Surface treatment method of threaded connecting piece and threaded connecting piece

Abstract

The invention relates to the technical field of hydrogen-resistant coatings, and provides a surface treatment method of a threaded connecting piece and the threaded connecting piece. The threaded connecting piece comprises a pipe body and a coupling which are matched with each other, and the surface treatment method comprises the steps that the pipe body and the coupling are placed into a tubular furnace, a hydrogen-resistant material is deposited on the thread surface of an internal thread of the coupling and the thread surface of an external thread of the pipe body, and the surfaces of the internal thread and the external thread are provided with hydrogen-resistant coatings; and depositing a self-lubricating material on the surface of the hydrogen-resistant coating to obtain the threaded connecting piece with the hydrogen-resistant self-lubricating composite coating. The hydrogen-resistant self-lubricating composite coating not only solves the problem of corrosion of a special threaded pipe in a hydrogen environment, but also effectively meets the requirements of thread gluing resistance and shaft sealing integrity, and the coating is low in production cost, high in controllability, suitable for industrial production and suitable for the working condition environment of an underground hydrogen storage library.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogen barrier coatings, and in particular to a surface treatment method for a threaded connector and a threaded connector. Background Art

[0002] In related technologies, gas storage facilities generally use special threaded pipes to ensure the sealing integrity of their wellbores. The hydrogen resistance of special threaded pipes is mainly achieved by covering the surface of the material with a coating to prevent or delay the penetration of hydrogen into the material, thereby preventing the occurrence of hydrogen embrittlement. However, the requirements for anti-galling performance of special threads are not considered. Summary of the invention

[0003] In view of this, the present application provides a surface treatment method for a threaded connector and a threaded connector.

[0004] Specifically, the present application is implemented through the following technical solutions:

[0005] According to a first aspect of the present application, a surface treatment method for a threaded connector is provided, the threaded connector comprising a pipe body and a coupling that cooperate with each other, the surface treatment method comprising: placing the pipe body and the coupling into a tubular furnace, depositing a hydrogen-blocking material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen-blocking coating; depositing a self-lubricating material on the surface of the hydrogen-blocking coating to obtain a threaded connector having a hydrogen-blocking self-lubricating composite coating.

[0006] In some embodiments, after placing the tube body and the coupling into the tube furnace, the method further includes: adjusting the gas pressure in the tube furnace to within a preset vacuum range, wherein the preset vacuum range is 0.04 MPa to 0.06 MPa.

[0007] In some embodiments, the step of depositing a hydrogen barrier material on the thread surfaces of the internal thread of the butt coupling and the external thread of the pipe body specifically includes: introducing an yttrium source into a tubular furnace, and depositing the hydrogen barrier material on the surfaces of the internal thread and the external thread by a chemical deposition method, wherein the hydrogen barrier material is yttrium oxide.

[0008] In some embodiments, the yttrium source is one of yttrium silicate, yttrium chloride, and yttrium ferrite.

[0009] In some embodiments, before introducing the yttrium source into the tubular furnace, the method further comprises: injecting a gas source into the tubular furnace at a flow rate of 300 ml / min to 450 ml / min, and adding an auxiliary gas into the tubular furnace.

[0010] In some embodiments, the gas source is a mixture of carbon dioxide and nitrogen, and the auxiliary gas is at least one of argon, nitrogen, helium and hydrogen.

[0011] In some embodiments, the step of depositing the self-lubricating material on the surface of the hydrogen barrier coating specifically includes: using a composite ion plating system with a unipolar pulsed magnetron sputtering function to deposit the self-lubricating material on the surface of the hydrogen barrier coating.

[0012] In some embodiments, the self-lubricating material is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, calcium diboride, and calcium difluoride.

[0013] In some embodiments, the hexagonal boron nitride is prepared by sintering boron nitride powder, and the purity of the boron nitride powder is greater than or equal to 99.5%.

[0014] In some embodiments, the operating parameters of the composite ion plating system are: vacuum degree: 6×10 -3 Pa, working gas pressure: 0.1Pa~0.19Pa, sputtering power: 3.6KW~4.5KW, DC bias: 20V~60V, pulse bias: 600V~800V, duty cycle: 15%~30%.

