A full-process anti-corrosion solution for lubricating oil circulation systems

Abstract

The application discloses a kind of lubricating oil circulation system whole-process anticorrosion solution, it is related to industrial equipment anticorrosion technical field, comprising the following steps: corrosion cause control is carried out to welding area, pipeline structure and oil tank cavity in lubricating oil circulation system, select the welding material matched with parent material, isolate stainless steel and carbon steel contact, configure RH4 metal transparent sealant on the surface of stainless steel;5 carbon steel phosphating rust preventive primer is applied to the surface of carbon steel component;6 oil-resistant inner cavity special coating is coated in the inner cavity of system;Anticorrosion control is executed in running phase.The application combines corrosion cause and material protection by whole-process anticorrosion control path, effectively inhibits weld corrosion, pitting and electrochemical corrosion, limits corrosion propagation and guarantees system stable operation;Meanwhile, through the synergistic application of various anticorrosion materials and normal temperature preparation process, the continuity of protection and the convenience of construction are improved, the oil pollution and equipment wear are reduced, and the long-term operation reliability of the system is maintained.

Description

Technical Field

[0001] This invention relates to the field of industrial equipment corrosion protection technology, specifically to a solution for corrosion protection of the entire process of a lubricating oil circulation system. Background Technology

[0002] In industries such as petroleum, chemical, energy, and metallurgy, compressors are key power equipment, and their operational stability directly affects the safety and continuity of production systems. The lubricating oil circulation system, as an important component of the compressor, undertakes multiple functions including lubrication, cooling, cleaning, sealing, and vibration damping, playing a decisive role in the equipment's operating efficiency and service life.

[0003] In existing technologies, components of lubrication systems such as oil tanks, pipelines, and valve assemblies are typically made of 316 stainless steel to take advantage of its good corrosion resistance. However, in practical engineering applications, existing anti-corrosion measures mainly rely on the corrosion resistance of the material itself, lacking systematic anti-corrosion control measures covering the entire manufacturing, assembly, and operation process. The main problems are as follows: 1. During the manufacturing stage: Problems such as improper matching of welding materials and base materials and non-standard welding support often exist during the welding process, which can easily lead to intergranular carburization corrosion and galvanic corrosion caused by contact between dissimilar metals in the weld area.

[0004] 2. During the assembly stage: Insufficient pickling and passivation treatment and inadequate control of chloride ion content in the cleaning water can easily induce pitting corrosion and stress corrosion cracking in stainless steel.

[0005] 3. During operation: Due to the presence of low-oil or oil-free cavities in the upper part of the lubricating oil tank and high positions of the pipeline, water vapor easily condenses in these areas and forms an electrolyte film, thereby creating an electrochemical corrosion environment and further aggravating the system corrosion problem.

[0006] Although existing technologies have certain anti-corrosion measures, such as surface coating treatment, pickling and passivation processes, or the selection of corrosion-resistant materials, they are still mainly based on single materials or single processes. There is a lack of a dedicated anti-corrosion material system for the complex working conditions of the lubricating oil circulation system (including oil resistance, hydrolysis resistance, water vapor resistance and chloride ion corrosion resistance), and a synergistic anti-corrosion mechanism covering the entire manufacturing, assembly and operation process has not been formed.

[0007] This lack of technical expertise makes it difficult to effectively control corrosion at its source, leading to a series of chain reactions such as oil contamination, pipeline blockage, seal failure, and abnormal equipment wear. In severe cases, it can even cause unplanned equipment downtime and significant economic losses.

[0008] Therefore, how to construct a systematic anti-corrosion solution that can adapt to the complex working conditions of the lubricating oil circulation system, combine material protection and process control, and achieve corrosion inhibition throughout the entire life cycle has become a key technical problem that urgently needs to be solved in this field.

[0009] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a solution for corrosion prevention throughout the entire process of a lubricating oil circulation system. By constructing a corrosion control system covering the entire process of manufacturing, assembly and operation, it solves the problems of weld corrosion, pitting corrosion and electrochemical corrosion existing in the prior art, and achieves corrosion inhibition throughout the entire life cycle of the lubricating oil circulation system.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a whole-process corrosion prevention solution for a lubricating oil circulation system, comprising the following steps: S1 Corrosion Cause Control: Corrosion causes are controlled in the welding area, pipeline structure and oil tank cavity of the lubricating oil circulation system. Welding materials that match the base material are selected, stainless steel and carbon steel are isolated from contact, the welded surface is pickled and passivated, water with chloride ion content meets the standard is used for cleaning, and ventilation is regulated in the upper part of the oil tank and the high-level cavity of the pipeline. S2 stainless steel surface protection is based on the stainless steel surface after corrosion cause control and the formulation of RH4 metal transparent sealant. RH4 metal transparent sealant includes fluorosilicone modified epoxy resin, stainless steel special silane coupling agent, rutile titanium dioxide, ultrafine precipitated barium sulfate, ultrafine talc powder, xylene and n-butanol composite solvent and modified aliphatic amine epoxy curing agent. S3 carbon steel surface protection involves applying No. 5 carbon steel phosphating rust inhibitor to the surface of carbon steel components according to the aforementioned treatment state. No. 5 carbon steel phosphating rust inhibitor includes alcohol-soluble phosphating base liquid, carbon steel rust converter, film-forming promoter, corrosion inhibitor, dispersant and alcohol dilution system. S4 internal cavity protection treatment involves coating the internal cavity of the lubricating oil circulation system with No. 6 oil-resistant internal cavity special coating after the above-mentioned metal surface protection treatment is completed. No. 6 oil-resistant internal cavity special coating includes oil-resistant epoxy modified resin, sealing and anti-permeability filler, oil-resistant toughening agent, anti-hydrolysis stabilizer, defoaming and leveling agent and oil-resistant diluent. S5 Operational Phase Control: This system performs operational phase corrosion prevention control on the lubricating oil circulation system after the aforementioned steps, regulates ventilation and dehumidification in the oil tank space, and periodically checks the status of each protective layer.

