A method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures

Abstract

The present invention discloses a method for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures, comprising the following steps: S1: Pretreatment; S2: Primer spraying: spraying a primer (2) on the surface of a marine steel structure metal substrate (1); S3: First intermediate layer paint spraying; S4: Second intermediate layer paint spraying: after the first intermediate layer paint (3) is completely cured, spraying the second intermediate layer paint (4); S5: Topcoat spraying; S6: First layer of cathodic protection; S7: Second layer of cathodic protection. By adding the cathodic protection effect to the anti-corrosion coating, the present invention strengthens the anti-corrosion ability of the anti-corrosion coating, extends the service life of the paint layer, enhances the anti-corrosion durability of the overall marine steel structure, applies the anti-corrosion means of dual cathodic protection in the overall anti-corrosion system of the marine steel structure, and while improving the anti-corrosion durability of the paint layer, strengthens the overall anti-corrosion performance of the marine steel structure.

Description

Technical Field

[0001] The present invention relates to an anti-corrosion method for marine steel structures, and particularly to a method for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures. Background Art

[0002] With the continuous depletion of land resources, humans have shifted resource development from the continent to the ocean. Ocean development has gradually become the leading force in resource development and scientific and technological construction. While China's economic strength has increased and its scientific and technological level has improved, the demand for energy has also increased, leading to a high degree of emphasis on the development of ocean resources. In its ocean construction, steel structure equipment is mainly used, such as offshore oil platforms, offshore gas platforms, marine power generation sets, and marine transportation (including pipeline transportation, ship transportation, and seaport terminals). However, the corrosion of steel structures by the ocean has caused extreme damage to ocean development and construction and has become the biggest enemy in the forefront of ocean development. To ensure the smooth progress of ocean development and construction, it is necessary to vigorously carry out anti-corrosion protection for steel structures in ocean development and construction. Currently, the installation and painting of the anti-corrosion system for marine steel structure buildings are particularly complex and cumbersome. The existence of objective factors such as high construction costs, long cycles, and difficulties in secondary processing and maintenance requires us to improve the anti-corrosion performance of the anti-corrosion system for marine steel structures and extend its service life. Summary of the Invention

[0003] To solve the above-mentioned existing technical problems, the present invention provides a method for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures. This method forms a double-layer cathodic protection for the overlapping of marine steel structures while improving the anti-corrosion durability of the paint layer, thereby improving the overall anti-corrosion performance of marine steel structures and extending the overall service life of marine steel structures.

[0004] Another object of the present invention is to provide a device for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures.

[0005] To solve the problems existing in the prior art, the technical solution adopted by the present invention is as follows:

[0006] A method for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures, comprising the following steps:

[0007] S1: Pretreatment: Grind and remove rust from the metal substrate (1) of the marine steel structure to ensure its surface is smooth and clean, and attach connecting wires;

[0008] S2: Primer spraying: Spray an epoxy-based anti-corrosion paint primer (2) on the surface of the metal substrate (1) of the marine steel structure under normal temperature conditions;

[0009] S3: First intermediate layer paint spraying: After the primer (2) is completely cured, spray the first intermediate layer paint under normal temperature conditions;

[0010] S4: Spraying the second intermediate layer paint: After the first intermediate layer paint (3) is completely cured, spray the second intermediate layer paint under normal temperature conditions. During the spraying process, attach a wire when the conductive anti-corrosion paint layer is not completely dry, and then locally spray the conductive anti-corrosion paint intermediate paint (4) at the position of the wire;

[0011] S5: Spraying the topcoat: After the second intermediate layer paint (4) is completely cured, spray the topcoat (5) under normal temperature conditions;

[0012] S6: The first layer of cathodic protection: Connect the marine steel structure metal substrate (1) to the sacrificial electrode or apply an external current (7) through a wire, and immerse it in seawater (6) to form an independent cathodic protection circuit;

[0013] S7: The second layer of cathodic protection: Connect the second intermediate layer paint (4) to the sacrificial electrode or apply an external current (8) through a wire, and immerse it in seawater (6) to form an independent cathodic protection circuit.

