Method and device for detecting non-metallic inclusion defect of base metal of gas transmission gathering and transportation pipeline

Abstract

The invention provides a method and a device for detecting non-metallic inclusion defects of base metal of a gas transmission gathering and transportation pipeline, and relates to the technical field of pipeline detection. The method comprises the following steps: scanning a wall thickness reduction area of the gas transmission gathering and transportation pipeline through an ultrasonic thickness gauge to obtain a detection value, and determining an area with a pipeline base metal inner wall metal loss defect according to the change process of the detection value; an ultrasonic transverse wave 45-degree angle probe is used for conducting end corner reflection echo detection on the area where the metal loss defect exists on the inner wall of the pipeline base metal, and whether metal loss exists in the middle of the base metal or not is determined; and performing defect detection on the area with the metal loss defect on the inner wall of the pipeline base metal through a ray instrument to obtain a ray detection negative film, so as to determine the defect boundary position of the metal loss point and obtain the defect property information of the metal loss point. According to the method, the problem that the non-metallic inclusion defect of the pipeline base material is difficult to judge can be effectively solved, and casualties and property losses caused by pipeline leakage failure accidents caused by internal defects are effectively avoided.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of pipeline detection, and particularly relates to a method and device for detecting non-metallic inclusion defects in the base material of gas transmission and gathering pipelines. Background Art

[0002] The safety of pipeline transportation is a matter of great concern to people at present, and it is necessary to regularly carry out pipeline risk and hidden danger investigations.

[0003] The usual practice is to conduct in-pipe inspections and then excavate and verify the abnormally detected parts inside the pipeline. During this process, there are often cases where the in-pipe inspection information of the abnormal part of the pipe body base material shows an external metal loss defect, but there is no obvious metal loss trace on the outer surface of the pipe body base material after excavation inspection, while the wall thickness inspection shows that there is a wall thickness thinning area at this place. In this case, it may be a metal loss defect on the inner wall of the pipeline, or a defect located in the middle of the wall thickness of the base material, including non-metallic inclusion defects or pipe body delamination defects. Pipe body delamination defects are relatively easy to judge, but it is very difficult to distinguish between non-metallic inclusion defects and metal loss on the inner wall of the pipeline. Metal loss defects on the inner wall of the pipeline are more harmful. If they cannot pass the applicability evaluation, the pipe replacement and repair method will be adopted. If it can be determined that they are non-metallic inclusion defects, the defect repair and disposal costs will be greatly reduced. Using a suitable method to detect non-metallic inclusion defects is crucial for ensuring the safe operation of gas transmission and gathering pipelines, improving the pipeline operation condition, and increasing the pipeline operation efficiency. Therefore, there is an urgent need for a fast and convenient detection method on-site for detecting non-metallic inclusion defects in the base material of gas transmission and gathering pipelines and quantifying their own height.

[0004] At present, using ray detection is the most intuitive and effective detection technical means for judging the morphology and nature of internal defects in the pipe body. However, ray detection also has limitations in the detection of the internal condition of the pipe body. Usually, ray detection cannot directly obtain the self-height of the defect, and it is also difficult to determine the position of the defect in the wall thickness direction. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for detecting non-metallic inclusion defects in the base material of gas transmission and gathering pipelines in view of the deficiencies of the prior art.

[0006] The technical solution of the present invention for solving the above technical problem is as follows: A method for detecting non-metallic inclusion defects in the base material of gas transmission and gathering pipelines includes the following steps:

[0007] Scanning the wall thickness thinning area of the gas transmission and gathering pipeline with an ultrasonic thickness gauge to obtain a plurality of detection values, and determining the area with metal loss defects on the inner wall of the pipeline base material according to the change process of the plurality of detection values;

[0008] Use a 45-degree shear wave ultrasonic probe to detect the end corner reflection echo in the area with metal loss defects on the inner wall of the pipeline base material, and determine whether there is metal loss in the middle of the base material according to the detected results;

[0009] Use a ray detector to detect defects in the area with metal loss defects on the inner wall of the pipeline base material, obtain a radiographic film, determine the defect boundary position of the metal loss point according to the blackness area on the radiographic film, and obtain the defect property information of the metal loss point according to the position of the defect boundary.

[0010] Furthermore, determine the area with metal loss defects on the inner wall of the pipeline base material according to the change process of multiple detection values, specifically:

[0011] If the difference change of multiple detection values corresponding to the wall thickness thinning area continues within the set range, then determine the wall thickness thinning area as the area with metal loss defects on the inner wall of the pipeline base material.