[0012] In a preferred embodiment, during the welding area treatment process in step S1, an isolation medium is set at the contact position between the stainless steel component and the carbon steel tooling to restrict the direct conduction path of dissimilar metals. Combined with welding heat input control measures, the precipitation of carbides in the heat-affected zone of the weld is suppressed, thereby reducing the sensitivity to intergranular corrosion and reducing the conditions for galvanic corrosion formation.

[0013] In a preferred embodiment, in step S1, the pickling and passivation treatment uses a composite system containing nitric acid and hydrofluoric acid. During the treatment, by controlling the reaction time and temperature parameters, the oxide scale, welding slag and iron ion contaminants in the welding area are completely removed, and a stable passivation film structure is formed on the metal surface to enhance the adhesion of the subsequent protective layer.

[0014] In a preferred embodiment, in step S1, the cleaning process uses water with a chloride ion content of no more than 25 mg / L, and reduces the concentration of residual ions by rinsing multiple times, so as to avoid the formation of a pitting corrosion-inducing environment on the metal surface, reduce the risk of stress corrosion cracking, and improve the stability of the overall anti-corrosion system.

[0015] In a preferred embodiment, in step S2, the fluorosilicone modified epoxy resin in the RH4 metal transparent sealant contains a bisphenol A type epoxy structure and a fluorinated organosilicon unit, which forms a three-dimensional network structure through a cross-linking reaction, so that the coating has both hydrophobic properties and interfacial bonding ability, restricting the water penetration path and enhancing the adhesion stability of the metal surface.

[0016] In a preferred embodiment, in step S3, the alcohol-soluble phosphating base liquid in the No. 5 carbon steel phosphating rust inhibitor undergoes a chemical conversion reaction with the carbon steel surface to generate a phosphate crystal structure. At the same time, it combines with film-forming promoting components to construct a dense conversion film layer, forming a chemically stable protective interface on the metal surface to reduce the oxidation reaction rate.

[0017] In a preferred embodiment, in step S4, the sealing and anti-permeability filler in the No. 6 oil-resistant inner cavity special coating is distributed in the form of fine particles inside the epoxy resin system. By extending the diffusion path of the corrosive medium and filling the pore structure of the coating, it forms a multiple barrier effect, reducing the migration rate of water vapor and electrolyte to the metal interface.

[0018] In a preferred embodiment, in step S4, the oil-resistant internal cavity special coating system contains a hydrolysis-resistant stabilizing component. By inhibiting the degradation reaction of the epoxy structure in a moisture environment, the stability of the coating molecular structure is maintained, so that the coating maintains its integrity and extends its service life in an environment where oil and water vapor interact.

[0019] In a preferred embodiment, in step S4, the coating treatment of the inner cavity of the lubricating oil circulation system is completed by spraying. By controlling the spraying path and coverage area, a continuous and uniform coating is formed on the inner surface of the oil tank and pipeline, avoiding the generation of corrosion initiation points in local exposed areas and improving the overall protection consistency.

[0020] In a preferred embodiment, during step S5, the humidity in the oil tank is reduced by ventilation regulation during the operation of the lubricating oil circulation system, and the protective layer status is evaluated by a periodic detection mechanism. Maintenance intervention is achieved by identifying the trend of changes in coating integrity, thereby limiting corrosion expansion and maintaining the long-term operational stability of the system.

[0021] Compared with the prior art, the present invention has the following advantages: 1. Comprehensive systemic protection throughout the entire process: This invention constructs a corrosion control path covering the entire process of manufacturing, assembly and operation, and systematically connects corrosion cause control with material protection measures to inhibit weld corrosion, pitting corrosion and electrochemical corrosion from the source, and prevent local corrosion from spreading to the overall structure.

[0022] 2. Multi-layered collaborative protection mechanism: This invention utilizes the synergistic application of three specialized anti-corrosion materials: RH4 metal transparent sealant, No. 5 carbon steel phosphate rust inhibitor, and No. 6 oil-resistant internal cavity coating, to form a differentiated protection system for different materials and different parts, significantly improving the continuity of protection.

[0023] 3. High ease of construction: This invention employs a room-temperature preparation process, reducing the dependence on energy and equipment conditions during construction and making on-site operation easier to implement.

[0024] 4. Significant overall benefits: This invention effectively reduces the risk of oil contamination, maintains smooth internal flow in pipelines, stabilizes the working condition of sealing parts, alleviates equipment wear, maintains good operational continuity during long-term use, and reduces maintenance costs. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0026] Figure 1 This is a process flow diagram of the whole-process anti-corrosion solution for the lubricating oil circulation system of the present invention. Detailed Implementation

[0027] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art.

