adhesive, with the coating amount controlled between 200g and 300g per square meter. After laying, the base pipe 1 is placed in a hot-pressing molding machine, with the hot-pressing temperature set to 120°C to 150°C and the pressure to 0.5MPa to 1.0MPa to ensure a tight bond between the fiber reinforcement layer 5 and the corrosion-resistant coating 4. Finally, an anti-wear outer layer 6 is covered on the outside of the fiber reinforcement layer 5. The wear-resistant outer layer 6 is made of polyurethane material and is fixed by a hot-pressing process. The hot-pressing temperature is 80℃ to 100℃, and the pressure is 0.3MPa to 0.6MPa. The surface of the wear-resistant outer layer 6 has several semi-circular grooves distributed along the axial direction. The design of these grooves reduces the impact force of the fluid on the pipe wall and improves the fluid transport efficiency.

[0027] During the laying of the composite protective layer 2, reinforcing ribs 3 are embedded into the fiber reinforcement layer 5 using a mechanical winding device. The reinforcing ribs 3 are made of stainless steel wire with a diameter of 2mm to 3mm and a pitch of 50mm to 80mm. The stainless steel wire is bonded and fixed with resin adhesive during the embedding process, forming a spiral structure. This structure not only enhances the overall rigidity of the pipe but also improves its resistance to deformation, enabling it to effectively resist the effects of external loads.

[0028] Next, flange connectors 7 are welded to both ends of the base pipe 1. During welding, argon arc welding is used, with a welding current set to 100A to 150A and a welding voltage of 18V to 22V to ensure welding quality. After welding, the weld seam is ground to ensure the flatness of the flange connectors 7. Subsequently, an annular sealing groove 8 is machined on the contact surface of the flange connectors 7, with a groove width of 3mm to 5mm and a depth of 1.5mm to 2.5mm. A rubber sealing ring 9, made of nitrile rubber with a hardness of 70 Shore A, is embedded in the annular sealing groove 8. During pipe connection, the rubber sealing ring 9 achieves a sealing effect through compression deformation. Furthermore, two locating pin holes 10 are machined on the outer side of the flange connectors 7, symmetrically distributed, with a diameter of 6mm to 8mm and a depth of 10mm to 15mm. The locating pin holes 10 are used to insert locating pins to ensure the coaxiality of the two pipe sections during connection.

[0029] During actual operation, hydrochloric acid solution flows in from one end of the pipeline. As it passes through the inner surface of the base pipe 1, the microporous ceramic coating adsorbs impurity particles in the solution, forming a dynamic protective film to prevent hydrochloric acid from directly contacting the inner wall of the base pipe 1. Simultaneously, the corrosion-resistant coating 4 of the composite protective layer 2 blocks the penetration of external corrosive media, the fiber-reinforced layer 5 provides excellent mechanical strength, and the wear-resistant outer layer 6 reduces fluid abrasion on the pipe wall. The spiral structure of the reinforcing ribs 3 enhances the overall rigidity and deformation resistance of the pipeline, ensuring its stability under high pressure or complex operating conditions. The sealing design of the flange connection 7 and the application of the locating pin holes 10 ensure the reliability and convenience of the pipeline connection.

[0030] Through the above steps, the chemical corrosion-resistant seamless steel pipe of this invention has achieved significant technical effects in practical applications. The dynamic protective film mechanism of the microporous ceramic coating, the multi-layered protective structure of the composite protective layer 2, and the spiral design of the reinforcing ribs 3 work together to enable the pipe to exhibit excellent corrosion resistance and mechanical strength in highly corrosive media environments, extending its service life and reducing maintenance costs. The above content details the operating principle and implementation method of this invention in specific application scenarios. The dimensions, materials, and process parameters of all components have been optimized to ensure that this invention can achieve the expected technical effects in practical applications.

[0031] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A corrosion-resistant seamless steel pipe for chemical applications, characterized in that, The seamless steel pipe is mainly composed of a base pipe (1), a composite protective layer (2) set on the outer surface of the base pipe (1), and reinforcing ribs (3) embedded in the composite protective layer (2). The composite protective layer (2) and the reinforcing ribs (3) are arranged around the base pipe (1) and combined into one. The composite protective layer (2) includes a corrosion-resistant coating (4), a fiber reinforcement layer (5), and an anti-wear outer layer (6) from the inside to the outside. The corrosion-resistant coating (4) is directly coated on the outer surface of the base pipe (1). The fiber reinforcement layer (5) is bonded to the corrosion-resistant coating (4) by a resin adhesive. The anti-wear outer layer (6) covers the outside of the fiber reinforcement layer (5) and is fixed by a hot pressing process.

2. The corrosion-resistant seamless steel pipe for chemical use according to claim 1, characterized in that: The corrosion-resistant coating (4) is made of epoxy resin and nano-oxide particles. The nano-oxide particles are uniformly dispersed in the epoxy resin matrix. The particle size of the nano-oxide particles ranges from 20 nm to 50 nm and the mass fraction is from 5% to 10%. The thickness of the corrosion-resistant coating (4) is from 0.1 mm to 0.3 mm.

3. The corrosion-resistant seamless steel pipe for chemical applications according to claim 2, characterized in that: The fiber reinforcement layer (5) is composed of multiple layers of cross-woven glass fiber cloth, with the weaving directions of adjacent layers of glass fiber cloth staggered at 90°. The thickness of a single layer of glass fiber cloth is 0.15 mm to 0.25 mm, and the total thickness of the fiber reinforcement layer (5) is 0.6 mm to 1.0 mm.

4. The corrosion-resistant seamless steel pipe for chemical use according to claim 3, characterized in that: The wear-resistant outer layer (6) is made of polyurethane material with a thickness of 1.5 mm to 2.5 mm. The surface of the wear-resistant outer layer (6) is provided with a number of grooves distributed along the axial direction. The cross-section of the grooves is semi-circular, the depth of the grooves is 0.5 mm to 1.0 mm, and the width is 2 mm to 3 mm.

5. The corrosion-resistant seamless steel pipe for chemical use according to claim 4, characterized in that: The reinforcing rib (3) has a spiral structure and is embedded in the fiber reinforcement layer (5) of the composite protective layer (2). The reinforcing rib (3) is made of stainless steel wire with a diameter of 2 mm to 3 mm and a pitch of 50 mm to 80 mm.

6. The corrosion-resistant seamless steel pipe for chemical use according to claim 1, characterized in that: The base pipe (1) is provided with flange connectors (7) at both ends. The flange connectors (7) are fixed to the base pipe (1) by welding. The contact surface of the flange connectors (7) is provided with an annular sealing groove (8). The annular sealing groove (8) is embedded with a rubber sealing ring (9). The outer side of the flange connectors (7) is provided with two symmetrically distributed positioning pin holes (10).

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