A steel cylinder based on a polytetrafluoroethylene composite liner structure

Abstract

The utility model discloses a kind of steel bottle based on polytetrafluoroethylene composite lining structure, the structure includes steel bottle body, its inner wall is equipped with sandblasting layer, glue layer is equipped on sandblasting layer, and polytetrafluoroethylene lining layer is pasted on glue layer;The polytetrafluoroethylene lining layer is spliced by multiple boards, V-shaped groove is formed at the joint of adjacent board, and polytetrafluoroethylene round welding rod is fused in V-shaped groove to form sealing weld. The utility model significantly enhances the mechanical embedding and chemical bonding strength of PTFE board and steel bottle matrix by the combination of sandblasting layer and glue layer, completely solves the problem that lining is easy to fall off;Unique V-shaped groove and round welding rod welding structure ensure the overall sealing of joint, effectively prevent medium penetration;Port flanging ring further improves the structural reliability;The structure has the advantages of firm combination, good sealing, strong corrosion resistance, long service life, etc. It is suitable for the storage and transportation of strong corrosive medium.

Description

Technical Field

[0001] This utility model relates to the field of steel cylinder lining technology, specifically to a steel cylinder based on a polytetrafluoroethylene composite lining structure. Background Technology

[0002] Polytetrafluoroethylene (PTFE or Teflon), commonly known as the "King of Plastics," is a polymer compound formed by the polymerization of tetrafluoroethylene. This material possesses extremely excellent chemical stability, outstanding corrosion resistance (resistant to strong acids, strong alkalis, and various organic solvents), high lubricity and non-stickiness due to its low coefficient of friction, excellent electrical insulation, and good anti-aging resistance. Based on these properties, PTFE is widely used as the lining or coating for high-performance corrosion-resistant pipes, reactors, tanks, and other chemical equipment to protect the metal substrate from corrosive media and extend the service life of the equipment.

[0003] In theory, large tanks or cylinders lined with polytetrafluoroethylene (PTFE) sheets can inherit all the excellent properties of PTFE, giving their inner walls excellent corrosion resistance and chemical inertness. However, in practical applications, especially in pressure vessels with specific shapes like cylinders, this solution faces a significant technical bottleneck: poor adhesion between the cylinder's metal substrate and the PTFE sheet results in insufficient overall lining strength, making it prone to warping, peeling, or even complete detachment during use.

[0004] The root causes of this problem lie primarily in the following aspects: First, polytetrafluoroethylene (PTFE) itself has extremely low surface energy, exhibiting high chemical inertness and non-stickiness. While this gives it excellent anti-adhesion capabilities, it also makes bonding with most adhesives very difficult, and traditional bonding processes struggle to establish a strong bond. Second, the inner wall of the gas cylinder is typically a smooth metal surface, and its bonding with the PTFE sheet relies mainly on the adhesive's adhesion. Lacking an effective mechanical interlocking structure, interfacial stress easily leads to bond failure when subjected to temperature changes, pressure fluctuations, or material erosion. Finally, for large liner systems composed of multiple sheet panels, the treatment of the joints between the panels is equally crucial. If the joints are not properly sealed or lack sufficient strength, corrosive media may seep in through the gaps, eroding the metal substrate and accelerating the liner's peeling. While some existing technologies attempt to enhance adhesion by improving adhesives or surface treatments, these methods often have limited effectiveness, are complex, or costly, failing to fundamentally solve the problem of the liner's strength and reliability under long-term use.

[0005] Therefore, in view of the above problems, this utility model provides a steel cylinder based on a polytetrafluoroethylene composite liner structure. Through innovative composite structure design, it effectively solves the technical problems of poor bonding between the traditional PTFE sheet liner and the steel cylinder substrate and poor joint sealing. It significantly improves the reliability, durability and safety of the anti-corrosion liner, and is particularly suitable for pressure vessels used for storing and transporting highly corrosive media. Utility Model Content

[0006] The purpose of this utility model is to provide a steel cylinder based on a polytetrafluoroethylene composite liner structure to solve the technical problems of poor bonding between the traditional PTFE sheet liner and the steel cylinder substrate, and poor joint sealing.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A steel cylinder based on a polytetrafluoroethylene (PTFE) composite liner structure includes a cylinder body (5), on the inner wall of the cylinder body (5) is a sandblasted layer (3) formed by sandblasting, on the sandblasted layer (3) is an adhesive layer (4), and on the adhesive layer (4) is a PTFE liner; the PTFE liner is spliced ​​from multiple PTFE sheets (2), and a V-shaped groove is formed at the joint of adjacent PTFE sheets (2), and the V-shaped groove is filled with a PTFE round welding rod (1) fused to the PTFE sheet (2) to form a sealed weld.