[0028] like Figure 1 As shown, Example 1: Fluorosilicone modified epoxy sealing protection solution for stainless steel components: This embodiment addresses the problem of weld corrosion, pitting corrosion, and localized electrochemical corrosion that easily occur in stainless steel components of lubricating oil circulation systems during long-term operation, and proposes a metal transparent sealing protection scheme based on a fluorosilicone modified epoxy system.

[0029] 1.1 Corrosion Cause Control and Treatment: Corrosion causes are controlled in the welding area, pipeline structure and oil tank cavity of the lubricating oil circulation system. Welding materials that match the base material are selected, stainless steel and carbon steel are isolated from contact, the welded surface is pickled and passivated, and water with chloride ion content meets the standard is used for cleaning. Ventilation is regulated in the upper part of the oil tank and the high-level cavity of the pipeline. Based on the corrosion-causing control of stainless steel surfaces, RH4 metal transparent sealant is formulated. RH4 metal transparent sealant includes fluorosilicone modified epoxy resin, stainless steel-specific silane coupling agent, rutile titanium dioxide, ultrafine precipitated barium sulfate, ultrafine talc powder, xylene and n-butanol composite solvent, and modified aliphatic amine epoxy curing agent. Based on the aforementioned treatment state, No. 5 carbon steel phosphate rust inhibitor is applied to the surface of the carbon steel parts. No. 5 carbon steel phosphate rust inhibitor includes alcohol-soluble phosphate base liquid, carbon steel rust converter, film-forming promoter, corrosion inhibitor, dispersant and alcohol dilution system. The inner cavity of the lubricating oil circulation system after the above-mentioned metal surface protection treatment is coated with No. 6 oil-resistant inner cavity special coating. No. 6 oil-resistant inner cavity special coating includes oil-resistant epoxy modified resin, sealing and anti-permeability filler, oil-resistant toughening agent, anti-hydrolysis stabilizer, defoaming and leveling agent and oil-resistant diluent. For the lubricating oil circulation system after the aforementioned steps, corrosion prevention control is implemented during operation, ventilation and dehumidification are regulated in the oil tank space, and the status of each protective layer is periodically checked.

[0030] In this embodiment, to address the problem of weld corrosion, pitting corrosion, and localized electrochemical corrosion that easily occur in stainless steel components of a lubricating oil circulation system during long-term operation, a metal transparent sealing protection scheme based on a fluorosilicone modified epoxy system is proposed. This scheme starts by controlling the causes of corrosion and combines the preparation of specialized anti-corrosion materials with surface treatment processes to achieve comprehensive protection for stainless steel components.

[0031] First, corrosion causes are controlled. During the manufacturing stage of the lubricating oil circulation system, strict process control is implemented in the stainless steel welding areas.

[0032] During the welding process, welding materials that match the composition and properties of the base material should be selected first to avoid the risk of electrochemical corrosion caused by compositional differences.

[0033] During welding operations, by using insulating gaskets or specialized fixtures, direct contact between stainless steel components and carbon steel tooling is avoided, thus eliminating the conditions for galvanic corrosion at the source. Simultaneously, the welding heat input is controlled to prevent excessive grain coarsening or carburization in the weld and heat-affected zone, thereby reducing susceptibility to intergranular corrosion.

[0034] After welding, pickling and passivation treatment is performed on the welded area and adjacent surfaces: The pickling process uses a composite pickling solution containing nitric acid and hydrofluoric acid to remove welding oxide scale, welding slag, and surface iron ion contaminants under controlled temperature and time conditions.

[0035] After pickling, rinse thoroughly with clean water containing no more than 25 mg / L of chloride ions to prevent residual chloride ions from inducing pitting and stress corrosion during subsequent operation.

[0036] After rinsing, allow the surface to air dry or dry at low temperature to ensure that no water film remains.

[0037] In terms of operating environment control, structural optimization or ventilation adjustment is carried out on the upper space of the lubricating oil tank and the high-level area of ​​the pipeline. By setting up ventilation holes or introducing dry air, the humidity in the cavity area is reduced, and the possibility of water vapor condensation forming an electrolyte film is reduced, thereby weakening the conditions for electrochemical corrosion.

[0038] 1.2 Preparation of RH4 metal transparent sealant: After controlling the causes of corrosion as described above, the preparation process of the RH4 metal transparent sealant begins: This sealing agent uses fluorosilicone-modified epoxy resin as the core film-forming material. By introducing fluorosilicone structural units, it improves the coating's water resistance, chemical resistance, and interfacial hydrophobicity.

[0039] (1) Preparation of active fluorosilicone monomers: Dimethyl carbonate was first added to the reactor as a reaction medium. After stirring evenly at room temperature, KH-570 silane coupling agent was added to induce pre-hydrolysis and coupling reactions. Subsequently, perfluorohexylethyl methacrylate was added, and a free radical-initiated polymerization reaction was carried out at approximately 85°C, forming a fluorinated organosilicon modified monomer structure under the action of benzoyl peroxide initiator. After the reaction was completed, unreacted solvent was removed under reduced pressure, and hydroquinone was added during the cooling process to terminate the reaction and stabilize the system.

[0040] (2) Preparation of composite inert diluent: A high-boiling-point aromatic solvent is mixed with xylene in a certain proportion and stirred at room temperature to form a transparent and homogeneous liquid, so as to adjust the viscosity and workability of the system, while ensuring a moderate evaporation rate.