[0012] Furthermore, determine whether there is metal loss in the middle of the base material according to the detected results, specifically:

[0013] If the detected result is that no end corner reflection echo is found, then determine whether there is metal loss in the middle of the base material.

[0014] Furthermore, determine the defect boundary position of the metal loss point according to the blackness area on the radiographic film, and obtain the defect property information of the metal loss point according to the position of the defect boundary, specifically:

[0015] Compare the blackness area to be determined on the radiographic film with the blackness area of the surrounding base material. If it is greater than the blackness area of the surrounding base material and the defect boundary position corresponding to the blackness area to be determined is located on the inner surface, then the defect property information of the metal loss point is lack of metal.

[0016] According to the defect boundary position corresponding to the blackness area to be determined on the radiographic film is located inside the base material and close to the outer surface, then the defect property information of the metal loss point is non-metallic inclusion or ellipsoidal pore.

[0017] Furthermore, when the defect property information of the metal loss point is lack of metal, it also includes:

[0018] Obtain the nominal wall thickness value of the pipeline from the pre-constructed database, calculate the difference between the nominal wall thickness value of the pipeline and the minimum wall thickness value of the gas transmission and gathering pipeline corresponding to the metal loss point, and obtain the metal loss value of the metal loss point.

[0019] Furthermore, when the defect property information of the metal loss point is non-metallic inclusion or ellipsoidal pore, it also includes:

[0020] Take the minimum wall thickness value of the gas transmission and gathering pipeline corresponding to the metal loss point as the remaining thickness value of the outer surface of the metal loss point.

[0021] Another technical solution for the present invention to solve the above technical problems is as follows: A detection device for non-metallic inclusion defects in the base material of a gas transmission and gathering pipeline includes an ultrasonic thickness gauge, a 45-degree shear wave ultrasonic probe, a ray instrument, and an analysis device:

[0022] The ultrasonic thickness gauge is used to scan the wall thickness thinning area of the gas transmission and gathering pipeline to obtain a plurality of detection values;

[0023] The analysis device is used to determine the area with metal loss defects on the inner wall of the pipeline base material according to the change process of the plurality of detection values;

[0024] The 45-degree shear wave ultrasonic probe is used to detect the end corner reflection echo of the area with metal loss defects on the inner wall of the pipeline base material;

[0025] The analysis device is also used to determine whether there is metal loss in the middle of the base material according to the result detected by the 45-degree shear wave ultrasonic probe;

[0026] The ray instrument is used to detect the defects in the area with metal loss defects on the inner wall of the pipeline base material to obtain a ray detection film;

[0027] The analysis device is also used to determine the defect boundary position of the metal loss point according to the blackness area on the ray detection film, and obtain the defect property information of the metal loss point according to the position of the defect boundary.

[0028] The beneficial effects of the present invention are: Through the combined non-destructive testing technology of an ultrasonic thickness gauge, a 45-degree shear wave ultrasonic probe, and a ray instrument, the area with metal loss defects on the inner wall of the pipeline base material, metal loss, and its defect property information are determined, which can effectively solve the problem of difficult determination of non-metallic inclusion defects in the pipeline base material, and effectively avoid casualties and property losses caused by pipeline leakage and failure accidents due to internal defects. Description of the Drawings

[0029] Figure 1 It is a schematic flow chart of the detection method for non-metallic inclusion defects in the base material of the gas transmission and gathering pipeline provided by the embodiment of the present invention;

[0030] Figure 2 It is a module block diagram of the detection device for non-metallic inclusion defects in the base material of the gas transmission and gathering pipeline provided by the embodiment of the present invention. Detailed Embodiments

[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0032] As Figure 1 shown, a method for detecting non-metallic inclusion defects in the base material of a gas transmission and gathering pipeline provided by an embodiment of the present invention includes the following steps:

[0033] Scanning the wall thickness thinning area of the gas transmission and gathering pipeline with an ultrasonic thickness gauge to obtain a plurality of detection values, and determining the area with metal loss defects on the inner wall of the pipeline base material according to the change process of the plurality of detection values;

[0034] Detecting the end corner reflection echo of the area with metal loss defects on the inner wall of the pipeline base material with an ultrasonic shear wave 45-degree inclined probe, and determining whether there is metal loss in the middle of the base material according to the detected result;

[0035] Detecting defects in the area with metal loss defects on the inner wall of the pipeline base material with a ray instrument to obtain a ray detection film, determining the defect boundary position of the metal loss point according to the blackness area on the ray detection film, and obtaining the defect property information of the metal loss point according to the position of the defect boundary.

