阅读说明：本技术 一种山区管道应变监测安全管环与方法 (Safety pipe ring and method for monitoring pipeline strain in mountainous area ) 是由 何腾蛟 廖柯熹 何国玺 杨淑婷 朱洪东 唐鉴 于 2020-12-01 设计创作，主要内容包括：本发明公开了一种山区管道应变监测安全管环与方法,所述安全管环包括磁力测试探头和保护所述磁力测试探头的保护壳,所述磁力测试探头设置4n个,n为大于等于1的自然数,相邻探头之间的夹角为180°/2n,且相邻探头之间通过数据传输线并联并通过数据传输接口接出,所述保护壳外层由无磁硬质合金制成,所述保护壳内层由非金属材料制成。本发明能够利用所述安全管环长期实时获取目标管段的磁测数据,并解析得到目标管段的轴向应变值,从而持续监控山区管道的安全状态。(The invention discloses a mountainous area pipeline strain monitoring safety pipe ring and a method, wherein the safety pipe ring comprises 4n magnetic force test probes and a protective shell for protecting the magnetic force test probes, n is a natural number which is more than or equal to 1, the included angle between every two adjacent probes is 180 degrees/2 n, the adjacent probes are connected in parallel through data transmission lines and are connected out through data transmission interfaces, the outer layer of the protective shell is made of nonmagnetic hard alloy, and the inner layer of the protective shell is made of nonmetal materials. The invention can utilize the safety pipe ring to obtain the magnetic measurement data of the target pipe section in real time for a long time, and analyze the magnetic measurement data to obtain the axial strain value of the target pipe section, thereby continuously monitoring the safety state of the mountain pipeline.)

1. The utility model provides a mountain area pipeline strain monitoring safety pipe ring, its characterized in that, includes magnetic force test probe and protection magnetic force test probe's protective housing, magnetic force test probe sets up 4n, and n is more than or equal to 1's natural number, and the contained angle between the adjacent probe is 180/2 n, and connects out through data transmission line parallel and through the data transmission interface between the adjacent probe, the skin of protective housing is made by no magnetism carbide, the inlayer of protective housing is made by non-metallic material.

2. The mountain pipeline strain monitoring safety pipe ring according to claim 1, wherein the protective shell comprises an upper half ring and a lower half ring which are connected and symmetrical, the left ends of the upper half ring and the lower half ring are hinged, the right ends of the upper half ring and the lower half ring are provided with support lugs, and the support lugs of the upper half ring and the support lugs of the lower half ring are connected through bolts; or the left end and the right end of the upper half ring and the right end of the lower half ring are respectively provided with a support lug, and the support lug at the left end of the upper half ring and the support lug at the left end of the lower half ring, and the support lug at the right end of the upper half ring and the support lug at the right end of the lower half ring are connected through bolts.

3. The mountain pipeline strain monitoring safety pipe ring of claim 2, wherein a rubber gasket is arranged between the upper half ring and the lower half ring.

4. The mountain pipeline strain monitoring safety pipe loop of any one of claims 1 to 3, wherein the magnetic force test probe comprises a single-axis fluxgate sensor and a housing protecting the single-axis fluxgate sensor, the single-axis fluxgate sensor is one or two, and the housing is made of a non-metallic material.

5. A mountainous area pipeline strain monitoring method is characterized by comprising the following steps:

determining a calibration factor of each magnetic test probe, and then assembling the calibration factors into the mountainous area pipeline strain monitoring safety pipe ring as claimed in any one of claims 1 to 4;

installing the safety pipe ring on a monitoring pipeline, and installing a matching device of the safety pipe ring, wherein the matching device comprises a data acquisition unit;

converting the change value of the normal induction strength of the surface of the monitoring pipeline acquired by the data acquisition unit into a local longitudinal strain value of the monitoring part according to the calibration factor;

calculating the integral axial strain value of the pipeline section according to the local longitudinal strain value;

and determining an axial strain early warning threshold value of the monitoring pipeline, comparing the axial strain early warning threshold value with the integral axial strain value, and determining a monitoring measure by combining the signal characteristics of the magnetic force testing probe.

