Method for measuring position of longitudinal weld defect of pipeline

Abstract

The invention discloses a pipeline longitudinal weld defect position measuring method, which uses an ultrasonic probe to detect the defects of a pipeline, and comprises the following steps: obtaining the refraction angle beta of the ultrasonic probe; placing an ultrasonic probe at a fixed point on the outer peripheral wall of the pipeline; acquiring a sound path distance S between the ultrasonic probe and the defect; the position of the defect is acquired. According to the method for measuring the position of the longitudinal weld defect of the pipeline, the refraction angle beta of an ultrasonic probe is obtained; placing an ultrasonic probe at a fixed point on the outer peripheral wall of the pipeline; acquiring a sound path distance S between the ultrasonic probe and the defect; the position of the defect is acquired. The position of the defect of the pipeline can be determined according to the refraction angle beta of the ultrasonic probe, the sound path distance S between the ultrasonic probe and the defect and the size of the pipeline, and powerful technical support is provided for formulating a repair scheme of a welding seam of the pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of defect measurement, and more particularly to a method for measuring the position of longitudinal weld defects of pipelines. Background Art

[0002] In the field of special equipment pressure pipelines, the safety of pipelines is of crucial importance. The longitudinal weld of a pipeline is a key part of the pipeline structure. Due to the influence of factors such as welding process, material quality, and construction environment, various defects may occur at the weld, such as cracks, pores, slag inclusions, etc. The existence of these defects will seriously weaken the load-bearing capacity of the pipeline, resulting in pipeline leakage or even rupture, thus triggering safety accidents. In order to ensure the safe operation of the pipeline, it is necessary to accurately detect and evaluate the defects of the longitudinal weld of the pipeline. Among them, determining the position of the defect is an important basis for formulating a repair plan. The traditional weld defect detection method, ultrasonic detection, can only detect the existence of defects, but it is difficult to accurately measure the position of the defects. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. For this reason, the present invention provides a method for measuring the position of longitudinal weld defects of pipelines. The method for measuring the position of longitudinal weld defects of pipelines can determine the position of pipeline defects through the refraction angle β of an ultrasonic probe, the sound path S between the ultrasonic probe and the defect, and the size of the pipeline, providing strong technical support for formulating a repair plan for the weld of the pipeline.

[0004] According to the method for measuring the position of longitudinal weld defects of pipelines according to an embodiment of the present invention, an ultrasonic probe is used to detect pipeline defects. The method for measuring the position of longitudinal weld defects of pipelines includes: obtaining the refraction angle β of the ultrasonic probe; placing the ultrasonic probe at a fixed point on the outer peripheral wall of the pipeline; obtaining the sound path S between the ultrasonic probe and the defect; and obtaining the position of the defect.

[0005] According to the method for measuring the position of longitudinal weld defects of pipelines according to an embodiment of the present invention, by obtaining the refraction angle β of the ultrasonic probe; placing the ultrasonic probe at a fixed point on the outer peripheral wall of the pipeline; obtaining the sound path S between the ultrasonic probe and the defect; and obtaining the position of the defect. The position of pipeline defects can be determined through the refraction angle β of the ultrasonic probe, the sound path S between the ultrasonic probe and the defect, and the size of the pipeline, providing strong technical support for formulating a repair plan for the weld of the pipeline.

[0006] In addition, according to the method for measuring the position of longitudinal weld defects of the present invention, the following additional technical features may also be included:

[0007] In some embodiments, obtaining the refraction angle β of the ultrasonic probe includes: confirming that the ultrasonic probe is placed on the test surface of the test block; reading the acoustic path Y between the ultrasonic probe and the test hole; and calculating the refraction angle β of the ultrasonic probe.

[0008] In some embodiments of the present invention, the outer peripheral wall of the test block includes a test surface and a reflection surface. The test surface is an arc surface with a radius R that is the same as the outer peripheral wall of the pipe, and the reflection surface is an arc surface centered on the installation position of the ultrasonic probe with a radius equal to the pipe thickness.

