Novel electrical equipment under-pressure plugging process

Abstract

The invention relates to the technical field of flange sealing, in particular to a novel electrical equipment under-pressure plugging process. Comprising the four steps of bolt sealing, construction of a first composite sealing layer, construction of a second composite sealing layer and construction of a main sealing and protection structure. Standardized efficient sealing of the bolt part is achieved through the prefabricated sealing cap, and the problems of construction dispersity and reliability of a traditional heap coating process are fundamentally solved; narrow and wide frameworks are laid in a staggered joint mode and compounded with colloid, a three-dimensional reinforced network capable of effectively dispersing and resisting complex stress is constructed, the sealing structure has good sealing strength and deformation resistance, and the defect that an existing auxiliary method is prone to failure under the working conditions of high pressure, vibration and heat circulation is successfully overcome; and through seamless fusion of multiple layers of colloids and the arrangement of the weather-proof outer protective layer, the long-term durability of the whole sealing system under the action of a harsh medium and an external environment is ensured.

Description

Technical Field

[0001] This invention relates to the field of flange sealing technology, and more specifically, to a novel pressurized sealing process for power equipment. Background Technology

[0002] In continuous production industries such as petrochemicals and power, oil and gas leaks are common in power equipment during substation operation. If these leaks are not dealt with promptly and effectively, they will directly affect the safe operation of the substation equipment and the reliability and safety of power supply. Therefore, it is extremely urgent to deal with oil and gas leaks as soon as possible.

[0003] Live sealing technology, more commonly known in the engineering field as "non-stop live sealing technology" or "online sealing technology," refers to a special technology that seals and repairs leaks in production equipment and pipelines when the fluid medium (such as oil, water, chemicals, steam, various gases, etc.) is under pressure, temperature, and in operation, without stopping production or discharging the medium.

[0004] In the field of live sealing technology for pressure equipment, a standard operating procedure typically involves installing a drain valve at the leak point. Drain valves are usually installed at leaking locations such as flanges and valves using non-welding methods, such as threaded connections or specialized clamps. Initially, the drain valve remains open, utilizing the internal pressure of the medium to safely drain the leaking medium. The core function of the drain valve is to create a temporary, media-free working interface for subsequent sealing operations.

[0005] Flange connections in power equipment are prone to leakage due to vibration, corrosion, or aging seals. Traditional live sealing technologies often rely on clamp-on adhesive injection or overall encapsulation. Clamp-on adhesive injection typically uses custom-made clamps to match the flanges, resulting in complex construction and unsuitability for space-constrained power sites. Overall encapsulation, on the other hand, often fails under pressure fluctuations and temperature changes due to poor overall sealing structure, stress concentration between layers, and inadequate sealing at critical points such as bolt roots. This leads to insufficient reliability, specifically in terms of sealing strength, resistance to media, and long-term reliability, which cannot meet the requirements for long-term stable operation under high pressure, high temperature, or harsh media environments. Summary of the Invention

[0006] This invention provides a novel live-line sealing process for power equipment. By employing prefabricated sealing caps, it achieves standardized and efficient sealing of bolt areas, fundamentally solving the problems of construction dispersion and reliability inherent in traditional coating processes. It also adapts to the spatial constraints of live-line sealing. Furthermore, through the staggered laying of narrow and wide skeletons and their composite with the colloid, a three-dimensional reinforcing network is constructed that effectively disperses and resists complex stresses. This gives the sealing structure effective sealing strength and deformation resistance, overcoming the shortcomings of existing live-line sealing methods that are prone to failure under high pressure, high temperature, and harsh media environments. Therefore, it solves the problems mentioned in the background art, namely: Among existing pressurized sealing technologies, the overall encapsulation method is difficult to meet the requirements for long-term stable operation under high pressure and high temperature conditions due to poor overall sealing structure, stress concentration between layers, and poor sealing at the bolt roots.

[0007] To achieve the above objectives, the novel live-line sealing process for power equipment includes the following steps: S1. Bolt sealing: Fill the inner cavity of the prefabricated sealing cap with sealing glue, press the sealing cap onto the bolt head, make the cap brim fit against the flange surface, and scrape the overflowing glue into a ring seal. S2. Construct the first composite sealing layer: Locate the leak point on the flange sealing surface and install a drainage valve; then apply the first layer of sealing adhesive to the entire flange sealing surface and the area of ​​the sealing cap lip, lay the first layer of skeleton with a width less than the total thickness of the flange, and roll it to embed the first layer of skeleton into the adhesive layer to form the first composite sealing layer. S3. Constructing the second composite sealing layer: After the first composite sealing layer has cured and passed the leak test, apply a second layer of sealing adhesive to the surface of the first composite sealing layer, lay a second layer of skeleton with a width greater than the total thickness of the flange, and the joints of the second layer of skeleton are spatially staggered from the joints of the first layer of skeleton by at least 50mm, and form the second composite sealing layer by roller pressing. S4. Construct the main sealing and protection structure: After the second composite sealing layer has cured, apply multiple layers of sealing adhesive alternately to completely cover all the sealing caps, drainage valves and skeleton system to form an integral main sealing structure; finally, apply epoxy resin weather-resistant sealing adhesive to the outer surface of the main sealing structure.

