Crossing section pipeline bearing state integrated detection and safety evaluation method

Abstract

The invention discloses a spanning section pipeline bearing state integrated detection and safety evaluation method, which comprises the following steps: collecting basic data of a to-be-detected spanning pipeline, including spanning section passing conditions, pipeline size, yield strength, pipeline material and the like; determining a detection scheme (including a handheld scheme and an unmanned aerial vehicle type scheme) suitable for field conditions; carrying out straight pipe stress damage rapid scanning and bent pipe ring measurement on the to-be-measured pipeline, calculating a magnetic gradient modulus, and obtaining the position of a pipeline stress damage point according to the change condition of the magnetic gradient modulus; according to pipeline data, the number of detection points is calculated, pipeline stress is inversed according to the measured coercive force value, and the whole circumferential stress state of stress damage points is obtained; calculating a stress state danger coefficient according to the full circumferential stress state of the pipeline; and an ultrasonic thickness measurement technology, an X-ray detection technology or a pipeline spanning pipe frame structure state and the like are combined to obtain a pipeline stress abnormity reason. Suggested measures are given in a targeted mode according to the pipeline stress abnormity reasons and the pipeline safety state level. According to the invention, the rapid and accurate positioning of the stress damage point of the pipeline and the full-circumferential detection of the stress at the stress damage point of the pipeline are realized, the safety evaluation is carried out, and powerful technical support is provided for the safe operation of the oil and gas pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of safe operation of oil and gas pipelines, and particularly relates to an integrated detection and safety evaluation method for the bearing state of pipeline crossing sections. Background of the Invention

[0003] As the main means of oil and gas energy transportation, pipelines are the "lifeline" to ensure the modern energy security of the country. The laying environment of China's long-distance oil and gas pipelines is complex along the way. When oil and gas pipelines pass through wide roads or rivers, they are mostly laid in a crossing manner. During the service process of long-distance oil and gas pipeline crossings, due to the superposition of welding residual stress, operating internal pressure, wind load, pipeline gravity load, vibration, etc., it is easy to cause significant stress concentration effects in the pipeline, threatening the safe operation of the crossing pipeline. Therefore, it is necessary to regularly carry out pipeline detection work to understand the pipeline operation status and evaluate the pipeline safety risk status.

[0004] The existing detection methods mainly include the blind hole method, indentation method, ultrasonic stress detection, etc. Among them, the blind hole method will damage the pipeline and is not suitable for in-service pipeline detection; the ultrasonic stress detection method requires seamless contact with the pipeline to be measured, and at the same time requires the pipeline surface to be smooth and flat, and cannot effectively measure discontinuous structures such as girth welds. On the other hand, these local directional detection methods need to determine the detection position based on prior information (such as the abnormal position of the pipeline); the detection data of traditional magnetic flux leakage internal detectors have large measurement errors of the odometer wheels, resulting in poor accuracy of pipeline abnormal position positioning. All these factors directly affect the overall efficiency of troubleshooting hidden dangers in the operation of crossing pipelines. Summary of the Invention

[0005] In view of the above problems, the present invention proposes an integrated detection and safety evaluation method for the bearing state of pipeline crossing sections, which mainly includes technical methods for rapid scanning of stress damage points on straight pipes, circumferential measurement of elbows, and contact full-circumferential stress detection. Among them, the rapid scanning of magnetic stress damage points on straight pipes and the circumferential measurement of elbows utilize the weak magnetic detection principle, which has the significant advantages of non-contact measurement, real-time acquisition of pipeline stress damage signals, and fast detection speed, and can quickly locate the pipeline stress damage points. The contact full-circumferential stress detection utilizes the stress detection method based on coercive force, which has the advantages of non-contact, full-circumferential measurement, and being unrestricted by the pipeline structure, and can perform stress detection on the pipeline stress damage points. It realizes the rapid and accurate positioning of pipeline stress damage points and the full-circumferential stress detection at the pipeline stress damage points, and conducts safety evaluation on them. It provides a strong technical support for the safe operation of oil and gas pipeline crossings.

[0006] The technical solution provided by the present invention is an integrated detection and safety evaluation method for the bearing state of pipeline crossing sections, including an integrated detection method and a safety evaluation method for the bearing state of pipeline crossing sections. The characteristics of the integrated detection method and the safety evaluation method for the bearing state of pipeline crossing sections include the following steps:

[0007] Main steps

[0008] S1. Collect the basic data of the pipeline to be detected for crossing, including but not limited to the passing conditions of the crossing section, pipeline span, pipeline wall thickness, yield strength, and pipeline material, etc., and complete the preliminary work of the integrated detection of the bearing state of the pipeline in the crossing section.