[0015] In some embodiments, the deposition time of the self-lubricating material is 20 min to 30 min.

[0016] In some embodiments, before placing the tube body and the coupling into the tube furnace, the process also includes: processing the external thread of the tube body and the internal thread of the coupling, performing decontamination and degreasing treatment on the internal and external threads, and inspecting the processed parts of the tube body and the coupling after the decontamination and degreasing treatment is completed.

[0017] In some embodiments, the step of processing the external thread of the pipe body and the internal thread of the coupling specifically includes: performing thread processing on the pipe body and the coupling so that the processing tolerance of the external thread of the pipe body and the internal thread of the coupling is ±0.15mm, the thread surface roughness of the internal thread and the external thread is less than or equal to 3.2, and the sealing surface roughness of the internal thread and the external thread is less than or equal to 1.6.

[0018] In some embodiments, the step of performing a decontamination and degreasing treatment on the internal thread and the external thread specifically includes: performing a decontamination and degreasing treatment on the internal thread and the external thread multiple times with an alkaline cleaning solution at room temperature.

[0019] In some embodiments, the step of inspecting the processed parts of the pipe body and the coupling specifically includes: inspecting the external threads of the pipe body and the internal threads of the coupling by using a color flaw detection method.

[0020] In some embodiments, before inspecting the processed parts of the pipe body and the coupling, the method further includes: performing water washing treatment on the inner surface and the outer surface of the coupling for multiple times.

[0021] In some embodiments, after obtaining the threaded connector with the hydrogen-blocking self-lubricating composite coating, the method further includes: drying, cleaning, spraying and marking the pipe body and the coupling for storage.

[0022] According to the second aspect of the present application, there is provided a threaded connection, which is manufactured by the surface treatment method of a threaded connection in any of the above embodiments, and the threaded connection comprises: a tube body, which is provided with an external thread; a coupling, which is provided with an internal thread matching the external thread; a hydrogen barrier coating, which is coated on the internal thread and the external thread; and a self-lubricating coating, which is coated on the hydrogen barrier coating.

[0023] In some embodiments, the hydrogen barrier coating is a yttrium oxide hydrogen barrier coating, and the self-lubricating coating is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, calcium diboride, and calcium difluoride.

[0024] In some embodiments, the hydrogen barrier coating and the self-lubricating coating form a hydrogen barrier self-lubricating composite coating, and the deposition thickness of the hydrogen barrier self-lubricating composite coating is 20 μm to 45 μm.

[0025] The technical solution provided by this application brings at least the following beneficial effects:

[0026] 1. The present application uses chemical vapor deposition + ion plating to prepare a functional gradient hydrogen barrier self-lubricating composite coating with a certain concentration gradient, so that the transition layer and the outermost coating are continuously and evenly distributed, further solving the problem of bonding strength between layers and ensuring the stable performance of the hydrogen barrier self-lubricating composite coating.

[0027] 2. The hydrogen-resistant self-lubricating composite coating of the present invention not only solves the corrosion problem of special threaded pipes in hydrogen environments, but also effectively solves the anti-galling performance of threads and ensures the requirements for the sealing integrity of the wellbore. The coating has low production cost and strong controllability, is suitable for industrial production, and is applicable to the working environment of underground hydrogen storage depots. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] Figure 1 One of the flow diagrams of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0031] Figure 2 A second flow chart of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0032] Figure 3 A third flow chart of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0033] Figure 4 A fourth flow chart of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0034] Figure 5 A fifth flow chart of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0035] Figure 6 A sixth flow chart of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0036] Figure 7 A seventh flow chart of a surface treatment method for a threaded connector provided in an embodiment of the present application;

[0037] Figure 8 A schematic structural diagram of a tube body of a threaded connector provided in an embodiment of the present application;

[0038] Fig. 9 A schematic structural diagram of a coupling of a threaded connection provided in an embodiment of the present application.