[0008] In the above technical solution, in S1, a sealing adhesive with specific properties is injected into the inner cavity of the prefabricated sealing cap. Here, the sealing adhesive is a long-lasting acrylic sealing adhesive, and the sealing cap is made of fluororubber material to ensure that the adhesive can completely fill and fully wrap the bolt head and any possible leakage gaps during installation. The sealing cap filled with colloid is then aligned and firmly pressed onto the bolt head. During this process, the applied pressure makes the flexible lip of the sealing cap fit tightly against the flange surface, thereby forming a preliminary encapsulated sealing isolation zone at the bolt root. At the same time, the excess adhesive that overflows controllably from the periphery of the cap due to the squeezing action is scraped off, so that the excess adhesive forms a continuous and complete annular sealing ring in the contact area between the root of the cap and the flange surface. This annular sealing ring not only serves as an effective supplement to the main sealing interface, but also enhances the overall sealing performance and long-term reliability of the entire bolt sealing point. Finally, by combining the filling of the inner cavity of the sealing cap with the scraping of the outer edge, a dynamic, efficient and durable dual sealing structure for the bolt area is constructed.

[0009] In S2, the leak point on the flange sealing surface is first precisely located and a drain valve is installed. This drain valve is used to drain the leaking medium in the initial stage to ensure construction safety, and serves as a channel for glue injection in subsequent processes. Then, apply the first layer of sealant evenly to the entire flange sealing surface to be sealed and the cap area of ​​the installed sealing cap. The sealant type is the same as S1. Next, lay a first layer of skeleton with a width less than the total thickness of the flange on the uncured adhesive layer. Specifically, the material of the first layer of skeleton is diamond-shaped perforated aluminum mesh with a hole diameter of 0.5mm. The laying path of this narrow first layer of skeleton covers the flange sealing surface. Finally, the laid skeleton is fully rolled using a roller pressing tool, so that the first layer of skeleton is completely and evenly embedded into the bottom sealing adhesive layer. This allows the adhesive to fully wet the skeleton and effectively eliminate interlayer air bubbles, ultimately making the sealing adhesive layer and skeleton material tightly bonded into a whole, forming a first composite sealing layer with both excellent sealing performance and preliminary reinforcement. The first composite sealing layer lays a reliable foundation for the construction of the subsequent sealing reinforcement layer.

[0010] In S3, a second layer of sealing adhesive is first applied evenly to the entire surface of the first composite sealing layer. The type of sealing adhesive is the same as in S1 to establish a strong interlayer bond. Then, a second layer of skeleton with a width greater than the total thickness of the flange is laid on top of this adhesive layer. The material of the second layer skeleton is the same as in S2, using diamond-shaped perforated aluminum mesh with a aperture of 0.5mm. The purpose of setting this wide second layer skeleton is to achieve full coverage and overall reinforcement of the flange sealing area. During the installation process, the joint position of the second layer of skeleton needs to be controlled to ensure that its joint is at least 50mm away from the joint of the first layer of skeleton below. This is to avoid the through weak channel that may be formed by the overlapping of the joints of multiple skeletons, thereby improving the integrity and reliability of the sealing structure. Finally, the second layer of the skeleton, after being laid, is fully rolled using a roller pressing tool. This ensures that the second layer of the skeleton is completely embedded in the second layer of sealing adhesive and that the two composite sealing layers are tightly bonded without gaps, thus forming the second composite sealing layer. This further enhances the thickness and mechanical strength of the sealing system. Furthermore, through its synergistic effect with the first composite sealing layer, it constructs a three-dimensional reinforced sealing system with misaligned joints and multi-layer interlocking, ultimately giving the entire flange pressure sealing structure excellent long-term pressure stability and media tolerance.