[0014] Furthermore, the marine steel structure metal substrate described in step S1 is A3 steel, which has the same corrosion resistance as anti-corrosion steels such as 08A1 steel, 20# steel, and D36 steel. Moreover, compared with the potential of common sacrificial electrodes, the potential of A3 steel in seawater has stronger applicability and is easier to achieve the expected cathodic sacrificial protection effect.

[0015] Furthermore, the primer described in step S2 is an epoxy-based anti-corrosion paint, which has the advantages of strong adhesion, acid and alkali resistance, corrosion resistance, high wear resistance, and low curing shrinkage rate. The spraying thickness of the primer in S2 is 60μm.

[0016] Furthermore, the first intermediate layer paint described in step S3 is an insulating anti-corrosion paint used as the intermediate layer paint, which has the advantage of good insulation performance. The spraying thickness of the first intermediate layer paint is 200μm.

[0017] Furthermore, the second intermediate layer paint described in step S4 is a conductive anti-corrosion paint used as the intermediate layer paint, which has the advantages of high conductivity, the ability to form a dense conductance layer, and good aging resistance. The spraying thickness of the second intermediate layer paint is 200μm.

[0018] The topcoat described in step S5 is a glass flake heavy anti-corrosion paint used as the topcoat, which has the advantages of high sealing, high anti-permeability, high anti-corrosion performance, high anti-pollution performance, high ultraviolet resistance, and excellent aging resistance. The spraying thickness of the topcoat is about 300μm.

[0019] The advantages and beneficial effects of the present invention are:

[0020] A method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures. Since a double cathodic protection anti-corrosion means is applied in the overall anti-corrosion system of the steel structure, by adding the cathodic protection effect to the anti-corrosion coating, the anti-corrosion ability of the anti-corrosion coating is enhanced, the life cycle of the paint layer is extended, and it is combined with the cathodic protection of the marine steel structure. While improving the anti-corrosion durability of the paint layer, a double cathodic protection anti-corrosion means overlapping the marine steel structure is formed, which can effectively solve the problem of improving the overall anti-corrosion performance of the marine steel structure and extending the overall life cycle of the marine steel structure. While improving the anti-corrosion durability of the paint layer, it improves the overall anti-corrosion performance of the marine steel structure, extends the overall life cycle of the marine steel structure, and reduces the daily maintenance cost of the marine steel structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in detail below with reference to the drawings and embodiments:

[0022] Figure 1 It is a schematic structural diagram of a method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to the present invention.

[0023] In the figure: 1 is the metal substrate of the marine steel structure; 2 is the primer; 3 is the first intermediate layer paint; 4 is the second intermediate layer paint; 5 is the topcoat; 6 is seawater; 7 is the sacrificial electrode or the applied external current; 8 is the sacrificial electrode or the applied external current. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The test methods described in the following embodiments are all conventional methods unless otherwise specified; the reagent materials, unless otherwise specified, can all be obtained from commercial channels.

[0025] Example 1:

[0026] As Figure 1 shown, a method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures in this embodiment includes the following steps:

[0027] S1: Pretreatment: Grind and remove rust from the metal substrate 1 of the marine steel structure to ensure that its surface is smooth and clean, and attach connecting wires; in this embodiment, the metal substrate of the marine steel structure is selected as A3 steel, and A3 steel has the same corrosion resistance as anti-corrosion steels such as 08A1 steel, 20# steel, and D36 steel. Moreover, compared with the potential of the commonly used sacrificial electrode, the potential of A3 steel in seawater has stronger applicability and is easier to achieve the expected cathodic sacrificial protection effect.

