Polymer flow hardening repairing method and device for pipeline defects and cracks

Abstract

The invention relates to a polymer flow hardening repairing method and device for pipeline defects and cracks. According to the method, crack conditions are positioned and determined; determining repair requirements according to pipeline crack conditions; cleaning the periphery of the crack surface, drilling a crack arrest hole in the end part of the crack, and activating and repairing an interface; injecting the nano-reinforced prepolymer composition into the crack area through a micro-injection head, applying a local vacuum negative pressure environment, and driving the nano-reinforced prepolymer composition to fill crack branches and pores; according to repair requirements, an alternating magnetic field is introduced by an electromagnetic induction coil, and / or near-infrared light with set wavelength and light intensity is introduced by an optical fiber to treat a repair area, so that dual-mode excitation particles are excited to generate a local heat effect, and a latent dialdehyde crosslinking catalyst is activated to initiate a reaction type thermoplastic prepolymer matrix polymerization reaction; forming a gradient hardening structure from the deep part of the crack to the outer surface; the dual-mode curing of the nano reinforced prepolymer composition is supported, a gradient hardening structure from the deep position of a crack to the outer surface is formed, and the structural performance is good.

Description

Technical Field

[0001] This invention relates to the field of pipeline repair technology, and in particular to a polymer flow hardening repair method and apparatus for pipeline defects and cracks. Background Technology

[0002] Currently, known technologies for repairing pipe cracks generally employ methods such as removal and replacement, crack welding, adding sleeves to the cracked area, and quick-connect fittings. All of these methods have drawbacks, including long repair times, cumbersome processes, and limitations imposed by crack length and pipe medium. For example, welding cannot quickly repair pipes containing flammable media or those with liquid spillage. Removal and replacement methods have long repair cycles, require a large work area, and can damage any deposits on the pipe. Sleeves and quick-connect fittings are generally pre-made to a fixed length, and their use is affected by crack length. If the crack length exceeds the length of the sleeve or quick-connect fitting, it will become unusable.

[0003] Currently, there is also a rapid repair method for pipe cracks using multi-layer composite wrapping. This method utilizes the rapid expansion, strong adhesion, and 10-15 minute curing properties of polyurethane foam. Fiberglass cloth coated with polyurethane foam is wrapped around the surface to be repaired. During wrapping, the operator wears protective gloves to compact air bubbles, tightly wrapping the cloth around the crack. Multiple layers are used, with fiberglass forming the framework. During drying, the polyurethane foam undergoes slight expansion, forming an inner leak-proof composite protective sleeve bonded to the pipe wall. Alternatively, a leak-stopping agent (fast-drying expansive cement) can be used. This agent is rapidly cured, undergoes slight expansion, and has high strength in a short time. The agent is mixed with water to form a thick slurry, and fiberglass cloth coated with this slurry is tightly wrapped around the inner leak-proof composite protective sleeve. Multiple layers are used. During drying, the agent undergoes slight expansion, and because the agent is applied to the fiberglass cloth... When the fiberglass cloth is wrapped around the pipe, it restricts the expansion of the sealant, forming a stronger outer composite protective sleeve with a fiberglass skeleton. After the outer composite protective sleeve cures, the pipe can be used normally with the medium. Once the medium is flowing smoothly without leakage, C20 concrete is poured into the outer formwork of the outer composite protective sleeve. After the concrete cures, a concrete protective pier is formed. This method utilizes the characteristics of various materials to achieve the purpose of quickly repairing pipe cracks. From cleaning the outer surface of the pipe to allowing the medium to flow through the pipe, the repair time is about one hour. The repair speed is fast, and it is effective in the repair of pipelines for water supply and drainage, gas, fuel oil, sulfuric acid, hydrochloric acid, chlorine and other chemical liquids and gases. It is easy to operate and fast. This technical solution can be widely used for gray cast iron pipes, ductile iron pipes, galvanized pipes, PVC pipes, PE pipes, PPR pipes, reinforced concrete pipes, seamless steel pipes and other pipelines.