[0011] In addition, before performing S1, a surface pretreatment step is included for the flange and bolt sealing area, which includes rust removal, grinding, cleaning and roughening; specifically, the pretreatment includes removing rust, scale and loose old coatings from the bolt sealing area by mechanical or chemical means to expose a stable metal substrate. Then, tools are used to grind every part to be sealed, including the flange sealing surface, bolt heads and adjacent areas, in order to eliminate sharp burrs and flash, and to ensure overall flatness. After sanding, use a highly volatile, residue-free specialized cleaning agent to repeatedly and thoroughly clean the entire sanded area to completely remove all tiny oil stains, dust, moisture, and other contaminants that may hinder adhesion, thereby obtaining an extremely clean and dry active surface. Finally, the clean surface is regularly roughened by sandblasting to form a micro-anchor pattern structure with a specific contour depth and uniform distribution. This step is used to increase the actual contact surface area between the subsequent sealing material and the base metal and to enhance the mechanical interlocking effect, ultimately laying the foundation for maximizing, durable and reliable structural bonding between all subsequent sealing layers and the base metal.

[0012] In S2, after the first layer of skeleton is laid and before the first composite sealing layer is cured, the leak detection is performed. Specifically, this includes closing the drain valve and observing whether a new leak point appears in the area covered by the first composite sealing layer. Specifically, the drain valve that was pre-installed in S2 is first completely closed to block the medium leakage channel through the original leak point, thereby temporarily sealing the sealing system. Subsequently, continuous and detailed observation was conducted on the entire flange sealing surface and cap area covered by the first composite sealing layer, with a focus on checking areas other than the drain valve itself, especially the newly covered surface of the first composite sealing layer, its edge joints, and the sealing parts of adjacent bolts for bubbling, dampness, media penetration, or any new leakage points. This leak detection method utilizes the plasticity of the uncured adhesive layer of the first composite sealing layer, so that any weak points that are not effectively sealed under pressure will immediately appear as visible signs of leakage. This allows for timely and accurate assessment of the immediate effectiveness of the initial sealing layer, and provides a reliable basis and operating window for making local repairs or reinforcements at this stage if necessary, ensuring the integrity of the entire underlying seal before proceeding to the subsequent S3 step to construct the second composite sealing layer.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: By using prefabricated sealing caps to achieve standardized and efficient sealing of bolt parts, the problems of construction dispersion and reliability of traditional overlay coating processes are fundamentally solved. Furthermore, by laying narrow and wide skeletons with staggered joints and combining them with colloids, a three-dimensional reinforcement network that can effectively disperse and resist complex stresses is constructed, giving the sealing structure good sealing strength and deformation resistance, and successfully overcoming the defects of existing auxiliary methods that are prone to failure under high pressure, vibration and thermal cycling conditions. The seamless fusion of multiple layers of colloids and the application of a weather-resistant outer protective layer ensure the long-term durability of the entire sealing system under harsh media and external environmental conditions. This synergistic process achieves a tensile strength increase of over 10 MPa in the sealing structure, enabling it to stably withstand rigorous temperature alternation tests. This allows for a fundamental shift from temporary leak sealing to long-term structural reinforcement without the need for custom fixtures or adaptation to confined spaces, effectively guaranteeing the reliability of continuous and safe operation of power equipment. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the method steps in Embodiment 3 of the present invention; Figure 2 This is a schematic diagram of the flange after the pressurized sealing is completed in Embodiment 3 of the present invention.

[0015] The meanings of the labels in the diagram are as follows: 100. Flange; 200. Bolt; 201. Sealing cap; 202. First layer skeleton; 203. Second layer skeleton; 204. Acrylic long-lasting sealant; 205. Epoxy resin weather-resistant sealant. Detailed Implementation

[0016] 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, and 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.

[0017] Currently, existing live sealing technologies, such as the integral wrapping method, suffer from poor overall sealing structure integrity, interlayer stress concentration, and inadequate sealing at bolt roots, making it difficult to meet the requirements for long-term stable operation under high pressure and high temperature conditions. This invention provides a novel live sealing process for power equipment, comprising the following steps: S1. Bolt 200 sealing: Fill the inner cavity of the prefabricated sealing cap 201 with sealing glue, press the sealing cap 201 onto the head of the bolt 200, so that the cap brim fits against the flange 100 surface, and scrape the overflowing glue into an annular sealing ring. S2. Construct the first composite sealing layer: Locate the leak point on the sealing surface of flange 100 and install a drain valve; then apply the first layer of sealing adhesive to the entire sealing surface of flange 100 and the cap area of ​​sealing cap 201, lay the first layer of skeleton 202 with a width less than the total thickness of flange 100, and roll it to embed the first layer of skeleton 202 into the adhesive layer to form the first composite sealing layer. S3. Constructing the second composite sealing layer: After the first composite sealing layer has cured and passed the leak test, apply the second layer of sealing adhesive to the surface of the first composite sealing layer, lay the second layer of skeleton 203 with a width greater than the total thickness of the flange 100, and the joints of the second layer of skeleton 203 and the joints of the first layer of skeleton 202 are spatially staggered by at least 50mm, and form the second composite sealing layer by roller pressing. S4. Construct the main sealing and protection structure: After the second composite sealing layer has cured, apply multiple layers of sealing adhesive alternately to completely cover all the sealing caps 201, drainage valves and skeleton system to form an integral main sealing structure; finally, apply epoxy resin weather-resistant sealing adhesive 205 to the outer surface of the main sealing structure. Example

[0018] This embodiment aims to explain in detail the structure and installation method of the sealing cap 201 in this invention and the core technical problems it solves.