[0028] S2: Spray the primer. Under normal temperature conditions, spray the epoxy-based anti-corrosion coating primer 2 on the surface of the foreign steel structure metal substrate 1. In this embodiment, the epoxy coal tar anti-corrosion primer produced by Shenyang Ship Paint Sales Co., Ltd. is used. Its advantages are strong adhesion, acid and alkali resistance, corrosion resistance, high wear resistance, and low curing shrinkage rate. The spraying thickness of the S2 primer is 60 μm. Using an epoxy-based anti-corrosion coating as the primer has strong anti-corrosion ability and penetration ability with steel. After curing and forming, if the paint film is too thick, it will affect the shrinkage synchronization of the paint film with the steel and the adhesion of the paint film. Therefore, the paint layer thickness is required to be relatively thin.

[0029] S3: Spray the first intermediate layer paint: After the primer 2 is completely cured, under normal temperature conditions, spray the first intermediate layer paint 3. The first intermediate layer paint uses an insulating anti-corrosion coating. In this embodiment, the ZS-1091 high-quality high-insulation anti-corrosion coating produced by Beijing Zhisheng Weihua Technology Development Co., Ltd. is used for the first intermediate layer paint. Its advantages are good insulation performance, and the spraying thickness is 200 μm. The insulating anti-corrosion coating has strong anti-corrosion and insulation performance. To ensure the dense, continuous and insulating performance of the first intermediate layer paint film, the paint film thickness should not be too thin. At the same time, considering that the total thickness of the overall anti-corrosion paint film being too thick will affect its shrinkage synchronization with the steel, it is appropriate that the spraying thickness of the first intermediate layer paint layer is 200 μm.

[0030] S4: Spray the second intermediate layer paint: After the first intermediate layer paint 3 is completely cured, under normal temperature conditions, spray the second intermediate layer paint 4. The second intermediate layer paint uses a conductive anti-corrosion coating. In this embodiment, the Qianhaihao static conductive anti-corrosion intermediate paint produced by Huachang Jiutai (Shandong) Special Coating Co., Ltd. is used. Its advantages are high conductivity, can form a dense conductive layer, and good aging resistance. During the spraying process, attach wires when the conductive anti-corrosion coating paint film is not completely dry, and then locally spray the conductive anti-corrosion coating intermediate paint at the wire position. The spraying thickness of the second intermediate layer paint in this embodiment is 200 μm. Among them, the conductive anti-corrosion coating has strong anti-corrosion and conductivity. To ensure the dense, continuous and conductive performance of the second intermediate layer paint film, the paint film thickness should not be too thin. At the same time, considering that the total thickness of the overall anti-corrosion paint film being too thick will affect its shrinkage synchronization with the steel, the spraying thickness of the first intermediate layer paint layer is 200 μm.

[0031] S5: Spraying topcoat: After the second intermediate coat 4 is completely cured, at normal temperature, spray the topcoat 5. The topcoat uses a glass flake heavy-duty anti-corrosion coating. In this embodiment, the glass flake anti-corrosion coating produced by Hebei Moni Environmental Protection Technology Co., Ltd. is used. Its advantages are high sealing, high impermeability, high anti-corrosion performance, high anti-pollution performance, high UV resistance, and excellent anti-aging performance. The spraying thickness of the topcoat is 300 μm. Since the glass flake heavy-duty anti-corrosion coating contains glass or ceramic flaky particles, a certain number need to be stacked per unit area to exert its special UV resistance and anti-aging performance. As a result, the film-forming thickness should be greater than that of ordinary paint films. At the same time, the poor deformation performance after film formation of the glass flake heavy-duty anti-corrosion coating restricts the thickness from being too high, otherwise brittleness will be rapidly manifested. Therefore, it is better to control the thickness of the glass flake heavy-duty anti-corrosion coating topcoat to just achieve the scale stacking effect, and 300 μm is more suitable.