[0004] Existing technology CN201110130841.0 discloses a method for repairing pipe cracks, belonging to the field of pipe repair technology. It consists of a concrete protective pier, an outer composite protective sleeve, an inner anti-leakage composite protective sleeve, a pipe, a crack, crack-stopping holes, and a conical wedge. The method is characterized by a crack in the pipe with crack-stopping holes at both ends, each containing a conical wedge. The pipe is first wrapped with multiple layers of an inner anti-leakage composite protective sleeve formed of polyurethane foam and glass fiber. The outer layer of the inner anti-leakage composite protective sleeve is then wrapped with multiple layers of an outer composite protective sleeve formed of a sealant and glass fiber. A C20 concrete protective pier is poured outside the outer composite protective sleeve. During repair, the leaking pipe is first shut off. Once the crack has essentially stopped overflowing, a crack-stopping hole is drilled at each end of the crack using an electric drill or a hand drill. The crack-stopping holes are then sealed with conical wedges. Finally, glass fiber cloth coated with polyurethane foam is wrapped around the pipe. On the surface to be repaired, the operator wears protective gloves to compact air bubbles and tightly wraps the cloth around the crack, repeating this process three or more times. Using fiberglass as a framework, the polyurethane foam expands slightly during drying, forming an inner leak-proof composite protective sleeve that adheres to the outer wall of the pipe. After the polyurethane foam cures, fiberglass cloth coated with a sealant slurry is tightly wrapped around the outer layer of this inner leak-proof composite protective sleeve, repeating this process three or more times. After the sealant cures, a stronger outer composite protective sleeve with a fiberglass framework is formed. Once the outer composite protective sleeve has cured, the pipe can be used normally with the medium. After confirming that there are no leaks, C20 concrete is poured into the outer composite protective sleeve using a formwork. After the concrete cures, a concrete protective pier is formed. This method achieves the purpose of rapid repair of pipe cracks and reinforcement of the repaired area.

[0005] Existing technologies suffer from the following drawbacks: Insufficient penetration and incomplete filling of microcracks: Existing repair materials (such as traditional epoxy resins or polyurethanes) often have excessively high initial viscosity and poor fluidity, making it difficult to effectively penetrate micron-sized cracks and complex internal network structures in pipelines that are not easily visible to the naked eye. This results in the repair material only remaining on the surface or shallow layer of the crack, failing to reach and completely fill the deepest and finest gaps of the defect. While it may appear to be sealed in the short term, it is prone to recurrence and leakage under long-term pressure fluctuations, creating safety hazards. High material brittleness and poor dynamic adaptability: Many existing cured repair materials are inherently brittle, lacking sufficient flexibility and ductility. In actual operation, pipelines inevitably experience internal pressure fluctuations, thermal expansion and contraction caused by temperature changes, and vibrations and slight deformations from the external environment. This dynamic load environment causes stress concentration within the brittle repair, easily leading to the initiation of new microcracks in the material itself or at the interface with the pipeline wall, or causing the original repair to crack, debond, or even completely peel off and fail. The repair cannot deform in sync with the pipeline, significantly reducing its long-term reliability and service life. Weak interfacial bonding and poor long-term sealing reliability: Existing methods mainly rely on the physical accumulation of repair materials at the crack opening and simple mechanical anchoring, or the formation of a hard filler after curing. This approach makes it difficult to form truly strong and durable chemical bonds or effective microscopic interlocking between the material and the pipe metal or composite matrix. Over time, the repair material is prone to gradually peeling off from the crack wall, shrinking, or aging, leading to interfacial seal failure, recurrence of leaks, and unsustainable repair effects. Complex construction relying on pipeline shutdown and excavation, and limited functionality: Current effective repair technologies (such as welding reinforcement, clamps, and traditional composite material winding) usually require the pipeline to be shut down and large-scale excavation and exposure at the defect location. The construction process is complex, time-consuming, costly, and causes significant disruption to social production and daily life. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, the present invention provides a polymer flow hardening repair method and apparatus for pipeline defect cracks.

[0007] In a first aspect, the present invention provides a polymer flow hardening repair method for pipeline defect cracks, comprising: Locate and determine the condition of the pipe crack; determine the repair requirements based on the crack condition; the repair requirements include: repair depth, crack extent, and pipe size; Clean the area around the crack surface and drill anti-crack holes at the crack ends to activate the repair interface; The nano-reinforced prepolymer composition is injected into the crack area through a micro-injection head. A local vacuum negative pressure environment is applied according to the repair needs to drive the nano-reinforced prepolymer composition to fill the crack branches and pores. According to the repair needs, an alternating magnetic field is introduced by an electromagnetic induction coil and / or an optical fiber is used to introduce near-infrared light with a set wavelength and intensity to treat the repair area. This stimulates the dual-mode excitation particles in the nano-reinforced prepolymer composition to generate a local thermal effect, which activates the latent dual-aldehyde crosslinking catalyst in the nano-reinforced prepolymer composition to initiate the polymerization reaction of the reactive thermoplastic prepolymer matrix, forming a gradient hardening structure from the depth of the crack to the outer surface. Post-treatment of hardened structures and testing of repair indicators.

[0008] Furthermore, locating and determining pipeline defects includes: using a robot with positioning capabilities to detect pipeline cracks, locating the crack position, scanning the crack, acquiring crack scanning data to construct a three-dimensional crack model, determining the crack length, depth, direction and branching, and determining the crack range.