[0019] This embodiment uses a prefabricated sealing cap 201. The sealing cap 201 is made of flexible fluororubber material, and its inner cavity shape is adapted to the head and part of the thread of the bolt 200 to be sealed, ensuring a tight seal. The cap 201 has an outwardly expanding flange on its brim to increase its contact area with the flange 100.

[0020] The specific installation steps for the sealing cap 201 are as follows: After cleaning, degreasing, and roughening the surfaces of flange 100 and bolt 200, first fill the inner cavity of sealing cap 201 with high thixotropic long-lasting acrylic sealant 204, filling the amount slightly higher than the inner cavity volume. Then, align sealing cap 201 with the head of bolt 200 and apply vertical pressure until its cap lip is completely in contact with the surface of flange 100.

[0021] During this pressing process, excess adhesive inside the sealing cap 201 is squeezed and overflows evenly from around the brim. The construction worker then uses a scraper to spread the overflowed adhesive along the outer perimeter of the brim into a continuous and complete annular sealing ring. This annular sealing ring, together with the sealing cap 201 body and the flange 100 surface, cures in situ to form an integrated sealing structure that combines chemical bonding and mechanical coating effects.

[0022] As a prefabricated, precisely sized sealing unit, the sealing cap 201 fundamentally eliminates blind spots and weak points caused by uneven coating. Simultaneously, the annular sealing ring formed by the overflowing adhesive after pressing, together with the sealing cap 201 body, constitutes a double sealing barrier. Furthermore, through large-area adhesion to the flange 100 surface, it enhances the vibration and peel resistance of the connection between the sealing cap 201 and the flange 100, thereby improving the sealing effect at the bolt 200 location. Example

[0023] This embodiment aims to explain in detail the method of laying the multi-layer skeleton in this invention and its role in constructing a long-lasting sealing structure.

[0024] After completing the initial sealing of the bolt 200 area as in Example 1, the construction of a composite sealing layer covering the entire sealing surface of flange 100 begins. The key to this embodiment is the use of two reinforcing frames with specific width relationships and laying requirements. Specifically, in this embodiment, the first frame 202 and the second frame 203 preferably use diamond-shaped perforated aluminum mesh with a aperture of 0.5mm.

[0025] The composite sealing layer installation includes the following steps: First, the leak points must be located and drained. Before laying the composite sealing layer, all media leak points must be accurately located on the circumference of the sealing surface of flange 100, and a drain valve must be installed. This drain valve is kept open during the initial stage of construction, using the pressure of the medium inside the equipment to safely drain the leaked medium, thus providing a clean and controllable interface free from media interference for subsequent adhesive application and laying operations. The valve is installed in a non-welding manner without damaging the structure of flange 100, using threaded connections or clamps.

[0026] Subsequently, the first composite sealing layer is constructed. After drainage is completed, a layer of acrylic long-lasting sealant 204 with a thickness of approximately 1.5 mm is evenly applied to the sealing surface of flange 100 (including the cap area of ​​the installed sealing cap 201). Then, a first-layer skeleton 202, with a width less than the total thickness of flange 100, is laid on top of the adhesive layer and repeatedly pressed using a special roller to ensure that the skeleton is completely embedded in the adhesive, tightly bonded to flange 100 and the cap 201 cap, and free of any air bubbles. Due to the small width of this skeleton layer, its edges are firmly anchored to the metal substrate of flange 100, forming a reinforcing base layer that strongly bonds with flange 100. The main function of this layer is to provide initial structural strength and establish a stable connection with flange 100.

[0027] Next, intermediate inspection and construction of the second composite sealing layer are carried out. After the first composite sealing layer has fully cured, a rigorous intermediate leak test is performed: the drainage valve is closed to block the flow path, and the entire area covered by the first composite sealing layer is then tested for leaks; once no leaks are confirmed, the immediate sealing effect of the first composite sealing layer is proven to be intact. This quality control point ensures the integrity of the underlying seal.

