Large-diameter steel pipe hydrogen doping simulation operation testing device

Abstract

The utility model relates to a testing device for simulation operation of a large-diameter steel pipe in a hydrogen-doped environment. The utility model aims to provide the large-diameter steel pipe hydrogen doping simulation operation testing device which is small in size, high in testing efficiency, high in testing precision and strong in adaptability. The utility model relates to a large-diameter steel pipe hydrogen-doped simulation operation testing device which comprises a testing part, a soaking part and a connecting part, and the connecting part comprises six connecting devices. A first connecting pipeline of the testing part is communicated with the large-diameter steel pipe through a connecting device, the first connecting pipeline is communicated with a first pipeline of the experimental platform through a connecting device, and a soaking pipeline of the soaking part is communicated with a first reducer union and a second reducer union through devices. The first reducing joint and the second reducing joint are respectively communicated with the experimental platform second pipeline and the experimental platform third pipeline, the experimental platform third pipeline is communicated with the second connecting pipeline through a connecting device, and the second connecting pipeline is communicated with the large-diameter steel pipe through a connecting device.

Description

Technical Field

[0001] This utility model relates to a hydrogen doping test device for steel pipes, and more particularly to a test device for simulating the operation of large-diameter steel pipes in a hydrogen-doped environment. Background Technology

[0002] Against the backdrop of global efforts to peak carbon emissions and achieve carbon neutrality, hydrogen energy, as a clean energy source, has become a core element in building a new energy system due to its high calorific value, high energy conversion efficiency, zero carbon emissions, and versatility in various applications. However, hydrogen differs from methane in its physicochemical properties, combustion characteristics, and flow properties. The smaller hydrogen atoms readily adsorb and diffuse onto metal surfaces, interacting with them and potentially causing metal degradation, thus leading to hydrogen embrittlement. Therefore, before actual hydrogen blending in in-service natural gas pipelines, systematic testing and verification of the hydrogen blending adaptability of steel pipelines are necessary to determine the stability and safety of hydrogen-blended operation in natural gas pipeline networks.

[0003] Currently, several hydrogen blending simulation experimental platforms have been established both domestically and internationally to simulate the blending, transmission, operation, and application processes of natural gas micropipelines under different hydrogen blending ratios, and to study the impact of steel pipes in hydrogen-blended natural gas pipelines. However, existing experimental systems generally suffer from the following technical bottlenecks: the research focuses on small and medium-diameter steel pipes (DN300 and below), lacking adaptability studies for in-service large-diameter gas transmission steel pipes (DN300 and above); current experimental schemes also lack systematic testing modules for large-diameter pipe sections; and traditional experimental systems often use multi-stage diameter reduction technology to connect to large-diameter pipes, gradually transitioning to the target large-diameter experimental pipe section through 3-4 sets of diameter reduction joints, resulting in redundant length of experimental test pipe sections, increased flow disturbance, and low installation and commissioning efficiency, making it difficult to meet the needs of high-frequency experiments. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a large-diameter steel pipe hydrogen doping simulation test device that is small in size, has high testing efficiency, high testing accuracy, and strong adaptability.

[0005] This utility model discloses a simulation test device for hydrogen doping of large-diameter steel pipes, comprising a testing section, an immersion section, and a connecting section. The connecting section includes a first connecting device, a second connecting device, a third connecting device, a fourth connecting device, a fifth connecting device, and a sixth connecting device. The testing section includes a large-diameter steel pipe, a first connecting pipe, and a first pipe of the experimental platform. One end of the first connecting pipe is connected to one end of the large-diameter steel pipe via a first connecting device, and the other end of the first connecting pipe is connected to the first pipe of the experimental platform via a second connecting device, forming a testing path. The immersion section includes an immersion pipe, a second connecting device, a third connecting device, a fourth connecting device, a fifth connecting device, and a sixth connecting device. The system includes a reducing connector, a second reducing connector, a second connecting pipe, a second pipe for the experimental platform, and a third pipe for the experimental platform. Both ends of the soaking pipe are connected to one end of the first reducing connector and one end of the second reducing connector via a third connecting device and a fourth connecting device, respectively. The other ends of the first reducing connector and the second reducing connector are connected to one end of the second pipe for the experimental platform and one end of the third pipe for the experimental platform, respectively. The other end of the third pipe for the experimental platform is connected to one end of the second connecting pipe via a fifth connecting device. The other end of the second connecting pipe is connected to the other end of the large-diameter steel pipe via a sixth connecting device, thus forming a soaking passage.