[0039] in, Figure 8 and Fig. 9 The corresponding relationship between the reference numerals and component names in the figure is:

[0040] 802 external thread, 804 internal thread, 806 hydrogen barrier coating, 808 self-lubricating coating, 810 pipe body, 820 coupling, 830 hydrogen barrier self-lubricating composite coating. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0042] like Figure 1 As shown, an embodiment of the present application provides a surface treatment method for a threaded connector, wherein the threaded connector includes a pipe body and a coupling that cooperate with each other. The method may include the following steps:

[0043] S102, placing the pipe body and the coupling into a tube furnace, and depositing a hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen barrier coating;

[0044] S104, depositing a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

[0045] In the present application, the tube body and coupling after pretreatment are placed in a tube furnace, which is a CVD tube furnace. The CVD tube furnace is mainly used for sintering, coating, heat treatment, ash content determination, etc. of graphite, ceramics, lithium batteries, rare metals, rare earths, biomaterials, etc. under atmosphere protection. Under the protection of the atmosphere of the tube furnace, a hydrogen barrier material is deposited on the thread surface of the internal thread of the coupling and the external thread of the tube body, so that the surface of the internal thread and the external thread have a hydrogen barrier coating. In the present application, a hydrogen barrier material is deposited on the thread surface by chemical vapor deposition, so that the surface of the internal thread and the external thread have a hydrogen barrier coating. The hydrogen barrier material can be yttrium oxide, which has excellent hydrogen permeability resistance and can prevent hydrogen from penetrating into the surface of the threaded connector and causing hydrogen corrosion.

[0046] Furthermore, a self-lubricating material is deposited on the surface of the hydrogen barrier coating. The self-lubricating material may be hexagonal boron nitride. Nitrogen and boron in hexagonal boron nitride form hexagonal mesh layers that overlap each other to form crystals. Hexagonal boron nitride has good chemical stability and does not react with water, acid, or alkali at room temperature. Hexagonal boron nitride is a high-temperature lubricant with good electrical insulation, thermal conductivity, corrosion resistance, and good lubricity. After depositing hexagonal boron nitride, a threaded connector with a hydrogen barrier self-lubricating composite coating can be obtained.

[0047] The present application prepares a functional gradient hydrogen-barrier self-lubricating composite coating with a certain concentration gradient by chemical vapor deposition + ion plating, so that the transition layer and the outermost coating are continuously and evenly distributed, further solving the problem of bonding strength between layers and ensuring the stable performance of the hydrogen-barrier self-lubricating composite coating.

[0048] The hydrogen-barrier self-lubricating composite coating of the present invention not only solves the corrosion problem of special threaded pipes in hydrogen environments, but also effectively solves the anti-galling performance of threads and ensures the requirements for the sealing integrity of the wellbore. In addition, the coating has low production cost and strong controllability, is suitable for industrial production, and is applicable to the working environment of underground hydrogen storage depots.

[0049] Based on the same inventive concept, the present application also provides a surface treatment method for a threaded connector, such as Figure 2 As shown, the method may include the following steps:

[0050] S202, placing the pipe body and the coupling into a tube furnace, adjusting the vacuum degree of the tube furnace to 0.04 MPa to 0.06 MPa, and depositing a hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen barrier coating;

[0051] S204, depositing a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

[0052] In this embodiment, before depositing the hydrogen barrier material on the thread surface, it is necessary to adjust the vacuum degree of the tube furnace to 0.04MPa~0.06MPa, so that the pipe body and the coupling are deposited with the hydrogen barrier material in a vacuum atmosphere of 0.04MPa~0.06MPa to ensure the effect of the hydrogen barrier material deposition, so that the hydrogen barrier coating can be evenly deposited on the surface of the internal thread and the external thread, and hydrogen is prevented from penetrating into the surface of the threaded connection and causing hydrogen corrosion.

[0053] Based on the same inventive concept, the present application also provides a surface treatment method for a threaded connector, such as Figure 3 As shown, the method may include the following steps:

[0054] S302, placing the tube body and the coupling into a tube furnace, introducing an yttrium source into the tube furnace, and depositing a hydrogen barrier material on the surface of the internal thread and the external thread by a chemical deposition method, so that the surface of the internal thread and the external thread has a hydrogen barrier coating;

[0055] S304, depositing a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

[0056] In this embodiment, after the tube body and the coupling are placed in a tube furnace, a yttrium source is introduced into the tube furnace. The yttrium source is one of yttrium silicate, yttrium chloride, and yttrium ferrite.

