Method for evaluating hydrogen doping adaptability of in-service natural gas pipeline

Abstract

The invention discloses an in-service natural gas pipeline hydrogen doping adaptability evaluation method which comprises the following steps: firstly, acquiring defect information of an in-service natural gas pipeline through an internal detection technology, performing statistical analysis, and screening to determine typical defect information; determining defects and sampling positions through an on-site recheck detection technology, and preparing a test sample; then respectively carrying out mechanical property testing on samples without defects and samples with defects in a hydrogen-free environment and a hydrogen-doped environment to obtain corresponding hydrogen-doped adaptability evaluation grades; and finally, carrying out data alignment on an adaptability evaluation result, an in-service natural gas pipeline internal detection result and an on-site recheck detection result, and dividing hydrogen doping safety levels of the in-service natural gas pipeline. According to the method, data alignment is carried out according to the single performance evaluation result, the internal detection result of the in-service natural gas pipeline and the field recheck detection result, and the hydrogen doping adaptability evaluation of the defect-containing material of the in-service natural gas pipeline is accurately obtained.

Description

Technical Field

[0001] The present invention relates to the field of performance testing and evaluation of metal materials, and particularly to a method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Hydrogen energy has the advantages of being clean, environmentally friendly, zero-carbon emission, rich in resources, and renewable, and is considered a secondary energy source with great development prospects. The storage and transportation of hydrogen energy is a key technology for the large-scale application of hydrogen energy. Among them, the blending and transportation of hydrogen in natural gas pipelines shows good economy in long-distance hydrogen transportation. However, hydrogen will enter the interior of materials through a series of continuous processes such as physical adsorption, dissociation, chemical adsorption, dissolution, and diffusion, making pipelines and related equipment face the risk of hydrogen embrittlement. Secondly, defects inevitably exist in the process of production, manufacturing, and use of pipeline materials, and stress concentration is likely to occur at the defect sites, and hydrogen is also likely to accumulate at the defect sites, which will significantly increase the hydrogen embrittlement risk of pipeline materials.

[0004] In order to achieve the safe hydrogen blending transportation of natural gas pipelines, researchers are actively carrying out pipeline evaluation. There is a patent document CN109308556A published on February 5, 2019, which provides a pipeline evaluation method and device based on in-line inspection data. The evaluation method includes: obtaining the basic information and in-line inspection data of the defective pipeline; obtaining at least one of the remaining strength data, remaining life data, and severity of the defect according to the basic information and the in-line inspection data; and obtaining the maintenance decision of the pipeline according to at least one of the remaining strength data, remaining life data, and severity of the defect, in combination with the influence data of the pre-established high-consequence area of the pipeline. However, the actual pipeline situation is relatively complex, and the evaluation accuracy is relatively low only by using the data of the in-line inspection alone, and the accurate pipeline situation cannot be obtained. There is a patent document CN116451516A published on July 18, 2023, which provides a low-pressure gas transmission pipeline internal corrosion evaluation system and method. The evaluation method includes: obtaining the critical inclination angle and the actual inclination angle of the easily corroded position according to the pipeline basic data, operation data, and routing data, and then obtaining the easily corroded position, analyzing the easily corroded position, obtaining the analysis data and corrosion influencing factors; obtaining the erosion-corrosion model according to the analysis data, and combining with the corrosion influencing factors to conduct risk ranking to obtain the ranking diagram of the easily corroded positions of the pipeline. According to the ranking diagram, processing the easily corroded positions to obtain the remaining wall thickness data of the pipeline. Using the pipeline remaining life formula to analyze the pipeline wall thickness data to obtain the remaining life data of the pipeline and obtain the pipeline evaluation period. However, the actual easily corroded positions and corrosion influencing factors of different pipelines will be different, which results in a longer evaluation period. There is a patent document CN112858583A published on May 28, 2021, which provides a method for determining the disposal of an oil and gas pipeline with an out-of-specification defective girth weld. The evaluation method includes: conducting an applicability evaluation on the defective girth weld, and calculating the Kr value and the Lr value through the failure assessment curve; dividing different intervals based on the magnitude of the Kr value or the Lr value; dividing into high-consequence areas and general areas based on the failure consequences of the girth weld; dividing different defect types based on the defects of the girth weld; dividing the geology into earthquake disaster areas and non-earthquake disaster areas according to the geology where the oil and gas pipeline is located; and disposing of the oil and gas pipeline based on the interval of the Kr or Lr where the defective girth weld is located, the failure consequences, the defect type, and the geology of the location. This evaluation method mainly targets defective girth welds, the scope of the evaluation object is small, and it is mainly evaluated through the failure assessment curve, and the evaluation method is relatively single. The existing pipeline hydrogen blending adaptability evaluation mainly uses the slow strain rate tensile test method to evaluate the hydrogen embrittlement risk of pipeline materials according to the change of the tensile properties of the pipe material in the hydrogen-containing environment and the non-hydrogen-containing environment; however, this method mainly prepares tensile specimens according to the requirements of relevant standards, does not consider the influence of defects on the hydrogen embrittlement performance of the pipe material, and cannot make full use of pipeline detection data to guide the hydrogen blending transportation project, and the reliability of the hydrogen blending adaptability evaluation results also needs to be improved.

