A method of connecting a joint of a basalt fiber-wound reinforced composite pipe

Abstract

This invention discloses a connection method for a basalt fiber wound reinforced composite pipe joint, relating to the field of pipeline connection technology. The basalt fiber wound reinforced composite pipe includes an inner lining layer and a structural layer. The inner lining layer comprises a first polyethylene layer, and the structural layer comprises basalt fiber roving impregnated with a second polyethylene layer to form a basalt fiber cloth. The method includes the following steps: the inner lining layer at the basalt fiber wound reinforced composite pipe joint is fused together by electrofusion connection using pre-embedded resistance wire capacitor fittings; then, the basalt fiber cloth is wound around the joint for protection. This invention mainly utilizes the pre-embedded resistance wire capacitor fitting electrofusion connection technology to fuse the molecules of the inner lining layer, combined with the reinforcing effect of the basalt fiber structural layer, to achieve long-term stable operation of the polyethylene composite pipe joint in complex working environments, extend the service life of the joint, and adapt to the operational needs of pipeline systems in multiple fields.

Description

Technical Field

[0001] This invention relates to the field of pipe connection technology, and in particular to a connection method for a basalt fiber wound reinforced composite pipe joint. Background Technology

[0002] Polyethylene (PE) pipes, with their advantages of light weight, chemical corrosion resistance, and excellent cost adaptability, have become the mainstream pipe material in municipal water supply and drainage, medium and low pressure gas transmission, agricultural irrigation, and industrial lightly corrosive media transportation. In pipeline systems, pipe joints are a critical weak point. To ensure the stable operation of the pipeline system, as the core component of pipe connection, PE pipe joints must not only meet basic sealing and structural strength requirements, but also maintain stable performance under complex conditions such as outdoor ultraviolet radiation, soil microbial erosion, high and low temperature cycling, underground compression, or overhead impact. This poses a severe challenge to existing PE pipe joint technology.

[0003] Currently, commonly used basic joint methods for polyethylene pipes generally suffer from insufficient protective performance. Hot-melt connections are significantly affected by ambient temperature and humidity; in low-temperature environments, rapid cooling can easily lead to cold weld gaps, and the molten zone has weak impact resistance. While electrofusion connections offer reliable sealing, the difference in thermal expansion coefficients between the built-in heating wire and polyethylene makes them prone to microcracks under long-term temperature cycling. In mechanical connections, the significant difference between metal fasteners and polyethylene materials makes them susceptible to galvanic corrosion in buried applications. Rubber sealing rings have also experienced increasing leakage rates in recent years due to aging. Adhesive joints have a low upper temperature resistance limit; when used outdoors, ultraviolet radiation accelerates their cracking and failure.

[0004] To compensate for the deficiencies in the protection of basic joints, current traditional protection methods have generated new problems. While fiberglass wrapping can enhance joint strength, its temperature resistance is limited, and its resistance to soil microbial corrosion is poor, with fiber degradation easily occurring after long-term burial. Metal sheaths offer strong impact resistance, but their excessive weight necessitates additional hoisting equipment for construction in high-altitude or narrow trench environments, causing inconvenience. Insufficiently thick anti-corrosion coatings are easily damaged by stones during burial, creating corrosion channels. These problems directly lead to a shortened average service life and increased maintenance costs for polyethylene composite pipe joints. Particularly in gas and chemical media transportation scenarios, joint leaks can also cause safety accidents and environmental pollution. Summary of the Invention

[0005] To address the above problems, this invention provides a connection method for basalt fiber wound reinforced composite pipe joints.

[0006] This invention provides a connection method for a basalt fiber wound reinforced composite pipe joint. The basalt fiber wound reinforced composite pipe includes an inner lining layer and a structural layer. The inner lining layer includes a first polyethylene layer, and the structural layer includes basalt fiber roving impregnated with a second polyethylene layer to form a basalt fiber cloth. The method includes the following steps: The inner lining layer at the joint of the basalt fiber-reinforced composite pipe is fused by electrofusion connection of pre-embedded resistance wire capacitor fittings; then the joint is protected by wrapping the basalt fiber cloth.