[0036] In this embodiment, by using a combined non-destructive testing technology of an ultrasonic thickness gauge, an ultrasonic shear wave 45-degree inclined probe and a ray instrument to determine the area with metal loss defects on the inner wall of the pipeline base material, the metal loss and its defect property information, it can effectively solve the problem of difficult determination of non-metallic inclusion defects in the pipeline base material, and effectively avoid personal injuries and property losses caused by pipeline leakage and failure accidents due to internal defects.

[0037] Preferably, determining the area with metal loss defects on the inner wall of the pipeline base material according to the change process of the plurality of detection values is specifically:

[0038] If the difference change of the plurality of detection values corresponding to the wall thickness thinning area continuously remains within the set range, then determine that the wall thickness thinning area is the area with metal loss defects on the inner wall of the pipeline base material.

[0039] It should be understood that in this embodiment, an ultrasonic thickness gauge is used to scan the wall thickness thinning area and observe the wall thickness change: if the ultrasonic thickness measurement result is very sensitive to the movement of the probe, it means that this is not a metal loss defect on the inner wall. Whether the metal loss defect on the inner wall is caused by corrosion, manufacturing or mechanical formation, the detection result has a slow change or a continuous non-obvious change process with the slight movement of the probe. For example, the set range is between 0 and a. If the difference change has been between 0 and a, it belongs to a slow change or a continuous non-obvious change process, then determine that the wall thickness thinning area is the area with metal loss defects on the inner wall of the pipeline base material.

[0040] Preferably, determining whether there is metal loss in the middle of the base material according to the detected result is specifically:

[0041] If the detected result is that no corner echo is found, determine whether there is metal loss in the middle of the base material.

[0042] It should be understood that in this embodiment, an ultrasonic shear wave 45-degree angle probe is used to detect this area: assuming that the defect is an internal corrosion defect and an ultrasonic flaw detector is used for detection, there are corner reflections at the edges of the defect in different wall thickness positions of the corrosion defect. If no corner echo is found when detected with an ultrasonic shear wave 45-degree angle probe, it can be determined that it is metal loss in the middle of the base material.

[0043] Preferably, determine the defect boundary position of the metal loss point according to the blackness area on the radiographic film, and obtain the defect property information of the metal loss point according to the position of the defect boundary. Specifically:

[0044] Compare the blackness area to be determined on the radiographic film with the blackness area of the surrounding base material. If it is greater than the blackness area of the surrounding base material and the defect boundary position corresponding to the blackness area to be determined is located on the inner surface, the defect property information of the metal loss point is lack of meat.

[0045] If the defect boundary position corresponding to the blackness area to be determined on the radiographic film is located inside the base material and close to the outer surface, the defect property information of the metal loss point is non-metallic inclusions or ellipsoidal pores.

[0046] It should be understood that in this embodiment, to determine the defect boundary, for the spiral welded pipe commonly used in gas gathering and transportation pipelines, its slag inclusion defect is generally caused by defects such as non-metallic inclusions, residual shrinkage cavities or severe porosity during the steel pipe manufacturing process, and its direction should extend along the steel plate rolling method. If the defect boundary is basically parallel to the spiral seam (plate edge), it conforms to the formation process of the inclusion defect.

[0047] Specifically, perform radiographic inspection on the defect. According to the blackness of the radiographic film, it is determined that there is a metal loss or non-metallic inclusion at 8:28 on the clock position. According to the image of the radiographic film, the area with a larger blackness on the film is determined as metal loss, and the metal loss may be located on the inner surface or inside the base material. The property is lack of meat or non-metallic inclusions, or ellipsoidal pores formed by spherical pores in the raw material steel plate of the steel pipe during the rolling process along the rolling direction.

[0048] Preferably, when the defect property information of the metal loss point is lack of meat, it further includes:

[0049] Obtain the nominal wall thickness value of the pipeline from the pre-constructed database, calculate the difference between the nominal wall thickness value of the pipeline and the minimum wall thickness value of the gas gathering and transportation pipeline corresponding to the metal loss point, and obtain the metal loss value of the metal loss point.

