Buried pipeline corrosion fatigue coupling test device and method

Abstract

The invention relates to the technical field of corrosion tests, and particularly provides a corrosion fatigue coupling test device and a corrosion fatigue coupling test method for a buried pipeline. Corrosion and fatigue coupling effects suffered by the buried pipeline are simulated through the circulating pressurizing system, the fatigue loading system and the corrosion environment adjusting system, and related data of the pipeline and soil in the corrosion process are recorded through the data collecting and monitoring system. According to the invention, the test process is closer to the real service environment of the buried water supply pipeline, the temperature, humidity, pH and other parameters in the test box can be kept relatively stable, and the influence of dead load of buildings, vehicles, vibration and other live loads in the pipeline operation process is fully considered, so that the test result is more reliable and accurate, and the test efficiency is improved. Meanwhile, all the systems are controlled in a centralized mode through the controller, so that the experiment period is relatively short, the automation degree is high, operation is easy and convenient, functions are comprehensive, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion testing, and in particular to a buried pipeline corrosion fatigue coupling test device and method. Background Art

[0002] The water supply network is an important lifeline of the city and an important infrastructure to ensure the normal operation of the city. With the increase in service time, pipeline aging, complex service environment (such as corrosive soil) and increased demand (such as urbanization), pipe bursts and leakage accidents occur frequently, seriously threatening water supply safety and public safety. Due to the increase in internal pressure of the pipeline caused by corrosion and increasing water supply demand, as well as the long-term reciprocating dynamic load on the ground, the safe operation of the pipeline is seriously affected. The corrosion research of buried pipelines is one of the basic theoretical research directions of pipeline corrosion failure, and it has been in the exploration and experimental stage so far.

[0003] In order to effectively improve the service reliability and service life of buried pipelines, it is urgent to explore the service performance degradation mechanism of pipelines under the action of multiple factors. At present, scholars have carried out a lot of work on pipeline corrosion and fatigue respectively. Some scholars consider the coupling effect of pipeline corrosion and fatigue by the test method of corrosion first and fatigue later, but fail to consider the coupling effect of corrosion and fatigue on pipelines at the same time, which is inconsistent with the actual service environment of buried pipelines. Therefore, it is very necessary to design a buried pipeline corrosion fatigue coupling test device. Summary of the invention

[0004] In view of this, the present invention proposes a buried pipeline corrosion fatigue coupling test device and method to solve the problems existing in the above-mentioned prior art.

[0005] On the one hand, to achieve the above-mentioned purpose, the present invention proposes a buried pipeline corrosion fatigue coupling test device, including a controller, a corrosion test chamber, a cyclic pressurization system, a fatigue loading system, a data acquisition monitoring system, and a corrosion environment adjustment system;

[0006] The corrosion test box is provided with buried pipelines and corrosive soil;

[0007] The circulating pressurizing system is provided with a circulating water inlet pipe, a water pressure tank, a circulating pump and water;

[0008] The fatigue loading system includes a loading plate, wheels and a drive;

[0009] The data acquisition monitoring system includes a computer, a data collector and a sensor component;

[0010] The corrosion environment regulating system comprises a humidity and pH regulating liquid water inlet pipe, an atomizing device, a plurality of jetting pipes and a regulating liquid tank.

[0011] Furthermore, the water in the water pressure tank enters the buried pipeline through the circulating water inlet pipe, and the controller controls the circulating pump to replenish water into the water pressure tank, thereby controlling the internal pressure of the water pressure tank and the buried pipeline.

[0012] Furthermore, the controller controls the drive to make the wheel perform fatigue loading on the loading plate, and transfer the fatigue to the buried pipeline through corroded soil.

[0013] Further, the sensor assembly includes a first temperature and humidity sensor, a second temperature and humidity sensor, a first pH sensor, a second pH sensor, a first water pressure gauge, and a second water pressure gauge;

[0014] The first temperature and humidity sensor, the second temperature and humidity sensor, the first pH sensor, and the second pH sensor are arranged inside the corrosion test box, and the first water pressure gauge and the second water pressure gauge are respectively arranged on the water inlet and outlet interfaces at both ends of the buried pipeline. The data measured by the sensor assembly is transmitted to the computer through the data acquisition device for analysis and processing.