[0057] Furthermore, a hydrogen barrier material is deposited on the surface of the internal and external threads by chemical deposition, and the hydrogen barrier material is yttrium oxide. The present application deposits yttrium oxide on the surface of the threads by chemical vapor deposition, so that the surface of the internal and external threads has an yttrium oxide hydrogen barrier coating, thereby preventing hydrogen from penetrating into the surface of the threaded connector and causing hydrogen corrosion.

[0058] Based on the same inventive concept, the present application also provides a surface treatment method for a threaded connector, such as Figure 4 As shown, the method may include the following steps:

[0059] S402, placing the tube body and the coupling into a tube furnace, injecting a gas source into the tube furnace at a flow rate of 300 ml / min to 450 ml / min, adding an auxiliary gas into the tube furnace, introducing an yttrium source into the tube furnace, and depositing a hydrogen barrier material on the surface of the internal thread and the external thread by a chemical deposition method, so that the surface of the internal thread and the external thread has a hydrogen barrier coating;

[0060] S404, depositing a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

[0061] In this embodiment, before the yttrium source is introduced into the tubular furnace, a gas source and an auxiliary gas need to be added into the tubular furnace. The gas source is a mixture of carbon dioxide and nitrogen, and the auxiliary gas is at least one of argon, nitrogen, helium and hydrogen. Specifically, a mixture of carbon dioxide and nitrogen is injected into the tubular furnace at a flow rate of 300ml / min to 450ml / min, and an auxiliary gas is added into the tubular furnace to form a gas atmosphere required for depositing the hydrogen barrier material in the tubular furnace, so that the hydrogen barrier coating can be evenly deposited on the surface of the internal and external threads, thereby preventing hydrogen from penetrating into the surface of the threaded connector and causing hydrogen corrosion.

[0062] Based on the same inventive concept, the present application also provides a surface treatment method for a threaded connector, such as Figure 5 As shown, the method may include the following steps:

[0063] S502, placing the pipe body and the coupling into a tube furnace, and depositing a hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen barrier coating;

[0064] S504, using a composite ion plating system with a unipolar pulse magnetron sputtering function to deposit a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector with a hydrogen barrier self-lubricating composite coating.

[0065] In this embodiment, the composite ion plating system with unipolar pulse magnetron sputtering function may refer to a vacuum multi-arc magnetron sputtering composite ion plating machine. Magnetron sputtering is a type of physical vapor deposition that can achieve high speed, low temperature and low damage. By introducing a magnetic field on the surface of the target cathode, the magnetic field is used to constrain charged particles to increase the plasma density and increase the sputtering rate. The composite ion plating system with unipolar pulse magnetron sputtering function deposits self-lubricating materials on the surface of the hydrogen barrier coating, which has the advantages of easy control, large coating area and strong adhesion.

[0066] Furthermore, the self-lubricating material is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, molybdenum diboride, and calcium difluoride.

[0067] Furthermore, the hexagonal boron nitride is prepared by sintering boron nitride powder, and the purity of the boron nitride powder is greater than or equal to 99.5%.

[0068] Furthermore, when the composite ion plating system with unipolar pulse magnetron sputtering function is used to deposit hexagonal boron nitride on the yttrium oxide hydrogen barrier coating, the operating parameters of the composite ion plating system are: vacuum degree: 6×10 -3 Pa, working gas pressure: 0.1Pa~0.19Pa, sputtering power: 3.6KW~4.5KW, DC bias: 20V~60V, pulse bias: 600V~800V, duty cycle: 15%~30%.

[0069] Furthermore, the deposition time of the self-lubricating material is 20 minutes to 30 minutes, so that the self-lubricating material of a preset thickness can be deposited on the surface of the hydrogen barrier coating. The deposition thickness of the hydrogen barrier self-lubricating composite coating can be 20 μm to 45 μm.