[0041] (3) Preparation by closed-loop neutralization and conditioning: First, an alcohol stabilizer is added as the base solvent, followed by dimethylethanolamine as the alkaline component. Under low-speed stirring, a dibasic weak acid neutralizer is gradually added dropwise to bring the system to a suitable acid-base balance, thereby improving the adhesion and stability of the sealing agent on the metal surface.

[0042] (4) Preparation of modified fatty amine epoxy curing agent: Diethylenetriamine was used as the amine active component and slowly added to E51 epoxy resin under stirring. By controlling the reaction temperature at around 65°C, the epoxy groups and amine groups underwent a ring-opening reaction to generate a curing agent structure with a certain degree of flexibility. After the reaction was completed, benzyl alcohol and salicylic acid were added to adjust the curing speed and leveling properties. Impurities were removed by allowing the mixture to stand to defoam and by filtration.

[0043] (5) Preparation of the final product: Bisphenol A type epoxy resin was dissolved in n-butanol by heating to form a basic resin system. The previously prepared active fluorosilicone monomer, methylsilane-modified monomer, and organosilicon crosslinking monomer were then added, and a condensation reaction was carried out under the action of a catalyst to form a fluorosilicone-modified epoxy resin with a three-dimensional network structure. Subsequently, a composite diluent and a blocking neutralizing agent were added, and after curing and filtration, the RH4 metallic transparent sealing agent was obtained.

[0044] 1.3 Applications and Effects: In practical applications, the sealant is applied evenly to the stainless steel weld and its surrounding surface area by brushing, spraying, or rolling, controlling the coating thickness within a reasonable range to form a continuous, dense, and transparent protective film. After curing, this protective film forms a stable interfacial bonding structure on the metal surface. On the one hand, it enhances adhesion through silane coupling; on the other hand, it provides a hydrophobic barrier through its fluorosilicone structure, thereby preventing moisture and chloride ions from penetrating to the metal interface.

[0045] Regarding the corrosion inhibition mechanism, this sealing layer isolates oxygen, moisture, and electrolytes through physical barriers, while simultaneously enhancing the bonding strength between the coating and the metal substrate through chemical bonding, preventing coating peeling and resulting localized corrosion. Furthermore, the introduction of fluorine significantly reduces surface energy, making it difficult for moisture to form a continuous liquid film on the surface, thereby reducing the probability of electrochemical corrosion.

[0046] Through the application of this embodiment, in the actual operating environment of the lubricating oil circulation system, no obvious pitting corrosion or intergranular corrosion was observed in the stainless steel weld area, and the surface maintained good integrity, verifying the long-term stable protective ability of the sealant in high humidity, oil-containing and trace chloride ion-containing environments.

[0047] Example 2: Phosphating anti-rust composite protection solution for carbon steel components: In this embodiment, to address the problems of oxidation, rust, electrochemical corrosion, and coating failure that easily occur in carbon steel support components, mounting bases, connectors, and auxiliary structures of the lubricating oil circulation system during long-term operation, an anti-corrosion treatment scheme based on a composite mechanism of phosphating conversion and organic protection is adopted. This scheme achieves long-term protection of carbon steel materials under complex working conditions through the synergistic effect of surface conversion film construction and organic coating.

[0048] 2.1 Surface pretreatment: The first step is to control the causes of corrosion and perform pretreatment. During the manufacturing and assembly of the lubricating oil circulation system, carbon steel components are often exposed to air, moisture, and residual stress, making them prone to initial oxidation. Therefore, a systematic pretreatment of the carbon steel surface is necessary before anti-corrosion treatment. The pretreatment process includes two stages: mechanical cleaning and chemical cleaning.

[0049] Mechanical cleaning: Use sandblasting, grinding or wire brushing to remove surface oxide scale, welding slag and attached impurities.

[0050] This creates a uniformly rough surface on the metal substrate, thereby improving the adhesion of subsequent coatings.

[0051] Chemical cleaning: Oil and processing residues are removed using an alkaline degreasing agent, followed by a thorough water rinse to remove any remaining chemicals. The chloride ion content in the cleaning water is controlled to a low level to prevent the introduction of subsequent corrosion factors.

[0052] 2.2 Preparation of Phosphating Anti-rust Primer for No. 5 Carbon Steel: After surface pretreatment, the preparation process of No. 5 carbon steel phosphate rust inhibitor begins. This primer uses an alcohol-soluble phosphate system as its core, which generates a stable phosphate protective film on the metal surface through a chemical conversion reaction, while combining with organic film-forming components to form a composite protective structure.

[0053] In the specific preparation process, an alcohol-soluble phosphating base solution is first added to the reaction vessel. This base solution, as the main active component of the phosphating reaction, can chemically react on the carbon steel surface to form a phosphate crystal structure. Subsequently, a carbon steel rust conversion agent is added. This component reacts with the existing iron oxide on the carbon steel surface, converting the unstable rust into a stable complex, thereby blocking further corrosion. Next, a film-forming promoter is added. This component regulates the reaction kinetics, making the phosphating reaction more uniform and promoting crystal densification, thus improving the integrity and adhesion of the conversion film.

[0054] Based on the above, a corrosion inhibitor is added. This component inhibits the anodic and cathodic reactions by forming an adsorption layer on the metal surface, thereby reducing the corrosion current density. A dispersant is then added to ensure uniform dispersion of all components in the system, preventing uneven film formation due to localized concentration differences. Finally, an environmentally friendly alcohol dilution system is added to adjust the overall viscosity, giving the primer good application and leveling properties.