[0007] Furthermore, the weight-average molecular weight of the first polyethylene is 5 million g / mol to 7 million g / mol, such as product models UHMWPEU050 (weight-average molecular weight of 5 million), UHMWPEU050 F (weight-average molecular weight of 5.5 million), and UHMWPEU070 (weight-average molecular weight of 7 million), etc.

[0008] Furthermore, the weight-average molecular weight of the second polyethylene is 3 million g / mol to 4 million g / mol, such as the product model UHMWPEU050 H (weight-average molecular weight of 3.7 million).

[0009] Furthermore, the preparation process of the basalt fiber wound reinforced composite pipe includes preparing an inner lining layer, winding basalt fiber cloth to form a structural layer, curing, trimming and demolding; wherein, the inner lining layer at the joint of the basalt fiber wound reinforced composite pipe is not covered by basalt fiber, and then a pre-embedded resistance wire capacitor fitting is used.

[0010] Furthermore, the basalt fiber cloth is wound to form the structural layer in a manner including continuous circumferential winding.

[0011] Furthermore, the basalt fiber roving accounts for 55%-65% of the mass of the basalt fiber cloth.

[0012] Furthermore, the connection method further includes: injecting an annular PE sleeve at the joint using a hot injection molding method.

[0013] Furthermore, temperature cycling tests were conducted according to ASTM D3039 standard and vibration fatigue tests were conducted according to API 17J standard, and no cracks were found in the joint.

[0014] The technical solutions provided in the embodiments of the present invention have at least the following advantages compared with the prior art: This invention provides a connection method for basalt fiber wound reinforced composite pipe joints. The invention primarily utilizes pre-embedded resistance wire capacitor fitting electrofusion connection technology to fuse the molecules of the inner lining layer. Combined with the reinforcing effect of the basalt fiber structural layer, this achieves long-term stable operation of the polyethylene composite pipe joint in complex working environments, extending the joint's service life and adapting to the operational needs of pipeline systems in various fields. Specifically, this invention selects a first molecular weight polyethylene (5 million g / mol-7 million g / mol) and a second molecular weight polyethylene (3 million g / mol-4 million g / mol) as the resin base materials for the inner lining and structural layers, respectively. Combined with pre-embedded resistance wire capacitor fitting electrofusion connection technology, this effectively avoids the problem of microcracks easily caused by long-term temperature cycling due to the difference in thermal expansion between the built-in heating wire and polyethylene in traditional electrofusion connections.

[0015] Meanwhile, this invention utilizes the material advantages of basalt fiber to replace glass fiber winding protection, thus improving the problems of low upper temperature resistance and weak resistance to soil microbial corrosion, meeting the protection requirements of medium and high temperature and long-term buried service scenarios; it replaces metal sheaths to reduce the weight of the protective structure, eliminating the extra hoisting steps in high-altitude and narrow trench construction, and simplifying on-site operation procedures; it replaces anti-corrosion coatings to form a three-dimensional protective structure, improving the joint's resistance to external impacts and preventing coating damage and corrosion channel formation caused by external impacts. This enables the polyethylene composite pipe joint to operate stably and sustainably in complex working environments, extending the joint's service life, reducing maintenance costs, and ensuring the operational safety and environmental friendliness of the pipeline system. It ensures that the joint is less prone to failure in scenarios such as municipal water supply and drainage, gas transmission, and agricultural irrigation, facing temperature and humidity fluctuations, soil corrosion, and external impacts, reducing the risk of safety accidents and environmental pollution caused by joint leaks, and adapting to the operational needs of pipeline systems in multiple fields.