[0070] Based on the same inventive concept, the present application also provides a surface treatment method for a threaded connector, such as Figure 6 As shown, the method may include the following steps:

[0071] S602, processing the external thread of the pipe body and the internal thread of the coupling, performing decontamination and degreasing treatment on the internal thread and the external thread, and after the decontamination and degreasing treatment is completed, inspecting the processed parts of the pipe body and the coupling;

[0072] S604, placing the pipe body and the coupling into a tube furnace, and depositing a hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen barrier coating;

[0073] S606, depositing a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

[0074] In this embodiment, before the pipe body and the coupling are placed in the tube furnace, the internal and external threads need to be processed, the internal and external threads need to be decontaminated and degreased, and the processed parts need to be inspected. Specifically, the pipe body and the coupling are machined using a CNC lathe, wherein the length of the pipe body is 0.5 m to 1 m, the steel grade is 110 ksi to 125 ksi, and the thread depth is processed according to the designed tooth height. Further, the internal thread of the coupling and the external thread of the pipe body need to be decontaminated and degreased to wash away the stains and oil stains on the thread surface. Further, after the decontamination and degreasing treatment is completed, the processed parts of the pipe body and the coupling are inspected to find out the defective parts in advance.

[0075] In the above embodiment, the step of processing the external thread of the pipe body and the internal thread of the coupling includes: performing thread processing on the pipe body and the coupling so that the processing tolerance of the external thread of the pipe body and the internal thread of the coupling is ±0.15mm, the thread surface roughness of the internal thread and the external thread is less than or equal to 3.2, and the sealing surface roughness of the internal thread and the external thread is less than or equal to 1.6.

[0076] In the above embodiment, the step of performing a decontamination and degreasing treatment on the internal thread and the external thread includes: performing a decontamination and degreasing treatment on the internal thread and the external thread multiple times with an alkaline cleaning solution at room temperature.

[0077] In this embodiment, after the internal and external threads are processed, they need to be decontaminated and degreased twice with a low-alkaline cleaning solution at room temperature to wash away dirt and oil stains on the thread surface.

[0078] In the above embodiment, the step of inspecting the processed parts of the pipe body and the coupling includes: inspecting the external threads of the pipe body and the internal threads of the coupling by dye flaw detection.

[0079] In this embodiment, the internal and external threads are inspected by dye flaw detection. The dye flaw detection method is a non-destructive testing method that can detect defects that cannot be identified by the naked eye. It is required that the processed parts are free of cracks, pores, and inclusion defects. The pipe body and coupling that meet the above requirements can be subsequently processed.

[0080] In some embodiments, before inspecting the processed parts of the pipe body and the coupling, the method further includes: performing water washing treatment on the inner surface and the outer surface of the coupling for multiple times.

[0081] In this embodiment, in order to ensure the cleanliness of the inner and outer surfaces of the coupling, water can be used to clean the inner and outer surfaces of the coupling. Specifically, the inner and outer surfaces of the coupling are first cleaned with hot water, and then cleaned with water at room temperature. After cleaning, the processed parts are inspected.

[0082] Based on the same inventive concept, the present application also provides a surface treatment method for a threaded connector, such as Figure 7 As shown, the method may include the following steps:

[0083] S702, placing the pipe body and the coupling into a tube furnace, and depositing a hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen barrier coating;

[0084] S704, depositing a self-lubricating material on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

[0085] S706. Take out the cooled pipe body and coupling, dry, clean, spray-label the pipe body and coupling, and put them into storage.

[0086] In this embodiment, after obtaining the hydrogen-blocking self-lubricating composite coating, it is necessary to wait for the pipe body and the coupling to be taken out after being cooled in the furnace. After the pipe body and the coupling are taken out, they are dried, cleaned, sprayed with a label and put into storage.

[0087] Based on the same inventive concept, the embodiment of the present application further provides a threaded connector, which is made by the surface treatment method of the threaded connector in any of the above embodiments, such as Figure 8 and Fig. 9 As shown, the threaded connector includes: a tube body 810, which is provided with an external thread 802; a coupling 820, which is provided with an internal thread 804 that matches the external thread 802; a hydrogen barrier coating 806, which is coated on the internal thread 804 and the external thread 802; and a self-lubricating coating 808, which is coated on the hydrogen barrier coating 806.