[0006] This utility model discloses a simulation test device for hydrogen doping of large-diameter steel pipes, wherein the first and second diameter reducing joints are both single-stage diameter reducing joints.

[0007] This utility model discloses a hydrogen doping simulation test device for large-diameter steel pipes. The test section further includes a sealing device. Both ends of the large-diameter steel pipe are sealed by the sealing device. The outer periphery of the large-diameter steel pipe is provided with a first interface and a second interface. The first connecting pipe is connected to the first interface, and the second connecting pipe is connected to the second interface.

[0008] This utility model discloses a simulation test device for hydrogen doping of large-diameter steel pipes, wherein the sealing device is a metal sealing device.

[0009] This utility model discloses a simulation test device for hydrogen doping of large-diameter steel pipes, wherein the first connecting pipe and the second connecting pipe are both metal corrugated pipes.

[0010] This utility model discloses a simulation test device for hydrogen doping of large-diameter steel pipes, wherein the first connecting device, the second connecting device, the third connecting device, the fourth connecting device, the fifth connecting device, and the sixth connecting device are all connecting flanges.

[0011] The difference between this invention and the prior art is that the large-diameter steel pipe of the testing section is connected to the experimental platform through a metal corrugated pipe, and the immersion pipeline of the immersion section is connected in series with the large-diameter steel pipe through a metal corrugated pipe. This not only breaks through the limitation of existing hydrogen doping simulation experimental platforms that lack research on large-diameter steel pipes, but also forms a dual-mode hydrogen damage testing structure, so that the local sample of the steel pipe in the immersion pipeline and the complete large-diameter steel pipe can be tested in the same environment.

[0012] This utility model provides a large-diameter steel pipe hydrogen doping simulation test device, which includes at least the following beneficial effects:

[0013] (1) A dual-mode hydrogen damage verification system was formed, which integrates the hydrogen-doped simulation test of the complete steel pipe section with the immersion test of the local steel pipe sample in the same test device. Simultaneously, comparative experiments were carried out on the immersion of steel pipe samples (non-destructive testing) and the sampling of steel pipe after operation (traditional thermal cutting) to analyze the contribution rate of hydrogen damage and processing damage to the changes in pipe performance, thereby improving the accuracy of detection.

[0014] (2) By using metal plug + metal corrugated hose direct connection technology, single-stage diameter change can be achieved without being affected by the diameter of the experimental pipeline. Opening holes in the side wall of the steel pipe saves experimental space and can also support parallel experiments of multiple diameter pipes, thereby improving the testing efficiency and adaptability of the testing device.

[0015] The present invention will be further described below with reference to the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a large-diameter steel pipe hydrogen doping simulation operation test device according to the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of the large-diameter steel pipe in this utility model.

[0018] Figure label:

[0019] 01-Testing section; 11-Large diameter steel pipe; 111-First interface; 112-Second interface; 12-First connecting pipe; 13-Experimental platform first pipe; 14-Sealing device; 02-Immersion section; 21-Immersion pipe; 22-First reducing joint; 23-Second reducing joint; 24-Second connecting pipe; 25-Experimental platform second pipe; 26-Experimental platform third pipe; 03-Connecting section; 31-First connecting device; 32-Second connecting device; 33-Third connecting device; 34-Fourth connecting device; 35-Fifth connecting device; 36-Sixth connecting device. Detailed Implementation