[0009] Furthermore, the nano-reinforced prepolymer composition comprises: Reactive thermoplastic prepolymer matrix with viscosity below a set threshold; A 5-15 wt% quaternary nano-reinforcement system; wherein, the quaternary nano-reinforcement system consists of surface amino-functionalized NiTi shape memory nanoparticles, chitosan-coated repair monomer self-healing capsules, reinforcing fillers and dual-mode excitation particles, the dual-mode excitation particles including gold nanorods that achieve photothermal triggering and Fe3O4 nanoparticles that achieve magnetothermal triggering. And, latent dialdehyde crosslinking catalysts; In this system, the nanoparticles of the quaternary nano-reinforced system are surface-modified with silane coupling agents and uniformly dispersed in a reactive thermoplastic prepolymer matrix.

[0010] Furthermore, the reactive thermoplastic prepolymer matrix, through molecular chain branching design and viscosity reducer compounding, reduces the viscosity to below a set viscosity threshold and the surface tension to below a set surface tension threshold.

[0011] Furthermore, the reinforcing filler uses carboxylated carbon nanotubes, which are oriented based on magnetic field induction and form an interlocking interface structure as they cure; the aspect ratio of the carboxylated carbon nanotubes is greater than the set aspect ratio threshold; after the nano-reinforced prepolymer composition is injected into the crack, a magnetic field with an orientation strength of 0.5-2T is applied, with the magnetic field direction perpendicular to the pipe surface, so that the carboxylated carbon nanotubes are vertically oriented in the interface region; after photothermal or magnetothermal triggered hardening, a nanoscale "pinning structure" of carboxylated carbon nanotubes is formed that penetrates the repair body and the pipe matrix.

[0012] Furthermore, surface-amino-functionalized NiTi shape memory nanoparticles undergo a reversible phase transition during thermal expansion or pressure fluctuations in the pipeline, dissipating strain energy and giving the repair a longer cyclic fatigue life.

[0013] Furthermore, the chitosan-coated self-healing capsules of the repair monomers enable the storage and release of the repair monomers. When the crack expands, the capsule is punctured, and the repair monomers penetrate into the crack under capillary action. The repair monomers encapsulated in the self-healing capsules are olefin or epoxy monomers with low viscosity and high reactivity, which can achieve rapid in-situ polymerization at room temperature or under mild triggering conditions. One or a combination of the following can be selected: dicyclopentadiene, methyl methacrylate, and propylene oxide.

[0014] Furthermore, a distributed fiber optic grating sensor array is embedded in the nano-reinforced prepolymer composition before curing. The distributed fiber optic grating sensor is encapsulated with a polyimide coating and then co-cured with the crack repair body formed by the nano-reinforced prepolymer composition. The distributed fiber optic grating sensor array monitors the strain and temperature of the repair area in real time, enabling online diagnosis and early warning of the service status of the repair body.

[0015] Furthermore, the repair indicators include: sealing test: slowly restore the pipeline pressure to the working pressure and hold the pressure for a set time. If the pressure drop during the pressure holding process is lower than the set pressure drop threshold, it is qualified; structural test: scan the repair area to confirm that the repair body is 100% integrated with the pipeline base and has no defects.

[0016] Secondly, the present invention provides a polymer flow hardening repair device for pipeline defects and cracks, comprising: a control unit, an injection unit, a vacuum generation unit, a dual-mode excitation unit, a material storage and mixing unit, and a crack detection unit, wherein the control unit controls the operation of the other units; The injection unit includes: an injection pressure source, which is connected to a material storage and mixing unit, and the material storage and mixing unit is connected to a multi-channel array micro-injection head via a pipeline equipped with a flow regulating valve. The vacuum generating unit includes an annular flexible sealing cover and a negative pressure generator connected to the annular flexible sealing cover; The dual-mode excitation unit includes: a near-infrared laser emitter, an optical fiber, and an electromagnetic induction coil. The electromagnetic induction coil generates an alternating magnetic field to generate a magnetothermal activation of a latent dual-aldehyde crosslinking catalyst. When a directional magnetic field with a set intensity range is generated, it is used to induce the directional alignment of the reinforcing filler. The material storage and mixing unit includes a storage tank and a mixing tank; the mixing tank is connected to an injection pressure source. The crack detection unit is used to locate and detect cracks and to test repair indicators.