[0009] S2. Determine the detection plan suitable for the on-site conditions according to the pipeline basic data and on-site situation. The detection plan includes the following two types:

[0010] Plan 1: For the crossing pipe sections where there is passage for the detection personnel (such as the construction of a pedestrian trestle), the detection personnel hold a non-contact stress damage detector to quickly scan the straight crossing pipe sections, and use a non-contact stress damage detector carried by a fire truck or a scaffolding with people to quickly perform a circumferential measurement on the crossing elbow sections. Through the signals real-time fed back by the magnetic detector, locate and record the pipeline stress damage points. Subsequently, the detection personnel hold a pipeline coercivity stress tester to perform a full circumferential stress detection on the pipeline stress damage points and record the data.

[0011] Plan 2: For the crossing pipe sections where there is no passage for the detection personnel. Use a drone carrying a non-contact stress damage detector to quickly scan the straight and elbow crossing pipe sections, and locate and record the pipeline stress damage points through the signals real-time fed back by the magnetic detector and the drone positioning system. Subsequently, a wall-climbing coercivity stress detector goes to the pipeline stress damage points to perform a full circumferential stress detection on the pipeline stress damage points and record the data.

[0012] S3. Conduct the detection on the pipeline to be measured to obtain the positions of the pipeline stress damage points: During the on-site actual measurement process, in Plan 1, the detection personnel hold a non-contact stress damage detector and move forward at a uniform speed at a height of about 30 cm directly above the pipeline, keeping the sensor axis perpendicular to the pipeline direction. In Plan 2, the drone flies to a locked height of about 30 cm directly above the pipeline and flies at a uniform speed, keeping the sensor axis perpendicular to the pipeline length direction.

[0013] Among them, the measurement result obtained by the non-contact stress damage detector is the gradient of the three components of the magnetic induction intensity at a certain point along the direction perpendicular to the pipeline axis. The gradient modulus G is calculated through Equation (1). M . When the pipeline has defects such as metal loss, mechanical damage caused by corrosion, third-party damage, etc., it will cause a mutation in the self-leakage magnetic field of the pipeline, which is manifested as magnetic anomaly in the background magnetic field. During the forward movement, if G M undergoes a mutation, it indicates that there is a stress damage in the pipeline below the non-contact stress damage detector. Among them, the direction along the pipeline length is the x direction. Among them, G M Calculation method:

[0014]

[0015] where: i, j - directions of x, y, z; ΔB ij —— difference in the j - component of the magnetic vector between sensors arranged in the i - direction, nT; Δl i —— distance between sensors arranged in the i - direction, m.

[0016] S4. Obtain the circumferential stress state of the stress damage point: During on - site measurement, in Scheme 1, the inspection personnel hold the pipeline coercivity stress detector to perform circumferential detection on the pipeline stress damage point; in Scheme 2, the wall - climbing coercivity stress detector performs circumferential detection on the pipeline. The number of circumferential detection points is related to the pipe diameter, and the calculation method is shown in Equation (2):

[0017] [n] = πd / 265 (2)

[0018] where: n is the number of detection points; [] is the rounding symbol; d is the pipeline diameter, mm.

[0019] When a ferromagnetic pipeline is stressed and has defects, it will change the magnitude of the characteristic parameter coercivity of the hysteresis loop, and there is a positive - correlation correspondence between them. Therefore, the stress distribution of the material can be reflected by measuring the coercivity of the ferromagnetic pipeline. Its corresponding coercivity - stress inversion model is shown in Equation (3):

[0020]

[0021] where: σ is the pipeline stress, MPa; a is the pipeline material coefficient; H c is the measured coercivity value, A / cm. S5. Calculate the stress - state risk coefficient SC according to the circumferential stress state of the pipeline. The calculation method is as follows:

[0022]

[0023] where: max(σ) is the maximum circumferential stress of the pipeline, MPa; σ s is the pipeline yield stress, MPa; η is the pipeline risk coefficient.