[0009] In some embodiments of the present invention, the test hole is spaced apart from the connection line between the installation position of the ultrasonic probe and the center of the test surface. The shortest distance between the test hole and the test surface is L. Calculating the refraction angle of the ultrasonic probe includes: calculating the distance H between the defect and the center of the test surface, where H = R - L; calculating

[0010] In some embodiments of the present invention, obtaining the position of the defect includes: determining, on the cross-section of the pipe at the position where the ultrasonic probe is provided, the installation position O2 of the ultrasonic probe, the center O of the pipe, the position O1 where the ultrasonic probe refracts on the inner peripheral wall of the pipe, the position O4 of the defect, and the intersection point O5 of the connection line between the defect and the pipe center O on the outer peripheral wall of the pipe. Among them, the distance between O2 and O is the outer diameter R of the pipe, and the distance between O1 and O is the inner diameter r of the pipe; calculating ∠O2OO1 and ∠O2O1O; calculating the length S1 of O2O1; calculating the length of O1O4; calculating the length of OO4; obtaining the shortest distance D between the defect and the outer surface of the pipe, where D = R - OO4.

[0011] In some embodiments of the present invention, obtaining the position of the defect further includes: determining, on the cross-section of the pipe at the position where the ultrasonic probe is provided, the installation position O2 of the ultrasonic probe, the center O of the pipe, the position O1 where the ultrasonic probe refracts on the inner peripheral wall of the pipe, the position O4 of the defect, and the intersection point O5 of the connection line between the defect and the pipe center O on the outer peripheral wall of the pipe. Among them, the distance between O2 and O is the outer diameter R of the pipe, and the distance between O1 and O is the inner diameter r of the pipe; calculating ∠O2OO1 and ∠O2O1O; calculating the length of O1O4; calculating the length of OO4; calculating ∠O1OO4; obtaining the included angle ∠O2OO5 between the connection line between the ultrasonic probe and the pipe center and the connection line between the defect and the center, where ∠O2OO5 = ∠O4OO1 + ∠O2OO1.

[0012] In some embodiments of the present invention, calculating ∠O1OO4 includes: calculating ∠ using the cosine theorem

[0013]

[0014] In some embodiments of the present invention, the position of obtaining the defect further includes: the arc length formed by the intersection point O5 of the connection line between the installation position O2 of the ultrasonic probe and the center O of the pipeline on the outer peripheral wall of the pipeline

[0015] In some embodiments of the present invention, the calculation of ∠O2OO1 and ∠O2O1O includes: calculating by using the law of arcsine It is obtained that ∠O2OO1 = 180° - ∠O2O1O - β.

[0016] In some embodiments of the present invention, the calculation of the length S1 of O2O1 includes: calculating by using the cosine theorem

[0017] In some embodiments of the present invention, the calculation of the length of O1O4 includes: calculating O1O4 = S - S1.

[0018] In some embodiments of the present invention, the calculation of the length of OO4 includes: according to the reflection law of ultrasonic wave obliquely incident on the interface, it is known that ∠O2O1O3 = ∠O3O1O4, and it is obtained that ∠O4O1O = 180 - ∠O3O1O4; calculating

[0019] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0021] Figure 1 is for the method of measuring the position of longitudinal weld defects of a pipeline according to an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of the cooperation between a pipeline and an ultrasonic probe according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of the cooperation between a test hole and an ultrasonic probe according to an embodiment of the present invention.

[0024] Reference numerals:

[0025] 10. Pipeline; 1. Weld; 11. Defect;

[0026] 20. Ultrasonic probe; 30. Test block; 3. Test surface; 31. Reflective surface; 32. Test hole. Detailed implementation manner

[0027] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0029] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] The method for measuring the position of longitudinal weld defects of a pipeline according to an embodiment of the present invention will be described below with reference to the drawings.

[0032] As Figure 2 shown, in the method for measuring the position of longitudinal weld defects of a pipeline according to an embodiment of the present invention, an ultrasonic probe 20 is used to detect a defect 11 of a pipeline 10.