[0017] The technical solutions provided in the embodiments of the present invention have the following advantages compared with the prior art: This invention utilizes vacuum-assisted dynamic infiltration technology and non-thermal triggering to achieve a gradient hardening mechanism. A localized negative pressure field is constructed to drive the material to actively fill crack branches, and a micro-injection head enables full-area, dead-angle-free infiltration. A dual-path triggering mechanism is employed: near-infrared light activates the photothermal conversion of gold nanorods, initiating polymerization with a dual-aldehyde catalyst; an alternating magnetic field excites Fe3O4 nanoparticles to generate eddy currents, also initiating polymerization with the dual-aldehyde catalyst. This forms a gradient hardening structure from the depth of the crack to the outer surface, completely avoiding bubble residue and resulting in excellent structural performance. The nano-reinforced thermoplastic repair formed by in-situ activated polymerization possesses both flexibility and shape memory / self-healing capabilities, dynamically adapting to pipeline pressure fluctuations and thermal deformation, significantly improving fatigue life. Interfacial chemical bonding and nanomechanical interlocking ensure a strong and tough bond, and combined with the material's aging resistance, it provides the repair with ultra-long-term sealing reliability. High-strength nanocomposite materials actively share the load and inhibit crack propagation, simultaneously achieving sealing and structural reinforcement. This repair method supports online or minimally excavated construction, and combined with real-time monitoring using embedded sensors, it significantly reduces downtime costs and maintenance risks, comprehensively improving pipeline safety and economy. Attached Figure Description

[0018] 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.

[0019] 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, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0020] Figure 1 A flowchart of a polymer flow hardening repair method for pipeline defects and cracks provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a polymer flow hardening repair device for pipeline defects and cracks provided in an embodiment of the present invention. Detailed Implementation

[0021] 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.

[0022] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0023] Example 1 This invention provides a nano-reinforced prepolymer composition for pipe crack repair, comprising: The reactive thermoplastic prepolymer matrix has a viscosity below a set threshold. The viscosity of the reactive thermoplastic prepolymer matrix at 25°C is below 100 cP. Preferably, the reactive thermoplastic prepolymer matrix is ​​a modified polyurethane or polyolefin oligomer. Traditional epoxy resins typically have a viscosity greater than 500 cP, making it difficult to penetrate microcracks smaller than 50 μm. The reactive thermoplastic prepolymer matrix of this invention, through molecular chain branching design and viscosity-reducing agent formulation, reduces the viscosity to below 100 cP and the surface tension to below 30 mN / m, enabling the material to spontaneously spread along cracks via capillary action. The exemplary molecular chain branching design introduces star-shaped oligomers, and the exemplary viscosity-reducing agent formulation uses a siloxane modifier.

[0024] The quaternary nano-reinforcement system consists of 5-15 wt% of surface amino-functionalized NiTi shape memory nanoparticles, chitosan-coated repair monomer self-healing capsules, reinforcing fillers, and dual-mode excitation particles with a particle size distribution of 50-500 nm. The dual-mode excitation particles include Fe3O4 nanoparticles that realize photothermal conversion to gold nanorods and magnetic conversion.

[0025] Nanoscale, surface-amino-functionalized NiTi shape memory nanoparticles are used to generate a "contraction closure" mechanical force on cracks during the repair process, actively reducing crack width at the nanoscale and ensuring uniform contraction closure stress. The amino groups (-NH2) of the surface-amino-functionalized NiTi shape memory nanoparticles can chemically react with the reactive thermoplastic prepolymer matrix or form strong hydrogen bonds, greatly enhancing the interfacial bonding force between the two, preventing interfacial failure, and achieving effective stress transfer from the matrix to the particles. The surface-amino-functionalized NiTi shape memory nanoparticles undergo a reversible phase transition during pipe thermal expansion or pressure fluctuations, dissipating more than 35% of strain energy, giving the repaired body a longer cyclic fatigue life, and achieving dual functional enhancement of stress adaptation and crack propagation inhibition.

[0026] Chitosan-encapsulated repair monomers form self-healing capsules that store and release the repair monomers. When a crack deforms, the capsule punctures, allowing the repair monomers to penetrate the crack through capillary action. The repair monomers encapsulated within the self-healing capsules are preferably low-viscosity, highly reactive olefin or epoxide monomers, capable of rapid in-situ polymerization at room temperature or under mildly triggered conditions. They can be selected from one or a combination of the following: dicyclopentadiene, methyl methacrylate, and propylene oxide.

[0027] The reinforcing filler is based on magnetic field-induced directional alignment and the formation of an interlocking interface structure during curing. The reinforcing filler is graphene or carboxylated carbon nanotubes. Taking carbon nanotubes as an example, the principle is as follows: 1-3 wt% of carboxylated carbon nanotubes are added to the above-mentioned reactive thermoplastic prepolymer matrix, and the aspect ratio of the carboxylated carbon nanotubes is greater than 1000; after injecting the crack, a magnetic field with an orientation intensity of 0.5-2T is applied, with the magnetic field direction perpendicular to the pipe surface, so that the carboxylated carbon nanotubes are vertically oriented in the interface region (orientation degree > 85%); after near-infrared photothermal / alternating magnetothermal excitation and hardening, a nanoscale "pinning structure" is formed that penetrates the repair body and the pipe matrix, thereby increasing the interfacial shear strength to ≥ 15 MPa.