[0055] Regarding the mixing process, a segmented mixing method is adopted: in the initial stage, the mixing speed is low at about 200 r / min to initially mix the components; in the middle stage, the speed is increased to 300 r / min to ensure the system is fully dispersed and uniform; in the final stage, the speed is reduced for stable mixing to avoid introducing air bubbles. After mixing, the system is allowed to stand for a certain period of time to allow air bubbles to escape and reach a stable state. Subsequently, impurities are removed by filtration to obtain a uniform and stable No. 5 carbon steel phosphate rust inhibitor finished product.

[0056] 2.3 Application and Effects: During application, the prepared primer is uniformly coated onto the pretreated carbon steel surface. The coating method can be brushing, spraying, or dipping, depending on the specific circumstances, to ensure complete coverage and uniform thickness. After coating, the active phosphating component in the primer reacts chemically with the carbon steel surface, gradually forming a conversion film structure composed of phosphate crystals. This conversion film typically exhibits a microcrystalline structure, enabling it to form a strong bond with the metal substrate and possessing a certain degree of porosity, providing an adhesion basis for subsequent organic film formation.

[0057] Meanwhile, the organic components in the system form a continuous film on the surface, constituting a double-layer protective structure with the phosphating conversion film. The inner layer is an inorganic phosphating film, which mainly inhibits the corrosion reaction; the outer layer is an organic coating, which mainly provides a physical barrier, preventing the penetration of moisture, oxygen, and corrosive media. The synergistic effect of the two gives the protective system both chemical stability and physical isolation capabilities.

[0058] Regarding the corrosion protection mechanism, this composite protection system operates through multiple pathways. First, the phosphating film reduces the surface activity of the metal, slowing down the anodic dissolution process. Second, the organic film layer reduces the rate of water penetration, decreasing the formation of an electrolyte environment. Third, the corrosion-inhibiting components interfere with the corrosion reaction pathway through adsorption, thereby reducing the overall corrosion rate. Furthermore, this system retains a certain degree of self-inhibition capability even when the coating is locally damaged, delaying corrosion propagation.

[0059] In practical applications of lubricating oil circulation systems, carbon steel components are typically subjected to intermittent humidity, oil-gas mixing, and temperature fluctuations. Through the protective treatment described in this embodiment, the carbon steel surface can maintain a stable state for a long period, effectively inhibiting oxidation even in environments with high humidity or trace amounts of corrosive media. Simultaneously, this protective layer exhibits excellent adhesion and durability, and is less prone to blistering, peeling, or other failures.

[0060] Furthermore, by considering the system's operating conditions, key carbon steel components can be monitored during the initial stage of operation after equipment assembly. The protective effect can be verified by inspecting surface condition and coating integrity. During long-term operation, this protective system can effectively reduce maintenance frequency and minimize structural damage and performance degradation caused by corrosion.

[0061] Through field application verification, under continuous operating conditions, the carbon steel support components and auxiliary structures treated with this protective agent did not show obvious rust expansion over many years of use. The surface protective layer remained intact and did not experience large-area peeling or failure, proving that the phosphating rust inhibitor has good adaptability and stability in complex industrial environments.

[0062] In summary, by systematically pretreating the surface of carbon steel and combining phosphating conversion with organic film-forming composite protection technology, the corrosion resistance of carbon steel in the lubricating oil circulation system can be effectively improved, the risk of corrosion can be reduced, and the service life of equipment can be extended, thus providing reliable support for the overall anti-corrosion system.

[0063] Example 3: Oil-resistant protective coating solution for system cavities: In this embodiment, a special protective coating system for the lubricating oil circulation system is proposed to address the complex corrosion problem caused by the combined effects of oil vapor, water vapor, and temperature fluctuations in the internal cavity. This system possesses oil resistance, hydrolysis resistance, and anti-permeability properties. By constructing a dense and continuous organic protective film, this system effectively blocks electrochemical corrosion pathways and improves the long-term stability of the internal cavity's metal surface.

[0064] In actual operation, the lubricating oil circulation system often operates in a semi-enclosed state within the oil tank and pipeline cavities, with areas containing little or no oil in the upper space. These areas are prone to water vapor condensation. The condensate forms a thin film on the metal surface, and oxygen from the air dissolves in this film, creating a typical electrochemical corrosion environment. Furthermore, trace impurities or moisture in the lubricating oil can further complicate the corrosion environment. Moreover, under conditions of periodic temperature changes, repeated condensation and evaporation of water vapor further exacerbate the corrosion process. Therefore, relying solely on external surface protection is insufficient to fundamentally solve the problem of internal cavity corrosion; a specialized protection system targeting the internal cavity environment is necessary.

[0065] 3.1. Pretreatment of the inner cavity: Before applying the internal coating, the lubrication system's internal cavities must first undergo a thorough cleaning. The cleaning process includes three stages: degreasing, rinsing, and drying.

[0066] Degreasing treatment: Remove oil and organic residues adhering to the inner wall by using a suitable cleaning agent.

[0067] This ensures that subsequent coatings can adhere directly to the metal surface.

[0068] Water washing: The water with low chloride ion content is then used for rinsing to avoid introducing new corrosive media.

