Old coating maintenance method for wind field tower drum

Abstract

The invention provides an old coating maintenance method for a wind field tower drum. The method comprises the steps that a to-be-maintained area on a coating is determined; the selected to-be-maintained area is processed; primer coating, wherein a first coating procedure and a second coating procedure are included; the primer adopts low surface treatment epoxy anti-corrosive primer; the first process comprises the following steps of: taking the primer with proper viscosity, and integrally coating the primer on a to-be-maintained area and an extension area of 2-3cm of the to-be-maintained area by a roller; secondly, after the surface of the primer obtained in the first process is cured, the primer with the proper viscosity continues to be taken and integrally coated on the to-be-maintained area and the area 3-4 cm away from the to-be-maintained area in a roller coating mode; and after the primer is cured for 1-2 h, the original finish paint is selected to be integrally coated on the to-be-maintained area and the area 4-5 cm away from the to-be-maintained area in a roller coating mode, and the coating process of the finish paint needs to be controlled to be completed within 1 h. The old coating maintenance method has the advantages that the tolerance to the construction environment is high, the adhesive force of the maintained coating is high, and the construction period is short.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine towers, and specifically relates to a method for repairing old coatings on wind farm towers. Background Technology

[0002] Wind turbine towers are crucial supporting structures in wind power systems. The base of the tower is fixed to the foundation, while the top connects to the wind turbine generator, serving as the primary support and load-bearing component. Because wind turbine towers are built outdoors, they must withstand prolonged exposure to wind, rain, and environmental corrosion. Therefore, they require extremely high corrosion and weather resistance to ensure a long service life. To extend the service life and ensure safe operation of wind turbines, efficient coatings are essential for protection. However, any coating has a limited lifespan. With the erosion of corrosive substances, varying degrees of rust penetration, re-rusting, and cracking will occur, necessitating systematic maintenance of the old coating after a certain point. Currently, most onshore wind turbine tower coatings are designed for a C4 environment. This typically involves an epoxy zinc-rich primer (60µm) containing 80% zinc, an epoxy intermediate coat (90µm), and a polyurethane topcoat (50µm). The technical solution explicitly stated in the relevant technologies when using international coatings is: epoxy zinc-rich paint Interzinc52E (60um) + epoxy micaceous iron oxide intermediate paint Intergard475HS (90um) + polyurethane topcoat Interthane990(E) - RAL9016 (50um). The technical solution when using Megacore color coatings is: epoxy zinc-rich primer WU130 (60um) + epoxy paint WU132 (90um) + polyurethane topcoat FU360-RAL9016 (50um). After a period of use, with the erosion of corrosive substances, varying degrees of rust penetration, rust re-emergence, and cracking will appear on the coating. Once these phenomena reach a certain point, systematic maintenance of the old coating is required.

[0003] While the appearance requirements for old coatings are relatively lower during maintenance, higher demands are placed on workability and corrosion resistance. For example, sandblasting is not possible, substrate preparation is difficult, outdoor high-altitude work is required, and the working window is short. Currently, most OEMs require old coating refurbishment to be carried out according to the original plan. For instance, relevant technical specifications clearly state that if the primer is damaged, the coating should be sanded down to the substrate. Surface cleaning should preferably be done by sandblasting to remove rust, achieving a rust removal grade of Sa2.5; when sandblasting is not feasible, power or manual rust removal can be used, achieving a grade of St3. During repair, the coating thickness and the interval between each coat should follow the original coating plan; environmental conditions during repair should be the same as required by the original coating plan; the repaired coating should be protected to prevent uncured coating from being stepped on or damaged; in areas that have been submerged in water or may be submerged, the repaired coating should be allowed to fully cure before immersion in water.