[0028] And, latent dialdehyde crosslinking catalysts; In this system, the nanoparticles of the quaternary nano-reinforced system are surface-modified with silane coupling agents and uniformly dispersed in a reactive thermoplastic prepolymer matrix to achieve synergistic control of micron-level crack depth penetration and photothermal triggering response.

[0029] This invention pioneers an ultra-low viscosity adaptive prepolymer composition and a quaternary nano-reinforcement system. Through a reactive thermoplastic prepolymer matrix, it integrates surface-functionalized NiTi shape memory nanoparticles, chitosan-coated self-healing capsules, high aspect ratio oriented graphene / carbon nanotube reinforcing fillers, and dual-mode excitation particles, including gold nanorods and Fe3O4 nanoparticles, breaking through the penetration limits of traditional materials for micron-sized cracks. The nanocomponents of the quaternary nano-reinforcement system, after surface modification and dispersion processes, stably coexist in the low-viscosity system, achieving synergistic effects of deep crack wetting and repair.

[0030] Example 2 See Figure 1 As shown in the figure, an embodiment of the present invention provides a polymer flow hardening repair method for pipeline defect cracks, comprising: The pipeline crack is located and its condition is determined; the repair requirements are determined based on the pipeline crack condition; the repair requirements include: crack range and pipeline size, the crack range and pipeline size determine the size of the subsequent vacuum generation unit, and the repair depth determines the selection of the two subsequent excitation modes.

[0031] Clean the area around the crack surface and drill anti-crack holes at the crack ends to activate and repair the interface.

[0032] In the specific implementation process, the area around the crack is cleaned with cleaning agents and laser cleaning; oxides are removed and the surface is activated to expose the pipe substrate.

[0033] The above-mentioned nano-reinforced prepolymer composition is injected into the crack region through a micro-injection head. The micro-injection head is a multi-channel array micro-injection head with an orifice diameter ≤0.5mm. The micro-injection head is connected to the material mixing tank. The injection is controlled by adjusting the opening of the pressure and flow valves. The injection pressure is dynamically adjustable within a range of 0.1-10MPa, the flow rate is controllable within a range of 0.1–5mL / min, and the injection flow rate accuracy is ±0.05mL / min.

[0034] Simultaneously, a local vacuum negative pressure environment is applied. The parameters of this example vacuum negative pressure environment are a vacuum degree of 0.01-0.1 MPa, preferably ≤0.05 MPa. This local vacuum negative pressure environment drives the nano-reinforced prepolymer composition to fill crack branches and pores. In specific implementation, an annular flexible sealing cover is selected based on the pipe crack range and pipe size required for repair. The pressure resistance index of the annular flexible sealing cover exceeds 0.1 MPa. The annular flexible sealing cover is fixed to the pipe crack using clamps. A negative pressure generator is connected to provide a vacuum negative pressure environment. The negative pressure generator supports a vacuum degree below 0.05 MPa.

[0035] According to the repair needs, an alternating magnetic field is introduced by an electromagnetic induction coil and / or near-infrared light with a set wavelength and intensity is introduced by an optical fiber to treat the repair area, which excites the dual-mode excitation particles to generate a local thermal effect or excites the gold nanorods in the dual-mode excitation particles to generate a local thermal effect, activates the latent dual-aldehyde crosslinking catalyst to initiate the polymerization reaction of the reactive thermoplastic prepolymer matrix, and forms a gradient hardening structure from the depth of the crack to the outer surface.

[0036] An example near-infrared light has a wavelength of 808±10nm and a light intensity of 10-100W / cm².

[0037] An example alternating magnetic field strength is 1-5 kA / m.

[0038] Photoexcitation is suitable for shallow cracks; magnetic excitation penetrates the pipe wall through eddy current heating, solving the hardening problem inside thick-walled pipes. Switching or superimposing excitation based on crack depth ensures uniform hardening.

[0039] An example of a dual-mode excitation coordination method is as follows:

[0040] A distributed fiber optic grating sensor array is embedded in the nano-reinforced prepolymer composition before curing. The spacing of the distributed fiber optic gratings does not exceed 2 cm, and the spatial density is not less than 5 gratings / cm². After being encapsulated with a polyimide coating, the distributed fiber optic grating sensors are co-cured with the crack repair body formed by the nano-reinforced prepolymer composition. The distributed fiber optic grating sensor array monitors the strain (range ±5000 με, accuracy ±1 με) and temperature (range -20-150℃, accuracy ±0.5℃) of the repair area in real time. The data is output through a wireless transmission module or an internal optical cable to realize online diagnosis and early warning of the service status of the repair body.