[0015] Furthermore, the outer end of the humidity and pH regulating liquid inlet pipe is connected to the regulating liquid tank, and the inner end is arranged below the buried pipeline in the corrosion test box, and a plurality of the jet pipes are vertically arranged on the inner end of the humidity and pH regulating liquid inlet pipe, and each of the jet pipes is provided with an atomizing device at the connection between the humidity and pH regulating liquid inlet pipe;

[0016] The regulating liquid tank is provided with regulating liquid, and the regulating liquid enters the corrosion test box through the humidity and pH regulating liquid water inlet pipe, and is atomized by the atomizing device and then sprayed out from the jet pipe to adjust the humidity and pH value of the corrosive soil.

[0017] On the other hand, to achieve the above-mentioned purpose, the present invention proposes a buried pipeline corrosion fatigue coupling test method, comprising the following steps:

[0018] Step 1: Prepare corrosive soil;

[0019] Step 2: Pre-process the buried pipeline and record the initial state of the pipeline;

[0020] Step 3: installing the buried pipeline into a corrosion test box, controlling the circulating pressurization system to pass water through the buried pipeline, and when the water pressure is stable within the test pressure range, adding corrosive soil layer by layer into the corrosion test box and installing the sensor assembly;

[0021] Step 4: Set the corrosion time and conduct the corrosion fatigue coupling test;

[0022] Step 5: After the corrosion time is reached, the fatigue loading system and the cyclic pressurization system are turned off, the corroded soil, the sensor and the buried pipeline are taken out in turn, the mass loss of the buried pipeline is measured, and fracture toughness, axial pressure and annular pressure tests are carried out.

[0023] Furthermore, the step one includes: for the target research area, three samples are evenly selected from the original soil around the buried pipeline for X-ray fluorescence spectroscopy analysis to obtain soil composition; hydrochloric acid is diluted with deionized water and mixed with 10 kg of soil for small-scale trial mixing, and the dilution ratio and corresponding soil dosage are gradually determined so that the pH reaches the experimental design value.

[0024] Furthermore, the step 2 includes: polishing the outer wall of the buried pipeline, removing 1 mm of coating to expose a smooth metal surface, using a three-dimensional scanning device to obtain the initial state of the pipeline, and measuring the initial weight of the pipeline.

[0025] Furthermore, the step four includes: the controller adjusts the water pressure in the buried pipeline by controlling the circulating pressurization system, adjusts the humidity and pH of the corrosive soil by controlling the corrosion environment adjustment system, and controls the fatigue loading system to fatigue load the buried pipeline, and at the same time the data acquisition device transmits the data measured by the sensor component to the computer for analysis and processing.

[0026] Furthermore, the step 4 also includes:

[0027] The fatigue loading system establishes the time matching relationship of corrosion-fatigue coupling action according to the power function followed by the metal atmospheric exposure, predicts the test time and load value when the buried pipeline reaches a certain corrosion depth, and thus realizes the fatigue loading of the buried pipeline.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention makes the test process closer to the actual service environment of the buried water supply pipeline, and can maintain the temperature, humidity, pH and other parameters in the test box relatively stable, so that the test results are more reliable and accurate.

[0030] 2. The circulating pressurization system and corrosion environment adjustment system provided by the present invention can ensure that during the test, the pipeline pressure is consistent with the actual operating state of the pipeline, the pipeline corrosion environment is close to the actual situation, and the influence of the internal pressure of the pipeline on the pipeline damage is taken into account.

[0031] 3. The fatigue loading system provided by the present invention fully considers the influence of constant loads such as buildings and live loads such as vehicles and vibrations during pipeline operation, and couples them with pipeline corrosion to ensure that the experiment restores the actual stress state of the pipeline.

[0032] 4. The present invention mainly includes a corrosion test chamber, a cyclic pressurization system, a fatigue loading system, a data acquisition monitoring system, and a corrosion environment adjustment system, and all systems are centrally controlled by a controller. The method has a relatively short experimental cycle, a high degree of automation, simple operation, and comprehensive functions, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0034] Figure 1 It is a schematic diagram of the overall structure of a buried pipeline corrosion fatigue coupling test device in an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the structure of the circulating pressurization system in an embodiment of the present invention;

[0036] Figure 3 is a schematic diagram of the structure of a fatigue loading system in an embodiment of the present invention;

[0037] Figure 4 It is a schematic diagram of the test method of the present invention;