[0033] Specifically, when the pipeline 10 is processed and manufactured, there is a weld seam 1 extending along the radial direction (longitudinal direction) of the pipeline 10. Due to the influence of factors such as welding process, material quality, and construction environment, various defects 11 may occur at the weld seam 1, such as cracks, pores, slag inclusions, etc. The existence of these defects 11 will seriously weaken the bearing capacity of the pipeline 10, resulting in leakage or even rupture of the pipeline 10, thereby triggering safety accidents.

[0034] Such as Figure 1 As shown, the method for measuring the position of longitudinal weld defects of the pipeline includes:

[0035] Obtain the refraction angle β of the ultrasonic probe 20; that is, the refraction angle of the ultrasonic probe 20 is the angle between the beam and the contact surface of the measured object when the ultrasonic signal enters the measured object from the probe, which is convenient for calculating the position of the defect 11 when the ultrasonic probe 20 detects the defect 11.

[0036] Place the ultrasonic probe 20 at a fixed point on the outer peripheral wall of the pipeline 10; so that the position of the ultrasonic probe 20 is relatively fixed and the detection of the ultrasonic probe 20 is more reliable.

[0037] Obtain the sound path S between the ultrasonic probe 20 and the defect 11; it can be understood that the sound path between the ultrasonic probe 20 and the defect 11 can be directly obtained from the ultrasonic probe 20, and the sound path between the ultrasonic probe 20 and the defect 11 includes the total sound path after the beam is reflected when it contacts the inner peripheral wall of the pipeline 10.

[0038] Obtain the position of the defect 11. The position of the defect 11 of the pipeline 10 can be determined, providing strong technical support for formulating a repair plan for the weld seam 1 of the pipeline 10.

[0039] According to the method for measuring the position of longitudinal weld defects of the pipeline according to the embodiment of the present invention, by obtaining the refraction angle β of the ultrasonic probe 20; placing the ultrasonic probe 20 at a fixed point on the outer peripheral wall of the pipeline 10; obtaining the sound path S between the ultrasonic probe 20 and the defect 11; obtaining the position of the defect 11. The position of the defect 11 of the pipeline 10 can be determined through the refraction angle β of the ultrasonic probe 20, the sound path S between the ultrasonic probe 20 and the defect 11, and the size of the pipeline 10, providing strong technical support for formulating a repair plan for the weld seam 1 of the pipeline 10.

[0040] In this embodiment, the ultrasonic probe 20 used is 5P8×8K1. 5P indicates that the probe frequency is 5 MHz, and P represents longitudinal wave (compression wave). 8×8: indicates that the probe wafer size is 8 mm×8 mm. K1: indicates that the probe type is an oblique probe, and K1 refers to a refraction angle of 45 degrees.

[0041] In some embodiments of the present invention, such as Figure 1 And Figure 3As shown, the outer peripheral wall of the test block 30 includes a test surface 3 and a reflection surface 31. The test surface 3 is an arc surface with a radius R that is the same as the outer peripheral wall of the pipeline 10. The reflection surface 31 is an arc surface made with the installation position of the ultrasonic probe 20 as the center and the thickness of the pipeline 10 as the radius. That is, the distance from the installation position of the ultrasonic probe 20 to the reflection surface 31 is equal everywhere, avoiding affecting the size of the refraction angle of the ultrasonic probe 20.

[0042] Furthermore, as Figure 1 and Figure 3 shown, obtaining the refraction angle β of the ultrasonic probe 20 includes:

[0043] Confirm that the ultrasonic probe 20 is placed on the test surface 3 of the test block 30; making the position of the ultrasonic probe 20 relatively fixed, the testing process of the ultrasonic probe 20 is more reliable. In addition, the ultrasonic probe 20 can be placed at any position on the test surface 3 and reflect through a depth equal to the wall thickness of the pipeline 10.