[0004] However, the actual maintenance of old coatings involves outdoor, high-altitude operations, making substrate treatment difficult. Following the original design specifications would result in extended working hours, increased labor costs, and significant safety risks. Furthermore, wind turbine towers are typically located on mountaintops, areas with strong updrafts, prone to fog, precipitation, and thunderstorms. Controlling environmental factors before and after coating is challenging, making it difficult to ensure the intervals between each coating layer and the environmental conditions adhere to the original coating plan. In addition, most current substrate treatment involves power or manual rust removal. However, in high-altitude operations, this method rarely achieves St3 grade, typically only reaching St2. Even if significant time is spent to achieve St3, power rust removal with an angle grinder is necessary, posing safety hazards at height. Even if St3 is achieved, using a high-zinc epoxy zinc-rich primer for old coating repair can lead to poor paint film adhesion due to insufficient roughness, affecting the overall coating maintenance quality later. Summary of the Invention

[0005] The purpose of this invention is to provide a method for repairing old coatings on wind farm towers, in order to solve the aforementioned technical problems.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for repairing old coatings on wind farm towers, the method comprising the following steps: S1: Identify the area to be repaired on the coating; S2: Process the maintenance area selected by S1; S3: Apply primer, including overlapping the first and second steps, wherein the primer is a low-surface-treatment epoxy anti-rust primer; First step: Apply an appropriate amount of primer with a roller to the area to be repaired and its outer 2-3cm area; Second step: After the primer surface completed in the first step has cured, take an appropriate amount of primer with a suitable viscosity and roll it onto the area to be repaired and the area extending 3-4cm beyond it. S4: Apply topcoat. After the primer in S3 has cured for 1-2 hours, use the original polyurethane topcoat to apply it to the area to be repaired and the area extending 4-5cm beyond it. The topcoat application process must be completed within 1 hour. Among them, low-surface-treatment epoxy anti-rust primers must meet the requirements of HG / T4564-2013 low-surface-treatment-tolerant epoxy coatings, with a volume solids content of 70%~80% and a specific gravity of 1.4~1.5.

[0007] Furthermore, in the first step of S3, a nylon bristle roller is used for application, with the angle between the roller handle and the area to be repaired maintained at 60°~90°, and the roller coating speed is 10~20cm / s; the viscosity of the primer is 15~20S, the roller coating speed is 10~20cm / s, and the paint film thickness is 20~30μm; in the second step, the viscosity of the primer is 40~60S, and the paint film thickness is 40~60μm.

[0008] Furthermore, in S4, the topcoat is selected as a polyurethane type topcoat with a viscosity of 60~80S, and the coating thickness of the topcoat is 60~80μm.

[0009] Furthermore, an appropriate amount of organotin needs to be added to the topcoat and mixed thoroughly before application.

[0010] Furthermore, the organotin content accounts for 0.1 to 0.3 wt% of the topcoat.

[0011] Furthermore, in S2, the processing flow includes: S21: Remove cracked paint film and loose coating from the surface of the area to be repaired; S22: Roughen the surface of the area to be repaired; S23: Create a slope at the edge of the coating in the area to be repaired, with a slope of 25~45°; S24: Clean the surface of the area to be repaired.

[0012] Furthermore, in S21, according to the "X" adhesion method, coatings with adhesion ≤2A are determined to be loose coatings.

[0013] Furthermore, in S1, according to the "X" adhesion method, the area where the coating adhesion is ≤2A is determined to be the area to be repaired.

[0014] The technical solution of the present invention has the following advantages: 1. The technical solution provided by this invention can save construction time. Traditional methods for maintaining old paint films often involve mechanical grinding due to the inconvenience of sandblasting. When the rust removal level reaches St3, traditional methods require high-altitude grinding operations, with each person grinding 5-10 meters. 2 / day; using this solution, each person can process 20~30m³ / day. 2 / day of substrate.

[0015] 2. Avoiding safety hazards. Traditional methods for maintaining old paint films require the use of angle grinders or sandblasting machines to treat the substrate. Given the high-altitude working environment, traditional methods pose significant safety risks; however, this solution eliminates these risks as it does not involve mechanical equipment.