[0008] Preferably, the surface roughness Ra of the blasted layer (3) is 50μm~100μm.

[0009] Preferably, a silane coupling agent undercoating layer is provided between the sandblasting layer (3) and the adhesive layer (4).

[0010] Preferably, the cross-sectional diameter of the polytetrafluoroethylene circular welding electrode (1) is greater than the width of the V-groove opening.

[0011] Preferably, the back surface of the polytetrafluoroethylene sheet (2) that contacts the adhesive layer (4) is an activated surface formed by activation treatment.

[0012] Preferably, the activated surface is a surface formed by treatment with sodium naphthalene solution or plasma treatment.

[0013] Preferably, the adhesive layer (4) is a high-temperature resistant epoxy resin adhesive layer or a modified polyurethane adhesive layer.

[0014] Preferably, the inner side of the port of the cylinder body (5) is also provided with a flanged pressure ring for pressing the end edge of the polytetrafluoroethylene sheet (2).

[0015] Preferably, the thickness of the polytetrafluoroethylene sheet (2) is 2mm to 5mm.

[0016] This application also provides a method for processing the above-mentioned polytetrafluoroethylene composite liner structure for steel cylinders, comprising the following steps: S1. Pretreatment of the inner wall of the gas cylinder: Before applying adhesive to the inner wall of the gas cylinder, it must first be pretreated. This pretreatment includes: Degreasing: Use organic solvents or alkaline cleaning agents to thoroughly clean the inner wall of the cylinder to remove all oil, grease and contaminants; Sandblasting: Compressed air is used to drive hard abrasives (such as diamond or alumina particles) to sandblast the degreased inner wall to remove oxide scale and form a clean surface with uniform roughness. Cleaning: After sandblasting, use dry, clean compressed air or solvents such as anhydrous ethanol to remove all residual abrasive dust and microparticles from the inner wall, ensuring that the substrate surface is clean and dry; S2. Applying adhesive and attaching lining: Coating the inner wall of the tank: A layer of special high-temperature resistant adhesive (such as high-temperature resistant epoxy resin or modified polyurethane adhesive) is evenly coated on the pre-treated inner wall of the steel cylinder to form an adhesive layer. Lining panel treatment and application: Simultaneously, the lining panels are treated as follows: Calculate the liner area: Calculate and cut the required number of PTFE sheets based on the geometry and dimensions of the cylinder's inner surface; Apply adhesive to the back of the liner: Apply the above adhesive evenly to the back (bonding surface) of the cut polytetrafluoroethylene sheet; then, accurately attach the treated liner to the corresponding position on the inner wall of the cylinder where the adhesive has been applied, and apply pressure to fix it in place. S3. Trimming and grooving: Trimming: Trim the edges of the attached inner liner to ensure it fits the cylinder port and other structures. Creating V-grooves: Using special tools, V-grooves are machined at the joint between two adjacent polytetrafluoroethylene sheets; S4. Welding and Inspection: Welding round welding rods: Using hot air welding process, round welding rods made of polytetrafluoroethylene are melted and filled into the V-shaped groove, so that they are fused with the plates on both sides of the groove wall to form a continuous and dense sealed weld. Weld inspection: After welding is completed, the weld is inspected for quality, including: Pinhole detection: Use equipment such as an electric spark tester to scan the entire weld seam to check for defects such as pinholes and leaks; Intense light inspection: Visually inspect the appearance, continuity, and fusion quality of the weld under intense light. S5, High-temperature curing: Steam treatment: Seal all openings of the steel cylinder, introduce steam at a pressure of 0.4MPa~0.5MPa and a temperature of 100℃~120℃ into the cylinder, and maintain this for a period of time. Utilize the heat and pressure of the steam to promote a full cross-linking reaction of the adhesive, achieving complete curing and thus reaching the highest bonding strength.