[0016] Furthermore, this invention achieves multiple breakthroughs in technical performance, economic cost, and social value. Its pressure resistance and sealing performance rank among the top in the high-pressure field. By using pre-embedded resistance wire capacitor fitting electrofusion connection technology to fuse the molecules of the inner lining layer, combined with the reinforcing effect of the basalt fiber structure layer, the joint pressure resistance reaches 3.5~35MPa, far exceeding PE pipes (0.4~1.6MPa), and comparable to steel pipes (4.0MPa+) in high-pressure applications. Tests show that the key performance of the connection meets the standards of burst pressure ≥70MPa (GB / T 5351-2023) and axial pull-out force ≥1.5 times the working load (ISO 14692-3:2017). Its sealing performance is better than flange connections (medium and high pressure ≤4MPa), comparable to induction heating embedded connections (high pressure ≥10MPa), and at a lower cost. Secondly, it represents a comprehensive breakthrough in corrosion resistance and environmental adaptability. Basalt fiber (BF) winding significantly improves the corrosion resistance of joints, solving the problem of steel pipes requiring an anti-corrosion layer, and is superior to the limitations of insufficient pressure resistance of PE pipes. After ASTM D3039 temperature cycling tests (-40~150℃, 100 cycles) and API 17J vibration fatigue tests, the joints showed no cracking or performance degradation, making them suitable for complex working conditions such as deep sea and chemical industries. In contrast, traditional PE pipe joints are prone to failure due to thermal expansion and contraction after temperature cycling. Furthermore, basalt fiber is lighter than metal sheaths, eliminating the need for high-altitude hoisting equipment and overcoming the inconvenience of metal sheath construction.

[0017] In terms of economic benefits, the extended lifespan reduces maintenance costs, and the ease of construction reduces labor and time costs. Basalt fiber winding does not require large equipment and is more efficient than metal sheath joints, making it particularly suitable for special scenarios such as narrow trenches and high altitudes.

[0018] In terms of social impact, the safety risks and environmental pollution of this invention are significantly reduced. In high-pressure gas transmission scenarios (pressure ≤ 0.4 MPa), the leakage rate of the joints of this invention is lower than that of traditional joints. Secondly, this invention has outstanding resource-saving and green low-carbon benefits. Due to the extended lifespan, the pipeline replacement cycle is longer, saving material costs and reducing carbon emissions generated by pipeline replacement, which meets the green development requirements of the "dual-carbon" strategy.

[0019] In summary, this invention surpasses existing traditional connection methods in terms of high-pressure sealing, corrosion protection, and cost control, providing a solution that combines technological advancement and economic feasibility for pipeline systems in high-pressure and highly corrosive environments. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the fusion bonding of the inner lining layer in the connection method of the basalt fiber wound reinforced composite pipe joint provided in the embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the connection of the basalt fiber wound reinforced composite pipe joint provided in an embodiment of the present invention after being wound with basalt fiber cloth. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods, such as first polyethylene, second polyethylene, etc. Meanwhile, this invention aims to provide a connection method for fiber-wound reinforced composite pipe joints. The core key involves electrofusion connection based on the existing fiber-wound reinforced composite pipe preparation process, combined with the selection of first polyethylene and second polyethylene. Unless otherwise specified or detailed, the steps and parameters involved can be carried out according to the existing technology (such as reference standards: GB / T 25045-2025 "Basalt Fiber Untwisted Roving", HG / T 6135-2022 "Basalt Fiber Reinforced Plastic Pipes and Fittings for Non-metallic Chemical Equipment", T / SHTIA 003-2024 "Basalt Fiber Reinforced Polyethylene MAS Composite Pipe", HG / T 4372-2025 "General Technical Specification for Fiber Reinforced Thermosetting Plastic Pipes and Fittings for Chemical Use"), or directly using existing equipment according to the instruction manual. This invention document will not elaborate on each step.

[0026] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed. Example

[0027] This example provides a connection method for a basalt fiber wound reinforced composite pipe joint. The basalt fiber wound reinforced composite pipe includes an inner lining layer and a structural layer. The inner lining layer includes a first polyethylene layer, and the structural layer includes basalt fiber roving impregnated with a second polyethylene layer to form a basalt fiber cloth. The method includes the following steps: The inner lining layer at the joint of the basalt fiber-reinforced composite pipe is fused by electrofusion connection of pre-embedded resistance wire capacitor fittings; then the basalt fiber cloth is wound around to protect the joint, and an annular PE sleeve is injected at the joint by hot injection molding. The manufacturing process of the basalt fiber wound reinforced composite pipe includes preparing an inner lining layer, winding basalt fiber cloth to form a structural layer, curing, trimming and demolding; wherein, the inner lining layer at the joint of the basalt fiber wound reinforced composite pipe is not covered by basalt fiber, and then a pre-embedded resistance wire capacitor fitting is used. The basalt fiber roving in the basalt fiber cloth accounts for 60% of the mass. The first polyethylene is UHMWPEU050 F, and the second polyethylene is UHMWPEU050 H.