[0041] Post-treatment of hardened structures and testing of repair indicators.

[0042] Repair index testing includes: Sealing test: Slowly restore the pipeline pressure to the working pressure and maintain the pressure for 24 hours. Monitor the pressure drop through the pressure sensor. If the pressure drop is less than the set pressure drop threshold, such as 1%, it is considered qualified.

[0043] Structural inspection: Ultrasonic phased array (PAUT) scanning was used to confirm that the composite material was 100% bonded to the matrix and had no defects.

[0044] Leakage detection: Apply a developing agent to the outer surface of the repaired body; if there is no leakage, the test is passed.

[0045] This invention utilizes vacuum-assisted dynamic infiltration technology and non-thermal triggering to achieve a gradient hardening mechanism. A localized negative pressure field is constructed to drive the material to actively fill crack branches, and a micro-injection head enables full-area, dead-angle-free infiltration. A dual-path triggering mechanism is employed: near-infrared light activates the photothermal conversion of gold nanorods, initiating polymerization with a dual-aldehyde catalyst; an alternating magnetic field excites Fe3O4 nanoparticles to generate eddy currents, also initiating polymerization with the dual-aldehyde catalyst. This forms a gradient hardening structure from the depth of the crack to the outer surface, completely avoiding air bubble residue. The nano-reinforced thermoplastic repair formed by in-situ activated polymerization possesses both flexibility and shape memory / self-healing capabilities, dynamically adapting to pipeline pressure fluctuations and thermal deformation, significantly improving fatigue life. Interfacial chemical bonding and nanomechanical interlocking ensure a strong and tough bond, and combined with the material's aging resistance, it provides the repair with ultra-long-term sealing reliability. High-strength nanocomposite materials actively share the load and inhibit crack propagation, simultaneously achieving sealing and structural reinforcement. This repair method supports online or minimally excavated construction, and combined with real-time monitoring by embedded sensors, it significantly reduces downtime costs and maintenance risks, comprehensively improving pipeline safety and economy.

[0046] This embodiment uses the repair of an axial surface microcrack, 150 mm long and 0.2 mm at its widest point, on an X52 steel oil pipeline measuring Φ323.9 mm × 7.1 mm. The pipeline operates at a pressure of 5.5 MPa, and the medium is crude oil. To achieve online repair, the pressure in the pipeline section is reduced to 2.0 MPa and maintained stable.

[0047] Pipe In-Gate (PIG) ​​detectors or Phased Ultrasonic Array (PAUT) are used to precisely scan the crack, obtain a three-dimensional model of the crack, and determine its length, depth, direction, and branching.

[0048] The repair steps are as follows: Cleaning, crack pretreatment, and interface activation: A cleaning agent with a flash point below a set threshold and volatility above a set threshold is used to spray and clean the crack and surrounding area to thoroughly remove oil stains. Subsequently, a laser cleaning device is used to clean a 30mm area on each side of the crack to remove oxides and activate the metal surface, exposing the pipe substrate. If there is significant stress concentration at the crack tip, micro-drills (Φ1mm) are used to drill arresting holes at both ends of the crack.

[0049] Based on the crack specifications determined by the pipe dimensions and the three-dimensional model of the crack, an annular flexible sealing cover is selected for installation. The annular flexible sealing cover is fixed to the pipe by clamps, ensuring that it forms a sealed cavity with the outer wall of the pipe. Vacuum-assisted injection of a nano-reinforced prepolymer composition into the crack includes: uniformly mixing the reactive thermoplastic prepolymer matrix of the present invention (whose main component is modified polyurethane oligomer with a viscosity <100 cP) with a quaternary nano-reinforcement system (including surface amino-functionalized NiTi shape memory nanoparticles, reinforcing fillers, and dual-mode excitation particles) in a specific ratio in a sealed, explosion-proof mixing tank. The material system remains stable and has low viscosity before triggering. The vacuum pump is started to stabilize the vacuum degree in the sealed cavity at -0.08 MPa. The nano-reinforced prepolymer composition is slowly injected from a preset multi-channel array micro-injection head at an injection pressure of 0.2-0.4 MPa. Under the combined action of the "suction" of the vacuum negative pressure and the extremely low viscosity of the material, the composite material rapidly penetrates and completely fills the main crack and all its micron-sized branches. Observation confirmed that the material was fully filled and free of air bubbles. After injection, the multi-channel array micro-injection head was removed, and the vacuum system was kept running briefly to stabilize the material.

[0050] For shallow regions (<5mm), a near-infrared laser emitter is used to emit a wavelength of 808nm with a light intensity of 50W / cm². 2 Near-infrared light is directed at the repair area through an optical fiber guide. The gold nanorods in the dual-mode excited particles absorb the light energy and generate local heat, activating the latent catalyst in the prepolymer system and initiating a polymerization reaction starting from the inside of the material.