[0069] Drying: After cleaning, remove residual moisture by natural drying or low-temperature drying to ensure that the inner cavity surface is dry, thereby avoiding bubbles or poor adhesion during coating application.

[0070] After the internal cavity pretreatment is completed, the preparation process for the No. 6 oil-resistant internal cavity special coating begins. This coating is based on oil-resistant epoxy modified resin, and by introducing a variety of functional additives, the coating possesses excellent comprehensive properties.

[0071] 3.2 Preparation of No. 6 oil-resistant inner cavity special coating: In the preparation process, oil-resistant epoxy modified resin is first added to a high-speed dispersion device and initially stirred at 500-600 r / min to make the resin system uniform and stable. Then, a sealing and impermeable filler is added. This filler has a fine particle size and uniform distribution, and is fully dispersed in the resin system under high-speed shearing, thereby forming a dense filled structure during the subsequent film formation process, effectively reducing the porosity of the coating.

[0072] After the filler dispersion is complete, the stirring speed is gradually reduced to approximately 300 rpm, and the oil-resistant toughening agent is added sequentially. This component improves the flexibility of the coating, making it less prone to cracking under temperature changes or mechanical vibration. Next, an anti-hydrolysis stabilizer is added. This component enhances the stability of the coating in long-term contact with moisture or humid environments, preventing hydrolytic degradation of the resin structure. Finally, an antifoaming and leveling agent is added. This component eliminates air bubbles and improves the surface smoothness of the coating during mixing, thereby ensuring the final film quality.

[0073] After the above components are uniformly mixed, an oil-resistant thinner is added to adjust the viscosity of the system, giving the coating suitable application fluidity. Stirring continues for a certain period to ensure thorough mixing of the components. The system is then allowed to stand, allowing internal air bubbles to gradually escape. Finally, filtration removes any remaining impurities, resulting in a uniform and stable No. 6 oil-resistant internal cavity coating.

[0074] 3.3 Application and Effects: During coating application, depending on the equipment's structural characteristics, spraying can be used to uniformly cover the inner cavity surface. During spraying, it is necessary to control the spraying pressure, nozzle distance, and moving speed to ensure a uniform and continuous coating thickness. For long and narrow structures such as pipelines, an extended spray gun or rotary spraying method can be used to ensure the coating covers the entire inner surface area.

[0075] After coating, a curing process is performed at a suitable temperature to induce a cross-linking reaction within the coating, forming a stable three-dimensional network structure. The cured coating forms a dense and continuous protective film on the metal surface, exhibiting excellent adhesion and durability.

[0076] In terms of protection mechanism, the inner cavity coating achieves its anti-corrosion effect through multiple functions. First, the dense organic film layer can prevent moisture, oxygen, and corrosive media from diffusing to the metal surface, thereby cutting off the electrolyte channels required for electrochemical corrosion reactions. Second, the anti-permeability filler forms a physical barrier path inside the coating, extending the path of corrosive media during diffusion, thus significantly reducing the penetration rate. Third, the anti-hydrolysis component improves the stability of the coating in humid environments, making it less prone to degradation or failure during long-term use. In addition, the oil-resistant resin structure can maintain stable performance in environments where lubricating oil is immersed for a long time, without swelling or softening.

[0077] During the operation of the lubricating oil circulation system, this inner cavity protective coating effectively addresses the corrosion risks posed by the mixed oil-gas and water-vapor environment. In the upper space of the oil tank, when water vapor condenses, the coating surface, due to its low surface energy, is less likely to form a continuous water film, thus reducing the probability of an electrolyte environment forming. Inside the pipeline, even if trace amounts of moisture or impurities are present, the coating prevents them from directly contacting the metal substrate, thereby avoiding localized corrosion.

[0078] Under long-term operating conditions, this coating system exhibits good stability. Even in environments with temperature fluctuations and mechanical vibrations, the coating maintains its integrity and is not prone to cracking or peeling. Furthermore, due to its flexibility, the coating can adapt to minor deformations during equipment operation.

[0079] Based on actual engineering applications, long-term monitoring of the lubricating oil system treated with this method revealed no obvious corrosion marks on the inner cavity surface. The coating remained in good condition, with no blistering, peeling, or localized failure. The impurity content in the oil remained at a low level, and no pollution problems caused by corrosion were observed, further verifying the effectiveness of this inner cavity protection solution under complex working conditions.

[0080] In summary, by constructing an internal cavity protective coating based on an oil-resistant epoxy modified system, and combining it with reasonable preparation processes and construction methods, the corrosion problem of the internal cavity of the lubricating oil circulation system in the oil-gas and water-vapor mixed environment can be effectively solved, achieving long-term stable protection of the internal structure of the equipment, thereby significantly improving the overall system's operational reliability and service life.

[0081] Example 4: A multi-stage, end-to-end collaborative corrosion prevention solution: In this embodiment, in response to the multi-source corrosion problem in the lubricating oil circulation system in practical engineering applications, a continuous anti-corrosion control path is constructed from three levels: manufacturing stage, assembly stage, and operation stage. Through the synergistic effect of material protection, process control, and operation management, the conditions for corrosion to occur are suppressed throughout the entire process, thereby improving the overall operational reliability of the system.