[0044] Read out the acoustic path Y between the ultrasonic probe 20 and the test hole 32; it can be understood that the acoustic path between the ultrasonic probe 20 and the test hole 32 can be directly obtained from the ultrasonic probe 20.

[0045] Calculate the refraction angle β of the ultrasonic probe 20. Facilitate calculating the position of the defect 11 when the ultrasonic probe 20 detects the defect 11.

[0046] Even further, as Figure 1 and Figure 3 shown, the test hole 32 is spaced apart from the connecting line between the installation position of the ultrasonic probe 20 and the center of the test surface 3. The shortest distance between the test hole 32 and the test surface 3 is L. Calculating the refraction angle of the ultrasonic probe 20 includes:

[0047] Calculate the distance H between the defect 11 and the center of the test surface 3 = R - L;

[0048] Calculate The refraction angle of the ultrasonic probe 20 can be calculated using the law of cosines.

[0049] In some embodiments of the present invention, as Figure 1 and Figure 2 shown, obtaining the position of the defect 11 includes:

[0050] On the cross-section of the position of the pipeline 10 where the ultrasonic probe 20 is provided, determine the installation position O2 of the ultrasonic probe 20, the center O of the pipeline 10, the position O1 where the ultrasonic probe 20 refracts on the inner peripheral wall of the pipeline 10, the position O4 of the defect 11, and the intersection point O5 of the line connecting the defect 11 and the center O of the pipeline 10 on the outer peripheral wall of the pipeline 10. Among them, the distance between O2 and O is the outer diameter R of the pipeline 10, and the distance between O1 and O is the inner diameter r of the pipeline 10; in addition, the refraction angle β of the ultrasonic probe 20 is known, which is convenient for calculating the position of the defect 11.

[0051] Calculate ∠O2OO1 and ∠O2O1O; after the beam of the ultrasonic probe 20 contacts the inner peripheral wall of the pipeline 10, it is reflected, and ∠O2O1O3 is the same as ∠O4O1O3, and then ∠O2O1O is the same as ∠O4O1O.

[0052] Calculate the length S1 of O2O1; calculate the length of O1O4; calculate the length of OO4;

[0053] Obtain the shortest distance D between the defect 11 and the outer surface of the pipeline 10 = R - OO4. It can be understood that the outer diameter of the pipeline 10 is R, the distance between the defect 11 and the center is OO4, and the shortest distance D between the defect 11 and the outer surface of the pipeline 10 is equivalent to the depth of the defect 11, which is convenient for obtaining the position of the defect 11 in the radial direction of the pipeline 10, convenient for positioning the defect 11, and providing strong technical support for formulating a repair plan.

[0054] Furthermore, as Figure 1 and Figure 2 shown, obtaining the position of the defect 11 further includes:

[0055] On the cross-section of the position of the pipeline 10 where the ultrasonic probe 20 is provided, determine the installation position O2 of the ultrasonic probe 20, the center O of the pipeline 10, the position O1 where the ultrasonic probe 20 refracts on the inner peripheral wall of the pipeline 10, the position O4 of the defect 11, and the intersection point O5 of the line connecting the defect 11 and the center O of the pipeline 10 on the outer peripheral wall of the pipeline 10. Among them, the distance between O2 and O is the outer diameter R of the pipeline 10, and the distance between O1 and O is the inner diameter r of the pipeline 10; in addition, the refraction angle β of the ultrasonic probe 20 is known, which is convenient for calculating the position of the defect 11.

[0056] Calculate ∠O2OO1 and ∠O2O1O; after the beam of the ultrasonic probe 20 contacts the inner peripheral wall of the pipeline 10, it is reflected, and ∠O2O1O3 is the same as ∠O4O1O3, and then ∠O2O1O is the same as ∠O4O1O.