[0016] 3. Improve the quality of refurbished old coatings. Traditional methods for maintaining old paint films generally require sandblasting or mechanical grinding of the substrate, followed by application of the original coating (epoxy zinc-rich primer + epoxy thick intermediate coat + polyurethane topcoat). Since sandblasting is inconvenient for high-altitude operations, mechanical grinding is usually used. Mechanical grinding, if performed to St3 grade, is extremely time-consuming; and the resulting substrate surface has virtually no roughness. In this case, using an epoxy zinc-rich primer results in low overall adhesion of the refurbished coating, increasing the risk of peeling later. Coatings repaired using this method have an adhesion ≥4A and a pull-out adhesion >5MPa.

[0017] 4. Increase the working window. When maintaining old paint films using traditional methods, the actual working time each day is short and wasteful due to the outdoor working environment, which is often affected by factors such as wind speed, humidity, and painting interval. This method can save on wasted time.

[0018] 5. Reduce the cost of paint during the renovation of old coatings. Taking the C4 environment of the tower outer wall as an example, the traditional maintenance coating structure is epoxy zinc-rich primer (60µm) + epoxy thick intermediate paint (90µm) + polyurethane topcoat (50µm), and the renovation process of old coatings generally follows the old coating scheme. This scheme uses low surface treatment epoxy anti-rust primer (60-90µm) + original old coating polyurethane topcoat (60-80µm), which reduces the overall paint film thickness, resulting in less raw material consumption; and the cost per square meter of 80% epoxy zinc-rich primer is higher than that of low surface treatment epoxy anti-rust primer. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments.

[0020] Embodiments of the present invention provide a method for repairing old coatings on wind farm towers, the method comprising the following steps: S1: Identify the area to be repaired on the coating.

[0021] In S1, areas where the coating adhesion is ≤2A are identified as areas requiring repair, based on the "X" adhesion test. These areas are primarily determined from two sources. First, the "X" adhesion test is applied to areas with visible rust, through-rust, or cracks. Second, the "X" adhesion test is applied to areas surrounding these areas where the coating adhesion is significantly reduced, thus ultimately identifying the areas requiring repair.

[0022] S2: Process the maintenance area selected in S1. The processing flow in S2 includes: S21: Remove cracked paint film and loose coating from the surface of the area to be repaired. In S21, according to the "X" adhesion method, coatings with an adhesion strength ≤2A are determined to be loose coatings. Use a scraper to remove the cracked paint film and loose coating.

[0023] S22: Use 60~180 grit sandpaper to roughen the area to be repaired in order to remove the loose rust on the surface of the old coating.

[0024] S23: Use 20-60 grit sandpaper to create a 25°-45° slope at the edge of the coating in the area to be repaired.

[0025] S24: Use a blower with a wind speed >20m / s to clean the surface of the area to be repaired before proceeding with the work, such as removing grinding powder, impurities, and dust.

[0026] S3: Apply primer, including the overlay of the first and second application processes. The primer is a low-surface-treatment epoxy anti-rust primer. The low-surface-treatment epoxy anti-rust primer must meet the requirements of HG / T4564-2013 Low-surface-treatment-tolerant epoxy coatings, with a volume solids content of 70%~80% and a specific gravity of 1.4~1.5.

[0027] The low-surface-treatment epoxy anti-rust primer selected is H06-DB low-surface-treatment epoxy anti-rust primer from Northwest Yongxin Coatings Co., Ltd.

[0028] In the first step, a nylon-bristled stiff-bristled roller is used for application. An appropriate amount of primer with suitable viscosity is applied by roller to the area to be repaired and an area extending 2-3 cm beyond it. During this process, the primer viscosity is 15-20S, the roller speed is 10-20 cm / s, and the angle between the roller handle and the area to be repaired is maintained at 60°-90°. The paint-laden bristles are fully compacted onto the roller core to ensure sufficient primer penetration, ultimately resulting in a paint film thickness of 20-30 μm.

[0029] After the primer surface from the first step has cured, proceed to the second step. In the second step, take an appropriate amount of primer with suitable viscosity and apply it to the area to be repaired and an area extending 3-4 cm beyond it using a standard roller and conventional techniques. During this process, the primer viscosity is 40-60S, and the film thickness is 40-60μm.