[0024] Determine the safety state of the current pipeline according to the stress - state risk coefficient SC. The safety - state classification and recommended measures of the pipeline are shown in Table 1;

[0025] Table 1 Safety - state classification and recommended measures

[0026] SC value Stress level Safety status Maintenance and repair suggestions 0 < SC ≤ 0.2 Ⅰ Low risk Regular inspection 0.2 < SC ≤ 0.8 Ⅱ Medium risk Monitor usage 0.8 < SC ≤ 1.0 Ⅲ High risk Check immediately

[0027] S6. Obtain the reasons for abnormal pipeline stress by combining ultrasonic thickness measurement technology, X-ray detection technology, or the structural state of pipeline crossing pipe racks. Give targeted suggestions and measures based on the reasons for abnormal pipeline stress in combination with the pipeline safety status level.

[0028] The present invention has the following advantages:

[0029] 1. The integrated detection method for the bearing state of the pipeline in the crossing section proposed by the present invention can quickly and accurately locate the pipeline stress damage point, quantitatively obtain the circumferential stress state of the whole pipeline, and quickly and accurately complete the pipeline stress detection.

[0030] 2. The integrated detection method for the bearing state of the pipeline in the crossing section proposed by the present invention can adapt to the detection of any crossing section pipeline, and realizes the detection of the crossing section pipeline under the condition of no personnel passage. It is of great significance to the safe operation of oil and gas pipelines.

[0031] 3. Referring to the pipeline safety status grading and evaluation method proposed by the present invention, determine the reasons for abnormal pipeline stress through data such as X-rays and the structural state of pipe racks, and can give targeted maintenance measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only relate to some embodiments of the present invention and do not limit the present invention.

[0033] Figure 1 Schematic diagram of rapid scanning detection of pipeline stress damage in the crossing pipeline of the present invention

[0034] Figure 2 Schematic diagram of the circumferential safety state detection of the pipeline stress damage point of the present invention

[0035] Figure 3 Schematic diagram of the stress damage signal - position of the straight pipe section of the crossing pipeline collected by the present invention

[0036] Figure 4 Schematic diagram of the circumferential stress distribution of the pipeline at a stress abnormal point selected by the present invention

[0037] As shown in the figure

[0038] 1 - Non-contact stress damage detector, 2 - Pipeline. SPECIFIC EMBODIMENTS

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the art to which this disclosure belongs. The clockwise orientation and the three directions of x, y, and z used in the present invention are only used to represent the relative position relationship. When the absolute position of the object being described changes, the relative position relationship may also change accordingly. The present invention will be further described below in conjunction with the drawings and embodiments.

[0040] In a specific embodiment, the above steps are executed in sequence.

[0041] The integrated detection and safety evaluation method for the load-bearing state of the pipeline in the crossing section includes the following steps

[0042] S1. Collect on-site data: In a specific embodiment, the natural gas pipeline in the crossing section has a pipeline material of X80 steel, a pipeline diameter of 1016 mm, a pipeline wall thickness of 22.7 mm, a pipeline yield strength of 555 MPa, a pipeline span of 200 m, and a pedestrian walkway is built.

[0043] S2. In a specific embodiment, Scheme 1 is adopted for the detection of the crossing pipeline. That is, the detector holds a non-contact stress damage detector to quickly scan the straight pipe section of the crossing, and uses a non-contact stress damage detector carried by a fire truck or a scaffold to quickly perform a circumferential measurement on the bent pipe section of the crossing. Through the signal real-time feedback of the magnetic detector, the pipeline stress damage points are located and recorded. Subsequently, the detector holds a pipeline coercivity stress tester to perform a full circumferential safety inspection on the pipeline stress damage points and record the data.

[0044] S3. Conduct a test on the pipeline to be tested to obtain the magnetic stress damage position of the pipeline: During the on-site measurement process, the detector holds a non-contact stress damage detector and advances at a uniform speed at a height of about 30 cm directly above the pipeline, keeping the sensor axis perpendicular to the pipeline direction.

[0045] Among them, the measurement result obtained by the non-contact stress damage detector is the gradient of the three components of the magnetic induction intensity at a certain point along the direction perpendicular to the pipeline axis. The gradient modulus G is calculated by formula (4) M . When the pipeline has defects such as metal loss and mechanical damage caused by corrosion and third-party damage, it will cause a mutation in the self-leakage magnetic field of the pipeline, which is manifested as a magnetic anomaly in the background magnetic field. During the forward movement, if G M undergoes a mutation, it indicates that there is a stress damage in the pipeline under the non-contact stress damage detector. Among them, the pipeline length direction is the x direction. Among them, the calculation method of G M is as follows:

[0046]

[0047] where: i, j are in the x, y, and z directions; ΔB ij —— the difference in the j-component of the magnetic vector between sensors arranged in the i direction, nT; Δl i —— the distance between sensors arranged in the i direction, m.