6. The method for monitoring the strain of the pipeline in the mountainous area as claimed in claim 5, wherein the calibration factor is determined by:

selecting a material with the same material as that of the monitoring pipeline to manufacture a flat plate test piece, and then clamping the flat plate test piece on a clamp of a tensile testing machine;

fixedly installing a magnetic force test probe right above a measurement line of a flat plate test piece, wherein the magnetic field test direction of the magnetic force test probe is consistent with the loading direction of the flat plate test piece;

starting the tensile testing machine, stretching the flat plate test piece, testing the normal magnetic induction intensity value of the surface of the flat plate test piece in the cyclic loading process within the elastic deformation range, and processing to obtain a change curve of the normal magnetic induction intensity change value;

after the test is finished, the actual strain curve of the flat test piece in the cyclic loading process is derived from an upper computer matched with the tensile testing machine;

and comparing and calibrating the change curve of the normal magnetic induction intensity change value with the actual strain curve, thereby determining the value of the calibration factor.

7. The method for monitoring the strain of the pipeline in the mountainous area as claimed in claim 5, wherein the change value of the normal induction strength of the surface of the monitoring pipeline acquired by the data acquisition unit is converted into the local longitudinal strain value of the monitoring part by the following formula:

Eε_L＝f_y·ΔB_y (1)

in the formula: e is the elastic modulus of the monitored pipeline material, MPa; epsilon_LIs the local longitudinal strain value, μ ε; f. of_yIs a calibration factor, dimensionless; delta B_yThe value of the change in normal induction, nT.

8. The method for monitoring the strain of the pipeline in the mountainous area as claimed in claim 7, wherein the calculation method of the overall axial strain value is as follows:

in the formula: epsilon_aIs the integral axial strain value, mu epsilon; 4n is the total number of the magnetic force test probes in the safety pipe ring, and is dimensionless; epsilon_LiThe local longitudinal strain value, mu epsilon, of the ith magnetic test probe; gamma is the poisson coefficient and has no dimension; epsilon_hpIs the hoop strain, μ ε; p is the running pressure of the monitoring pipeline, MPa; d is the pipe diameter of the monitoring pipeline, and is mm; delta is the wall thickness of the monitoring pipeline, mm.

9. The method for monitoring the strain of the pipeline in the mountainous area according to claim 8, wherein the axial strain early warning threshold value is as follows:

in the formula: epsilon_TIs an axial strain early warning threshold value, mu epsilon; sigma_sMonitoring the yield strength of the pipeline material in MPa; eta is a safety factor and has no dimension.

10. The method for monitoring the strain of the pipeline in the mountainous area according to any one of claims 5 to 9, wherein the monitoring measure is specifically as follows:

when the integral axial strain value is smaller than the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a separation state, monitoring the circumferential weld of the pipeline for use, and normally operating the pipeline body;

when the integral axial strain value is smaller than the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a similar trend state, monitoring normal operation of the circumferential weld of the pipeline and the pipeline body;

when the integral axial strain value is greater than or equal to the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a separation state, immediately maintaining the circumferential weld of the monitoring pipeline, and monitoring and using the pipeline body;

when the integral axial strain value is larger than or equal to the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a similar trend state, the circumferential weld of the monitoring pipeline and the pipeline body are monitored and used.

Technical Field

The invention relates to the technical field of oil and gas pipeline structure health monitoring, in particular to a mountainous area pipeline strain monitoring safety pipe ring and a method.

Background

The mountain area pipeline geographical environment along the line is complicated, the discrepancy in elevation is big, under many loads and unstable geological conditions effect, the pipeline easily receives concentrated load influence, has risks such as deformation, fracture, consequently, needs to take corresponding management and control means to ensure mountain area pipeline safe and stable operation. The solution widely applied at home and abroad is to identify dangerous pipe sections by a weak magnetic testing technology, the technology determines a local stress concentration area of a pipeline by detecting ground magnetic anomalies along the pipeline under a non-excavation condition, and indirectly evaluates the damage level of the pipeline by a semi-quantitative method so as to determine the safety state of the pipeline.

At present, the weak magnetic testing technology is mainly used for the instant detection of oil and gas pipelines and has the following defects:

(1) the weak magnetic testing technology can only detect and evaluate the current relative mechanical state of the mountain pipeline, but cannot continuously monitor the safety state of the mountain pipeline; in addition, after the pipeline magnetic field data are acquired by using the weak magnetic testing technology, the relative risk level of the stress concentration pipeline section needs to be determined in a manual evaluation mode, so that the efficiency is low, and the misjudgment rate is high.