[0017] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art: 1. This utility model creates a physical anchoring interface with high roughness by setting a sandblasting layer on the inner wall of the steel cylinder, which greatly increases the specific surface area of ​​the metal substrate. The adhesive layer can fully penetrate into the micro-pits formed by the sandblasting layer, and form a strong mechanical interlocking force after curing. This dual combination mechanism of "mechanical interlocking + chemical bonding" fundamentally overcomes the inherent problems of low surface energy and difficult bonding of polytetrafluoroethylene materials, which improves the bonding strength between the inner lining plate and the steel cylinder substrate and effectively avoids the risk of the inner lining peeling, peeling and falling off during long-term use. 2. This utility model adopts a unique sealing structure of V-groove and round welding rod. This design not only achieves sealing of the weld surface, but also deep fusion sealing. After the round welding rod melts, it is integrated with the base material on both sides of the V-groove to form a seamless overall barrier. This can completely block the path of corrosive media to penetrate into the metal matrix through the joint, greatly improving the long-term safety and reliability of the cylinder in harsh corrosive environments. 3. This utility model connects multiple independent plates into a complete and uninterrupted inner lining by hot air welding, which significantly enhances the structural strength and rigidity of the inner lining layer. This overall structure can better withstand the pressure of the internal medium, the thermal stress caused by temperature fluctuations, and the scouring effect of materials. It has a stronger ability to resist deformation and displacement, thereby extending the service life of the inner lining. 4. The structural design of this utility model facilitates effective quality inspection. The uniform sandblasting layer provides a visual quality foundation for bonding, and the regular V-groove weld facilitates electrical discharge testing, pinhole detection, and strong light visual inspection. This ensures that the quality of each step from substrate treatment to final molding is controllable and inspectable, thereby guaranteeing the overall quality of the final product and its long-term reliability. 5. This utility model has wide applicability and good durability. The composite structure fully retains all the excellent chemical properties of polytetrafluoroethylene material, such as excellent corrosion resistance, non-stickiness and electrical insulation. At the same time, its enhanced physical bonding performance makes it suitable for a wider range of working conditions, including occasions with frequent temperature changes, certain pressure or negative pressure operation. It is a high-performance, long-life anti-corrosion lining structure. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the polytetrafluoroethylene composite liner structure for steel cylinders according to Embodiment 1 of this utility model; Figure 2 This is a schematic diagram of the steel cylinder according to Embodiment 1 of this utility model; Among them, 1-round welding rod; 2-polytetrafluoroethylene sheet; 3-sandblasting layer; 4-adhesive layer; 5-cylinder body. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present utility model in a schematic manner. Therefore, they only show the components related to the present utility model. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0021] Example 1 As attached Figure 1 - Appendix Figure 2 As shown, this embodiment provides a steel cylinder based on a polytetrafluoroethylene (PTFE) composite liner structure, including a cylinder body 5. A sandblasted layer 3, formed by sandblasting, is disposed on the inner wall of the cylinder body 5. An adhesive layer 4 is disposed on the sandblasted layer 3, and a PTFE liner is adhered to the adhesive layer 4. The PTFE liner is composed of multiple PTFE sheets 2 spliced ​​together. A V-shaped groove is formed at the joint of adjacent PTFE sheets 2, and the V-shaped groove is filled with a PTFE circular welding rod 1 fused integrally with the PTFE sheet 2, forming a sealing weld. Furthermore, the surface roughness Ra of the sandblasted layer 3 is 75 μm; Furthermore, a silane coupling agent undercoating layer is provided between the sandblasting layer 3 and the adhesive layer 4; Furthermore, the cross-sectional diameter of the polytetrafluoroethylene circular welding electrode 1 is larger than the width of the V-groove opening; Furthermore, the back surface of the polytetrafluoroethylene sheet 2 that contacts the adhesive layer 4 is an activated surface formed through an activation treatment; Furthermore, the activated surface is a surface formed by treatment with sodium naphthalene solution or plasma treatment; Furthermore, the adhesive layer 4 is a high-temperature resistant epoxy resin adhesive layer or a modified polyurethane adhesive layer. Furthermore, a flanged pressure ring for pressing the end edge of the polytetrafluoroethylene sheet 2 is also provided on the inner side of the port of the cylinder body 5. Furthermore, the thickness of the polytetrafluoroethylene sheet 2 is 3 mm.