[0057] Calculate the length of O1O4; calculate the length of OO4; calculate ∠O1OO4;

[0058] The included angle ∠O2OO5 between the line connecting the centers of the ultrasonic probe 20 and the pipe 10 and the line connecting the defect 11 and the center is obtained as ∠O2OO5 = ∠O4OO1 + ∠O2OO1. It can be understood that by obtaining the included angle between the line connecting the centers of the ultrasonic probe 20 and the pipe 10 and the line connecting the defect 11 and the center, and combining with the shortest distance D between the defect 11 and the outer surface of the pipe 10, it is convenient to obtain the position of the defect 11 in the radial direction of the pipe 10, which is convenient for positioning the defect 11 and provides strong technical support for formulating a repair plan.

[0059] In some embodiments of the present invention, such as Figure 1 and Figure 2 shown, calculating ∠O1OO4 includes:

[0060] Using the cosine theorem to calculate It can be understood that the length of OO1 is the same as the inner diameter r of the pipe 10. After knowing the lengths of the three sides of a triangle, it is relatively convenient to calculate the length of any side of the triangle.

[0061] In some embodiments of the present invention, such as Figure 1 and Figure 2 shown, obtaining the position of the defect 11 further includes:

[0062] The arc length formed by the intersection point O5 of the line connecting the installation position O2 of the ultrasonic probe 20 and the center O of the pipe 10 on the outer peripheral wall of the pipe 10 It can be understood that by obtaining the arc length formed by the intersection point O5 of the line connecting the installation position O2 of the ultrasonic probe 20 and the center O of the pipe 10 on the outer peripheral wall of the pipe 10, and combining with the included angle between the line connecting the ultrasonic probe 20 and the center of the pipe 10 and the line connecting the defect 11 and the center, as well as the shortest distance D between the defect 11 and the outer surface of the pipe 10, it is convenient to obtain the position of the defect 11 in the pipe 10, which is convenient for positioning the defect 11 and provides strong technical support for formulating a repair plan.

[0063] In some embodiments of the present invention, such as Figure 1 and Figure 2 shown, calculating ∠O2OO1 and ∠O2O1O includes:

[0064] Using the arcsine theorem to calculate wherein, the refraction angle β is known, the length of OO2 is the same as the outer diameter R of the pipe 10, and the length of OO1 is the same as the inner diameter r of the pipe 10.

[0065] It is obtained that ∠O2OO1 = 180° - ∠O2O1O - β. It can be relatively conveniently calculated by using the fact that the sum of the three angles of a triangle is 180°.

[0066] In some embodiments of the present invention, such as Figure 1 and Figure 2As shown, calculating the length S1 of O2O1 includes:

[0067] Calculating using the cosine theorem wherein, the length of OO2 is the same as the outer diameter R of the pipe 10, and the length of OO1 is the same as the inner diameter r of the pipe 10.

[0068] In some embodiments of the present invention, such as Figure 1 and Figure 2 As shown, calculating the length of O1O4 includes:

[0069] Calculating O1O4 = S - S1. It can be understood that the sound path between the ultrasonic probe 20 and the defect 11 can be directly obtained from the ultrasonic probe 20. The sound path between the ultrasonic probe 20 and the defect 11 includes the total sound path S after the beam is reflected when contacting the inner peripheral wall of the pipe 10. The total length of O1O4 and O1O2 is the same as the sound path S.

[0070] In some embodiments of the present invention, such as Figure 1 and Figure 2 As shown, calculating the length of OO4 includes:

[0071] Using the reflection law of ultrasonic wave obliquely incident on the interface, it is known that ∠O2O1O3 = ∠O3O1O4, and ∠O4O1O = 180 - ∠O3O1O4 can be obtained;

[0072] Calculating The values of each angle and each side of the triangle O4O1O can be obtained, which is convenient for calculating the position of the defect 11.

[0073] Other components and operations of the method for measuring the position of longitudinal weld defects in pipes according to the embodiments of the present invention are known to those of ordinary skill in the art and will not be described in detail here.