[0005] Therefore, it is urgent to develop a reasonable and effective evaluation method for the hydrogen blending adaptability of in-service natural gas pipelines. The in-service natural gas pipelines are detected by internal inspection technology and on-site re-inspection technology, and the influence of defects on the hydrogen embrittlement performance of the pipe material is considered. According to the single performance evaluation results, the internal inspection results and the on-site re-inspection results of the in-service natural gas pipelines are aligned, and the evaluation results of the hydrogen blending adaptability of the defective materials in the in-service natural gas pipelines are accurately obtained to guide the actual hydrogen blending transportation project of the natural gas pipeline network and ensure the safe and reliable hydrogen energy transportation. Summary of the Invention

[0006] The purpose of the present invention is to provide an evaluation method for the hydrogen blending adaptability of in-service natural gas pipelines in view of the problems existing in the prior art. The in-service natural gas pipelines are detected by internal inspection technology and on-site re-inspection technology, and the influence of defects on the hydrogen embrittlement performance of the pipe material is considered. According to the single performance evaluation results, the internal inspection results and the on-site re-inspection results of the in-service natural gas pipelines are aligned, and the evaluation of the hydrogen blending adaptability of the defective materials in the in-service natural gas pipelines is accurately obtained, thus solving the above problems.

[0007] The technical solution of the present invention is as follows:

[0008] An evaluation method for the hydrogen blending adaptability of in-service natural gas pipelines includes:

[0009] Step S1: Obtain the defect information of the in-service natural gas pipeline through internal inspection technology;

[0010] Step S2: Statistically analyze the internal inspection results and screen and determine the typical defect information;

[0011] Step S3: Through on-site re-inspection technology, excavate and detect the in-service natural gas pipeline with defects detected by internal inspection, cut the pipe section for defect information re-verification, determine the defect and sampling position, and prepare test specimens according to the standard requirements so that the test specimens contain the above various typical defects;

[0012] Step S4: Conduct mechanical property tests on the specimens without defects and with defects in hydrogen-free and hydrogen-blended environments respectively, compare and analyze the test results, clarify the influence law of hydrogen-blended transportation on the performance of the defective materials in the in-service natural gas pipeline, and obtain the corresponding hydrogen blending adaptability evaluation grade;

[0013] Step S5: Align the adaptability evaluation results with the internal inspection results and the on-site re-inspection results of the in-service natural gas pipeline, and divide the hydrogen blending safety grade of the in-service natural gas pipeline according to the adaptability evaluation grade.

[0014] Furthermore, the internal inspection technology includes: magnetic flux leakage detection, ultrasonic detection, electromagnetic ultrasonic detection;

[0015] The defect information includes: defect type, location, and size.

[0016] Furthermore, the typical defect information includes: typical defect type, location, and size.

[0017] Furthermore, the typical defect types include: holes, cracks, deformations, corrosion pits, and scratches;

[0018] The location includes: surface, subsurface, and core;

[0019] The size includes: the maximum value and median value of the detection result.

[0020] Furthermore, the on-site recheck detection technology includes: appearance detection, ray detection, TOFD detection, and phased array ultrasonic detection.

[0021] Furthermore, step S3 also includes:

[0022] When the pipe section to be analyzed cannot meet the sample preparation requirements, a defect-free specimen can be prepared first, and then defects can be artificially simulated according to the defect characteristics.