[0082] 4.1 Protection during the manufacturing stage: During the manufacturing phase, targeted protective treatments are applied to components of different materials within the system. For stainless steel components, the focus is on treating the weld area and its adjacent areas. Before welding, welding materials with properties matching the base material are selected, and isolation measures are taken during welding to prevent direct contact between stainless steel and carbon steel tools or supports, reducing the risk of galvanic corrosion. After welding, the weld area is cleaned to remove weld slag and oxide layers, and the microstructure of the heat-affected zone is controlled appropriately to reduce intergranular corrosion susceptibility. After the basic treatment, an RH4 metallic transparent sealant is uniformly coated onto the stainless steel surface to form a continuous and dense protective layer. This protective layer forms a hydrophobic interface through a fluorosilicone structure and provides adhesion through an epoxy system, making the metal surface less susceptible to moisture and corrosive media intrusion during subsequent use.

[0083] For carbon steel supports, connecting components, and auxiliary structures, a No. 5 carbon steel phosphating rust inhibitor primer is used for protective treatment during the manufacturing stage. Before coating, the carbon steel surface is derusted, degreased, and cleaned to ensure a clean metal surface. The primer is then evenly applied to the surface, forming a composite structure of phosphating conversion film and organic film. This composite structure provides initial protection and also provides corrosion inhibition for subsequent environmental exposure, thereby reducing the risk of oxidation corrosion of the carbon steel during manufacturing and storage.

[0084] 4.2 Assembly Stage Processing: After the manufacturing stage is completed, the assembly stage begins. In this stage, the focus is on further treating the welded areas and internal cavities of the system to eliminate potential corrosion sources. After all welding is completed, the welds and related areas undergo pickling and passivation treatment. This chemical reaction removes residual oxide scale and impurities from the surface, forming a stable passivation film structure on the metal surface. After pickling, the system is rinsed with water containing no more than 25 mg / L of chloride ions to avoid pitting corrosion caused by residual chloride ions. After rinsing, drying is performed to ensure that no residual moisture remains inside the system.

[0085] In a critical stage of assembly, a protective coating is applied to the inner cavity of the lubricating oil circulation system. After the oil tank and piping are installed, the inner cavity is cleaned to remove dust, oil, and impurities that may have been generated during installation. Once the inner cavity surface is confirmed to be clean, a No. 6 oil-resistant inner cavity coating is evenly applied to the inner wall surface using a spraying method. During spraying, the spraying angle and movement path are adjusted according to the structural characteristics to ensure the coating covers all inner surface areas. After coating, a curing process is performed under suitable environmental conditions to form a dense and continuous protective film. This protective film exhibits excellent oil resistance, hydrolysis resistance, and impermeability, effectively preventing direct contact between moisture and corrosive media and the metal surface during subsequent operation.

[0086] 4.3 Operational Phase Control: During operation, environmental control and periodic testing further enhance corrosion resistance. To address the issue of condensation in the upper space of the lubricating oil tank and high-level pipeline areas, ventilation and dehumidification are implemented. By installing ventilation devices or introducing dry air, internal humidity is maintained at a low level, thereby reducing water vapor condensation. During operation, the lubricating oil may carry trace amounts of moisture and impurities during circulation; controlling oil quality and conducting regular maintenance reduces the possibility of corrosive media entering the system.

[0087] In terms of operation and maintenance, a periodic inspection mechanism has been established, with the condition of the protective layer checked every six months. The inspection includes the integrity of the stainless steel surface sealing layer, the adhesion of the primer on the carbon steel surface, and the coverage of the inner cavity coating. The stability of the protective system is assessed through visual inspection, thickness testing, and local sampling analysis. If any damage or performance degradation is found in the coating, it can be repaired promptly to prevent corrosion spread.

[0088] From the perspective of overall protection mechanism, this end-to-end corrosion prevention solution achieves synergistic effects through phased control. In the manufacturing stage, material protection reduces the formation of corrosion sources; in the assembly stage, process treatment eliminates residual corrosion risks; and in the operation stage, environmental control reduces the conditions for corrosion to occur. These three stages are interconnected, making it difficult to simultaneously satisfy the electrolyte, oxygen, and active metal interface required for corrosion reactions, thus significantly reducing the probability of corrosion.

[0089] Further analysis from the perspective of corrosion pathways reveals that in traditional systems, corrosion is often initiated by localized defects and gradually spreads. However, in this embodiment, a multi-layered protective structure is constructed using an outer surface sealing layer, a carbon steel phosphate layer, and an inner cavity protective coating, effectively blocking the corrosion pathway multiple times. Even if a layer experiences localized damage, the remaining protective layers can still provide some protection, thereby slowing down corrosion development.

[0090] 4.4 Application Validation: In practical engineering applications, long-term operational verification was conducted on the lubricating oil circulation system treated with this method. During three years of continuous operation, regular inspections of key components of the system revealed no intergranular corrosion or pitting in the weld areas, no significant rust expansion on the carbon steel components, and the inner cavity coating remained intact. Lubricating oil testing results showed that oil cleanliness remained at a stable level, with no particulate contamination or performance degradation caused by corrosion. No malfunctions or unplanned downtimes due to corrosion occurred during equipment operation.

[0091] By comparing similar systems that did not employ this protection scheme, it was found that traditional systems exhibited varying degrees of corrosion after one to two years of operation, while the system treated using the method described in this embodiment demonstrated significantly higher stability and durability under the same operating conditions. This result indicates that through end-to-end corrosion prevention control, the development of corrosion problems can be suppressed at the source, thereby significantly extending the service life of equipment.