[0088] The threaded connector provided in the present application has a functional gradient hydrogen-barrier self-lubricating composite coating 830 with a certain concentration gradient prepared by chemical vapor deposition + ion plating, so that the transition layer and the outermost coating are continuously and evenly distributed, further solving the problem of bonding strength between layers and ensuring the stable performance of the hydrogen-barrier self-lubricating composite coating 830.

[0089] The hydrogen-resistant self-lubricating composite coating 830 of the present application not only solves the corrosion problem of special threaded pipes in hydrogen environments, but also effectively solves the anti-galling performance of threads and ensures the requirements for the sealing integrity of the wellbore. In addition, the coating has low production cost and strong controllability, is suitable for industrial production, and is applicable to the working environment of underground hydrogen storage depots.

[0090] In some embodiments, the hydrogen barrier coating 806 is a yttrium oxide hydrogen barrier coating, and the self-lubricating coating 808 is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, calcium diboride, and calcium difluoride.

[0091] In this embodiment, the hydrogen barrier coating 806 is a yttrium oxide hydrogen barrier coating, and the self-lubricating coating 808 is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, tin diboride, and calcium difluoride. Molybdenum disulfide, silicon dioxide, tin diboride, and calcium difluoride all have good lubricity and can reduce friction and wear between contacting objects. Molybdenum disulfide has low friction characteristics, high load-bearing capacity, good thermal stability, strong chemical stability, radiation resistance, and high vacuum resistance.

[0092] In some embodiments, the hydrogen barrier coating 806 and the self-lubricating coating 808 form a hydrogen barrier self-lubricating composite coating 830 , and the deposition thickness of the hydrogen barrier self-lubricating composite coating 830 is 20 μm to 45 μm.

[0093] In this embodiment, the deposition thickness of the hydrogen-blocking self-lubricating composite coating 830 is 20 μm to 45 μm. Setting the deposition thickness of the hydrogen-blocking self-lubricating composite coating 830 to 20 μm to 45 μm can, on the one hand, enable the composite coating to have the characteristics of hydrogen-blocking self-lubricating. On the other hand, it can prevent the pipe body 810 and the coupling 820 from being unable to perform threaded matching when the deposition thickness is greater than 45 μm.

[0094] At present, depleted oil and gas reservoirs generally have the characteristics of structural fragmentation, deep burial, strong reservoir heterogeneity, and water invasion in the middle and late stages of development. When using depleted oil and gas reservoirs to store hydrogen, since the physical and chemical properties of natural gas and hydrogen are very different, it is necessary to conduct a comprehensive assessment of its geological conditions, wellbore integrity, etc. based on the natural gas storage in depleted oil and gas reservoirs.

[0095] Gas storage facilities generally use special threaded pipes to ensure the sealing integrity of their wellbore. However, compared with natural gas, hydrogen is more corrosive and permeable. Combined with the operating mode of underground hydrogen storage facilities - multiple cycles of large pressure differences and complex environmental cyclic alternating loads, hydrogen can easily penetrate into the surface of threaded joints and cause hydrogen corrosion.

[0096] In a specific embodiment, the threaded connector is a special threaded connector for an underground hydrogen storage tank, and the surface treatment method of the threaded connector includes the following steps:

[0097] Step 1: Use CNC lathe to machine the pipe body and coupling. The thread depth is machined according to the designed tooth height, with a tolerance range of ±0.15mm. After the internal and external threads are machined, use low-alkaline cleaning liquid to perform decontamination and degreasing treatments twice at room temperature, and then use hot water washing and water washing to clean the inner and outer surfaces of the coupling, and use color flaw detection to inspect the processed parts, requiring that the processed parts are free of cracks, pores, and inclusion defects.

[0098] Step 2: Place the tube body and coupling after pretreatment in step 1 into a CVD tube furnace, introduce a yttrium source, and use a chemical deposition method to deposit yttrium oxide on the inner and outer thread surfaces to obtain a hydrogen barrier coating yttrium oxide. The method parameters are: vacuum degree of 0.04MPa to 0.06MPa, gas source of carbon dioxide + nitrogen mixed gas flow rate of 300ml / min to 450ml / min, auxiliary gas of argon, and cool with the furnace after completion.