[0051] For deep regions (≥5mm) and the inside of the tube wall: An alternating magnetic field with a strength of 3kA / m and a frequency of 100kHz is applied to the repair area using an alternating magnetic field generator. Fe3O4 nanoparticles generate eddy current heating under the alternating magnetic field, and heat is transferred from the inside to the outside, triggering the polymerization of deep materials.

[0052] By controlling the irradiation time and magnetic field strength of near-infrared laser, gradient curing of the material is achieved from the deepest part of the crack to the surface and from the center to the periphery. This process effectively avoids internal stress and interface defects caused by curing shrinkage. The entire curing process is basically completed within 30 minutes.

[0053] After curing, remove the fixture and smooth the repaired area. Then perform the following tests: Sealing test: Slowly restore the pipeline pressure to the working pressure and maintain the pressure for 24 hours. Monitoring with a pressure sensor shows that a pressure drop below the set threshold of 1% is acceptable. Structural test: Use ultrasonic phased array (PAUT) scanning to confirm 100% bonding between the composite material and the matrix, with no defects. Leakage detection: Apply a developing agent (such as fluorescent penetrant) to the outer surface of the repaired area for leakage detection; no leakage indicates compliance.

[0054] Example 3 See Figure 2 As shown, this application provides a polymer flow hardening repair device for pipeline defects and cracks, including: a control unit, an injection unit, a vacuum generation unit, a dual-mode excitation unit, a material storage and mixing unit, and a crack detection unit. The control unit controls the operation of the other units to realize the polymer flow hardening repair method for pipeline defects and cracks. The injection unit includes a multi-channel array micro-injection head, which is connected to the material storage and mixing unit via a pipeline equipped with a flow regulating valve. The vacuum generating unit includes an annular flexible sealing cover and a negative pressure generator connected to the annular flexible sealing cover; The dual-mode excitation unit includes: a near-infrared laser emitter, an optical fiber, and an electromagnetic induction coil. The electromagnetic induction coil generates an alternating magnetic field to generate a magnetothermal activation of a latent dual-aldehyde crosslinking catalyst. When a directional magnetic field with a set intensity range is generated, it is used to induce the directional alignment of the reinforcing filler. The system includes a sensor unit comprising a viscosity sensor, a pressure sensor, a temperature sensor, and a flow sensor; it monitors viscosity, pressure, temperature, and flow parameters in real time and provides feedback control for injection and triggering parameters. A multi-parameter feedback control module is developed to adjust the injection flow rate, vacuum intensity, and triggering energy (light intensity 10-100 W / cm²; magnetic field 1-5 kA / m) based on the injection and triggering parameters. A distributed fiber optic grating sensor array is embedded within the repair body to capture strain / temperature changes in real time, constructing an intelligent closed-loop system covering the entire lifecycle from construction to service.

[0055] In the embodiments provided by this invention, it should be understood that the disclosed structures and methods can be implemented in other ways. For example, the structural embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, structures, or units, and may be electrical, mechanical, or other forms.

[0056] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0057] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0058] 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 polymer flow hardening repair method for pipeline defect cracks, characterized in that, include: Locate the crack in the pipeline and determine its condition; Determine repair needs based on the condition of the pipe cracks; The repair requirements include: repair depth, crack extent, and pipe size; Clean the area around the crack surface and drill anti-crack holes at the crack ends to activate the repair interface; The nano-reinforced prepolymer composition is injected into the crack area through a micro-injection head. A local vacuum negative pressure environment is applied according to the repair needs to drive the nano-reinforced prepolymer composition to fill the crack branches and pores. According to the repair needs, an alternating magnetic field is introduced by an electromagnetic induction coil and / or near-infrared light with a set wavelength and intensity is introduced by an optical fiber to treat the repair area, which stimulates the dual-mode excitation particles in the nano-reinforced prepolymer composition to generate a local thermal effect, activates the latent dual-aldehyde crosslinking catalyst in the nano-reinforced prepolymer composition to initiate the polymerization reaction of the reactive thermoplastic prepolymer matrix, and forms a gradient hardening structure from the depth of the crack to the outer surface. Post-treatment of hardened structures and testing of repair indicators.

2. The polymer flow hardening repair method for pipeline defect cracks according to claim 1, characterized in that, Locating and determining pipeline defects involves: using a robot with positioning capabilities to detect pipeline cracks, locating the crack position, scanning the crack, acquiring crack scanning data to construct a three-dimensional crack model, determining the crack length, depth, direction and branching, and determining the crack range.

