A method and system for real-time monitoring of pipe wall thickness based on strain measurement

Abstract

The application discloses a kind of method and system for monitoring pipeline wall thickness in real time based on strain measurement, the initial circumferential strain and initial axial strain of the position of the pipeline to be measured are measured, the circumferential strain and axial strain caused by the internal pressure of pipeline are obtained, the relationship between the strain is obtained, and drift correction is carried out, the circumferential drift and axial drift in a cycle are solved, the circumferential strain and axial strain caused by the internal pressure of pipeline after correction are obtained, the dynamic pressure in pipeline is calculated, and the initial pulsating pressure maximum of pipeline is obtained;Real-time circumferential strain and real-time axial strain are obtained by real-time measurement, and drift correction is carried out, and the maximum value of the circumferential strain and axial strain caused by the internal pressure in each cycle after correction is obtained;According to the initial pulsating pressure maximum, the maximum value of the circumferential strain and axial strain caused by the internal pressure in each cycle after correction, the pipeline inner diameter is solved, the real-time wall thickness of the pipeline to be measured is obtained, and the wall thickness of the pipeline can be monitored in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressor monitoring, and more particularly to a method and system for real-time monitoring of pipeline wall thickness based on strain measurement. BACKGROUND

[0002] Pipeline wall thickness monitoring refers to the process of real-time or periodic detection and monitoring of the wall thickness of the pipeline in the pipeline system. The pipeline system is subjected to complex working conditions such as high pressure and high temperature during operation, and pipeline wall thickness monitoring is very important to ensure the safety and integrity of the pipeline. Strain measurement for monitoring pipeline wall thickness can improve the safety and reliability of monitoring, and will not interfere with the flow of fluid in the pipeline and affect the safe and stable operation of the pipeline. It can more safely and reliably monitor the pipeline wall thickness. Strain measurement is flexible and can achieve real-time monitoring of the same position and different positions of the pipeline, thereby monitoring the pipeline wall thickness with high precision and improving the accuracy of the monitoring data.

[0003] The existing pipe wall thickness calculation method obtains the theoretical calculation formula of the pipe wall thickness according to the strength condition of the three-way stress not exceeding the basic allowable stress of the pipe material, studies the stress distribution law of the pipeline, and has guiding significance for the selection of the wall thickness of the pipeline in the design stage. The existing monitoring wall thickness method is mainly based on the principle of ultrasonic pulse reflection, and this method has a certain convenience, but the measurement principle determines that it cannot be deployed on a large scale and for a long time in the position that needs to be monitored. The ultrasonic wall thickness measurement technology has certain requirements for the sound wave propagation speed and acoustic impedance of the material, and different materials have different effects on the propagation speed and attenuation coefficient of ultrasonic waves, so it is necessary to calibrate different materials. In addition, the ultrasonic wall thickness measurement technology has certain requirements for the surface state of the measured object, such as no coating, oxide skin, etc., otherwise it will affect the measurement accuracy.

[0004] Although the above method can obtain the theoretical calculation formula of the pipe wall thickness, it is only applicable to the design level of the pipe wall thickness, and in some extreme cases, once the wall thickness is rapidly thinned, the risk cannot be predicted, and additional correction coefficients are needed to avoid pipeline failure, so the above method cannot monitor the pipe wall thickness in real time. SUMMARY

[0005] In view of the problems existing in the above field, the present application provides a method and system for real-time monitoring of pipeline wall thickness based on strain measurement, which can solve the technical problem that the pipe wall thickness cannot be monitored in real time.

[0006] To solve the above technical problems, the present application discloses a method for real-time monitoring of pipeline wall thickness based on strain measurement, comprising the following steps:

[0007] Measuring the inner radius and outer radius of the pipeline to be measured;

[0008] Measure the initial circumferential strain and initial axial strain at a certain location in the pipeline under test;

[0009] Based on the internal pressure of the pipe under test, the circumferential strain and axial strain caused by the internal pressure are obtained, and the relationship between the axial strain and circumferential strain caused by the internal pressure is obtained.