[0048] Using a non-contact stress damage detector, a rapid scan is carried out along the pipeline axis. According to the magnetic signals, a total of 8 pipeline stress damage points are located. For the pipeline section spanning the elbow, a total of 2 pipeline stress damage points are located. The schematic diagram of the stress damage signal - position results for the straight section of the pipeline is as shown in Figure 3 shown.

[0049] S4. Obtaining the full circumferential safety state of the pipeline stress damage point: During the on-site measurement process, the detection personnel hold a pipeline coercivity stress detector to perform a full circumferential detection of the pipeline stress damage point. The number of circumferential detection points is related to the pipe diameter, and the calculation method is as shown in Equation (5):

[0050] [n] = π * d / 265 (6)

[0051] where: n is the number of detection points; [] is the rounding symbol; d is the pipeline diameter, mm. In a specific embodiment, d = 1016 mm.

[0052] The calculated number of detection points is 12. The stress distribution of the material is reflected by measuring the coercivity of the ferromagnetic pipeline. Its corresponding coercivity - stress inversion model is as shown in (7):

[0053]

[0054] where: σ is the pipeline stress, MPa; H c is the measured coercivity, A / cm.

[0055] Based on the coercivity values measured for the full circumference of the pipeline, the full circumferential stress distribution state of the pipeline is calculated. To better demonstrate the present invention, a stress damage point with the maximum stress is selected for display, and this point is a circumferential weld. The full circumferential stress distribution of this circumferential weld is as shown in Figure 3 shown.

[0056] S5. According to the full circumferential stress state of the pipeline circumferential weld, calculate the stress state risk coefficient SC, and its calculation method is as follows:

[0057]

[0058] where: max(σ) is the maximum full circumferential stress of the pipeline circumferential weld, max(σ) = 420 MPa; σ sis the yield stress of the pipeline, σ s = 555 MPa; η is the pipeline hazard coefficient, η = 1.1.

[0059] It is calculated that: SC = 0.83. According to Table 1, the current stress grade of the pipeline girth weld is Grade III, and the safety status is a high-risk state. Immediate inspection is required.

[0060] S6. Combine ultrasonic thickness measurement technology, X-ray detection technology, or the structural state of the pipeline crossing pipe rack, etc. to obtain the reasons for abnormal pipeline stress. Ultrasonic thickness measurement shows that there is no obvious local thinning phenomenon in the circumferential direction of the pipeline girth weld at this location, and the average wall thickness loss is 0.25 mm, which is within the normal range; the pipe rack structure shows that there is no offset or dislocation of the pipeline at this location. X-ray detection shows that there is an internal undercut defect in the girth weld at the 7:53 direction at this location. Through comprehensive judgment, the stress concentration at this girth weld is caused by the internal undercut. It is recommended to install a stress and strain monitoring system at this girth weld to monitor the stress change in real time and ensure the safe operation of the pipeline crossing section.