[0028] After passing inspection, apply a second layer of long-lasting acrylic sealant 204 over the cured first layer of skeleton 202, followed by laying a second layer of skeleton 203 with a width greater than the total thickness of flange 100. The seams of the second layer of skeleton 203 must be spatially staggered from the seams of the first layer of skeleton 202 by at least 50mm. Roller pressing is then used to ensure full impregnation and to remove air bubbles.

[0029] This combination of a narrow first-layer skeleton 202 and a wide second-layer skeleton 203, along with a forced staggered laying process, mimics the reinforcement principle of reinforced concrete in building engineering. The staggered joints of the two skeletons ensure that any potential weak points at one layer's joint are covered and reinforced by the other complete skeleton, thus constructing a three-dimensional network reinforcement system within the seal that can redistribute and effectively dissipate internal stress throughout the entire plane. This structure effectively enhances the seal's resistance to deformation and stress concentration, effectively preventing cracking and re-leakage caused by the brittleness or fatigue of the colloid itself, and is the core of achieving long-term reliable sealing. Example

[0030] This embodiment provides an application of the present invention in a pressurized sealing operation where insulating oil leakage occurs at the bottom flange 100 connection of a 110kV oil circuit breaker in a substation.

[0031] Scenario Analysis: During operation, the circuit breaker experienced persistent oil leakage at one of its flange 100 connection surfaces, with a system oil pressure of approximately 0.8 MPa. This flange 100 is located at the bottom of the equipment in a confined space, surrounded by other live components and connecting pipelines, making it difficult to accurately measure and smoothly install traditional injection-type sealing clamps. Furthermore, the circuit breaker generates instantaneous mechanical vibrations during opening and closing operations, placing higher demands on the fatigue resistance of the sealing structure.

[0032] like Figures 1 to 2 As shown, the pressurized sealing process includes the following steps: First, implement safety measures such as power outage, isolation, and voltage testing, and lay insulating blankets in the work area. Use special metal scrapers, sandpaper, and special cleaning agents to thoroughly remove rust, grind, and deeply clean the sealing surface of the leaking flange 100, bolts 200, and their surrounding areas to ensure that the surface is oil-free, dirt-free, and moderately roughened for bonding.

[0033] S1. For the M12 bolts 200 of the flange 100, a sealing cap 201 that is precisely matched is selected. The sealing cap 201 is made of oil-resistant fluororubber, and its flexibility ensures that it can be installed smoothly even in confined spaces.

[0034] During operation, first fully inject the long-lasting acrylic sealant 204 into the inner cavity of the sealing cap 201, and then press the sealing cap 201 one by one and precisely onto the head of the bolt 200, applying sufficient pressure to achieve complete microscopic fit between the cap and the flange 100.

[0035] Subsequently, the excess adhesive around the cap brim is scraped with a scraper to form a continuous, smooth, annular sealing band. When scraping the excess adhesive to form an annular sealing ring, the scraping direction is radial from the center of bolt 200 outwards. This step effectively solves the technical defect of traditional overlay processes that cannot guarantee the uniformity and integrity of adhesive application at bolt 200 in narrow spaces where visibility is obstructed and operation is inconvenient, thus establishing a reliable first barrier for the entire sealing structure.

[0036] S2. Accurately locate the media leak point on the circumference of the flange 100 sealing surface and install a miniature drainage valve. Then, evenly apply a 2mm thick layer of acrylic long-lasting sealant 204 to the entire flange 100 sealing surface and the area of ​​the bolt 200 sealing cap 201. Immediately lay the first layer of skeleton 202, 35mm wide (less than the total thickness of the flange 100, 40mm), on the adhesive layer and fully roll it using a special narrow-faced roller to ensure the skeleton is completely embedded in the adhesive layer without any air bubbles. This narrow first layer of skeleton 202 is firmly anchored to the flange 100, forming a reinforcing base layer that is tightly bonded to the flange 100 body.

[0037] S3. Allow the first composite sealing layer to fully cure, which takes approximately 1.5 hours. Then, close the drain valve and perform a rigorous intermediate leak test. After confirming no leaks, apply a second layer of long-lasting acrylic sealant 204 to the surface of the first composite sealing layer. Next, lay a second layer of reinforcement 203 with a width of 50mm (greater than the total thickness of the flange 100), ensuring that the joints of the second layer of reinforcement 203 are spatially staggered from the joints of the first layer of reinforcement 202 by at least 60mm. Roll the layer thoroughly again to form a three-dimensional reinforcing network that works synergistically with the first layer of reinforcement 202.

[0038] In S3, after the second composite sealing layer has cured, the drainage valve is kept open. The pressurized medium is first safely guided to the outside through the drainage valve, rather than directly impacting and damaging the entire sealing structure, thus effectively preventing unrestrained leakage of the medium. At the same time, keeping the drainage valve open ensures that the interlayer area between the two composite sealing layers is connected to the outside atmosphere, avoiding the accumulation of interlayer pressure that may be caused by temperature fluctuations or minor leakage, and fundamentally eliminating the risk of interlayer bulging or peeling.