[0020] like Figure 1As shown, this utility model discloses a large-diameter steel pipe hydrogen doping simulation test device, comprising a test section 01, an immersion section 02, and a connecting section 03. The connecting section 03 includes a first connecting device 31, a second connecting device 32, a third connecting device 33, a fourth connecting device 34, a fifth connecting device 35, and a sixth connecting device 36. The test section 01 includes a large-diameter steel pipe 11, a first connecting pipe 12, and a first pipe 13 of the experimental platform. One end of the first connecting pipe 12 is connected to one end of the large-diameter steel pipe 11 through the first connecting device 31, and the other end of the first connecting pipe 12 is connected to the first pipe 13 of the experimental platform through the second connecting device 32, forming a test path. The immersion section 02 includes an immersion pipe 21. The first reducing connector 22, the second reducing connector 23, the second connecting pipe 24, the second pipe 25 of the experimental platform, and the third pipe 26 of the experimental platform are connected to one end of the first reducing connector 22 and the second reducing connector 23 respectively through the third connecting device 33 and the fourth connecting device 34. The other ends of the first reducing connector 22 and the second reducing connector 23 are connected to one end of the second pipe 25 and the third pipe 26 of the experimental platform respectively. The other end of the third pipe 26 of the experimental platform is connected to one end of the second connecting pipe 24 through the fifth connecting device 35. The other end of the second connecting pipe 24 is connected to the other end of the large-diameter steel pipe 11 through the sixth connecting device 36, thus forming an immersion passage.

[0021] The testing device of this invention is connected to a hydrogen-doped simulation experimental platform, which supplies hydrogen-doped natural gas to the testing device to simulate the transmission, distribution and operation of steel pipes of various specifications in micro-pipelines with natural gas of different hydrogen doping ratios, thereby studying the impact of hydrogen-doped natural gas on steel pipes.

[0022] The main forms and contents of hydrogen doping adaptability verification for steel pipelines include:

[0023] (1) Simulation of hydrogen doping operation of in-service steel pipelines for urban gas: Based on the urban gas pipeline system, a hydrogen doping simulation test platform was built to simulate the operation test of in-service steel pipelines of different steel grades, diameters and service years under different hydrogen doping ratios, pressure levels and other conditions.

[0024] (2) Study on the changes in mechanical properties of steel pipe materials after hydrogen doping: covering the changes in mechanical properties such as yield strength, tensile strength, and elongation of pipes with different hydrogen doping ratios, pressure levels, pipe steel grades, diameters and service years, and analyzing the sensitivity of pipe materials to hydrogen-induced crack propagation.

[0025] (3) Hydrogen compatibility assessment of weak links such as welded joints and corrosion defects in steel pipes: The focus is on studying the material properties and hydrogen-induced crack propagation performance of weak links in the pipes, and assessing the remaining life of the pipes after hydrogen doping.

[0026] The connection part 03 includes six identical connection devices, which are mainly used for connecting various pipes. Through a specific structural design, the sealing and firmness of the pipe connection are effectively ensured.

[0027] The testing unit 01 is used to conduct hydrogen enrichment tests on the large-diameter steel pipe 11. The first connecting device 31 is connected between the large-diameter steel pipe 11 and the first connecting pipe 12. This arrangement ensures both the robustness of the connection between the large-diameter steel pipe 11 and the first connecting pipe 12, preventing them from detaching, and the airtightness of the connection, preventing leakage of hydrogen-enriched natural gas from the connection point. Similarly, the second connecting device 32 is connected between the first connecting pipe 12 and the first pipe 13 of the experimental platform, ensuring both the robustness and airtightness of the connection. This constructs a simulated hydrogen-enriched natural gas transportation scenario, forming a test path to facilitate hydrogen enrichment simulation tests on the large-diameter steel pipe 11.

[0028] During testing, the testing device is connected to the hydrogen-blending simulation experimental platform. Hydrogen-blended natural gas flows into the first connecting pipe 12 through the first pipeline 13 of the experimental platform, and then into the large-diameter steel pipe 11 to be tested. The system is run for a certain period of time (e.g., 3 months, 6 months, 9 months, 12 months, etc.) according to testing requirements. After completing the target duration of continuous pressurized hydrogen-blending simulation operation, the first connecting device 31 and the sixth connecting device 36 are disassembled, and the large-diameter steel pipe 11 that has completed the test is removed and replaced with a new steel pipe to be tested. The new steel pipe can be of the same diameter or of different steel grades, diameters, and service lives. Therefore, based on the testing objectives, comparative tests of large-diameter steel pipe 11 were conducted for different durations. After the tests, samples were taken from designated parts of the large-diameter steel pipe 11 to prepare slow tensile specimens and CT crack specimens. Slow tensile tests and pre-crack propagation tests were carried out in the laboratory. The test results were compared and analyzed to obtain the fracture characteristics and hydrogen-induced cracking mechanism of steel pipes of different grades, diameters, and service years under different hydrogen doping ratios, pressure levels, and other conditions. Based on the test data and the Paris formula, a hydrogen environment crack propagation rate model was established, and a prediction model for the remaining service life of existing steel pipelines was also established.