[0030] The viscosity of the primer is adjusted by adding different proportions of X-7 epoxy thinner to the low-surface-treatment epoxy anti-rust primer. Specifically, adding 40-50 wt% X-7 epoxy thinner to the low-surface-treatment epoxy anti-rust primer yields a primer with a viscosity of 15-20S for use in the first process; adding 3-15 wt% X-7 epoxy thinner to the low-surface-treatment epoxy anti-rust primer yields a primer with a viscosity of 40-60S for use in the second process.

[0031] S4: Topcoat application. After the primer in S3 has cured for 1-2 hours, use the same original polyurethane topcoat as the old coating. Apply the topcoat to the area to be repaired and its outer 4-5cm using a conventional short-nap roller and conventional methods. The topcoat application process must be completed within 1 hour.

[0032] In S4, a polyurethane-type topcoat with a viscosity of 60~80S is selected. Before applying the topcoat, 0.1~0.3wt% of organotin is added and mixed evenly. The coating thickness of the topcoat is 60~80μm.

[0033] Example 1 After identifying the area to be repaired and removing any cracked paint film and loose coating, roughen the surface of the area with 60-grit sandpaper. Then, use 20-grit sandpaper to create a 25° slope at the edges of the coating in the area to be repaired. After cleaning the surface of the area to be repaired with a blower at a wind speed of 25 m / s, proceed with the repair work, such as removing sanding powder, impurities, and dust.

[0034] The first and second coating processes were performed using H06-DB low-surface-treatment epoxy anti-rust primer. In the first process, a nylon-bristled stiff-bristled roller was used. A primer with a viscosity of 20S was applied to the area to be repaired and an area extending 2cm beyond it at a roller speed of 10 cm / s. During this process, the angle between the roller handle and the area to be repaired was maintained at 60°, ensuring that all the paint-laden bristles were compacted onto the roller core, guaranteeing full penetration of the primer, and ultimately achieving a film thickness of 30μm.

[0035] After the primer surface of the first process has cured, the second process is carried out. In the second process, a primer with a viscosity of 60S is taken and applied to the area to be repaired and its outer 3cm area using a conventional roller and conventional method, and the paint film thickness is controlled to be 60μm.

[0036] The topcoat used is a polyurethane type with a viscosity of 80S, the same type as the topcoat used on the old coating. Before application, 0.3wt% organotin should be added and mixed thoroughly. After the primer has cured for 2 hours, apply the topcoat to the area to be repaired and its outer 4cm using a standard short-nap roller and standard hand technique. The final topcoat thickness should be 80μm. It is important to note that the topcoat application process must be completed within 1 hour.

[0037] Example 2 After identifying the area to be repaired and removing cracked paint and loose coating, roughen the surface with 180-grit sandpaper to remove any loose rust from the old coating. Continue by using 60-grit sandpaper to create a 45° slope at the edges of the coating in the area to be repaired. After cleaning the surface of the area with a blower at 25 m / s to remove dirt, impurities, and dust, proceed with the repair work.

[0038] The first and second coating processes were performed using H06-DB low-surface-treatment epoxy anti-rust primer. In the first process, a nylon-bristled stiff-bristled roller was used. A primer with a viscosity of 15S was applied to the area to be repaired and an area extending 3cm beyond it at a roller speed of 20cm / s. The angle between the roller handle and the area to be repaired was maintained at 90°, ensuring that all the paint-laden bristles were compacted onto the roller core, guaranteeing full penetration of the primer, resulting in a final film thickness of 20μm.

[0039] After the primer surface from the first step has cured, proceed to the second step. In the second step, take a primer with a viscosity of 40S and apply it to the area to be repaired and its outer 4cm using a conventional roller and manual technique. Control the paint film thickness to 40μm.