[0038] Figure numbers: 1. Computer; 2. Controller; 3. Data acquisition device; 4. Corrosion test chamber; 5. Corrosive soil; 6. Circulating pressurization system; 7. Buried pipeline; 8. Pipeline support; 9. Fatigue loading system; 10. Circulating water inlet pipe; 11. Water inlet interface; 12. Water outlet interface; 13. Circulating return pipe; 14. Humidity and pH regulating liquid inlet pipe; 15. Atomizing device; 16. Jet pipe; 17. First temperature and humidity sensor; 18. Second temperature and humidity sensor; 19. First pH sensor; 20. Second pH sensor; 21. First water pressure gauge; 22. Second water pressure gauge; 23. Circulating pump; 24. Water pressure tank; 25. Third water pressure gauge; 26. Water supply port; 27. Water; 28. Regulating liquid tank; 29 Drain port; 30. Regulating liquid discharge port; 31. Loading plate; 32. Wheel; 33. Drive. DETAILED DESCRIPTION

[0039] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] This embodiment proposes a method and device for coupling corrosion fatigue testing of buried pipelines. The device includes a controller 2, a corrosion test chamber 4, a cyclic pressurization system 6, a fatigue loading system 9, a data acquisition monitoring system, and a corrosion environment adjustment system. The cyclic pressurization system provides internal pressure to the buried pipeline to simulate the internal pressure of the pipeline in daily operation. The fatigue loading system is used to simulate the effects of constant loads such as buildings, and live loads such as vehicles and vibrations on the buried pipeline. The data acquisition monitoring system and the corrosion environment adjustment system ensure the stability of the corrosion environment.

[0041] The corrosion test box 4 is composed of a buried pipeline 7 , a pipeline support 8 and corrosive soil 5 .

[0042] The circulating pressurizing system 6 is composed of a circulating pump 23, a water pressure tank 24, a third water pressure gauge 25, a water supply port 26, water 27, a regulating liquid tank 28, a drain port 29, a regulating liquid drain port 30, a circulating water inlet pipe 10, a buried pipeline 7, and a circulating water return pipe 13. The circulating water inlet pipe 10, the buried pipeline 7, and the circulating water return pipe 13 are in the corrosion test box 4. Under the action of the controller 2, water 27 is continuously replenished into the water pressure tank 24 through the circulating pump 23 to ensure the pressure inside the water pressure tank 24 and the buried pipeline 7.

[0043] The fatigue loading system 9 is composed of a loading plate 31, wheels 32, a drive 33, etc. The loading plate 31 is used to simulate a constant load such as a ground building. The controller 2 controls the drive 33 to make the wheels 32 perform fatigue loading on the loading plate 31 at a certain frequency, and then the loading plate 31 is transmitted to the buried pipeline 7 through the corrosive soil.

[0044] The data acquisition monitoring system is composed of a computer 1, a data collector 3, a first water pressure gauge 21, a second water pressure gauge 22, a first temperature and humidity sensor 17, a second temperature and humidity sensor 18, a first pH sensor 19, and a second pH sensor 20. The first water pressure gauge 21 and the second water pressure gauge 22 are respectively arranged on the water inlet interface 11 and the water outlet interface 12 at both ends of the buried pipeline 7, the first temperature and humidity sensor 17, the second temperature and humidity sensor 18, the first pH sensor 19, and the second pH sensor 20 are located inside the corrosion test box 4, and the measured data is transmitted to the computer 1 through the data collector 3 for analysis and processing.

[0045] The corrosion environment regulating system is composed of a regulating liquid tank 28, a regulating liquid outlet 30, a humidity and pH regulating liquid water inlet pipe 14, an atomizer device 15, and an air jet pipe 16. The humidity and pH regulating liquid water inlet pipe 14, the atomizer device 15, and the air jet pipe 16 are located in the corrosion test box 4. The regulating liquid is a solution of pH=1 mixed with hydrochloric acid and deionized water in a certain proportion or deionized water. The deionized water is used to regulate soil humidity. When the regulating liquid needs to be replaced, the current liquid is discharged through the regulating liquid outlet.

[0046] In view of the above device, this embodiment provides a buried pipeline corrosion fatigue coupling test method, comprising the following steps:

[0047] (1) Prepare corrosive soil. Take the original soil around the buried pipeline in a certain area, and evenly select three samples of about 10g from the original soil for X-ray fluorescence spectrum analysis to obtain the soil composition. After the original soil is naturally dried, it is crushed with a crusher and passed through an 8-mesh sieve for later use. Dilute it with hydrochloric acid and deionized water in a ratio of 1:10, 1:5, and 1:1. Use 10kg of soil for small-scale trial mixing to determine the dilution ratio and corresponding soil dosage so that the pH reaches the experimental design value.