[0023] Furthermore, the mechanical property tests include: tensile properties, impact toughness, fracture toughness, fatigue properties, and anti-explosion performance tests of defect-containing materials, which can systematically and comprehensively evaluate the influence law of hydrogen-doped transportation on the comprehensive mechanical properties of defect-containing materials in in-service natural gas pipelines.

[0024] Furthermore, the acquisition of the hydrogen-doping adaptability evaluation level includes: scoring and grading the hydrogen-doping adaptability of the detected defect-containing materials in in-service natural gas pipelines according to the changes in mechanical properties in the defect-containing hydrogen-doped environment and the defect-free hydrogen-free environment, and evaluating its applicability in different hydrogen-doped environments.

[0025] Furthermore, according to the hydrogen-doping safety level of in-service natural gas pipelines, pipelines with a lower safety level mileage can be actively repaired or replaced, etc., to improve the safety and reliability of the hydrogen-doped transportation of natural gas pipelines along the line and avoid the occurrence of unnecessary safety accidents.

[0026] The beneficial effects of the present invention compared with the existing technology are:

[0027] A method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines uses in-line inspection technology and on-site re-inspection technology to inspect in-service natural gas pipelines, and considers the influence of defects on the hydrogen embrittlement performance of pipe materials. According to the single-property evaluation results, data alignment is performed with the in-line inspection results and on-site re-inspection results of the in-service natural gas pipelines, so as to accurately obtain the evaluation of the hydrogen blending adaptability of the defective materials in the in-service natural gas pipelines. At the same time, based on this, pipeline inspection technology and the evaluation of the hydrogen blending adaptability of natural gas pipeline materials can be effectively combined. After accurately detecting the defects in the materials of in-service natural gas pipelines, a series of tests for evaluating the hydrogen blending adaptability of defective materials in in-service natural gas pipelines with different pressures and gas components are designed. According to the single-property evaluation results, data alignment is performed with the in-line inspection results and on-site re-inspection results of the in-service natural gas pipelines. According to the hydrogen blending safety level of the pipeline, for pipelines with a lower safety level mileage, maintenance or pipe replacement treatment is actively carried out, etc., to improve the safety and reliability along the hydrogen blending transmission pipeline and avoid the occurrence of unnecessary safety accidents. Description of the Drawings

[0028] Figure 1 It is a flowchart of a method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines. Detailed Implementation Modes

[0029] It should be noted that 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 actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0030] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0031] Embodiment 1

[0032] Please refer to Figure 1 , a method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines, specifically including the following steps:

[0033] Step S1: Obtain the defect information of the in-service natural gas pipeline through in-line inspection technology;

[0034] Step S2: Statistically analyze the in-line inspection results and screen and determine the typical defect information;

[0035] Step S3: Through on-site recheck and detection technology, excavate and detect the in-service natural gas pipelines with defects detected by internal detection, cut pipe segments for defect information recheck, determine the defect and sampling positions, and prepare test specimens according to standard requirements, so that the test specimens contain the above various typical defects;

[0036] Step S4: Conduct mechanical property tests on the defect-free and defective specimens respectively in a hydrogen-free and hydrogen-doped environment, compare and analyze the test results, clarify the influence law of hydrogen-doped transportation on the properties of defective materials in in-service natural gas pipelines, and obtain the corresponding hydrogen-doping adaptability evaluation grades; that is, according to the changes in mechanical properties in the hydrogen-doped environment with defects and the hydrogen-free environment without defects, score and grade the hydrogen-doping adaptability of the defective materials in the detected in-service natural gas pipelines, and evaluate their applicability in different hydrogen-doped environments;

[0037] Step S5: Align the adaptability evaluation results with the internal detection results and on-site recheck and detection results of in-service natural gas pipelines, and classify the hydrogen-doping safety grades of in-service natural gas pipelines according to the adaptability evaluation grades.

[0038] In this embodiment, specifically, the internal detection technology includes, but is not limited to: magnetic flux leakage detection, ultrasonic detection, electromagnetic ultrasonic detection;

[0039] The defect information includes, but is not limited to: defect type, position, size.