[0061] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An integrated detection and safety evaluation method for the load-bearing state of pipeline crossing sections, characterized in that It includes the following steps: S1. Collect the basic information of the pipeline to be detected for crossing, including but not limited to the passing conditions of the crossing section, pipeline span, pipeline wall thickness, yield strength, pipeline material, etc., and complete the preliminary work of the integrated detection of the bearing state of the pipeline in the crossing section. S2. Determine the detection plan suitable for the on-site conditions according to the pipeline basic information and on-site situation. The detection plan includes the following two types: Plan 1: For the crossing pipeline section where the detection personnel can pass (such as the construction of a pedestrian trestle), the detection personnel hold a non-contact stress damage detector to quickly scan the straight pipeline section of the crossing. The non-contact stress damage detector is used by the aerial ladder truck or scaffolding with people to quickly perform a circumferential measurement on the crossing elbow section. Through the signal real-time feedback by the magnetic detector, locate and record the pipeline stress damage points. Subsequently, the detection personnel hold a pipeline coercivity stress tester to perform a full circumferential stress detection on the pipeline stress damage points and record the data. Plan 2: For the crossing pipeline section where there is no passage for the detection personnel. Use a drone equipped with a non-contact stress damage detector to quickly scan the straight pipeline section and elbow section of the crossing. Through the signal real-time feedback by the magnetic detector and the drone positioning system, locate and record the pipeline stress damage points. Subsequently, the wall-climbing coercivity stress detector goes to the pipeline stress damage points to perform a full circumferential stress detection on the pipeline stress damage points and record the data. S3. Carry out the detection on the pipeline to be measured to obtain the position of the pipeline stress damage points: During the on-site actual measurement process, in Plan 1, the detection personnel hold a non-contact stress damage detector and move forward at a uniform speed at a height of about 30 cm directly above the pipeline, keeping the sensor axis perpendicular to the pipeline direction. In Plan 2, the drone flies to a locked height of about 30 cm directly above the pipeline and flies at a uniform speed, keeping the sensor axis perpendicular to the pipeline length direction Among them, the measurement result obtained by the non-contact stress damage detector is the gradient of the three components of the magnetic induction intensity at a certain point along the direction perpendicular to the axial direction of the pipeline. The gradient modulus G is calculated by Equation (1). M . When defects such as metal loss and mechanical damage caused by corrosion and third-party damage occur in the pipeline, it will cause a mutation in the self-leakage magnetic field of the pipeline, which is manifested as a magnetic anomaly in the background magnetic field. During the forward movement, if G M undergoes a mutation, it indicates that there is stress damage in the pipeline under the non-contact stress damage detector. Among them, the length direction along the pipeline is the x direction. Among them, the calculation method of G M is as follows: where: i, j - directions of x, y, z; ΔB ij - difference in the j-component of the magnetic vector between sensors arranged in the i-direction, nT; Δl i - distance between sensors arranged in the i-direction, m. S4. Obtain the full circumferential stress state of the stress damage points: During the on-site actual measurement process, in Plan 1, the detection personnel hold a pipeline coercivity stress detector to perform a full circumferential detection on the pipeline stress damage points; in Plan 2, the wall-climbing coercivity stress detector performs a full circumferential detection on the pipeline. The number of circumferential detection points is related to the pipe diameter, and the calculation method is shown in Equation (2): [n] = πd / 265 (Equation 2) where: n is the number of detection points; [] is the rounding symbol; d is the pipeline diameter, in mm. When a ferromagnetic pipeline is stressed and has defects, it will change the magnitude of the characteristic parameter coercivity of the hysteresis loop, and there is a positive correlation between the two. Therefore, the stress distribution of the material can be reflected by measuring the coercivity of the ferromagnetic pipeline. Its corresponding coercivity-stress inversion model is shown in (3): Where: σ is the pipeline stress, in MPa; a is the pipeline material coefficient; H c is the measured coercivity value, in A / cm. S5. Calculate the stress state risk coefficient SC according to the full circumferential stress state of the pipeline. The calculation method is as follows: where: max(σ) is the maximum circumferential stress of the pipeline, MPa; σ s is the yield stress of the pipeline, MPa; η is the pipeline hazard coefficient. Determine the safety state of the current pipeline according to the stress state risk coefficient SC. The safety state classification and recommended measures of the pipeline are shown in Table 1; Table 1 Safety state classification and recommended measures table S6. Obtain the reasons for abnormal pipeline stress by combining ultrasonic thickness measurement technology, X-ray detection technology or the structural state of the pipeline crossing pipe rack. Give targeted suggestions and measures according to the reasons for abnormal pipeline stress in combination with the pipeline safety status level.

2. The integrated detection and safety evaluation method for the bearing state of the pipeline in the spanning section according to claim 1, characterized in that: In step S2, the passing conditions of the pipeline in the crossing section are considered, and two sets of detection schemes including hand-held and drone types are set up.

3. The integrated detection and safety evaluation method for the bearing state of the pipeline in the spanning section according to claim 1, wherein: In step S3, during the forward movement, based on the change in the magnetic gradient modulus the location of the pipeline stress damage can be accurately located.

4. The integrated detection and safety evaluation method for the bearing state of the spanning section pipeline according to claim 1, wherein: In step S4, the calculation method for the number of detection points established: [n] = πd / 265 and the established coercivity-stress inversion model:

5. The integrated detection and safety evaluation method for the load-bearing state of the pipeline in the spanning section according to claim 1, characterized in that: In step S5, the calculation method for the danger coefficient of the established stress state: And the safety state classification and recommended measures table for the pipeline.

6. The integrated detection and safety evaluation method for the bearing state of the spanning section pipeline according to claim 1, wherein: In step S6, a method for obtaining the reasons for abnormal pipeline stress by combining ultrasonic thickness measurement technology, X-ray detection technology or the structural state of the pipeline crossing pipe rack.

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