[0039] S4. After the second composite sealing layer has cured, apply at least three layers of acrylic long-lasting sealant 204 alternately, with each layer applied after the previous layer has dried to the touch. This will completely cover all the sealing caps 201, the root of the drainage valve, and the two skeleton layers, forming a unified main sealing structure with no clear interface and internal fusion. It should be noted that the coating thickness of each layer of acrylic long-lasting sealant 204 is 1.5 mm.

[0040] Finally, a layer of gray epoxy resin weather-resistant sealant 205 is uniformly coated on the outer surface of the entire main sealing structure. This protective layer can not only effectively resist ultraviolet rays, rain and chemical corrosion in the outdoor environment, but its smooth surface also facilitates subsequent inspection and cleaning.

[0041] Application effect: The successful application of this embodiment demonstrates that the composite sealing structure constructed by this invention not only solves the problem of traditional clamps being unable to be installed in confined spaces, but more importantly, its standardized bolt 200 sealing achieved through the sealing cap 201 and the three-dimensional reinforcement system constructed through a multi-layered staggered skeleton endow the sealing structure with excellent vibration fatigue resistance and long-term structural stability. After the sealing operation was completed, the circuit breaker flange 100 achieved zero leakage under 0.8MPa oil pressure and mechanical vibration generated by frequent opening and closing. After a complete temperature seasonal cycle test, the sealing structure remained intact, fully verifying the technical advantages of this invention in ensuring the safe, reliable, and long-term operation of power equipment. Example

[0042] This embodiment demonstrates the comprehensive application of the technology of the present invention in a specific high-pressure oil pipeline flange 100 leak sealing operation.

[0043] Scenario analysis: An oil leak was found at the 100 connecting bolt 200 of a DN150 flange. The system pressure was 1.6MPa, and the ambient temperature fluctuated between -20℃ and 50℃.

[0044] The pressurized sealing process includes the following steps: Prepare for the operation in accordance with safety regulations, then thoroughly clean the sealing area of ​​the leaking flange 100 and all bolts 200, use an angle grinder with a wire brush to remove rust and old paint, then use a special cleaning agent to remove oil, and finally blow dry with compressed air.

[0045] S1. Select the corresponding sealing cap 201 according to the bolt 200 specification (M16). After filling the cap with acrylic long-lasting sealant 204, press it onto the bolt 200 one by one, and carefully scrape the overflowing sealant evenly to ensure that each bolt 200 part forms an integrated seal.

[0046] S2. Accurately locate the leakage point in the flange 100 gap and install a special drainage valve. Then, apply acrylic long-lasting sealant 204 to the entire flange 100 sealing surface, lay a first layer of skeleton 202 with a width of 45mm (less than the flange 100 thickness of 50mm), roll it to compact it, and form the first composite sealing layer.

[0047] S3. Allow the first composite sealing layer to cure, which takes approximately 2 hours. Close the drain valve and perform a preliminary leak check to confirm that there are no new leaks except at the drain point. After passing the check, apply a second layer of adhesive to the first composite sealing layer, then lay a second layer of aluminum mesh with a width of 60mm (greater than the flange thickness of 100mm), ensuring that its seams are staggered from the first layer by at least 50mm. Roll it compacted again to form the second composite sealing layer.

[0048] S4. After the second composite sealing layer has cured, apply three layers of acrylic long-lasting sealant 204 alternately, ensuring each layer is applied only after the previous layer has fully dried. The total thickness should completely cover the sealing cap 201, forming a seamless, integrated main sealing structure. Finally, uniformly coat the entire outer surface of the structure with a layer of gray epoxy resin weather-resistant sealant 205 as a protective layer.

[0049] Application effect: After the sealing operation was completed, the flange 100 showed no leakage under an operating pressure of 1.6 MPa. After six months of operational testing and several periods of drastic temperature changes, the sealing structure remained intact, proving that it had achieved its design goal of long-term, reliable sealing.

[0050] Example 5: Performance Testing and Verification of Sealing Materials This embodiment aims to verify the comprehensive performance of the composite sealing structure and the materials used in this invention. We designed and implemented a series of standardized laboratory tests. These tests were designed to simulate harsh conditions such as mechanical stress, temperature fluctuations, media corrosion, and pressure cycling in actual working conditions. The specific test methods and results are as follows.

[0051] Exp.1: Tensile strength and bond strength tests Test objective: To quantify the strength of the sealing material itself and its adhesion to the metal substrate, and to evaluate its ability to resist mechanical peeling.