[0032] S6: First layer of cathodic protection: Connect the marine steel structure metal substrate 1 to the sacrificial electrode or impressed current 7 through a wire and immerse it in seawater 6 to form an independent cathodic protection circuit. In this embodiment, the first layer of cathodic protection is to connect the marine steel structure metal substrate 1 to the sacrificial electrode 7 and immerse it in seawater 6 to form an independent circuit, and form the first layer of cathodic protection for the steel structure metal substrate through the cathodic protection principle of electrochemistry, improving the anti-corrosion performance of the anti-corrosion coating of the steel structure metal substrate. In this embodiment, the sacrificial electrode metal 7 uses magnesium alloy.

[0033] S7: Second layer of cathodic protection: Connect the second intermediate coat 4 to the sacrificial electrode or impressed current 8 through a wire and immerse it in seawater 6 to form an independent cathodic protection circuit. In this embodiment, the second layer of cathodic protection is to connect the second intermediate coat 4 to the sacrificial electrode 8 through a wire and immerse it in seawater 6 to form an independent circuit, and form the second layer of cathodic protection for the second intermediate coat through the cathodic protection principle of electrochemistry, improving the anti-corrosion performance of the anti-corrosion paint layer and extending the service life of the paint layer. In this embodiment, the sacrificial electrode metal 8 uses magnesium alloy.

[0034] Example 2:

[0035] The difference between this embodiment and Example 1 is only that steps S6 and S7 are different. In the first layer of cathodic protection in step S6 of this embodiment, the marine steel structure metal substrate 1 is connected to the impressed current 7 through a wire and immersed in seawater 6 to form an independent cathodic protection circuit.

[0036] In the second layer of cathodic protection in step S7 of this embodiment, the second intermediate coat 4 is connected to the impressed current 8 through a wire and immersed in seawater 6 to form an independent cathodic protection circuit. The rest is the same as Example 1.

[0037] Example 3:

[0038] As Figure 1 shown, an apparatus for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures in this embodiment includes a primer 2, a first intermediate layer paint 3, a second intermediate layer paint 4, and a topcoat 5. The four layers of paint are sequentially coated on the surface of the marine steel structure metal substrate 1 to form a coating barrier, which plays a role in coating anti-corrosion for the steel structure metal substrate. The primer 2 uses an epoxy-based anti-corrosion coating, and the epoxy-based anti-corrosion coating uses an epoxy coal tar anti-corrosion primer. The spraying thickness is 60 μm. The first intermediate layer paint 3 uses an insulating anti-corrosion coating, and the spraying thickness of the insulating anti-corrosion coating is 200 μm. The second intermediate layer paint 4 uses a conductive anti-corrosion coating, and the conductive anti-corrosion coating uses a submerged electrostatic conductive anti-corrosion intermediate paint, and the spraying thickness is 200 μm. The topcoat 5 uses a glass flake heavy anti-corrosion coating, and the spraying thickness of the glass flake heavy anti-corrosion coating is 300 μm. The second intermediate layer paint 4 is connected to a sacrificial electrode 8, and a first cathodic protection is formed for the anti-corrosion coating through the cathodic protection principle of electrochemistry, improving the anti-corrosion performance of the anti-corrosion paint layer and extending the service life of the anti-corrosion paint layer. The marine steel structure metal substrate 1 is connected to a sacrificial electrode 7, and a second cathodic protection is formed for the steel structure metal substrate through the cathodic protection principle of electrochemistry, improving the anti-corrosion performance of the anti-corrosion coating of the steel structure metal substrate. The sacrificial electrode uses magnesium alloy. The two-layer cathodic protection is superimposed to improve the overall anti-corrosion performance of the steel structure metal substrate in seawater. The painted marine steel structure metal substrate 1 and the sacrificial electrode are all immersed in seawater 6, and a complete circuit for cathodic protection is formed through the ions in the seawater.