[0050] Pre-built database, specifically, a database is pre-constructed by establishing the relationship between the blackness of ray detection for pipeline metal loss and the actual metal loss value, so as to achieve the qualitative and quantitative analysis of such defects.

[0051] Preferably, when the defect nature information of the metal loss point is non-metallic inclusions or ellipsoidal pores, it further includes:

[0052] Taking the minimum wall thickness value of the gas transmission and gathering pipeline corresponding to the metal loss point as the remaining thickness value on the outer surface of the metal loss point.

[0053] The following uses a specific example to elaborate in detail on the detection method for non-metallic inclusion defects in the base material of gas transmission and gathering pipelines:

[0054] For the external metal loss detected inside a certain gas pipeline, excavation detection is carried out. After excavation, there is no obvious metal loss trace on the outer surface of the pipe body base material, but wall thickness detection shows that there is a wall thickness reduction area at this place. The detection personnel use the combined detection method of ultrasonic thickness measurement, ultrasonic testing, and ray detection described in the present invention to detect the metal loss part of the pipeline base material and evaluate the height of the defect itself. The pipeline specifications are Φ711mm×7.1mm, the material is L415, the design pressure is 5.5MPa, and the operating pressure is 4.0MPa:

[0055] 1. Perform ultrasonic thickness measurement on the defect: The minimum wall thickness of the metal loss point or inclusion is 1.53mm, length×width: 20mm×9mm, and the minimum wall thickness of the discontinuous part is 2.39mm, length×width: 134mm×35mm. The ultrasonic thickness measurement results are very sensitive to the movement of the probe, indicating that this is not an inner wall metal loss defect.

[0056] 2. Ultrasonic testing: No defect exceeding the standard is found by ultrasonic 45-degree angle probes. Ultrasonic testing is carried out on the defect, and it is found that there is a discontinuous interlayer in the pipe body, at clock position 8:28, the interlayer is parallel to the spiral weld, 100mm away from the spiral weld, length×width: 134mm×35mm. No end corner reflection echo is found by ultrasonic shear wave 45-degree angle probes, so it can be determined that it is a metal loss in the middle of the base material.

[0057] 3. Ray detection: Ray detection is carried out on the defect. According to the blackness of the ray detection film, it is determined that there is a metal loss or non-metallic inclusion at clock position 8:28. According to the image of the ray detection film, the part with a larger blackness on the film is determined as metal loss, and the metal loss may be located on the inner surface or inside the base material. The nature is lack of material or non-metallic inclusions, or ellipsoidal pores formed by spherical pores in the steel plate of the steel pipe raw material during rolling along the rolling direction. There are the following 2 cases:

[0058] 1) The metal loss is located on the inner surface and is in the nature of lack of metal. It can be observed from the radiographic film that the blackening degree at the metal loss area is significantly greater than that of the surrounding base metal, indicating that the metal loss has a certain depth. If the metal loss is located on the inner surface, considering the minimum wall thickness measured at this location is 1.53 mm and the nominal wall thickness of the pipeline is 7.1 mm, then the metal loss is 7.1 mm - 1.53 mm = 5.57 mm.

[0059] 2) The metal loss is located inside the base metal, close to the outer surface, and is in the nature of non-metallic inclusions or ellipsoidal pores. The in-line inspection results show that this defect is an external metal loss. No outer surface defect was found during the on-site excavation verification, so it is inferred that the metal loss is likely to be close to the outer surface. Ultrasonic testing belongs to the reflection method. The acoustic impedance of inclusions or pores is relatively large compared to that of steel, and it is difficult for sound waves to pass through the metal loss to measure the wall thickness below. The minimum wall thickness of 1.53 mm measured at the defect is the remaining thickness of the outer surface at the metal loss point.

[0060] From the perspective of ensuring the safe operation of the pipeline, the safety and applicability evaluation should be carried out based on the remaining minimum wall thickness at the defect, that is, the minimum wall thickness of 1.53 mm.