[0048] (2) The outer wall of the buried pipeline 7 is polished by a lathe to remove about 1 mm of coating to expose a smooth metal surface. A three-dimensional scanning device is used to obtain the initial state and related parameters of the pipeline and measure the initial weight of the pipeline.

[0049] (3) Add corrosive soil 5 layer by layer in the corrosion test box 4 and compact it evenly. First, install the bottom humidity, pH adjustment liquid water inlet pipe 14, atomization device 15, jet pipe 16, and pipe bracket 8. Then install the buried pipe 7 on the pipe bracket 8, and ensure the buried pipe is level by adjusting the bracket. The buried pipe 7 is connected to the circulating pressurization system 6 through the water inlet interface 11. After the connection, water is passed through the pressure test. Observe that the water pressure gauge (21, 22, 25) can be stable within the test pressure range. After ensuring that the pipeline is leak-proof, add corrosive soil 5 layer by layer in the corrosion test box 4. After reaching the predetermined position, install various sensors, turn on the data collector 3, and continue to add corrosive soil 5 to the highest point after ensuring that data can be collected normally.

[0050] (4) After the internal structure of the corrosion test chamber is installed and debugged, set the corrosion time and conduct the corrosion fatigue coupling test;

[0051] During the test, the controller 2 adjusts the water pressure in the buried pipeline 7 by controlling the circulating pressurization system 6, adjusts the humidity and pH of the corrosive soil 5 by controlling the corrosion environment adjustment system, and controls the fatigue loading system 9 to perform fatigue loading on the buried pipeline 7. At the same time, the data acquisition device 3 transmits the data measured by the sensor assembly to the computer 1 for analysis and processing to simulate the corrosion process of the buried pipeline;

[0052] When the sensor assembly detects that the humidity and pH value of the corrosive soil exceed the preset value by 10%, the corrosive environment adjustment system is promptly turned on and controlled by the controller 2 to stabilize the relevant parameters of the corrosive soil.

[0053] (5) When the value of the third pressure gauge 25 on the water pressure tank 24 in the circulating pressurization system 6 is lower than the set value, water needs to be added, and the first pressure gauge 21 and the second pressure gauge 22 at the connection of the buried pipeline 7 are observed to determine whether there is a water leak. If there is, the water inlet interface 11 and the water outlet interface 12 need to be tightened in time. When adjusting the humidity and pH value, ensure that there is corresponding liquid in the regulating liquid tank 28.

[0054] (6) If necessary, the data acquisition monitoring system can be supplemented with corrosion current monitoring function by adding electrodes using the linear polarization resistance method (LPR).

[0055] (7) Fatigue loading system 9 needs to establish a time matching relationship for the corrosion-fatigue coupling process, based on the power function D = At ​​followed by the existing metal atmospheric exposure n , where D is the corrosion depth (mm), t is the exposure time (years), and A and n are constants. Within the set corrosion time, the actual load conversion of the buried pipeline that is expected to reach the corrosion depth matching time is selected, and the loading plate 31 and the wheel 32 are selected to simulate their fatigue through the drive 33.

[0056] (8) After the predetermined corrosion time is reached, the fatigue loading system 9 and the circulating pressurization system 6 are turned off, the drain port 29 and the regulating liquid outlet 30 are opened and recovered, the corrosive soil 5 and the sensors in the corrosion test box 4 are taken out in turn, the pipe support 8 is opened to take out the pipe, the mass loss of the pipe is measured, and the fracture toughness, axial pressure and annular pressure tests are carried out.

[0057] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A buried pipeline corrosion fatigue coupling test device, characterized in that: It includes a controller (2), a corrosion test chamber (4), a cyclic pressurization system (6), a fatigue loading system (9), a data acquisition and monitoring system, and a corrosion environment adjustment system; The corrosion test box (4) is provided with a buried pipeline (7) and corrosive soil (5); The circulating pressurizing system (6) is provided with a circulating water inlet pipe (10), a water pressure tank (24), a circulating pump (23) and water (27); The fatigue loading system (9) includes a loading plate (31), a wheel (32) and a drive (33); The data acquisition and monitoring system comprises a computer (1), a data collector (3) and a sensor assembly; The corrosion environment regulating system comprises a humidity and pH regulating liquid inlet pipe (14), an atomizing device (15), a plurality of jet pipes (16) and a regulating liquid tank (28).