[0039] Example 4:

[0040] As Figure 1As shown in the figure, an apparatus for improving the anti-corrosion performance of an anti-corrosion system for marine steel structures in this embodiment includes a primer 2, a first intermediate layer paint 3, a second intermediate layer paint 4, and a topcoat 5. The four layers of paint are sequentially coated on the surface of the metal substrate 1 of the marine steel structure to form a coating barrier, which plays a role in coating anti-corrosion for the metal substrate of the steel structure. The primer 2 uses an epoxy-based anti-corrosion coating, and the epoxy-based anti-corrosion coating uses an epoxy coal tar anti-corrosion primer. The spraying thickness is 60μm. The first intermediate layer paint 3 uses an insulating anti-corrosion coating, and the spraying thickness of the insulating anti-corrosion coating is 200μm. The second intermediate layer paint 4 uses a conductive anti-corrosion coating, and the conductive anti-corrosion coating uses a submarine conductive static anti-corrosion intermediate paint, and the spraying thickness is 200μm. The topcoat 5 uses a glass flake heavy anti-corrosion coating, and the spraying thickness of the glass flake heavy anti-corrosion coating is 300μm. An external current 8 is applied to the second intermediate layer paint 4, and the first cathodic protection of the anti-corrosion coating is formed through the cathodic protection principle of electrochemistry, improving the anti-corrosion performance of the anti-corrosion paint layer and extending the service life of the anti-corrosion paint layer. An external current 7 is applied to the metal substrate 1 of the marine steel structure, and the second cathodic protection of the metal substrate of the steel structure is formed through the cathodic protection principle of electrochemistry, improving the anti-corrosion performance of the anti-corrosion coating of the metal substrate of the steel structure. The superposition of the two layers of cathodic protection improves the overall anti-corrosion performance of the metal substrate of the steel structure in seawater. The painted metal substrate 1 of the marine steel structure is completely immersed in seawater 6, and a complete circuit of cathodic protection is formed through the ions in the seawater.

[0041] The present invention adopts an anti-corrosion means of dual cathodic protection. Among them, an anti-corrosion means of dual cathodic protection is applied in the overall anti-corrosion system of the marine steel structure. The second layer of cathodic protection enhances the anti-corrosion ability and service life of the anti-corrosion coating. At the same time, it combines with the first layer of cathodic protection of the marine steel structure itself. The dual superposition cathodic protection method strengthens the overall performance of the anti-corrosion system of the marine steel structure.

[0042] Simulation experiment:

[0043] The simulation test environment is as follows: The marine steel structure undergoes a test of controlled temperature at 40 degrees and normal pressure ultraviolet aging in simulated seawater immersion, and sacrificial electrode metals 7 and 8 both use sacrificial electrodes.

[0044] The first group of simulation single-layer cathodic protection tests:

[0045] The simulated single-layer cathodic protection overall anti-corrosion system of the marine steel structure is shown in Figure 1 , where the film thickness of the epoxy-based anti-corrosion coating is 60μm, the film thickness of the insulating anti-corrosion coating is 200μm, the film thickness of the conductive anti-corrosion coating is 200μm, the film thickness of the glass flake heavy anti-corrosion coating is 300μm, the metal substrate 1 of the marine steel structure is connected to the sacrificial electrode metal 7, and the second intermediate layer paint 4 is disconnected from the sacrificial electrode metal 8.

[0046] After 4848 hours, air bubbles appeared in the overall anti-corrosion paint layer, and rust spots appeared at individual points on the metal substrate.

[0047] The second group of simulated dual cathodic protection tests:

[0048] The overall anti-corrosion system for simulating dual cathodic protection of marine steel structures is shown in Figure 1 , where the film thickness of the epoxy anti-corrosion coating is 60 μm, the film thickness of the insulating anti-corrosion coating is 200 μm, the film thickness of the conductive anti-corrosion coating is 200 μm, the film thickness of the glass flake heavy anti-corrosion coating is 300 μm, the metal substrate 1 of the marine steel structure is connected to the sacrificial electrode metal 7, and the second intermediate layer paint 4 is connected to the sacrificial electrode metal 8.