[0099] Step 3: Use a multifunctional composite ion plating system with unipolar pulsed magnetron sputtering function to deposit hexagonal boron nitride on the surface of yttrium oxide in step 2, so as to obtain a hydrogen-blocking self-lubricating composite coating. The method parameters are: the target material is sintered from boron nitride powder with a purity of ≥99.5%; the vacuum degree is 6×10 -3Pa; auxiliary gas is argon; working gas pressure: 0.1Pa~0.19Pa; sputtering power: 3.6KW~4.5KW; DC bias: 20V~60V, pulse bias: 600V~800V; duty cycle: 15%~30%, deposition time 20min~30min.

[0100] Step 4: Finally, the hydrogen-blocking self-lubricating composite coating is obtained, and the pipe body and the coupling are taken out with the furnace cooling, dried, cleaned, sprayed with labels and put into storage.

[0101] In step 1, further, the thread surface roughness value is Ra≤3.2, and the sealing surface roughness value is Ra≤1.6;

[0102] Further, the length of the pipe body is 0.5 m to 1 m, and the steel grade is 110 ksi to 125 ksi;

[0103] In step 2, the auxiliary gas is at least one of argon, nitrogen, helium and hydrogen, and the yttrium source is mainly one of yttrium silicate, yttrium chloride and yttrium ferrite;

[0104] In step 3, the self-lubricating coating may also be one of molybdenum disulfide, silicon dioxide, calcium diboride, and calcium difluoride;

[0105] Furthermore, the deposition thickness of the hydrogen-barrier self-lubricating composite coating is 20 μm to 45 μm.

[0106] Although this specification includes many specific implementation details, these should not be interpreted as limiting the scope of any invention or the scope of protection claimed, but are mainly used to describe the features of the specific embodiments of specific inventions. Certain features described in multiple embodiments in this specification may also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although features may work in certain combinations as described above and even initially claim protection, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may point to a sub-combination or a variation of a sub-combination.

[0107] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring that these operations be performed in the particular order shown or performed sequentially, or requiring that all illustrated operations be performed to achieve the desired results. In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of various system modules and components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product, or packaged into multiple software products.

[0108] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the particular order or sequential order shown to achieve the desired results. In some implementations, multitasking and parallel processing may be advantageous.

[0109] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0110] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A surface treatment method for a threaded connection, characterized in that: The threaded connector includes a pipe body and a coupling that cooperate with each other, and the surface treatment method includes: Putting the pipe body and the coupling into a tube furnace, depositing hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body, so that the surfaces of the internal thread and the external thread have a hydrogen barrier coating; A self-lubricating material is deposited on the surface of the hydrogen barrier coating to obtain a threaded connector having a hydrogen barrier self-lubricating composite coating.

2. The surface treatment method according to claim 1, characterized in that: After placing the tube body and the coupling into a tube furnace, the method further comprises: The gas pressure in the tube furnace is adjusted to within a preset vacuum range, wherein the preset vacuum range is 0.04 MPa to 0.06 MPa.

3. The surface treatment method according to claim 1, characterized in that: The step of depositing hydrogen barrier material on the thread surfaces of the internal thread of the coupling and the external thread of the pipe body specifically comprises: A yttrium source is introduced into the tube furnace, and a hydrogen barrier material is deposited on the surfaces of the internal thread and the external thread by a chemical deposition method, wherein the hydrogen barrier material is yttrium oxide.

4. The surface treatment method according to claim 3, characterized in that: The yttrium source is one of yttrium silicate, yttrium chloride and yttrium ferrite.

5. The surface treatment method according to claim 3, characterized in that: Before introducing the yttrium source into the tube furnace, the method further comprises: A gas source is injected into the tubular furnace at a flow rate of 300 ml / min to 450 ml / min, and an auxiliary gas is added into the tubular furnace.