[0010] Based on the relationship between strain drift and axial strain and circumferential strain caused by internal pressure, drift correction is performed to obtain the circumferential drift and axial drift within one cycle; based on the circumferential drift and axial drift, the corrected circumferential strain and axial strain caused by the internal pressure of the pipeline are obtained.

[0011] Based on the circumferential and axial strains caused by the corrected initial cycle pressure, the dynamic pressure inside the pipeline is calculated, and the maximum value of the initial pulsating pressure of the pipeline is obtained. The real-time circumferential and axial strains are obtained through real-time measurement, and drift correction is performed to obtain the maximum value of the circumferential strain and axial strain caused by the pressure in each cycle after correction.

[0012] The inner diameter of the pipeline is determined based on the maximum value of the initial pulsating pressure of the pipeline, the maximum value of the circumferential strain caused by the pressure in each cycle after correction, and the maximum value of the axial strain.

[0013] The real-time wall thickness of the pipe under test is obtained by measuring the initial outer diameter of the pipe and calculating the inner diameter of the pipe.

[0014] Preferably, the measurement of the inner and outer radii of the pipeline under test includes measuring its inner radius (D) before the pipeline is installed and put into operation. i,0 and outer diameter D e,0 Obtain the inner radius R of the pipeline. i,0 and outer radius R e,0 .

[0015] Preferably, measuring the initial circumferential strain and initial axial strain at a certain location in the pipeline includes determining the initial circumferential strain gauge and the initial axial strain gauge at that location in the pipeline, and measuring the initial circumferential strain ε corresponding to the initial circumferential strain gauge and the initial axial strain gauge. c,0 and initial axial strain ε a,0 The initial circumferential strain gauge and the initial axial strain gauge were connected to a 1 / 4 bridge to measure the initial circumferential strain and the initial axial strain.

[0016] Preferably, determining the circumferential drift and axial drift within one period includes the following steps:

[0017] For the biaxial stress state caused by internal pressure, according to Hooke's law for isotropic materials, we get:

[0018]

[0019] wherein: v is the Poisson's ratio of the material; E is the elastic modulus of the material;

[0020] According to the pressure vessel theory:

[0021] The relationship between the axial strain and the circumferential strain caused by the internal pressure is obtained as:

[0022] According to the relationship between the strain drift and the strain caused by the internal pressure: ε c,0 = ε c,o + ε c,p , ε a,0 = ε a,o + ε a,p ,

[0023] Based on a period f / F of circumferential strain measurement values ε c and axial strain measurement values ε a , the least square method is used to obtain the circumferential drift ε c,o and the axial drift ε a,o in a period, and the f / F initial circumferential strain and axial strain ε c,p0 , ε a,p0 caused by the internal pressure of the pipeline are obtained:

[0024]

[0025] Preferably, the initial pulsating pressure maximum value of the pipeline is obtained as:

[0026]

[0027] The initial gas flow pulsating pressure maximum value p max is recorded.

[0028] Preferably, the maximum value of the circumferential strain and the axial strain caused by the internal pressure in each period after correction includes measuring the circumferential strain and the axial strain, obtaining real-time circumferential strain and axial strain, real-time correction according to the drift correction process, and recording the maximum value of the strain caused by the internal pressure in each period after correction ε c,pmax and ε a,pmax .

[0029] Preferably, the calculation formula for obtaining the inner diameter D i of the pipeline is:

[0030]

[0031] Preferably, the real-time wall thickness S of the pipeline to be measured is obtained as:

[0032]

[0033] Preferably, the system further comprises a system for monitoring the wall thickness of the pipeline in real time based on strain measurement, characterized in that it comprises:

[0034] a strain measurement module for measuring the inner radius and the outer radius of the pipeline to be measured, and measuring the initial circumferential strain and the initial axial strain of the pipeline at a certain position;

[0035] a bridge module for obtaining the circumferential strain and the axial strain caused by the internal pressure of the pipeline according to the internal pressure of the pipeline to be measured, and obtaining the relationship between the axial strain and the circumferential strain caused by the internal pressure;

[0036] a power supply module for electrically connecting the strain measurement module, the bridge module, the signal acquisition module and the digital signal processing module, and providing power supply;