[0040] The topcoat used is a polyurethane type with a viscosity of 60S, the same type as the topcoat used on the old coating. Before application, 0.1wt% organotin should be added and mixed thoroughly. After the primer has cured for 1 hour, apply the topcoat to the area to be repaired and its outer 5cm using a standard short-nap roller and standard hand technique, achieving a final topcoat thickness of 60μm. It is important to note that the topcoat application process must be completed within 1 hour.

[0041] An embodiment of the present invention is used to repair 1m 2 The old paint film was used as the experimental subject. Table 1 lists the repair solutions and effects corresponding to the embodiments of the present invention and traditional processes.

[0042] Table 1. Overview of Repair Plan and Repair Results ; As shown in Table 1, using traditional process 1 (manual tool treatment) to repair the substrate, the St2 grade can be barely achieved. This process consists of a 60µm epoxy zinc-rich primer, a 90µm epoxy intermediate coat, and a 50µm polyurethane topcoat. Using traditional process 2 (power tool treatment), the St2 grade can also be achieved, again with the same process. Using traditional process 3 (power tool treatment), the St3 grade can be barely achieved, again with the same process. In summary, compared to Example 2 of this invention, all three traditional processes have drawbacks: longer total process time, lower coating pull-out adhesion, and higher coating costs. This indicates that the technical solution of this invention has the potential for widespread application in wind power systems, especially in wind turbine tower repair.

Claims

1. A method for repairing old coatings on wind farm towers, characterized in that, The method for repairing the old coating includes the following steps: S1: Identify the area to be repaired on the coating; S2: Process the maintenance area selected by S1; S3: Apply primer, including overlapping the first and second steps, wherein the primer is a low-surface-treatment epoxy anti-rust primer; First step: Apply an appropriate amount of primer with a roller to the area to be repaired and its outer 2-3cm area; Second step: After the primer surface completed in the first step has cured, take an appropriate amount of primer with a suitable viscosity and roll it onto the area to be repaired and the area extending 3-4cm beyond it. S4: Apply topcoat. After the primer in S3 has cured for 1-2 hours, use the original polyurethane topcoat to apply it to the area to be repaired and the area extending 4-5cm beyond it. The topcoat application process must be completed within 1 hour. Among them, low-surface-treatment epoxy anti-rust primers must meet the requirements of HG / T4564-2013 low-surface-treatment-tolerant epoxy coatings, with a volume solids content of 70%~80% and a specific gravity of 1.4~1.

5.

2. The method for repairing old coatings on wind farm towers according to claim 1, characterized in that, In the first step of S3, a nylon bristle roller is used for application. The angle between the roller handle and the area to be repaired is maintained at 60°~90°. The roller speed is 10~20cm / s. The viscosity of the primer is 15~20S. The film thickness is 20~30μm. In the second step, the viscosity of the primer is 40~60S. The film thickness is 40~60μm.

3. The method for repairing old coatings on wind farm towers according to claim 1, characterized in that, In S4, the topcoat is a polyurethane type topcoat with a viscosity of 60~80S, and the coating thickness of the topcoat is 60~80μm.

4. The method for repairing old coatings on wind farm towers according to claim 3, characterized in that, Before applying the topcoat, an appropriate amount of organic tin needs to be added and mixed well.

5. The method for repairing old coatings on wind farm towers according to claim 4, characterized in that, The organotin content accounts for 0.1~0.3 wt% of the topcoat.

6. The method for repairing old coatings on wind farm towers according to claim 1, characterized in that, In S2, the processing flow includes: S21: Remove cracked paint film and loose coating from the surface of the area to be repaired; S22: Roughen the surface of the area to be repaired; S23: Create a slope at the edge of the coating in the area to be repaired, with a slope of 25~45°; S24: Clean the surface of the area to be repaired.

7. The method for repairing old coatings on wind farm towers according to claim 6, characterized in that, In S21, according to the "X" adhesion method, coatings with adhesion ≤2A are determined to be loose coatings.

8. The method for repairing old coatings on wind farm towers according to claim 1, characterized in that, In S1, according to the "X" adhesion method, the area where the coating adhesion is ≤2A is determined to be the area to be repaired.