6. The surface treatment method according to claim 5, characterized in that: The gas source is a mixed gas of carbon dioxide and nitrogen, and the auxiliary gas is at least one of argon, nitrogen, helium and hydrogen.

7. The surface treatment method according to claim 1, characterized in that: The step of depositing a self-lubricating material on the surface of the hydrogen barrier coating specifically comprises: A composite ion plating system with a unipolar pulse magnetron sputtering function is used to deposit a self-lubricating material on the surface of the hydrogen barrier coating.

8. The surface treatment method according to claim 7, characterized in that: The self-lubricating material is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, molybdenum diboride and calcium difluoride.

9. The surface treatment method according to claim 8, characterized in that: The hexagonal boron nitride is made by sintering boron nitride powder, and the purity of the boron nitride powder is greater than or equal to 99.5%.

10. The surface treatment method according to claim 7, characterized in that: The operating parameters of the composite ion plating system are: Vacuum degree: 6×10 -3 Pa, working gas pressure: 0.1Pa~0.19Pa, sputtering power: 3.6KW~4.5KW, DC bias: 20V~60V, pulse bias: 600V~800V, duty cycle: 15%~30%.

11. The surface treatment method according to claim 7, characterized in that: The step of depositing a self-lubricating material on the surface of the hydrogen barrier coating further comprises: The deposition time of the self-lubricating material is 20 to 30 minutes.

12. The surface treatment method according to any one of claims 1 to 11, characterized in that: Before placing the tube body and the coupling into the tube furnace, the method further comprises: The external threads of the pipe body and the internal threads of the coupling are processed, and the internal threads and the external threads are subjected to decontamination and degreasing treatment. After the decontamination and degreasing treatment is completed, the processed parts of the pipe body and the coupling are inspected.

13. The surface treatment method according to claim 12, characterized in that: The step of processing the external thread of the pipe body and the internal thread of the coupling specifically includes: The pipe body and the coupling are threaded so that the machining tolerance of the external thread of the pipe body and the internal thread of the coupling is ±0.15 mm, the thread surface roughness of the internal thread and the external thread is less than or equal to 3.2, and the sealing surface roughness of the internal thread and the external thread is less than or equal to 1.

6.

14. The surface treatment method according to claim 12, characterized in that: The step of performing a decontamination and degreasing treatment on the internal thread and the external thread specifically comprises: The internal thread and the external thread are subjected to multiple decontamination and degreasing treatments using an alkaline cleaning solution at room temperature.

15. The surface treatment method according to claim 12, characterized in that: The step of inspecting the processed parts of the pipe body and the coupling specifically includes: The external threads of the pipe body and the internal threads of the coupling are inspected by dye flaw detection.

16. The surface treatment method according to claim 12, characterized in that: Before inspecting the processed parts of the pipe body and the coupling, the method further includes: The inner surface and the outer surface of the coupling are subjected to multiple water washing treatments.

17. The surface treatment method according to any one of claims 1 to 11, characterized in that: After obtaining the threaded connector with the hydrogen-blocking self-lubricating composite coating, the method further comprises: The pipe body and the coupling are dried, cleaned, spray-labeled and put into storage.

18. A threaded connector, characterized in that: The threaded connector is manufactured by the surface treatment method of any one of claims 1 to 17, wherein the threaded connector comprises: A tube body (810), wherein the tube body (810) is provided with an external thread (802); A coupling (820), wherein the coupling (820) is provided with an internal thread (804) that matches the external thread (802); A hydrogen barrier coating (806) is coated on the internal thread (804) and the external thread (802); A self-lubricating coating (808) is coated on the hydrogen barrier coating (806).

19. The threaded connection according to claim 18, characterized in that The hydrogen barrier coating (806) is an yttrium oxide hydrogen barrier coating, and the self-lubricating coating (808) is one of hexagonal boron nitride, molybdenum disulfide, silicon dioxide, molybdenum diboride, and calcium difluoride.

20. The threaded connection according to claim 18, wherein: The hydrogen barrier coating (806) and the self-lubricating coating (808) form a hydrogen barrier self-lubricating composite coating (830), and the deposition thickness of the hydrogen barrier self-lubricating composite coating (830) is 20 μm to 45 μm.

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