[0037] a signal acquisition module for drift correction according to the strain drift provided by the bridge module and the relationship between the axial strain and the circumferential strain caused by the internal pressure, and obtaining the circumferential drift and the axial drift in a cycle; and obtaining the corrected circumferential strain and the axial strain caused by the internal pressure of the pipeline according to the circumferential drift and the axial drift;

[0038] a digital signal processing module for calculating the dynamic pressure in the pipeline according to the corrected circumferential strain and the axial strain caused by the internal pressure in the initial cycle obtained by the signal acquisition module, and obtaining the maximum value of the initial pulsating pressure of the pipeline; obtaining the real-time circumferential strain and the real-time axial strain by real-time measurement, and performing drift correction to obtain the maximum value of the circumferential strain and the maximum value of the axial strain caused by the internal pressure in each cycle after correction; and obtaining the inner diameter of the pipeline according to the obtained maximum value of the initial pulsating pressure of the pipeline, the maximum value of the circumferential strain and the maximum value of the axial strain caused by the internal pressure in each cycle after correction; and obtaining the real-time wall thickness of the pipeline to be measured according to the measured initial outer diameter of the pipeline and the obtained inner diameter of the pipeline.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The present application can obtain the maximum value of the pulsating pressure of the pipeline after strain measurement and correction, and the maximum value of the circumferential strain and the axial strain caused by the internal pressure in each cycle, further monitor the real-time strain reconstruction of the wall thickness of the pipeline, and monitor the wall thickness of the pipeline in real time. The strain measurement can improve the safety and reliability of the monitoring, and will not interfere with the flow of the fluid in the pipeline, will not affect the safe and stable operation of the pipeline, and can more safely and reliably monitor the wall thickness of the pipeline. The strain measurement can monitor the wall thickness of the pipeline with high precision, and improve the accuracy of the monitoring data. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The present application is a whole method flowchart;

[0042] Figure 2 This is an image acquisition result diagram of the present invention;

[0043] Figure 3 This is an experimental diagram of the strain measurement and monitoring pipeline wall of the present invention;

[0044] Figure 4 This is an analysis diagram of the initial strain correction values ​​of the present invention;

[0045] Figure 5 This is the initial airflow pulsation analysis diagram of the present invention;

[0046] Figure 6 This is an analysis graph of the real-time strain measurement values ​​of the present invention. Detailed Implementation

[0047] The following will refer to the appendices in the embodiments of the present invention. Figures 1-6 The technical solutions in the embodiments of the present invention will be clearly and completely described. It should be understood that the terminology used in the present invention is only for describing particular implementation methods and is not intended to limit the present invention.

[0048] Many industrial pressure vessels and pipelines experience a gradual reduction in wall thickness due to long-term corrosion. Thinning or damage to pipeline walls can lead to safety accidents such as leaks and explosions, causing personal injury, environmental risks, and economic losses. Monitoring pipeline wall thickness allows for the timely detection of corrosion, wear, and corrosion fatigue, enabling necessary repairs or replacements to ensure the safe operation of the pipeline system.

[0049] Monitoring pipe wall thickness allows for structural reliability assessments and lifespan predictions, enabling timely maintenance planning, reducing system failures and downtime, and improving production efficiency and operational reliability. Pipeline system maintenance and repair costs are typically high. Pipeline wall thickness monitoring allows for early detection of problems, facilitating appropriate repair and maintenance measures to extend pipeline life and reduce maintenance costs.

[0050] Furthermore, monitoring data can be used to optimize pipeline design and operation strategies, improve energy efficiency, and reduce operating costs. Pipeline wall thickness monitoring is of great significance in ensuring the safety, reliability, and economy of pipeline systems, and is crucial for pipeline operation and maintenance across various industries.

[0051] Example

[0052] like Figure 1 As shown in the figure, this invention provides a method for real-time monitoring of pipeline wall thickness based on strain measurement. The method includes the following steps:

[0053] S1: Before pipeline installation and operation, measure the inner diameter D of the pipeline to be measured according to the manufacturer's specified dimensions or using professional measuring tools.i,0 and outer diameter D e,0 , according to the inner and outer diameters, the inner radius R i,0 and outer radius R e,0 .