[0022] This embodiment also provides a method for processing the above-mentioned polytetrafluoroethylene composite liner structure for steel cylinders, including the following steps: S1. Pretreatment of the inner wall of the gas cylinder: Before applying adhesive to the inner wall of the gas cylinder, it must first be pretreated. This pretreatment includes: Degreasing: Use organic solvents or alkaline cleaning agents to thoroughly clean the inner wall of the cylinder to remove all oil, grease and contaminants; Sandblasting: Compressed air is used to drive hard abrasives to sandblast the degreased inner wall to remove oxide scale and form a clean surface with uniform roughness. Cleaning: After sandblasting, use dry, clean compressed air or solvents such as anhydrous ethanol to remove all residual abrasive dust and microparticles from the inner wall, ensuring that the substrate surface is clean and dry; S2. Applying adhesive and attaching lining: Coating the inner wall of the tank: A special high-temperature resistant adhesive is evenly coated on the pre-treated inner wall of the steel cylinder to form an adhesive layer; Lining panel treatment and application: Simultaneously, the lining panels are treated as follows: Calculate the liner area: Calculate and cut the required number of PTFE sheets based on the geometry and dimensions of the cylinder's inner surface; Apply adhesive to the back of the liner: Apply the above adhesive evenly to the back (bonding surface) of the cut polytetrafluoroethylene sheet; then, accurately attach the treated liner to the corresponding position on the inner wall of the cylinder where the adhesive has been applied, and apply pressure to fix it in place. S3. Trimming and grooving: Trimming: Trim the edges of the attached inner liner to ensure it fits the cylinder port and other structures. Creating V-grooves: Using special tools, V-grooves are machined at the joint between two adjacent polytetrafluoroethylene sheets; S4. Welding and Inspection: Welding round welding rods: Using hot air welding process, round welding rods made of polytetrafluoroethylene are melted and filled into the V-shaped groove, so that they are fused with the plates on both sides of the groove wall to form a continuous and dense sealed weld. Weld inspection: After welding is completed, the weld is inspected for quality, including: Pinhole detection: Use equipment such as an electric spark tester to scan the entire weld seam to check for defects such as pinholes and leaks; Intense light inspection: Visually inspect the appearance, continuity, and fusion quality of the weld under intense light. S5, High-temperature curing: Steam treatment: Seal all openings of the cylinder, introduce steam at a pressure of 0.4 MPa and a temperature of 100°C into the cylinder, and maintain this for a period of time. Utilize the heat and pressure of the steam to promote a full cross-linking reaction of the adhesive, achieving complete curing and thus reaching the highest bonding strength.

[0023] Comparative Example 1 This comparative example provides a conventional PTFE liner for a steel cylinder. The inner wall of the cylinder is only treated with simple rust removal and no regular sandblasting layer is formed. PTFE sheets without any surface activation treatment are directly bonded with epoxy resin adhesive. The joints of the sheets are sealed by simply overlapping and covering the surface with PTFE sealing tape. There is no mechanical fixing structure at the cylinder port.

[0024] Comparative Example 2 The difference between the cylinder liner in this comparative example and Comparative Example 1 is that the inner wall of the cylinder underwent the same sandblasting treatment as in Example 1 (surface roughness Ra≈75μm), forming a sandblasted layer; however, the PTFE sheet used is still an ordinary sheet without activation treatment, and the joint treatment method and port structure are the same as those in Comparative Example 1.

[0025] The performance of the cylinder liner samples from the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0026] Table 1 Peel strength (N / cm) 60.4 8.7 (Early interface failure) 15.2 (Cohesive failure) Sealing performance (electric spark test) No leakage (8kV) Multiple leaks (≥3kV) Minor leaks at weld joints (≥5kV) Resistance to thermal cycling No abnormalities were observed after 50 cycles (-20℃ to 120℃). The edges curl up after 5 cycles The seam cracked after 18 cycles. Anti-negative pressure performance -0.08MPa No abnormality Lining detachment at -0.03MPa -0.05MPa localized bulge

[0027] As shown in Table 1, the composite lining structure provided in Embodiment 1 of this utility model is far superior to Comparative Example 1 and Comparative Example 2 in terms of peel strength, sealing performance, environmental stress resistance, and negative pressure resistance. Embodiment 1, through its composite interface structure of "sandblasted layer-adhesive layer-PTFE activated surface," achieves a peel strength far exceeding that of the comparative examples. This indicates that its bonding mechanism has evolved from simple physical adsorption to a synergistic effect of mechanical interlocking and chemical bonding. The unique V-groove circular welding rod weld structure ensures the integrity and density of the joint, achieving zero leakage under high pressure. Its sealing reliability is far superior to the simple lap seals of Comparative Example 1 and Comparative Example 2. The mechanical locking structure of the port flange pressure ring further enhances the ability to resist complex stresses (such as thermal cycling and negative pressure), ensuring the long-term stability of the structure. Comparative Example 1, lacking all the core components of this utility model, has the worst performance and fails early. Comparative Example 2 only adds a sandblasted layer, improving peel strength, but due to the lack of an effective sealing weld structure and plate activated surface, its overall performance, especially sealing and durability, still fails to meet the usage requirements.