[0040] In this embodiment, specifically, the typical defect information includes, but is not limited to: typical defect type, position, size.

[0041] In this embodiment, specifically, the typical defect types include at least: holes, cracks, deformations, corrosion pits, scratches;

[0042] The position includes at least: surface, subsurface, core;

[0043] The size includes at least: the maximum value and median value of the detection results; in addition, accurate regulations should be made for the characteristic parameters of various defects respectively. Taking holes as an example, the shape should include at least oval and circular. Taking deformation as an example, the degree of deformation should at least cover the maximum value and median value of the detection results, etc.

[0044] In this embodiment, specifically, the on-site recheck and detection technology includes, but is not limited to: appearance detection, ray detection, TOFD detection and phased array ultrasonic detection.

[0045] In this embodiment, specifically, Step S3 further includes:

[0046] When the pipe segment to be analyzed cannot meet the sample preparation requirements, defect-free specimens can be prepared first, and then defects can be artificially simulated according to the defect characteristics.

[0047] In this embodiment, specifically, the mechanical property test includes: tensile property, impact toughness, fracture toughness, fatigue property and anti-explosion property tests of defective materials, which can systematically and comprehensively evaluate the influence law of hydrogen-doped transportation on the comprehensive mechanical properties of defective materials in in-service natural gas pipelines.

[0048] In this embodiment, specifically, the acquisition of the hydrogen-doping adaptability evaluation level includes: scoring and grading the hydrogen-doping adaptability of the detected defective materials in in-service natural gas pipelines according to the changes in mechanical properties in the defective hydrogen-doped environment and the defect-free and hydrogen-free environment, and evaluating its applicability in different hydrogen-doped environments.

[0049] Taking the slow strain rate tensile test method as an example, the hydrogen-doping adaptability of defective metal materials can be graded according to the tensile property ratio A (formula as follows) in the defective hydrogen-doped environment and the defect-free and hydrogen-free environment, in combination with relevant standards or empirical limit regulations.

[0050] A = (φ 不含缺陷无氢环境 - φ 含缺陷掺氢环境 ) / φ 不含缺陷无氢环境 × 100%

[0051] where φ is the reduction of area.

[0052] In this embodiment, specifically, according to the hydrogen-doping safety level of in-service natural gas pipelines, for pipelines with a lower safety level mileage, maintenance or pipe replacement can be actively carried out, etc., to improve the safety and reliability of the hydrogen-doped transportation along the natural gas pipelines and avoid the occurrence of unnecessary safety accidents.

[0053] Embodiment 2

[0054] Embodiment 2 is a specific application of a method for evaluating the hydrogen-doping adaptability of in-service natural gas pipelines proposed based on Embodiment 1.

[0055] (1) Determine the typical defect information of in-service natural gas pipelines according to the internal inspection technology.

[0056] First, obtain information such as defect type, location, and size of in-service hydrogen-doped transportation pipelines through magnetic flux leakage detection. The specific detection reference standard is GB / T 27699-2023. Secondly, through statistical analysis of the magnetic flux leakage detection results, screen and determine typical defects, locations, sizes, etc. Table 1 shows the magnetic flux leakage detection results.

[0057] Table 1 Magnetic Flux Leakage Detection Results

[0058]

[0059] (2) Excavate and sample the defective in-service natural gas pipelines according to the on-site re-inspection detection technology.

[0060] The in-service natural gas pipelines with detected defects by magnetic flux leakage testing are verified by on-site recheck and testing techniques, mainly including appearance inspection and radiographic inspection. The basic information of the appearance inspection of girth welds is shown in Table 2 and Table 3. According to the excavation verification, 1 out-of-specification defect with a length of 16 mm was detected at the weld, and the nature of the defect is a crack. The specific information is shown in Table 4. After radiographic inspection and analysis, the defect at the 0:22 position was characterized as a crack. The cracked pipe section was cut and test specimens were prepared according to the standard requirements. For example, the processing of slow strain rate tensile specimens refers to the standard GB / T 15970.7-2017, so that the test specimens contain the above-mentioned various typical defects. When the pipe section to be analyzed cannot meet the sample preparation requirements, specimens without defects can be prepared first, and then defects can be artificially simulated according to the defect characteristics.