[0054] S2: At a certain position of the pipeline, circumferential strain gauges and axial strain gauges are attached, and the strain gauges are connected with the bridge and then connected to the data collector. After the measured pipeline is operated, the initial periodic circumferential strain ε c,0 and axial strain ε a,0 of the circumferential strain gauges and axial strain gauges are measured first.

[0055] S3: The initial circumferential strain ε c,p0 and axial strain ε a,p0 obtained by the data collector are drift-corrected, and then the initial circumferential strain ε c,p0 and axial strain ε a,p0 caused by the internal pressure of the pipeline are obtained.

[0056] For the biaxial stress state caused by the internal pressure, according to the Hook's law of isotropic material, it is obtained that:

[0057]

[0058] In the formula: ν is the Poisson's ratio of the material; E is the elastic modulus of the material;

[0059] According to the pressure vessel theory:

[0060] The relationship between the axial strain and the circumferential strain caused by the internal pressure is obtained as:

[0061] According to the relationship between the strain drift and the strain caused by the internal pressure: ε c,0 = ε c,o + ε c,p , ε a,0 = ε a,o + ε a,p ,

[0062] Based on a periodic f / F circumferential strain measurement value ε c and axial strain measurement value ε a , the least square method is used to obtain the circumferential drift ε c,o and axial drift ε a,o in a period, and the f / F initial circumferential strain and axial strain ε c,p0 , ε a,p0 caused by the internal pressure of the pipeline are obtained.

[0063]

[0064] S4: Calculate the dynamic pressure in the pipe according to the circumferential strain and axial strain caused by the initial cycle pressure, the Hooke's law of isotropic material in S3 and the calculation formula derived from the pressure vessel theory:

[0065]

[0066] And record the maximum value of the initial gas flow pulsation pressure p max .

[0067] S5: Measure the circumferential strain and axial strain, and obtain the real-time circumferential strain and axial strain. According to the correction process in S3, correct in real time, and record the maximum value of the strain caused by the internal pressure ε c,pmax and ε a,pmax .

[0068] S6: According to the maximum value of the initial gas flow pulsation pressure p max obtained in S4, the maximum value of the strain caused by the internal pressure ε c,pmax and ε a,pmax obtained in S5, and the dynamic pressure calculation formula of the pipe in S4, calculate in real time to obtain the inner diameter D i of the pipe:

[0069]

[0070] According to the measured outer diameter D e,0 and the obtained inner diameter D i of the pipe, obtain the real-time wall thickness S of the pipe to be measured:

[0071]

[0072] As shown in Figures 3-6 , it is the experimental verification analysis result of the present application. The exhaust pipe of the diaphragm compressor is taken as an example for verification.

[0073] As shown in Figure 3 , the initial inner diameter of the pipe is 3.175mm, and the outer diameter is 9.575mm. According to the correction process in S3, the initial circumferential strain and axial strain values measured by the strain gauge are corrected, and the dynamic pressure is calculated, as shown in Figure 4 , to obtain the maximum value of the initial gas flow pulsation pressure of 118.58Mpa, as shown in Figure 5 . The real-time measurement of the circumferential strain and axial strain of the pipe and the real-time correction obtain the maximum value of the circumferential strain caused by the internal pressure of 128.79×10 -6 , and the maximum value of the axial strain of 34.24×10 -6 , as shown in Figure 6 , the inner diameter of the pipe obtained by calculation is 3.177mm, and the wall thickness is 3.199mm.