(2) Unlike the direct calculation of the strain value of the pipe wall, the weak magnetic testing technology adopts a semi-quantitative evaluation method, and the relative mechanical state of the pipeline is determined through the damage index F value, so that the real safety state of the pipeline in the mountainous area cannot be determined.

(3) The elastic bending strain at the circumferential weld of the high-steel-grade pipeline is a common factor causing weld failure, but the weak magnetic testing technology can only determine whether the pipeline has local stress concentration, and cannot judge whether elastic bending deformation occurs.

(4) The weak magnetic testing technology is a non-excavation pipeline detection technology, the buried depth of the mountain pipeline is large, and the pipeline magnetic field information with weak ground is easily covered by a strong background magnetic field, so that the state data of the mountain pipeline is difficult to obtain effectively.

Disclosure of Invention

In view of the above problems, the present invention provides a safety pipe loop and a method for monitoring pipeline strain in a mountain area, which are used for acquiring magnetic measurement data of a target pipe section in real time for a long time, so as to continuously monitor the safety state of the pipeline in the mountain area.

The technical scheme of the invention is as follows:

on the one hand, provide a mountain area pipeline strain monitoring safety pipe ring, including magnetic force test probe and protection the protective housing of magnetic force test probe, magnetic force test probe sets up 4n, and n is more than or equal to 1's natural number, and the contained angle between the adjacent probe is 180/2 n, and connects out through data transmission line parallel and in parallel through the data transmission interface between the adjacent probe, the protective housing skin is made by no magnetism carbide, the protective housing inlayer is made by non-metallic material.

Preferably, the protective shell comprises an upper half ring and a lower half ring which are connected and symmetrical, the left ends of the upper half ring and the lower half ring are hinged, the right ends of the upper half ring and the lower half ring are provided with support lugs, and the support lugs of the upper half ring and the support lugs of the lower half ring are connected through bolts; or the left end and the right end of the upper half ring and the right end of the lower half ring are respectively provided with a support lug, and the support lug at the left end of the upper half ring and the support lug at the left end of the lower half ring, and the support lug at the right end of the upper half ring and the support lug at the right end of the lower half ring are connected through bolts.

Preferably, a rubber gasket is arranged between the upper half ring and the lower half ring.

Preferably, the magnetic force test probe comprises a single-axis fluxgate sensor and a housing for protecting the single-axis fluxgate sensor, the single-axis fluxgate sensor is one or two of the single-axis fluxgate sensors, and the housing is made of a non-metal material.

On the other hand, the strain monitoring method for the mountainous area pipeline is further provided, and the strain monitoring method comprises the following steps:

determining a calibration factor of each magnetic test probe, and then assembling the calibration factors into the mountain pipeline strain monitoring safety pipe ring;

installing the safety pipe ring on a monitoring pipeline, and installing a matching device of the safety pipe ring, wherein the matching device comprises a data acquisition unit;

converting the change value of the normal induction strength of the surface of the monitoring pipeline acquired by the data acquisition unit into a local longitudinal strain value of the monitoring part according to the calibration factor;

calculating the integral axial strain value of the pipeline section according to the local longitudinal strain value;

and determining an axial strain early warning threshold value of the monitoring pipeline, comparing the axial strain early warning threshold value with the integral axial strain value, and determining a monitoring measure by combining the signal characteristics of the magnetic force testing probe.

Preferably, the calibration factor is determined by:

selecting a material with the same material as that of the monitoring pipeline to manufacture a flat plate test piece, and then clamping the flat plate test piece on a clamp of a tensile testing machine;

fixedly installing a magnetic force test probe right above a measurement line of a flat plate test piece, wherein the magnetic field test direction of the magnetic force test probe is consistent with the loading direction of the flat plate test piece;

starting the tensile testing machine, stretching the flat plate test piece, testing the normal magnetic induction intensity value of the surface of the flat plate test piece in the cyclic loading process within the elastic deformation range, and processing to obtain a change curve of the normal magnetic induction intensity change value;

after the test is finished, the actual strain curve of the flat test piece in the cyclic loading process is derived from an upper computer matched with the tensile testing machine;

and comparing and calibrating the change curve of the normal magnetic induction intensity change value with the actual strain curve, thereby determining the value of the calibration factor.