[0029] Immersion section 02 is connected to the large-diameter pipeline and is used for non-destructive testing of steel pipes. When sampling the large-diameter steel pipe 11 tested by testing section 01, the traditional thermal cutting method is often used. Thermal cutting generates a heat-affected zone, and the temperature in the affected zone can reach 800-1000℃ during cutting. This causes changes in the internal structure of the steel pipe material, and even damages the microcracks formed inside the steel pipe during hydrogen doping testing. This leads to deviations in experimental data results, significantly affecting the distinction between hydrogen damage and processing damage, and reducing test accuracy. The immersion section 02 effectively avoids thermal interference caused by cutting, and can more accurately measure the impact of hydrogen-doped natural gas on the pipeline.

[0030] The immersion pipeline 21 is cylindrical, and the first reducing connector 22 and the second reducing connector 23 are conical structures with the same radius as the immersion pipeline 21. The third connecting device 33 is connected between the immersion pipeline 21 and the first reducing connector 22, and the fourth connecting device 34 is connected between the immersion pipeline 21 and the second reducing connector 23, so that the left and right ends of the immersion pipeline 21 are connected to the first reducing connector 22 and the second reducing connector 23, forming an immersion chamber with protruding left and right ends that can be opened. By disassembling the third connecting device 33 and the fourth connecting device 34, it is convenient to take and put in steel pipe samples of various diameters, so as to meet the testing needs of steel pipe samples of various diameters.

[0031] The second pipe 25 and the third pipe 26 of the experimental platform are welded to the tapered ports of the first reducer 22 and the second reducer 23, respectively. The right end of the third pipe 26 is connected to the second connecting pipe 24 through the fifth connecting device 35. The second connecting pipe 24 is connected to the left end of the large-diameter steel pipe 11 through the sixth connecting device 36, thereby forming an immersion passage in series with the test passage.

[0032] During operation, hydrogen-blended natural gas flows into the large-diameter steel pipe 11 through the first pipeline 13 and the first connecting pipeline 12 of the experimental platform, and then flows into the soaking chamber formed by the soaking pipeline 21 and two reducing joints through the second connecting pipeline 24 and the third pipeline 26 of the experimental platform. It then flows out of the soaking chamber to the second pipeline 25 of the experimental platform and finally flows back to the experimental platform. In this way, a dual-mode hydrogen damage verification system is formed, which integrates the hydrogen-blended simulation operation test of the complete steel pipe section with the soaking operation test of the steel pipe partial sample in the same test device. Simultaneously, comparative experiments are carried out on the soaking steel pipe sample (non-destructive testing) and the steel pipe sample taken after operation (traditional thermal cutting) to analyze the contribution rate of hydrogen damage and processing damage to the changes in pipe performance, thereby improving the accuracy of detection.

[0033] In addition, this testing device can test steel pipes of various diameters, and has strong adaptability.

[0034] like Figure 1 As shown, both the first reducing connector 22 and the second reducing connector 23 are single-stage reducing connectors.

[0035] Both reducing couplings are single-stage reducing couplings. On the one hand, this saves space and reduces the overall size of the testing device. On the other hand, it avoids flow field distortion in the immersion chamber during testing, preventing any impact on the test results of the immersed steel pipe samples. In addition, the small size of the single-stage reducing coupling makes it easy to operate.