[0074] The application also provides a system for monitoring the wall thickness of a pipeline in real time based on strain measurement, comprising:

[0075] a strain measurement module for measuring the inner radius and outer radius of the pipeline to be measured and measuring the initial circumferential strain and initial axial strain of the pipeline at a certain position;

[0076] a bridge module for obtaining the circumferential strain and axial strain caused by the internal pressure of the pipeline according to the internal pressure of the pipeline to be measured, and obtaining the relationship between the axial strain and the circumferential strain caused by the internal pressure;

[0077] a power supply module for electrically connecting the strain measurement module, the bridge module, the signal acquisition module and the digital signal processing module and providing power supply;

[0078] a signal acquisition module for performing drift correction according to the strain drift provided by the bridge module and the relationship between the axial strain and the circumferential strain caused by the internal pressure, and calculating the circumferential drift and the axial drift in a cycle; and obtaining the circumferential strain and the axial strain caused by the internal pressure of the pipeline after correction according to the circumferential drift and the axial drift;

[0079] a digital signal processing module for calculating the dynamic pressure in the pipeline according to the circumferential strain and the axial strain caused by the internal pressure in the initial cycle after correction obtained by the signal acquisition module, and obtaining the maximum value of the initial pulsating pressure of the pipeline; obtaining the real-time circumferential strain and the real-time axial strain by real-time measurement, performing drift correction, and obtaining the maximum value of the circumferential strain and the maximum value of the axial strain caused by the internal pressure in each cycle after correction; and calculating the inner diameter of the pipeline according to the maximum value of the initial pulsating pressure of the pipeline, the maximum value of the circumferential strain and the maximum value of the axial strain caused by the internal pressure in each cycle after correction; and obtaining the real-time wall thickness of the pipeline to be measured according to the measured initial outer diameter of the pipeline and the calculated inner diameter of the pipeline.

[0080] The application can be used for real-time monitoring of the wall thickness of the pipeline, online diagnosis, timely alarm when the wall thickness is reduced to below the allowable value, and prevention of major safety accidents. The strain measurement for monitoring the wall thickness of the pipeline can improve the safety and reliability of the monitoring, does not interfere with the fluid flow in the pipeline, does not affect the safe and stable operation of the pipeline, and can more safely and reliably monitor the wall thickness of the pipeline. The strain measurement can monitor the wall thickness of the pipeline with high precision, and improve the accuracy of the monitoring data.

[0081] The strain gauge is low in price, and the strain measurement for monitoring the wall thickness of the pipeline does not need to replace or maintain the sensor regularly, so that the monitoring cost and maintenance cost can be reduced. The application has the advantages of safety, high precision and low cost.

[0082] The above describes only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art, according to the technical solution and the inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

[0083] In addition, 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. All references mentioned in this specification are incorporated by reference to disclose and describe the methods associated with the described documents. In the event of a conflict between any incorporated document and the content of this specification, the content of this specification controls.

Claims

1. A method for real-time monitoring of pipeline wall thickness based on strain measurement, characterized in that, Includes the following steps: Measure the inner and outer radii of the pipeline to be tested; Measure the initial circumferential strain and initial axial strain at a certain location in the pipeline under test; Based on the internal pressure of the pipe under test, the circumferential strain and axial strain caused by the internal pressure are obtained, and the relationship between the axial strain and circumferential strain caused by the internal pressure is obtained. Based on the relationship between strain drift and axial strain and circumferential strain caused by internal pressure, drift correction is performed to obtain the circumferential drift and axial drift within one cycle; based on the circumferential drift and axial drift, the corrected circumferential strain and axial strain caused by the internal pressure of the pipeline are obtained. Based on the circumferential and axial strains caused by the corrected periodic pressure, the dynamic pressure inside the pipeline is calculated, and the maximum value of the initial pulsating pressure of the pipeline is obtained. Real-time circumferential and axial strains are obtained through real-time measurements. Real-time corrections are performed based on the drift correction process of circumferential and axial drift within one cycle, and the maximum value of pressure-induced strain in each cycle after correction is recorded. and ; The inner diameter of the pipeline is determined based on the maximum value of the initial pulsating pressure of the pipeline, the maximum value of the circumferential strain caused by the pressure in each cycle after correction, and the maximum value of the axial strain. The real-time wall thickness of the pipe under test is obtained by measuring the initial outer diameter of the pipe and calculating the inner diameter of the pipe. The process of determining the circumferential drift and axial drift within a period includes the following steps: For the biaxial stress state caused by internal pressure, according to Hooke's law for isotropic materials, we get: ； In the formula: E is the material's Poisson's ratio; E is the material's elastic modulus. and These are the inner and outer radii of the pipeline, respectively. According to pressure vessel theory: ; The relationship between the axial strain and the circumferential strain caused by internal pressure is as follows: ; Based on the relationship between strain drift and strain caused by internal pressure: , , ; Based on a one-cycle circumferential strain measurement value and axial strain measurement values The circumferential drift within one period is obtained using the least squares method. With axial drift To obtain the pressure caused by the pipeline Initial circumferential strain and axial strain , : ； The initial pulsating pressure of the pipeline is obtained as follows: ； Record the maximum value of the initial pulsating pressure in the pipeline. ; The determination of the pipe inner diameter The calculation formula is: ； The real-time wall thickness S of the pipe under test is obtained as follows: 。 2. The method for real-time monitoring of pipeline wall thickness based on strain measurement according to claim 1, characterized in that, The measurement of the inner and outer radii of the pipeline under test includes measuring its inner diameter before installation and operation. and outer diameter To obtain the inner radius of the pipeline. and outer radius .