[0052] Testing Standard: Based on ASTM D638 standard, three different sets of samples were prepared for comparative analysis. Group 1: Standard dumbbell-shaped samples cured solely from the acrylic long-lasting sealant 204 selected in this invention.

[0053] Group 2: A standard dumbbell-shaped sample was made by embedding a single layer of perforated aluminum mesh with a pore size of 0.5 mm into the pre-cured acrylic long-lasting sealing adhesive 204 as a reinforcing skeleton and then curing it.

[0054] Group 3: The composite material from Group 2 is bonded to a treated metal specimen for testing the bond interface strength (method as per ASTM D1002).

[0055] Testing equipment: Universal testing machine.

[0056] The test results are as follows: Table 1: Test results of the reinforcement effect of the skeleton on tensile strength

[0057] Test conclusions: According to the test data in Table 1, by introducing perforated aluminum mesh as a reinforcing skeleton, the tensile strength of the composite sealing material was increased from 4.2 MPa of pure colloid to 10.5 MPa, and its failure mode changed from brittle fracture to ductile failure, proving the core role of the skeleton in bearing the main load. Meanwhile, the bonding test between the composite material and the metal matrix showed a strength as high as 8.8 MPa, and all of them were cohesive failures. This further verifies that the reinforcement system not only improves the strength of the material itself, but also ensures that the bonding reliability between the composite material and the matrix interface is much higher than the strength of the material itself, thus providing key mechanical performance guarantee for achieving long-term reliable pressure sealing.

[0058] Exp.2: Thermal Cycling Aging Test Test objective: To evaluate the fatigue resistance and bonding durability of the sealing structure using this solution under drastic temperature alternation.

[0059] Test method: The flange 100 specimen with a complete composite sealing layer (including sealing cap 201 and two layers of staggered skeleton) was placed in a high and low temperature alternating test chamber (ESPEC TABAI); the flange 100 specimens were divided into three groups, namely A-01, A-02 and A-03.

[0060] Test conditions: Temperature cycling: -30℃ (+2℃) to +80℃ (+2℃), holding at each extreme temperature for 2 hours, with a heating / cooling rate of approximately 5℃ / minute. A total of 200 cycles were performed.

[0061] Inspection and Results: After the cycle was completed, the specimens were subjected to macroscopic inspection and high-magnification microscopy (50x) observation in accordance with ASTM D4587 standard.

[0062] Table 2: Inspection Results After Thermal Cycling Test

[0063] Test Conclusion: As shown in Table 2, all samples using this sealing scheme maintained their composite sealing structure intact after undergoing 200 severe thermal cycles, without any form of damage. This result proves that the sealing structure of this invention can effectively withstand long-term thermal cycling over a wide temperature range, exhibiting excellent thermal stability and resistance to thermal fatigue.

[0064] Exp.3: Transformer oil resistance test (comparison before and after immersion) Test objective: To evaluate the retention rate of the physical and mechanical properties of sealing materials after long-term immersion in high-temperature transformer oil, with a focus on the changes in key indicators such as swelling, hardness, and strength.

[0065] Test standards and methods: The test was conducted according to ASTM D471, "Rubber properties—Test method for the effect of standard liquids." The cured acrylic long-lasting sealant 204 of this invention was prepared into standard dumbbell-shaped specimens and completely immersed in 120# transformer oil.

[0066] Test conditions: Test temperature: 90°C ± 2°C; Trial duration: 504 hours (21 days); Testing equipment: Constant temperature oil bath aging test chamber.

[0067] Performance Evaluation and Results: After the test, the sample was removed, the surface residual oil was wiped off within a specified time, and the sample was cooled to room temperature. Its hardness (Shore D) and tensile strength were then immediately measured and compared with the initial values ​​before immersion. The results are shown in the table below.

[0068] Table 3: Test results of resistance to transformer oil (comparison before and after immersion)

[0069] Test Conclusion: As shown in Table 3, after 504 hours of harsh oil immersion aging at 90℃, the hardness and tensile strength of the sealing material of this invention showed minimal decrease. This fully demonstrates that the material has good chemical resistance and long-term stability to transformer oil, effectively resisting the plasticizing, swelling, and other degradation effects of the oil medium, thus ensuring its long-term reliable sealing performance in transformer sealing applications.

[0070] Exp.4: Pressure Cycle Life Test Test objective: To evaluate the interfacial sealing stability and pressure resistance life of the composite sealing structure of the present invention under constant internal pressure and alternating temperature environments, and to compare it with traditional sealing methods.