[0061] As Figure 2 shown, the embodiment of the present invention also provides a detection device for non-metallic inclusion defects in the base metal of a gas gathering and transportation pipeline, including an ultrasonic thickness gauge, a 45-degree shear wave ultrasonic probe, a ray detector, and an analysis device:

[0062] The ultrasonic thickness gauge is used to scan the wall thickness thinning area of the gas gathering and transportation pipeline to obtain multiple detection values;

[0063] The analysis device is used to determine the area with metal loss defects on the inner wall of the pipeline base metal according to the change process of the multiple detection values;

[0064] The 45-degree shear wave ultrasonic probe is used to detect the end corner reflection echo of the area with metal loss defects on the inner wall of the pipeline base metal;

[0065] The analysis device is also used to determine whether there is metal loss in the middle of the base metal according to the results detected by the 45-degree shear wave ultrasonic probe;

[0066] The ray detector is used to detect the defects in the area with metal loss defects on the inner wall of the pipeline base metal to obtain a radiographic film;

[0067] The analysis device is also used to determine the defect boundary position of the metal loss point according to the blackening area on the radiographic film, and obtain the defect property information of the metal loss point according to the position of the defect boundary.

[0068] Preferably, in the analysis device, the area with metal loss defects on the inner wall of the pipeline base material is determined according to the change process of multiple detection values, specifically as follows:

[0069] If the change in the difference of multiple detection values corresponding to the wall thickness thinning area continues within the set range, then the wall thickness thinning area is determined as the area with metal loss defects on the inner wall of the pipeline base material.

[0070] Preferably, in the analysis device, it is determined whether there is metal loss in the middle of the base material according to the detected result, specifically as follows:

[0071] If the detected result is that no end corner echo is found, then it is determined whether there is metal loss in the middle of the base material.

[0072] Preferably, in the analysis device, the defect boundary position of the metal loss point is determined according to the blackness area on the radiographic film, and the defect property information of the metal loss point is obtained according to the position of the defect boundary, specifically as follows:

[0073] The to-be-determined blackness area on the radiographic film is compared with the blackness area of the surrounding base material. If it is greater than the blackness area of the surrounding base material and the defect boundary position corresponding to the to-be-determined blackness area is located on the inner surface, then the defect property information of the metal loss point is lack of flesh.

[0074] According to the defect boundary position corresponding to the to-be-determined blackness area on the radiographic film being located inside the base material and close to the outer surface, the defect property information of the metal loss point is non-metallic inclusions or ellipsoidal pores.

[0075] Aiming at the problems of difficult determination of non-metallic inclusion defects in the base material of gas gathering and transportation pipelines and lack of effective technical means for its own high-precision quantification, the present invention effectively solves the problem of difficult determination of non-metallic inclusion defects in the pipeline base material through a combined non-destructive testing technology of ultrasonic thickness gauges, 45-degree shear wave ultrasonic probes and ray detectors, and realizes the qualitative and quantitative analysis of such defects by establishing a database of the radiographic blackness of pipeline metal loss and the actual metal loss value. It can avoid casualties and property losses caused by pipeline leakage and failure accidents due to internal defects, and has significant economic and social benefits. The design process of the present invention is simple, easy to implement, low in economic cost, high in reliability, and convenient for on-site promotion and use by oilfields and pipeline operation enterprises.

[0076] It should be noted that in this text, 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 term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0077] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A detection method for non-metallic inclusion defects in the base metal of gas gathering and transportation pipelines, characterized in that, It includes the following steps: Use an ultrasonic thickness gauge to scan the wall thickness thinning area of the gas transmission and gathering pipeline to obtain multiple detection values, and determine the area with metal loss defects on the inner wall of the pipeline base metal according to the change process of the multiple detection values; Use a 45-degree oblique probe of ultrasonic shear wave to detect the end corner reflection echo of the area with metal loss defects on the inner wall of the pipeline base metal, and determine whether there is metal loss in the middle of the base metal according to the detected result; Use a ray instrument to detect defects in the area with metal loss defects on the inner wall of the pipeline base metal to obtain a ray detection film, determine the defect boundary position of the metal loss point according to the blackness area on the ray detection film, and obtain the defect property information of the metal loss point according to the position of the defect boundary; 2. The detection method for non-metallic inclusion defects of the base metal of gas transmission and gathering pipelines according to claim 1, characterized in that, Determine the area with metal loss defects on the inner wall of the pipeline base metal according to the change process of the multiple detection values, specifically: If the difference change of the multiple detection values corresponding to the wall thickness thinning area continues within the set range, determine that the wall thickness thinning area is the area with metal loss defects on the inner wall of the pipeline base metal.

3. The detection method for non-metallic inclusion defects in the base material of gas transmission and gathering pipelines according to claim 1, wherein, Determine whether there is metal loss in the middle of the base metal according to the detected result, specifically: If the detected result is that no end corner reflection echo is found, determine whether there is metal loss in the middle of the base metal.