3. The polymer flow hardening repair method for pipeline defect cracks according to claim 1, characterized in that, The nano-reinforced prepolymer composition comprises: Reactive thermoplastic prepolymer matrix with viscosity below a set threshold; A 5-15 wt% quaternary nano-reinforcement system; wherein, the quaternary nano-reinforcement system consists of surface amino-functionalized NiTi shape memory nanoparticles, chitosan-coated repair monomer self-healing capsules, reinforcing fillers and dual-mode excitation particles, the dual-mode excitation particles including gold nanorods that achieve photothermal triggering and Fe3O4 nanoparticles that achieve magnetothermal triggering. And, latent dialdehyde crosslinking catalysts; In this system, the nanoparticles of the quaternary nano-reinforced system are surface-modified with silane coupling agents and uniformly dispersed in a reactive thermoplastic prepolymer matrix.

4. The polymer flow hardening repair method for pipeline defect cracks according to claim 3, characterized in that, The reactive thermoplastic prepolymer matrix reduces the viscosity to below a set viscosity threshold and the surface tension to below a set surface tension threshold through molecular chain branching design and viscosity reducer compounding.

5. The polymer flow hardening repair method for pipeline defect cracks according to claim 3, characterized in that, The reinforcing filler uses carboxylated carbon nanotubes, which are oriented and interlocked with curing based on magnetic field induction. The aspect ratio of the carboxylated carbon nanotubes is greater than the set aspect ratio threshold. After the nano-reinforcing prepolymer composition is injected into the crack, a magnetic field with an orientation strength of 0.5-2T is applied, with the magnetic field direction perpendicular to the pipe surface, so that the carboxylated carbon nanotubes are vertically oriented in the interface region. After photothermal or magnetothermal triggering curing, a nanoscale "pinning structure" of carboxylated carbon nanotubes is formed that penetrates the repair and the pipe matrix.

6. The polymer flow hardening repair method for pipeline defect cracks according to claim 3, characterized in that, The surface amino-functionalized NiTi shape memory nanoparticles undergo a reversible phase transition when the pipeline expands thermally or experiences pressure fluctuations, dissipating strain energy and giving the repair a longer cyclic fatigue life.

7. The polymer flow hardening repair method for pipeline defect cracks according to claim 3, characterized in that, Chitosan-coated self-healing capsules store and release repair monomers. When a crack expands, the capsule is punctured, and the repair monomers penetrate the crack through capillary action. The repair monomers encapsulated in the self-healing capsules are olefin or epoxy monomers with low viscosity and high reactivity, which can achieve rapid in-situ polymerization at room temperature or under mild triggering conditions. One or a combination of the following can be selected: dicyclopentadiene, methyl methacrylate, and propylene oxide.

8. The polymer flow hardening repair method for pipeline defect cracks according to claim 1, characterized in that, A distributed fiber grating sensor array is embedded in the nano-reinforced prepolymer composition before curing. The distributed fiber grating sensor is encapsulated with a polyimide coating and then co-cured with the crack repair body formed by the nano-reinforced prepolymer composition. The distributed fiber grating sensor array monitors the strain and temperature of the repair area in real time, realizing online diagnosis and early warning of the service status of the repair body.

9. The polymer flow hardening repair method for pipeline defect cracks according to claim 1, characterized in that, Repair index inspection includes: sealing inspection: slowly restore the pipeline pressure to the working pressure and hold the pressure for a set time. If the pressure drop is lower than the set pressure drop threshold during the pressure holding process, it is qualified; structural inspection: scan the repair area to confirm that the repair body is 100% integrated with the pipeline substrate and has no defects; leakage detection: apply a developer to the outer surface of the repair body to perform leakage detection. If there is no leakage, it meets the standard.

10. A polymer flow hardening repair device for pipeline defect cracks, implementing the polymer flow hardening repair method for pipeline defect cracks as described in any one of claims 1-9, characterized in that, include: The unit includes a control unit, an injection unit, a vacuum generation unit, a dual-mode excitation unit, a material storage and mixing unit, and a crack detection unit. The control unit controls the operation of the other units. The injection unit includes: an injection pressure source, which is connected to a material storage and mixing unit, and the material storage and mixing unit is connected to a multi-channel array micro-injection head via a pipeline equipped with a flow regulating valve. The vacuum generating unit includes an annular flexible sealing cover and a negative pressure generator connected to the annular flexible sealing cover; The dual-mode excitation unit includes: a near-infrared laser emitter, an optical fiber, and an electromagnetic induction coil. The electromagnetic induction coil generates an alternating magnetic field to generate a magnetothermal activation of a latent dual-aldehyde crosslinking catalyst. When a directional magnetic field with a set intensity range is generated, it is used to induce the directional alignment of the reinforcing filler. The material storage and mixing unit includes a storage tank and a mixing tank; the mixing tank is connected to an injection pressure source. The crack detection unit is used to locate and detect cracks and to test repair indicators.

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