[0036] like Figure 1 , 2As shown, the testing unit 01 also includes a sealing device 14. Both ends of the large-diameter steel pipe 11 are sealed by the sealing device 14. The outer periphery of the large-diameter steel pipe 11 is provided with a first interface 111 and a second interface 112. The first connecting pipe 12 is connected to the first interface 111, and the second connecting pipe 24 is connected to the second interface 112. Both the first connecting pipe 12 and the second connecting pipe 24 are metal corrugated pipes.

[0037] Existing hydrogen doping simulation experimental platforms have limitations. For example, they lack experimental research on high-pressure, large-diameter in-service steel pipes. Large-diameter steel pipes are typically DN300-DN1000, requiring test spacing greater than 1m. However, the experimental platform's reserved connection pipe diameter is DN50-DN150, with a reserved test spacing of approximately 0.5m-1m. It does not consider the compatibility interface of large-diameter experimental steel pipes. If traditional multi-stage reducing joints are used for transitional connection with large-diameter steel pipes, additional space is required for the experimental pipe section. This also leads to distortion of the flow field within the pipe, deviating from the actual pipe operating environment, resulting in low testing efficiency and accuracy.

[0038] This testing device innovatively designs a hydrogen doping test adaptation technology for large-diameter steel pipe sections. A first interface 111 and a second interface 112 are opened on the side wall of the steel pipe to be tested. The openings at both ends of the steel pipe are sealed with a sealing device 14. A flexible metal corrugated pipe (first connecting pipe 12) is used to flexibly connect the large-diameter steel pipe 11 to the first pipe 13 of the experimental platform. Similarly, another metal corrugated pipe (second connecting pipe 24) is used to connect the large-diameter steel pipe 11 to the immersion pipe 21, which solves the problem of size mismatch between the experimental platform pipe and the immersion pipe 21 and the high-pressure large-diameter steel pipe 11, and realizes the high-pressure hydrogen doping simulation test of the full-size large-diameter steel pipe 11.

[0039] The metal corrugated hose is manufactured according to the GB / T 14525 standard process. The first interface 111 and the second interface 112 opened on the side wall of the large-diameter steel pipe 11 are both standardized interfaces of DN50-DN150, which meet the experimental operation and testing requirements.

[0040] By using the 14+ metal corrugated hose direct connection technology of the sealing device, single-stage diameter change (e.g., DN50→DN1000) can be achieved without being affected by the diameter of the test pipeline. The opening of the steel pipe side wall saves test space and can also support parallel testing of multi-diameter pipes, thereby improving the testing efficiency and adaptability of the testing device.

[0041] like Figure 1 As shown, the sealing device 14 is a metal seal.

[0042] The sealing device 14 uses metal plugs, and two metal plugs are welded to the openings at both ends of the large-diameter steel pipe 11 to ensure the airtightness of the large-diameter steel pipe 11 and prevent gas leakage from affecting the accuracy of the test.

[0043] like Figure 1 As shown, the first connecting device 31, the second connecting device 32, the third connecting device 33, the fourth connecting device 34, the fifth connecting device 35 and the sixth connecting device 36 are all connecting flanges.

[0044] All six connecting devices are identical connecting flanges used to connect various pipelines. This ensures the robustness and stability of the pipeline connections, as well as their sealing performance. They can also be easily disassembled, making operation convenient and improving testing efficiency.

[0045] The specific testing method is as follows:

[0046] (1) Installation of experimental test pipe section: After processing the large-diameter steel pipe 11, place and fix it on the load-bearing plane next to the pipeline of the experimental platform. Connect the large-diameter steel pipe 11, the first connecting pipeline 12 and the first pipeline 13 of the experimental platform in sequence through the connecting flange. Introduce hydrogen-blended natural gas into the pipe and construct a simulation of the operation of hydrogen-blended natural gas transportation for a certain period of time (such as 3 months, 6 months, 9 months, 12 months, etc.).

[0047] (2) Immersion of test specimens: Before the simulation test, prepare slow tensile specimens (GB / T228.1 "Metallic materials, tensile testing - Part 1: Room temperature test method") and CT crack specimens (GB / T 20120.2 "Corrosion of metals and alloys - Corrosion fatigue testing - Part 2: Crack propagation test of pre-cracked specimens") according to the standard requirements, and place them in the immersion pipeline 21 for testing; according to the experimental requirements, multiple parallel experiments can be set up, and the specimens can be taken out after immersion for different durations (such as 3 months, 6 months, 9 months, 12 months, etc.), and placed in sealed bags for storage until testing.