Preferably, the change value of the normal induction strength of the surface of the monitoring pipeline acquired by the data acquisition unit is converted into a local longitudinal strain value of the monitoring part by the following formula:

Eε_L＝f_y·ΔB_y (1)

in the formula: e is the elastic modulus of the monitored pipeline material, MPa; epsilon_LIs the local longitudinal strain value, μ ε; f. of_yIs a calibration factor, dimensionless; delta B_yThe value of the change in normal induction, nT.

Preferably, the method for calculating the overall axial strain value includes:

in the formula: epsilon_aIs the integral axial strain value, mu epsilon; 4n is the total number of the magnetic force test probes in the safety pipe ring, and is dimensionless; epsilon_LiThe local longitudinal strain value, mu epsilon, of the ith magnetic test probe; gamma is the poisson coefficient and has no dimension; epsilon_hpIs the hoop strain, μ ε; p is the running pressure of the monitoring pipeline, MPa; d is the pipe diameter of the monitoring pipeline, and is mm; delta is the wall thickness of the monitoring pipeline, mm.

Preferably, the axial strain early warning threshold is:

in the formula: epsilon_TIs an axial strain early warning threshold value, mu epsilon; sigma_sMonitoring the yield strength of the pipeline material in MPa; eta is a safety factor and has no dimension.

Preferably, the monitoring measures are specifically:

when the integral axial strain value is smaller than the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a separation state, monitoring the circumferential weld of the pipeline for use, and normally operating the pipeline body;

when the integral axial strain value is smaller than the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a similar trend state, monitoring normal operation of the circumferential weld of the pipeline and the pipeline body;

when the integral axial strain value is greater than or equal to the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a separation state, immediately maintaining the circumferential weld of the monitoring pipeline, and monitoring and using the pipeline body;

when the integral axial strain value is larger than or equal to the axial strain early warning threshold value and the signal characteristic of the magnetic force test probe is in a similar trend state, the circumferential weld of the monitoring pipeline and the pipeline body are monitored and used.

The invention has the beneficial effects that:

the magnetic force test probe is arranged in the strain monitoring safety pipe ring of the mountain pipeline, so that magnetic measurement data of a target pipe section can be acquired in real time for a long time, and the safety state of the mountain pipeline is continuously monitored; based on the calibration calculation model, the normal magnetic induction intensity variation value can be converted into local longitudinal strain, the efficiency is high, and the misjudgment rate is low; the axial strain value of the monitoring pipe section can be directly calculated by a magnetic signal calibration and axial total strain regression analysis method, so that the mechanical safety state of the mountain pipeline can be accurately identified; whether the monitored pipe section is elastically bent and deformed can be judged through the characteristics of the multi-channel magnetic signals; the safety pipe ring is arranged close to the surface of the pipeline, so that the problem that a weak magnetic signal acquired remotely is covered by a strong background signal can be solved, and reliable pipeline magnetic field data can be acquired.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a mountain pipeline strain monitoring safety pipe ring according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of a magnetic force test probe for a mountain pipeline strain monitoring safety pipe ring according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the process of determining the calibration factor of the magnetometric test probe according to the present invention;

FIG. 4 is a schematic structural diagram of an embodiment of a supporting device for the mountain pipeline strain monitoring method of the present invention;

FIG. 5 is a schematic diagram of one embodiment of magnetometric test probe signals characterized by following similar trend states;

FIG. 6 is a schematic diagram of one embodiment of a magnetometric test probe characterized by a disengaged state of signal signature;

FIG. 7 is a diagram illustrating a variation curve of normal magnetic induction variation according to an embodiment;

FIG. 8 is a graph illustrating an actual strain curve of one embodiment.

Reference numbers in the figures:

1-a magnetic force test probe, 101-a single-axis fluxgate sensor, 102-a shell, 2-a protective shell, 201-an upper half ring, 202-a lower half ring, 203-a protective shell outer layer, 204-a protective shell inner layer, 3-a data transmission line, 4-a data transmission interface, 5-a support lug, 6-a bolt and 7-a rubber gasket;

11-monitoring pipeline, 12-flat plate test piece, 13-data collector, 14-soil, 15-industrial router, 16-solar panel, 17-fan, 18-storage battery, 19-power supply controller and 20-inverter.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

It should be noted that, in the present application, the embodiments and the technical features of the embodiments may be combined with each other without conflict.