[0049] After 5232 hours, air bubbles appeared in the overall anti-corrosion paint layer, and rust spots appeared at individual points on the metal substrate.

[0050] Comparing the two groups of experiments, the steel structure substrate, anti-corrosion types, brands, models, painting processes, and painting thicknesses are all the same. The difference lies in whether the second intermediate layer paint 4 is connected to the sacrificial electrode metal 8, that is, whether a complete circuit of the second layer of heavy cathodic protection is formed. The results show that the anti-corrosion system under simulated dual cathodic protection has a 7.9% longer anti-aging time than the anti-corrosion system under single-layer cathodic protection, significantly improving the life cycle of the overall anti-corrosion system of marine steel structures.

[0051] Supplementary description of the test:

[0052] In this experimental method, in the simulation experiment, due to laboratory condition factors, the cathodic protection of the sacrificial electrode formed by the natural potential difference is applied. In actual working conditions and use, it can be replaced by impressed current cathodic protection, which will have a more stable and obvious cathodic protection effect. When applying cathodic protection and dual cathodic protection to the overall marine steel structure with large volume, large mass, and complex structure, multiple-point detection is required, and a reflux point (power-on point) is set to detect and control the potential of each part of the marine steel structure in real time. In impressed current cathodic protection, when the output current is too small, the cathodic protection of the marine steel structure will be insufficient. When the output current is too large, the metal near the auxiliary anode will be overpolarized, and there is a risk of hydrogen embrittlement. Therefore, specific data analysis and current regulation need to be carried out according to the specific overall marine steel structure, and the input current and reflux current are adjusted respectively to achieve overall balance through system matching, and the protection potential range is optimally controlled within -0.85~-0.95V.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures, characterized in that , it includes the following steps: S1： Pretreatment: Grind and remove rust from the metal substrate (1) of the marine steel structure to ensure its surface is smooth and clean, and attach connecting wires; S2: Primer spraying: Under normal temperature conditions, spray primer (2) on the surface of the metal substrate (1) of the marine steel structure; S3: First intermediate layer paint spraying: After the primer (2) is completely cured, under normal temperature conditions, spray the first intermediate layer paint (3); The first intermediate layer paint described in step S3 uses an insulating anti-corrosion coating; S4: Second intermediate layer paint spraying: After the first intermediate layer paint (3) is completely cured, under normal temperature conditions, spray the second intermediate layer paint (4). During the spraying process, attach wires when the paint layer of the second intermediate layer paint (4) is not completely dry, and then locally spray additional second intermediate layer paint (4) at the wire position; The second intermediate layer paint described in step S4 uses a conductive anti-corrosion coating; S5: Topcoat spraying: After the second intermediate layer paint (4) is completely cured, under normal temperature conditions, spray topcoat (5); S6: First layer of cathodic protection: Connect the metal substrate (1) of the marine steel structure to a sacrificial electrode or an impressed current (7) through a wire, and immerse it in seawater (6) to form an independent cathodic protection circuit; S7: Second layer of cathodic protection: Connect the second intermediate layer paint (4) to a sacrificial electrode or an impressed current (8) through a wire, and immerse it in seawater (6) to form an independent cathodic protection circuit.

2. The method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to claim 1, characterized in that: The metal substrate (1) of the marine steel structure described in step S1 is made of A3 steel.

3. The method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to claim 1, characterized in that: The primer described in step S2 uses an epoxy anti-corrosion coating.

4. The method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to claim 1, characterized in that: The conductive anti-corrosion coating uses a conductive static electricity-resistant intermediate paint.

5. The method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to claim 1, characterized in that: The topcoat described in step S5 uses a glass flake heavy anti-corrosion coating.

6. The method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to claim 1, characterized in that: The sacrificial electrode described in step S6 uses magnesium alloy.

7. The method for improving the anti-corrosion performance of the anti-corrosion system of marine steel structures according to claim 1, characterized in that: The sacrificial electrode described in step S7 uses magnesium alloy.

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