[0071] Test sample preparation: Three sets of flange 100 connectors incorporating the complete sealing structure of this invention were prepared as experimental groups. Simultaneously, two sets of flange 100 using the traditional direct coating sealing method were prepared as comparative examples; the experimental groups were numbered P-01, P-02, and P-03; the comparative examples were numbered C-01 and C-02.

[0072] Test method: The sample is installed on the pressure cycling test bench inside the programmable high and low temperature test chamber, and the system is filled with transformer oil.

[0073] Test conditions: Constant pressure: 0.65 MPa.

[0074] Temperature cycling: The temperature is cycled between three points: -40°C (low temperature), 25°C (normal temperature), and 85°C (high temperature). Each temperature point is maintained stably for 8 hours, forming a complete 24-hour cycle.

[0075] Detection and Termination Conditions: The pressure inside the sealed cavity is continuously monitored using a high-precision pressure sensor. During the pressure holding period at any temperature stage, if the system pressure drops by more than 5% of the initial value within 1 hour (i.e., pressure holding fails), the sample is deemed to have failed to seal, and the number of thermal cycles completed is recorded.

[0076] Test results: Table 4: Results of Pressure Cycle Life Test

[0077] Test conclusion: According to the test results in Table 4, after 63 rigorous thermo-coupling cycles (21 each of high, medium and low temperatures) set by this invention, all sealing samples of this invention did not leak and maintained perfect sealing performance.

[0078] In contrast, traditional sealing components fail to maintain pressure after an average of only 16.5 cycles due to interface failure. This result fully demonstrates that the composite sealing structure of this invention can excellently adapt to material expansion and contraction and stress fluctuations caused by temperature changes, and its sealing interface has extremely high stability. This solves the technical problem of early failure of traditional sealing methods under thermal cycling conditions, and provides a key guarantee for achieving full life cycle sealing reliability of power equipment.

[0079] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A novel pressurized plugging process for power equipment, characterized in that, Includes the following steps: S1. Bolt (200) sealing: Fill the cavity of the prefabricated sealing cap (201) with sealing glue, press the sealing cap (201) onto the head of the bolt (200) so that the cap brim fits against the flange (100) surface, and scrape the overflowing glue into an annular sealing ring. S2. Construct the first composite sealing layer: Locate the leak point on the sealing surface of the flange (100) and install a drain valve; then apply the first layer of sealing adhesive to the entire sealing surface of the flange (100) and the cap area of ​​the sealing cap (201), lay the first layer of skeleton (202) with a width smaller than the total thickness of the flange (100), and roll press the first layer of skeleton (202) into the adhesive layer to form the first composite sealing layer; S3. Constructing the second composite sealing layer: After the first composite sealing layer has cured and passed the leak test, apply the second layer of sealing adhesive to the surface of the first composite sealing layer, lay the second layer skeleton (203) with a width greater than the total thickness of the flange (100), and the joint of the second layer skeleton (203) is spatially staggered from the joint of the first layer skeleton (202) by at least 50mm, and form the second composite sealing layer by roller pressing; S4. Construct the main sealing and protection structure: After the second composite sealing layer has cured, apply multiple layers of sealing adhesive alternately to completely cover all the sealing caps (201), drainage valves and skeleton system to form an overall main sealing structure; finally, apply epoxy resin weather-resistant sealing adhesive (205) to the outer surface of the main sealing structure.

2. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In S1, the sealing cap (201) is made of fluororubber material.

3. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In S1 and S2, the sealing adhesive is a long-lasting acrylic sealing adhesive (204).

4. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In S2 and S3, the first layer skeleton (202) and the second layer skeleton (203) are perforated metal mesh.

5. The novel live-line sealing process for power equipment according to claim 4, characterized in that: The perforated metal mesh is a diamond-shaped perforated aluminum mesh with a aperture of 0.5 mm.

6. The novel live-line sealing process for power equipment according to claim 1, characterized in that: Before performing S1, a surface pretreatment step is included for the sealing areas of the flange (100) and bolts (200), the pretreatment including rust removal, grinding, cleaning and roughening.

7. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In S2, after the first layer of skeleton (202) is laid and before the first composite sealing layer is cured, the leak detection is performed, which specifically includes closing the drainage valve and observing whether a new leak point appears in the area covered by the first composite sealing layer.

8. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In step S3, after the second composite sealing layer is cured, the drainage valve remains in the open state.

9. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In S1, when the overflowing colloid is scraped into an annular sealing ring, the scraping direction is radial from the center of the bolt (200) outward.

10. The novel live-line sealing process for power equipment according to claim 1, characterized in that: In step S4, multiple layers of sealing adhesive are alternately applied, including at least three layers of sealing adhesive being alternately applied, with each layer having a thickness of 1-2 mm.

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