[0061] Table 2 Measurement results of the steel pipe wall thickness on both sides of the girth weld

[0062]

[0063] Table 3 Appearance inspection results of girth welds

[0064] Position 1:00 2:00 3:00 4:00 5:00 6:00 Edge misalignment mm 1.0 0.5 0.5 1.0 0.0 0.0 Excess weld reinforcement mm 1.5 1.0 1.5 1.5 2.0 2.5 Width mm 18.0 19.0 20.09 20.0 21.0 20.0 Position 7:00 8:00 9:00 10:00 11:00 12:00 Edge misalignment mm 1.0 0.5 0.0 1.0 0.5 0.5 Excess weld reinforcement mm 1.5 2.0 1.5 2.0 2.0 1.5 Width mm 22.0 21.0 20.0 20.0 21.0 21.0

[0065] Table 4 Information on out-of-specification defects detected by radiography

[0066] Defect number Defect clock position Defect length Defect type Quality classification 1 0:22 16mm Crack Ⅳ

[0067] (3) Evaluate the hydrogen doping adaptability according to the tensile properties of the defective materials of the natural gas pipeline.

[0068] First, a high-temperature and high-pressure hydrogen reaction kettle is used in the test to simulate high-pressure hydrogen-free and hydrogen-doped environments, with the pressure controlled at 2.5 MPa, the temperature at room temperature, the gas being a mixture of methane and hydrogen, and the hydrogen doping ratio being 10%; second, the test objects are natural gas pipeline materials containing various typical defects and without defects detected by pipeline detection techniques. The specimens are rod-shaped tensile specimens, and the specimen processing refers to the standard GB / T 15970.7-2017, with 3 to 5 parallel samples in each group of tests; then, uniaxial tensile stress is applied to the slow strain rate tensile specimens, and they are stretched at a rate of 1×10-6 s-1 until the specimens break to test the stress-strain curves in hydrogen-free and hydrogen-doped environments; finally, compare the elongation rates of the defective hydrogen-doped environment and the defect-free hydrogen-free environment of the natural gas pipeline materials. As shown in Table 5, according to the ratio range of the reduction of area of the defective hydrogen-doped environment and the defect-free hydrogen-free environment, score and grade the hydrogen doping adaptability of the defective materials of the in-service natural gas pipeline. The ratio of the tensile properties of the defective hydrogen-doped environment to the defect-free hydrogen-free environment is denoted as A. where is the reduction of area.

[0069] Table 5 Score and grade division for the hydrogen-doping adaptability of defective materials in in-service natural gas pipelines

[0070]

[0071] (4) Evaluate the hydrogen-doping adaptability of defective materials in in-service natural gas pipelines according to the single-performance evaluation results and pipeline detection results.

[0072] Align the single-performance safety evaluation results of defective materials in natural gas pipelines under hydrogen-doping environment with the in-line inspection results and on-site re-inspection results of in-service natural gas pipelines, and classify the hydrogen-doping safety level of the pipeline according to the adaptability evaluation grade. It is divided into 3 grades according to the ratio of the cross-sectional shrinkage rate of the defective hydrogen-doping environment to the defect-free non-hydrogen environment, corresponding to high safety area, potential risk area, and relatively high risk area in safety evaluation, and the corresponding suggestions are all recommended for use, suggest optimizing working conditions, and not recommended for use. The higher the single-performance safety evaluation result, the better the hydrogen-doping adaptability of the detected defective natural gas pipeline material, the smaller the impact of hydrogen-doping on the performance of the defective natural gas pipeline material, the higher the safety of the pipeline when operating under this hydrogen-doping condition, and under the corresponding working conditions of the test conditions, it is recommended to use this defective natural gas pipeline material. On the contrary, the lower the single-performance safety evaluation result, the worse the hydrogen-doping adaptability of the defective natural gas pipeline material, the greater the impact of hydrogen-doping on the performance of the defective natural gas pipeline material, the higher the safety risk of the pipeline when operating under this hydrogen-doping condition, and under the corresponding working conditions of the test conditions, it is recommended to optimize the working conditions or not recommend using this defective natural gas pipeline material.