[0028] The schematic diagrams of the fusion bonding of the inner lining layer and the bonding diagram after winding basalt fiber cloth in the connection method of the basalt fiber reinforced composite pipe joint provided in this embodiment of the invention are as follows: Figure 1 (also, Figure 1 Embedded armored optical fibers enable composite pipelines to possess real-time sensing, precise positioning, and early warning capabilities, achieving intelligent monitoring throughout the pipeline's entire lifecycle. This is of significant importance for monitoring pipeline leaks, deformation, cracking, delamination, and third-party damage. Figure 2 As shown.

[0029] Comparative Example 1 This example provides a connection method for a basalt fiber wound reinforced composite pipe joint, which differs from Example 1 only in that: (1) Both the first polyethylene and the second polyethylene are UHMWPEU050 F.

[0030] Comparative Example 2 This example provides a connection method for a basalt fiber wound reinforced composite pipe joint, which differs from Example 1 only in that: (1) Both the first polyethylene and the second polyethylene are UHMWPEU050 H.

[0031] Test case In this example, the basalt fiber wound reinforced composite pipe joints obtained in the above embodiments and comparative examples were subjected to temperature cycling tests according to ASTM D3039 standard and vibration fatigue tests according to API 17J standard to determine whether the joints were cracked. The test results are shown in Table 1.

[0032] Table 1 Test sample Are the joints cracked? Example 1 none Comparative Example 1 have Comparative Example 2 have In summary, the embodiments of the present invention provide a connection method for basalt fiber wound reinforced composite pipe joints. The present invention mainly uses the electrofusion connection technology of pre-embedded resistance wire capacitor pipe fittings to make the molecules of the inner lining layer melt and fuse, and combined with the reinforcing effect of the basalt fiber structural layer, to achieve long-term stable operation of polyethylene composite pipe joints in complex working environments, extend the service life of the joints, and adapt to the operation requirements of pipeline systems in multiple fields.

[0033] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0034] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these 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 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 claimed herein.

Claims

1. A connection method for a basalt fiber wound reinforced composite pipe joint, characterized in that, The basalt fiber wound reinforced composite pipe includes an inner lining layer and a structural layer. The inner lining layer includes a first polyethylene layer, and the structural layer includes basalt fiber roving impregnated with a second polyethylene layer to form a basalt fiber cloth. The process includes the following steps: The inner lining layer at the joint of the basalt fiber-reinforced composite pipe is fused by electrofusion connection of pre-embedded resistance wire capacitor fittings; then the joint is protected by wrapping the basalt fiber cloth.

2. The connection method of the basalt fiber wound reinforced composite pipe joint according to claim 1, characterized in that, The weight-average molecular weight of the first polyethylene is 5 million g / mol to 7 million g / mol.

3. The connection method of the basalt fiber wound reinforced composite pipe joint according to claim 1, characterized in that, The weight-average molecular weight of the second polyethylene is 3 million g / mol to 4 million g / mol.

4. The connection method of the basalt fiber wound reinforced composite pipe joint according to claim 1, characterized in that, The preparation process of the basalt fiber wound reinforced composite pipe includes preparing an inner lining layer, winding basalt fiber cloth to form a structural layer, curing, trimming and demolding; wherein, the inner lining layer at the joint of the basalt fiber wound reinforced composite pipe is not covered by basalt fiber, and then a pre-embedded resistance wire capacitor fitting is used.

5. The connection method of the basalt fiber wound reinforced composite pipe joint according to claim 4, characterized in that, The basalt fiber cloth is wound to form structural layers in a manner including continuous circumferential winding.

6. The connection method of the basalt fiber wound reinforced composite pipe joint according to claim 4, characterized in that, The basalt fiber roving in the basalt fiber cloth accounts for 55%-65% of the total mass.

7. The connection method of the basalt fiber wound reinforced composite pipe joint according to claim 1, characterized in that, The connection method further includes: injecting an annular PE sleeve at the joint using a hot injection molding method.

8. The connection method of the basalt fiber wound reinforced composite pipe joint according to any one of claims 1-7, characterized in that, Temperature cycling tests were conducted according to ASTM D3039 standard and vibration fatigue tests were conducted according to API 17J standard; no cracks were found in the joint.

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