It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

In the present invention, the terms "first", "second", and the like are used for distinguishing similar objects, but not for describing a particular order or sequence order, unless otherwise specified. It is to be understood that the terms so used; the terms "upper", "lower", "left", "right", and the like are used generally with respect to the orientation shown in the drawings, or with respect to the component itself in a vertical, or gravitational orientation; likewise, "inner", "outer", and the like refer to the inner and outer relative to the contours of the components themselves for ease of understanding and description. The above directional terms are not intended to limit the present invention.

As shown in fig. 1-2, the invention provides a mountainous area pipeline strain monitoring safety pipe loop, which comprises a magnetic force test probe 1 and a protective shell 2 for protecting the magnetic force test probe 1, wherein 4n magnetic force test probes 1 are arranged, n is a natural number greater than or equal to 1, an included angle between adjacent probes is 180 degrees/2 n, the adjacent probes are connected in parallel through a data transmission line 3 and are connected out through a data transmission interface 4, the outer layer of the protective shell 2 is made of nonmagnetic hard alloy, and the inner layer of the protective shell 2 is made of nonmetal materials

In a specific embodiment, the protective shell 2 includes an upper half ring 201 and a lower half ring 202 which are connected and symmetrical, the upper half ring 201 is composed of an outer protective shell layer 203 and an inner protective shell layer 204, the outer protective shell layer 203 is made of nonmagnetic hard alloy, the inner protective shell layer 204 is made of non-metallic material, and 2n magnetic force test probes 1 are arranged between the outer protective shell layer 203 and the inner protective shell layer 204.

Optionally, the upper half ring 201 and the lower half ring 202 are integrally formed. The safety pipe ring arranged in this way can be directly sleeved on the monitoring pipeline when the monitoring pipeline is not buried in the ground.

Optionally, the left ends of the upper half ring 201 and the lower half ring 202 are hinged, the right end is provided with a support lug 5, and the support lug 5 of the upper half ring 201 is connected with the support lug 5 of the lower half ring 202 through a bolt 6; or the left end and the right end of the upper half ring 201 and the lower half ring 202 are both provided with a support lug 5, and the support lug 5 at the left end of the upper half ring 201 is connected with the support lug 5 at the left end of the lower half ring 202 through a bolt 6, and the support lug 5 at the right end of the upper half ring 201 is connected with the support lug 5 at the right end of the lower half ring 202 through a bolt 6. The safety pipe ring can be applied to pipelines to be buried or buried in the ground, the sensors, the data cables, the protection accessories and the like do not need to be welded and assembled on site, and the field installation period can be shortened. It should be noted that, besides the structure adopted in the embodiment for facilitating the installation of the safety pipe ring on the monitoring pipeline, other structures facilitating the installation in the prior art may also be applied to the safety pipe ring of the present invention.

In order to prevent excessive turning of the nut of the bolt, the protective casing is damaged by pressure, optionally a rubber gasket 7 is provided between the upper half ring 201 and the lower half ring 202.

In a specific embodiment, the magnetic force testing probe 1 comprises a single-axis fluxgate sensor 101 and a housing 102 for protecting the single-axis fluxgate sensor 101, one or two of the single-axis fluxgate sensors 101 are provided, and the housing 102 is made of a non-metallic material. Optionally, the single-axis fluxgate sensor 101 employs a single-axis low-field fluxgate sensor capable of testing magnetic induction at uT level or nT level. It should be noted that, the single-axis fluxgate sensor and other magnetic force test probes, such as a three-axis fluxgate sensor, may be adopted in the present invention, but only the normal magnetic induction intensity needs to be tested during the monitoring process, so that the single-axis fluxgate sensor is selected to meet the requirement, and the cost can be saved. In addition, when the single-axis fluxgate sensor 101 is provided with two sensors, one sensor is used after another, which is more suitable for the field engineering practice.

In a specific embodiment, the non-metallic material used for the inner layer 204 of the protective shell and the outer shell 102 is the same, and optionally, the non-metallic material is a carbon fiber material. In another specific embodiment, the non-metallic material used for the inner layer 204 of the protective shell is different from the non-metallic material used for the outer shell 102, the inner layer 204 of the protective shell is made of carbon fiber, and the outer shell 102 is made of rubber. It should be noted that the inner layer 204 of the protective casing and the housing 102 of the magnetic force test probe 1 according to the present invention are not limited to the above two non-metal materials, as long as they are made of non-metal materials. However, the service life of the selected carbon fiber material is longer than that of non-metal materials such as plastics or ceramics.