4. The detection method for non-metallic inclusion defects of the base material of gas gathering and transportation pipelines according to claim 1, wherein, Determine the defect boundary position of the metal loss point according to the blackness area on the ray detection film, and obtain the defect property information of the metal loss point according to the position of the defect boundary, specifically: Compare the to-be-determined blackness area on the ray detection film with the blackness area of the surrounding base metal. If it is greater than the blackness area of the surrounding base metal and the defect boundary position corresponding to the to-be-determined blackness area is located on the inner surface, obtain that the defect property information of the metal loss point is lack of metal; According to the defect boundary position corresponding to the to-be-determined blackness area on the ray detection film is located inside the base metal and close to the outer surface, obtain that the defect property information of the metal loss point is non-metallic inclusion or ellipsoidal air hole.

5. The detection method for non-metallic inclusion defects in the base metal of gas gathering and transportation pipelines according to claim 4, wherein, When the defect property information of the metal loss point is lack of metal, it further includes: Obtain the nominal wall thickness value of the pipeline from the pre-constructed database, calculate the difference between the nominal wall thickness value of the pipeline and the minimum wall thickness value of the gas transmission and gathering pipeline corresponding to the metal loss point, and obtain the metal loss value of the metal loss point.

6. The detection method for non-metallic inclusion defects in the base metal of gas gathering and transportation pipelines according to claim 4, characterized in that When the defect property information of the metal loss point is non-metallic inclusion or ellipsoidal air hole, it further includes: Take the minimum wall thickness value of the gas transmission and gathering pipeline corresponding to the metal loss point as the remaining thickness value of the outer surface of the metal loss point.

7. A detection device for non-metallic inclusion defects in the base metal of a gas gathering and transportation pipeline, characterized in that, It includes an ultrasonic thickness gauge, a 45-degree oblique probe of ultrasonic shear wave, a ray instrument and an analysis device: The ultrasonic thickness gauge is used to scan the wall thickness thinning area of the gas transmission and gathering pipeline to obtain multiple detection values; The analysis device is used to determine the area with metal loss defects on the inner wall of the pipeline base metal according to the change process of the multiple detection values; The 45-degree oblique probe of ultrasonic shear wave is used to detect the end corner reflection echo of the area with metal loss defects on the inner wall of the pipeline base metal; The analysis device is also used to determine whether there is metal loss in the middle of the base metal according to the result detected by the 45-degree oblique probe of ultrasonic shear wave; The ray detector is used to detect defects in the area with metal loss defects on the inner wall of the pipeline base material, and obtain a radiographic film. The analysis device is further configured to determine the defect boundary position of the metal loss point according to the blackness area on the radiographic film, and obtain the defect property information of the metal loss point according to the position of the defect boundary.

8. The detection device for non-metallic inclusion defects in the base metal of gas transmission and gathering pipelines according to claim 7, characterized in that, In the analysis device, the area with metal loss defects on the inner wall of the pipeline base material is determined according to the change process of multiple detection values. Specifically: If the difference change of multiple detection values corresponding to the wall thickness thinning area continues within the set range, it is determined that the wall thickness thinning area is the area with metal loss defects on the inner wall of the pipeline base material.

9. The detecting device for non-metallic inclusion defects of the base metal of gas gathering and transportation pipelines according to claim 7, characterized in that, In the analysis device, it is determined whether there is metal loss in the middle of the base material according to the detected result. Specifically: If the detected result is that no end corner echo is found, it is determined whether there is metal loss in the middle of the base material.

10. The detection device for non-metallic inclusion defects in the base metal of gas gathering and transportation pipelines according to claim 7, wherein In the analysis device, the defect boundary position of the metal loss point is determined according to the blackness area on the radiographic film, and the defect property information of the metal loss point is obtained according to the position of the defect boundary. Specifically: The to-be-determined blackness area on the radiographic film is compared with the blackness area of the surrounding base material. If it is greater than the blackness area of the surrounding base material and the defect boundary position corresponding to the to-be-determined blackness area is located on the inner surface, the defect property information of the metal loss point is obtained as lack of metal. According to the defect boundary position corresponding to the to-be-determined blackness area on the radiographic film being located inside the base material and close to the outer surface, the defect property information of the metal loss point is obtained as non-metallic inclusions or ellipsoidal pores.

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