[0092] In summary, by implementing targeted protective measures during the manufacturing, assembly, and operation stages and forming a continuous and coordinated anti-corrosion control path, the corrosion problem of the lubricating oil circulation system under complex working conditions can be effectively solved, achieving stable protection for the entire life cycle of the equipment. This has good engineering application value and promotion significance.

[0093] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A solution for corrosion prevention throughout the entire process of a lubricating oil circulation system, characterized in that, Includes the following steps: S1. Control the corrosion causes of the welding area, pipeline structure and oil tank cavity in the lubricating oil circulation system, select welding materials that match the base material, isolate stainless steel from carbon steel, perform pickling and passivation treatment on the welded surface, use water with chloride ion content that meets the standard for cleaning, and regulate ventilation in the upper part of the oil tank and the high-level cavity of the pipeline. S2. Based on the stainless steel surface after corrosion cause control, RH4 metal transparent sealant is prepared. RH4 metal transparent sealant includes fluorosilicone modified epoxy resin, stainless steel special silane coupling agent, rutile titanium dioxide, ultrafine precipitated barium sulfate, ultrafine talc powder, xylene and n-butanol composite solvent and modified aliphatic amine epoxy curing agent. S3. Apply No. 5 carbon steel phosphate rust inhibitor to the surface of carbon steel parts. No. 5 carbon steel phosphate rust inhibitor includes alcohol-soluble phosphate base liquid, carbon steel rust converter, film-forming promoter, corrosion inhibitor, dispersant and alcohol dilution system. S4. Apply No. 6 oil-resistant inner cavity special coating to the inner cavity of the lubricating oil circulation system after the metal surface protection treatment is completed. No. 6 oil-resistant inner cavity special coating includes oil-resistant epoxy modified resin, sealing and anti-permeability filler, oil-resistant toughening agent, anti-hydrolysis stabilizer, defoaming and leveling agent and oil-resistant diluent. S5. Implement anti-corrosion control during the operation phase for the treated lubricating oil circulation system, regulate ventilation and dehumidification in the oil tank space, and periodically check the status of each protective layer.

2. The solution for full-process corrosion prevention of a lubricating oil circulation system according to claim 1, characterized in that, In step S1, during the welding area treatment process, an isolation medium is set at the contact position between the stainless steel component and the carbon steel tooling to restrict the direct conduction path of dissimilar metals. Combined with welding heat input control measures, the precipitation of carbides in the heat-affected zone of the weld is suppressed.

3. The solution for full-process corrosion prevention of a lubricating oil circulation system according to claim 1, characterized in that, In step S1, the pickling and passivation treatment uses a composite system containing nitric acid and hydrofluoric acid. During the treatment, by controlling the reaction time and temperature parameters, the oxide scale, welding slag and iron ion contaminants in the welding area are completely removed, and a passivation film structure is formed on the metal surface.

4. The solution for corrosion prevention throughout the entire process of a lubricating oil circulation system according to claim 1, characterized in that, In step S1, the cleaning process uses water with a chloride ion content of no more than 25 mg / L, and reduces the concentration of residual ions by rinsing multiple times to prevent the formation of a pitting corrosion-inducing environment on the metal surface.

5. The solution for full-process corrosion prevention of a lubricating oil circulation system according to claim 1, characterized in that, In step S2, the fluorosilicone modified epoxy resin in the RH4 metal transparent sealant contains a bisphenol A type epoxy structure and a fluorinated organosilicon unit, which forms a three-dimensional network structure through a cross-linking reaction, so that the coating has both hydrophobic properties and interfacial bonding ability.

6. The solution for full-process corrosion prevention of a lubricating oil circulation system according to claim 1, characterized in that, In step S3, the alcohol-soluble phosphating base liquid in the No. 5 carbon steel phosphating rust inhibitor reacts chemically with the carbon steel surface to generate a phosphate crystal structure. At the same time, it combines with the film-forming promoting component to construct a dense conversion film layer, forming a chemically stable protective interface on the metal surface.

7. The solution for corrosion prevention throughout the entire process of a lubricating oil circulation system according to claim 1, characterized in that, In step S4, the sealing and anti-permeability filler in the No. 6 oil-resistant inner cavity special coating is distributed in the form of fine particles inside the epoxy resin system. By extending the diffusion path of the corrosive medium and filling the pore structure of the coating, a multiple barrier effect is formed.

8. The solution for full-process corrosion prevention of a lubricating oil circulation system according to claim 1, characterized in that, In step S4, the oil-resistant internal cavity special coating system is provided with anti-hydrolysis stabilizing components, which maintain the stability of the coating molecular structure by inhibiting the degradation reaction of the epoxy structure in the moisture environment.

9. The solution for corrosion prevention throughout the entire process of a lubricating oil circulation system according to claim 1, characterized in that, In step S4, the coating treatment of the inner cavity of the lubricating oil circulation system is completed by spraying. By controlling the spraying path and coverage area, a continuous and uniform coating is formed on the inner surface of the oil tank and pipeline.

10. The solution for full-process corrosion prevention of a lubricating oil circulation system according to claim 9, characterized in that, In step S5, during the operation of the lubricating oil circulation system, the humidity in the oil tank space is reduced by ventilation regulation, and the protective layer status is evaluated by a periodic detection mechanism. Maintenance intervention is achieved by identifying the trend of changes in coating integrity, thereby limiting corrosion expansion.

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