On the other hand, the invention also provides a mountainous area pipeline strain monitoring method, which comprises the following steps:

s1: determining a calibration factor for each magnetometric test probe, the calibration factor being determined by the sub-steps of:

s11: selecting a material with the same material as that of the monitoring pipeline 11 to manufacture a flat plate test piece 12, and then clamping the flat plate test piece 12 on a clamp of a tensile testing machine;

s12: as shown in fig. 3, the magnetic force test probe 1 is fixedly installed right above the measurement line of the flat plate test piece 12, and the magnetic field test direction of the magnetic force test probe 1 is consistent with the loading direction of the flat plate test piece 12;

s13: starting the tensile testing machine, stretching the flat plate test piece 12, testing the normal magnetic induction intensity value of the surface of the flat plate test piece 12 in the cyclic loading process within the elastic deformation range, and processing to obtain a change curve of the normal magnetic induction intensity change value;

s14: after the test is finished, the actual strain curve of the flat plate test piece 12 in the cyclic loading process is derived from an upper computer matched with the tensile testing machine;

s15: and comparing and calibrating the change curve of the normal magnetic induction intensity change value with the actual strain curve, thereby determining the value of the calibration factor.

During the whole loading process, the magnetic force test probe 1 is in the ferromagnetic component environment, and the test value of the magnetic force test probe 1 comprises the magnetic signal P of the test piece_iMagnetic signal F caused by the loading_iAnd a background magnetic signal E_i. In the method for determining the calibration factor, in the loading process, the magnetic measurement position of the flat plate test piece 12 is close to the clamp part, and the size change range of the test piece is smaller, so that the magnetic signal P of the test piece per se_iWith background magnetic signal E_iAlmost invariable, the magnetic signal variation value is delta B ═ F_i+1-F_i. Therefore, the magnetic signal P of the test piece is eliminated without carrying out noise reduction treatment on the experimental test signal_iWith background magnetic signal E_iImpact on the analysis of the results.

S2: the magnetic force test probe 1 is assembled into the mountain pipeline strain monitoring safety pipe ring according to any one of the embodiments.

S3: the safety pipe ring is installed on a monitoring pipeline 11, and a matching device of the safety pipe ring is installed, wherein the matching device comprises a data collector 13, and the number of communication channels of the data collector 13 is the same as that of the magnetic force test probes 1 in the safety pipe ring.

In a specific embodiment, as shown in fig. 4, the monitoring pipeline 11 is buried in the soil 14, and the supporting device further includes an industrial router 15, a solar panel 16, a fan 17, a storage battery 18, a power supply controller 19, an inverter 20, a data cable, a power supply cable, and the like. The data collector 13, the industrial router 15 and the data cable are mainly used for real-time collection and remote transmission of monitoring data. The solar panel 16, the fan 17, the storage battery 18, the power supply controller 19, the inverter 20 and the power supply cable are mainly used for long-term stable power supply of the whole monitoring system. After the installation is completed, the online monitoring software logs in the cloud platform to check whether the pipeline state data can be normally received, then the safety pipe ring real-time testing pipeline surface is provided with the normal magnetic induction intensity value of the magnetic testing probe 1, the monitoring data is transmitted to the cloud platform through the data acquisition unit 13 and the industrial router 15, and the online monitoring software logs in the cloud platform to check.

S4: according to the calibration factor, converting the change value of the normal induction intensity of the surface of the monitoring pipeline acquired by the data acquisition unit into a local longitudinal strain value of a monitoring part by using a formula (1):

Eε_L＝f_y·ΔB_y (1)

in the formula: e is the elastic modulus of the monitored pipeline material, MPa; epsilon_LIs the local longitudinal strain value, μ ε; f. of_yIs a calibration factor, dimensionless; delta B_yThe value of the change in normal induction, nT.

S5: calculating the integral axial strain value of the pipeline section according to the local longitudinal strain value, wherein the calculation method of the integral axial strain value comprises the following steps:

in the formula: epsilon_aIs the integral axial strain value, mu epsilon; 4n is the total number of the magnetic force test probes in the safety pipe ring, and is dimensionless; epsilon_LiThe local longitudinal strain value, mu epsilon, of the ith magnetic test probe; gamma is the poisson coefficient and has no dimension; epsilon_hpIs the hoop strain, μ ε; p is the running pressure of the monitoring pipeline, MPa; d is the pipe diameter of the monitoring pipeline, and is mm; delta is the wall thickness of the monitoring pipeline, mm.