3. The method for real-time monitoring of pipeline wall thickness based on strain measurement according to claim 1, characterized in that, The measurement of the initial circumferential strain and initial axial strain at a certain location in the pipeline under test includes determining the initial circumferential strain gauge and the initial axial strain gauge at that location in the pipeline, and measuring the initial circumferential strain corresponding to the initial circumferential strain gauge and the initial axial strain gauge. and initial axial strain The initial circumferential strain gauge and the initial axial strain gauge were connected to a 1 / 4 bridge to measure the initial circumferential strain and the initial axial strain.

4. A system for real-time monitoring of pipeline wall thickness based on strain measurement, characterized in that, include: The strain measurement module is used to measure the inner and outer radii of the pipeline under test, as well as the initial circumferential strain and initial axial strain at a certain location in the pipeline. The bridge module is used to obtain the circumferential strain and axial strain caused by the internal pressure of the pipe under test, and to obtain the relationship between the axial strain and the circumferential strain caused by the internal pressure. The power supply module is used to electrically connect the strain measurement module, the bridge module, the signal acquisition module, and the digital signal processing module, and provide power. The signal acquisition module is used to perform drift correction based on the relationship between strain drift and axial strain and circumferential strain caused by internal pressure provided by the bridge module, and to obtain the circumferential drift and axial drift within one cycle; based on the circumferential drift and axial drift, the corrected circumferential strain and axial strain caused by the internal pressure of the pipeline are obtained. The digital signal processing module is used to calculate the dynamic pressure inside the pipeline and obtain the maximum value of the initial pulsating pressure of the pipeline based on the circumferential strain and axial strain caused by the corrected initial periodic pressure obtained by the signal acquisition module. Real-time circumferential and axial strains are obtained through real-time measurements. Real-time corrections are performed based on the drift correction process of circumferential and axial drift within one cycle, and the maximum value of pressure-induced strain in each cycle after correction is recorded. and Based on the obtained maximum initial pulsating pressure of the pipeline, the maximum circumferential strain caused by the pressure in each cycle after correction, and the maximum axial strain, the inner diameter of the pipeline is determined; based on the measured initial outer diameter of the pipeline and the determined inner diameter, the real-time wall thickness of the pipeline to be measured is obtained. The process of determining the circumferential drift and axial drift within a period includes the following steps: For the biaxial stress state caused by internal pressure, according to Hooke's law for isotropic materials, we get: ； In the formula: E is the material's Poisson's ratio; E is the material's elastic modulus. and These are the inner and outer radii of the pipeline, respectively. According to pressure vessel theory: ; The relationship between the axial strain and the circumferential strain caused by internal pressure is as follows: ; Based on the relationship between strain drift and strain caused by internal pressure: , , ; Based on a one-cycle circumferential strain measurement value and axial strain measurement values The circumferential drift within one period is obtained using the least squares method. With axial drift To obtain the pressure caused by the pipeline Initial circumferential strain and axial strain , : ； The initial pulsating pressure of the pipeline is obtained as follows: ； Record the maximum value of the initial pulsating pressure in the pipeline. ; The determination of the pipe inner diameter The calculation formula is: ； The real-time wall thickness S of the pipe under test is obtained as follows: 。

Images