[0073] (5) Safe operating conditions for defective materials in in-service natural gas pipelines based on pipeline detection technology

[0074] To ensure the safe operation of in-service natural gas pipelines, the single-performance safety evaluation of defective natural gas pipeline materials should be recommended for use, and the in-line inspection results and on-site re-inspection results of in-service natural gas pipelines should both meet the requirements, otherwise it is not recommended to use defective natural gas pipeline materials in this hydrogen-doping environment. At the same time, based on this, pipeline detection technology can be effectively combined with the hydrogen-doping adaptability evaluation of defective natural gas pipeline materials. After accurately detecting the defects in in-service natural gas pipeline materials, design a series of tests on the hydrogen-doping adaptability evaluation of defective natural gas pipeline materials with different pressures and gas components. Align the single-performance evaluation results with the in-line inspection results and on-site re-inspection results of in-service natural gas pipelines. According to the hydrogen-doping safety level of the pipeline, actively repair or replace the pipeline for the pipeline section with a lower safety level, improve the safety and reliability along the hydrogen-doping transmission pipeline, and avoid the occurrence of unnecessary safety accidents.

[0075] The above-described embodiments merely represent specific implementation manners of the present application. Although the description is relatively specific and detailed, it should not be construed as a limitation on the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several variations and improvements can still be made, and these all fall within the protection scope of the present application.

[0076] This Background of the Invention section is provided to generally present the context of the present invention. Work of the presently named inventors, to the extent it is described in this Background of the Invention section, and work that is not prior art to the extent it is described herein, is neither expressly nor impliedly admitted as prior art to the present invention.

Claims

1. A method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines, characterized in that, Including: Step S1: Obtain the defect information of in-service natural gas pipelines through internal inspection technology; Step S2: Conduct statistical analysis on the internal inspection results, and screen and determine the typical defect information; Step S3: Through on-site re-inspection and testing technology, conduct excavation inspection on the in-service natural gas pipelines with defects detected by internal inspection, cut pipe segments for defect information re-verification, determine the defect and sampling positions, and prepare test specimens according to the standard requirements so that the test specimens contain typical defects; Step S4: Conduct mechanical property tests on the specimens without defects and with defects respectively in a non-hydrogen and hydrogen-doped environment, compare and analyze the test results, clarify the influence law of hydrogen-doped transportation on the properties of in-service natural gas pipeline materials with defects, and obtain the corresponding hydrogen-doped adaptability evaluation grade; Step S5: Align the adaptability evaluation results with the internal inspection results and on-site re-inspection and testing results of in-service natural gas pipelines, and divide the hydrogen-doped safety grades of in-service natural gas pipelines according to the adaptability evaluation grades.

2. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, The internal inspection technology includes: magnetic flux leakage detection, ultrasonic detection, electromagnetic ultrasonic detection; The defect information includes: defect type, position, size.

3. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, The typical defect information includes: typical defect type, position, size.

4. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 3, characterized in that, The typical defect types include: holes, cracks, deformations, corrosion pits, scratches; The position includes: surface, subsurface, core; The size includes: maximum value and median value of the detection results.

5. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, The on-site re-inspection and testing technology includes: appearance inspection, ray detection, TOFD detection and phased array ultrasonic detection.

6. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, Step S3 also includes: When the pipe segment to be analyzed cannot meet the sample preparation requirements, specimens without defects can be prepared first, and then defects can be artificially simulated according to the defect characteristics.

7. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, The mechanical property tests include: tensile property, impact toughness, fracture toughness, fatigue property and anti-explosion property tests of materials with defects, which can systematically and completely evaluate the influence law of hydrogen-doped transportation on the comprehensive mechanical properties of in-service natural gas pipeline materials with defects.

8. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, The acquisition of the hydrogen-doped adaptability evaluation grade includes: scoring and grading the hydrogen-doped adaptability of the in-service natural gas pipeline materials with defects detected according to the change of mechanical properties in the hydrogen-doped environment with defects and the non-hydrogen environment without defects, and evaluating its applicability in different hydrogen-doped environments.

9. The method for evaluating the hydrogen blending adaptability of in-service natural gas pipelines according to claim 1, characterized in that, It can actively carry out maintenance or pipe replacement treatment on pipelines with a lower safety grade according to the hydrogen-doped safety grade of in-service natural gas pipelines, improve the safety and reliability of the hydrogen-doped transportation along the natural gas pipelines, and avoid the occurrence of unnecessary safety accidents.

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