[0048] (3) Replacement of experimental test pipe section: After completing the continuous pressurized hydrogen-blended simulation operation for the target duration, disassemble the first connecting device 31 and the sixth connecting device 36, remove the large-diameter steel pipe 11 that has been tested, replace it with a new steel pipe to be tested and connect and fix it through the first connecting device 31; disassemble the third connecting device 33 or the fourth connecting device 34 on the soaking pipeline 21, replace the experimental test sample in the soaking pipeline 21, reconnect it, and re-introduce hydrogen-blended natural gas for simulation operation.

[0049] (4) Comprehensive Laboratory Testing: After completing the continuous pressurized hydrogen doping simulation for the target duration, samples were taken from designated locations in the test pipe section according to GB / T 228.1 and GB / T 20120.2 standards to prepare slow tensile specimens and CT crack specimens. Slow tensile tests and pre-crack propagation tests were conducted in the laboratory. The specimens immersed in pipe 21 were removed and tested under the same laboratory conditions. The test results were compared and analyzed.

[0050] (5) Experimental data analysis: SEM (Scanning Electron Microscope) was used to analyze the slow tensile fracture morphology changes of the pipe section operating samples and soaking samples to obtain the fracture characteristics and hydrogen-induced cracking mechanism of steels of different grades, diameters and service years under different hydrogen doping ratios, pressure levels and other conditions; a hydrogen environment crack propagation rate model was established based on test data and Paris formula, and a prediction model for the remaining service life of existing steel pipelines was established.

[0051] It should be noted that the terms "center", "upper", "lower", "front", "rear", "left", "right", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0052] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0053] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A simulation test device for hydrogen doping in large-diameter steel pipes, characterized in that: The system includes a testing section, an immersion section, and a connecting section. The connecting section includes a first connecting device, a second connecting device, a third connecting device, a fourth connecting device, a fifth connecting device, and a sixth connecting device. The testing section includes a large-diameter steel pipe, a first connecting pipe, and a first experimental platform pipe. One end of the first connecting pipe is connected to one end of the large-diameter steel pipe via the first connecting device, and the other end of the first connecting pipe is connected to the first experimental platform pipe via the second connecting device, forming a testing path. The immersion section includes an immersion pipe, a first reducing joint, a second reducing joint, a second connecting pipe, a second experimental platform pipe, and a third experimental platform pipe. Both ends of the immersion pipe are connected to one end of the first reducing joint and the second reducing joint via the third connecting device and the fourth connecting device, respectively. The other ends of the first reducing joint and the second reducing joint are connected to one end of the second experimental platform pipe and the third experimental platform pipe, respectively. The other end of the third experimental platform pipe is connected to one end of the second connecting pipe via the fifth connecting device, and the other end of the second connecting pipe is connected to the other end of the large-diameter steel pipe via the sixth connecting device, forming an immersion path.

2. The hydrogen doping simulation test device for large-diameter steel pipes according to claim 1, characterized in that: Both the first and second reducing connectors are single-stage reducing connectors.

3. The hydrogen doping simulation test device for large-diameter steel pipes according to claim 2, characterized in that: The testing section also includes a sealing device. Both ends of the large-diameter steel pipe are sealed by the sealing device. The outer periphery of the large-diameter steel pipe is provided with a first interface and a second interface. The first connecting pipe is connected to the first interface, and the second connecting pipe is connected to the second interface.

4. The hydrogen doping simulation test device for large-diameter steel pipes according to claim 3, characterized in that: The sealing device is a metal seal.

5. The hydrogen doping simulation test device for large-diameter steel pipes according to claim 4, characterized in that: Both the first connecting pipe and the second connecting pipe are metal corrugated pipes.

6. The hydrogen doping simulation test device for large-diameter steel pipes according to claim 5, characterized in that: The first connecting device, the second connecting device, the third connecting device, the fourth connecting device, the fifth connecting device, and the sixth connecting device are all connecting flanges.

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