[0028] In summary, this invention creates a highly rough physical anchoring interface by setting a sandblasting layer on the inner wall of the gas cylinder, greatly increasing the specific surface area of ​​the metal substrate. The adhesive layer can fully penetrate into the micro-pits formed by the sandblasting layer, forming a strong mechanical interlocking force after curing. This dual combination mechanism of "mechanical interlocking + chemical bonding" fundamentally overcomes the inherent problems of low surface energy and difficult bonding of polytetrafluoroethylene (PTFE) materials, resulting in a qualitative improvement in the bonding strength between the inner lining plate and the gas cylinder substrate, effectively avoiding the risk of warping, peeling, and detachment of the inner lining during long-term use. This invention adopts a unique sealing structure of V-groove and circular welding rod welding. This design not only achieves surface sealing of the weld but also deep fusion sealing. After the circular welding rod melts, it fuses with the base material on both sides of the V-groove to form a seamless overall barrier, which can completely block the path of corrosive media to penetrate into the metal substrate through the joint, greatly improving the long-term safety and reliability of the gas cylinder in harsh corrosive environments. This invention connects the originally independent multiple plates through hot air welding. By joining the components into a complete and uninterrupted lining, the structural strength and rigidity of the lining layer are significantly enhanced. This integrated structure can better withstand the pressure of the internal medium, the thermal stress caused by temperature fluctuations, and the scouring effect of materials. It also has a stronger ability to resist deformation and displacement, thereby extending the service life of the lining. The structural design of this utility model facilitates effective quality inspection. The uniform sandblasting layer provides a visual quality basis for bonding, and the regular V-groove welds facilitate EDM and strong light visual inspection, ensuring that the quality of each step from substrate treatment to final molding is controllable and inspectable, thus guaranteeing the overall quality of the final product and its long-term reliability. This utility model has wide applicability and good durability. The composite structure fully retains all the excellent chemical properties of polytetrafluoroethylene (PTFE), such as excellent corrosion resistance, non-stick properties, and electrical insulation. At the same time, its enhanced physical bonding performance makes it suitable for a wider range of working conditions, including occasions with frequent temperature changes, certain pressure, or negative pressure operation. It is a high-performance, long-life anti-corrosion lining structure.

[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to the above embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A steel cylinder based on a polytetrafluoroethylene composite liner structure, comprising a cylinder body (5), characterized in that, The inner wall of the cylinder body (5) is provided with a sandblasted layer (3) formed by sandblasting treatment. An adhesive layer (4) is provided on the sandblasted layer (3). A polytetrafluoroethylene (PTFE) liner is attached to the adhesive layer (4). The PTFE liner is made of multiple PTFE sheets (2) spliced ​​together. A V-shaped groove is formed at the joint of adjacent PTFE sheets (2). The V-shaped groove is filled with a PTFE round welding rod (1) that is fused to the PTFE sheet (2) to form a sealed weld.

2. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, The surface roughness Ra of the blasted layer (3) is 50μm~100μm.

3. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, A silane coupling agent undercoating layer is also provided between the sandblasting layer (3) and the adhesive layer (4).

4. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, The cross-sectional diameter of the polytetrafluoroethylene round welding electrode (1) is greater than the width of the V-groove opening.

5. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, The back surface of the polytetrafluoroethylene sheet (2) that contacts the adhesive layer (4) is an activated surface formed by activation treatment.

6. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 5, characterized in that, The activated surface is a surface formed by treatment with sodium naphthalene solution or plasma treatment.

7. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, The adhesive layer (4) is a high-temperature resistant epoxy resin adhesive layer or a modified polyurethane adhesive layer.

8. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, The inner side of the port of the cylinder body (5) is also provided with a flanged pressure ring for pressing the end edge of the polytetrafluoroethylene sheet (2).

9. A steel cylinder based on a polytetrafluoroethylene composite liner structure according to claim 1, characterized in that, The thickness of the polytetrafluoroethylene sheet (2) is 2mm to 5mm.

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