S6: determining an axial strain early warning threshold of a monitoring pipeline, wherein the axial strain early warning threshold is as follows:

in the formula: epsilon_TIs an axial strain early warning threshold value, mu epsilon; sigma_sMonitoring the yield strength of the pipeline material in MPa; eta is a safety factor and has no dimension. Optionally, the safety factor eta is 1.5-2.5.

S7: comparing the integral axial strain value with the axial strain early warning threshold value, determining monitoring measures by combining the signal characteristics of a magnetic force test probe, and formulating grading early warning indexes shown in table 1:

TABLE 1 grading early warning index

In one particular embodiment, the signal features follow similar trends as shown in FIG. 5, and the signal features separate as shown in FIG. 6. The method of distinguishing whether signal features are separated or follow similar trends is well known in the art and will not be described herein.

In a specific embodiment, taking a mountain pipeline of a certain place as an example, the mountain pipeline is made of X80 steel. The safety pipe ring installed on the mountain pipeline adopts the safety pipe ring in the embodiment comprising the upper half ring 201 and the lower half ring 202, the number of the magnetic force test probes 1 in the upper half ring 201 and the lower half ring 202 is 4, the total number of the magnetic force test probes is 8, and the included angle between the adjacent probes is 45 degrees.

Fig. 7 shows a variation curve of the normal magnetic induction variation value of a certain magnetic force test probe 1 obtained in step S13, and fig. 8 shows an actual strain curve of the magnetic force test probe 1 obtained in step S14; the two curves in fig. 7 and fig. 8 are calibrated by comparing to obtain the correction factor of the magnetometric test probe, and thus the correction factors of all the magnetometric test probes in step S1 are repeatedly obtained.

Then, the local longitudinal strain value of each magnetic force test probe monitoring part obtained by the formula (1), and the overall axial strain value obtained by the formulas (2) and (3) are shown in table 2:

TABLE 2 monitoring results of pipeline embodiments in certain mountainous areas

And finally, the axial strain early warning threshold value obtained by the formula (4) is 491 mu epsilon, the magnitude of the integral axial strain of each time interval in the table 2 is compared with the magnitude of the axial strain early warning threshold value, and corresponding monitoring measures are taken according to the grading early warning indexes shown in the table 1 by combining the signal characteristics of each magnetic force test probe.

The pipeline strain magnetic monitoring method based on the safety pipe ring can continuously monitor the safety state data of the pipeline in the mountainous area, and the measured normal magnetic induction intensity change value delta B can be calibrated by a magnetic signal calibration method_yQuantitative conversion to longitudinal strain value epsilon_LThe device is used for evaluating the mechanical safety state of the pipeline, and is high in efficiency and strong in reliability. Wherein, the pipeline strain magnetic monitoring method adopts a calibration calculation model and an axial total strain regression analysis method to directly obtain an axial strain value epsilon of the pipeline_aTherefore, the mechanical safety state of the pipeline can be accurately identified. In addition, through the characteristics of the multi-channel normal magnetic induction intensity signals, whether the monitoring pipe section is elastically bent and deformed can be directly judged, the failure risk of the circumferential weld of the pipeline can be found in time, and the safe operation of the pipeline can be effectively guaranteed. Furthermore, the safety pipe ring is directly arranged on the surface of the pipeline, and the magnetic field intensity of the pipeline collected in a short distance is far higher than that of a background magnetic field in general conditionsThe degree of interference of external noise signals is relatively small, so that the test data can more accurately reflect the health state of the pipeline. In specific implementation, the safety pipe ring can adopt an integrated design structure, so that a sensor, a data cable, a protection accessory and the like do not need to be welded and assembled on site, and the on-site installation period is shortened; meanwhile, the traditional strain sensor needs to be adhered to the surface of the metal pipeline, and the traditional strain sensor can be fixed on the pipeline by adopting bolts and nuts during integrated design, so that an anticorrosive layer does not need to be peeled off and the surface of the pipeline does not need to be treated, and the installation cost is saved.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.