[0074] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0075] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for measuring the position of longitudinal weld defects of a pipeline, characterized in that, Detecting the defects of a pipeline using an ultrasonic probe, the method for measuring the longitudinal weld defect position of the pipeline includes: Obtaining the refraction angle β of the ultrasonic probe; Placing the ultrasonic probe at a fixed point on the outer peripheral wall of the pipeline; Obtaining the acoustic path S between the ultrasonic probe and the defect; Determining the position of the defect.

2. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 1, characterized in that The obtaining of the refraction angle β of the ultrasonic probe includes: Confirming that the ultrasonic probe is placed on the test surface of the test block; Reading out the acoustic path Y between the ultrasonic probe and the test hole; Calculating the refraction angle β of the ultrasonic probe.

3. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 2, characterized in that, The outer peripheral wall of the test block includes a test surface and a reflecting surface. The test surface is an arc surface with the same radius R as the outer peripheral wall of the pipeline, and the reflecting surface is an arc surface made with the installation position of the ultrasonic probe as the center and the pipeline thickness as the radius.

4. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 2, characterized in that The test hole is spaced from the connecting line between the installation position of the ultrasonic probe and the center of the test surface. The shortest distance between the test hole and the test surface is L. The calculating of the refraction angle of the ultrasonic probe includes: Calculating the distance H between the defect and the center of the test surface as H = R - L; Calculation 5. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 1, characterized in that, The determining of the position of the defect includes: On the cross-section of the pipeline where the ultrasonic probe is located, determining the installation position O2 of the ultrasonic probe, the center O of the pipeline, the refraction position O1 of the ultrasonic probe on the inner peripheral wall of the pipeline, the position O4 of the defect, and the intersection point O5 of the connection line between the defect and the pipeline center O on the outer peripheral wall of the pipeline. Among them, the distance between O2 and O is the outer diameter R of the pipeline, and the distance between O1 and O is the inner diameter r of the pipeline; Calculating ∠O2OO1 and ∠O2O1O; Calculating the length S1 of O2O1; Calculating the length of O1O4; Calculating the length of OO4; Obtaining the shortest distance D between the defect and the outer surface of the pipeline as D = R - OO4.

6. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 5, characterized in that, The determining of the position of the defect further includes: On the cross-section of the pipeline where the ultrasonic probe is located, determining the installation position O2 of the ultrasonic probe, the center O of the pipeline, the refraction position O1 of the ultrasonic probe on the inner peripheral wall of the pipeline, the position O4 of the defect, and the intersection point O5 of the connection line between the defect and the pipeline center O on the outer peripheral wall of the pipeline. Among them, the distance between O2 and O is the outer diameter R of the pipeline, and the distance between O1 and O is the inner diameter r of the pipeline; Calculating ∠O2OO1 and ∠O2O1O; Calculating the length of O1O4; Calculating the length of OO4; Calculating ∠O1OO4; Obtaining the included angle ∠O2OO5 between the connection line of the ultrasonic probe and the pipeline center and the connection line of the defect and the center as ∠O2OO5 = ∠O4OO1 + ∠O2OO1.

7. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 6, characterized in that, The calculating of ∠O1OO4 includes: Calculate using the cosine theorem 8. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 7, characterized in that, The determining of the position of the defect further includes: The arc length formed by the intersection point O5 on the outer peripheral wall of the pipeline of the connection line between the installation position O2 of the ultrasonic probe and the center O of the pipeline 9. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 5, wherein The calculating of ∠O2OO1 and ∠O2O1O includes: Calculate using the law of sines Obtaining ∠O2OO1 = 180° - ∠O2O1O - β.

10. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 9, characterized in that, The calculating of the length S1 of O2O1 includes: Calculate using the cosine theorem 11. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 10, characterized in that The calculating of the length of O1O4 includes: Calculating O1O4 = S - S1.

12. The method for measuring the position of longitudinal weld defects of a pipeline according to claim 11, wherein The calculating of the length of OO4 includes: According to the reflection law of ultrasonic wave obliquely incident on the interface, it is known that ∠O2O1O3 = ∠O3O1O4, and it can be obtained that ∠O4O1O = 180 - ∠O3O1O4; Calculation

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