2. The buried pipeline corrosion fatigue coupling test device according to claim 1 is characterized in that: The water in the hydraulic tank (24) enters the buried pipeline (7) through the circulating water inlet pipe (10), and the controller (2) controls the circulating pump (23) to replenish water (27) into the hydraulic tank (24), thereby controlling the internal pressure of the hydraulic tank (24) and the buried pipeline (7).

3. The buried pipeline corrosion fatigue coupling test device according to claim 1 is characterized in that: The controller (2) controls the drive (33) to cause the wheel (32) to perform fatigue loading on the loading plate (31), and transmits the fatigue to the buried pipeline (7) through the corrosive soil (5).

4. The buried pipeline corrosion fatigue coupling test device according to claim 1, characterized in that: The sensor assembly includes a first temperature and humidity sensor (17), a second temperature and humidity sensor (18), a first pH sensor (19), a second pH sensor (20), a first water pressure gauge (21), and a second water pressure gauge (22); The first temperature and humidity sensor (17), the second temperature and humidity sensor (18), the first pH sensor (19), and the second pH sensor (20) are arranged inside the corrosion test box (4); the first water pressure gauge (21) and the second water pressure gauge (22) are respectively arranged on the water inlet interface (11) and the water outlet interface (12) at both ends of the buried pipeline (7); and the data measured by the sensor components are transmitted to the computer (1) through the data collector (3) for analysis and processing.

5. The buried pipeline corrosion fatigue coupling test device according to claim 1, characterized in that: The outer end of the humidity and pH regulating liquid inlet pipe (14) is connected to the regulating liquid tank (28), and the inner end is arranged below the buried pipeline (7) in the corrosion test box (4); a plurality of the air injection pipes (16) are vertically arranged on the inner end of the humidity and pH regulating liquid inlet pipe (14), and an atomizing device (15) is provided at the connection between each of the air injection pipes (16) and the humidity and pH regulating liquid inlet pipe (14); The regulating liquid tank (28) is provided with regulating liquid. The regulating liquid enters the corrosion test chamber (4) through the humidity and pH regulating liquid inlet pipe (14), is atomized by the atomizing device (15), and is then sprayed out through the jet pipe (16), thereby regulating the humidity and pH value of the corrosive soil (5).

6. A buried pipeline corrosion fatigue coupling test method, characterized in that: The following steps are involved: Step 1: preparing corrosive soil (5); Step 2: pre-processing the buried pipeline (7) and recording the initial state of the pipeline; Step 3: Install the buried pipeline (7) into the corrosion test box (4), control the circulating pressurization system (6) to pass water through the buried pipeline (7), and when the water pressure is stable within the test pressure range, add corrosive soil (5) layer by layer into the corrosion test box (4) and install the sensor assembly; Step 4: Set the corrosion time and conduct the corrosion fatigue coupling test; Step 5: After the corrosion time is reached, the fatigue loading system (9) and the cyclic pressurization system (6) are turned off, the corroded soil (5), the sensor and the buried pipeline (7) are taken out in sequence, the mass loss of the buried pipeline (7) is measured, and fracture toughness, axial pressure and annular pressure tests are carried out.

7. The buried pipeline corrosion fatigue coupling test method according to claim 6, characterized in that: The first step includes: uniformly selecting three samples from the undisturbed soil surrounding the buried pipeline in the target study area for X-ray fluorescence spectroscopy analysis to obtain soil composition; diluting hydrochloric acid with deionized water and mixing it with 10 kg of soil for a small-scale trial, gradually determining the dilution ratio and corresponding soil dosage to ensure that the pH reaches the experimental design value.

8. The buried pipeline corrosion fatigue coupling test method according to claim 6, characterized in that: The second step comprises: polishing the outer wall of the buried pipeline (7), removing 1 mm of coating to expose a smooth metal surface, obtaining the initial state of the pipeline using a three-dimensional scanning device, and measuring the initial weight of the pipeline.

9. The buried pipeline corrosion fatigue coupling test method according to claim 6, characterized in that: The fourth step comprises: the controller (2) adjusts the water pressure in the buried pipeline (7) by controlling the circulating pressurization system (6), adjusts the humidity and pH of the corrosive soil (5) by controlling the corrosion environment adjustment system, and controls the fatigue loading system (9) to perform fatigue loading on the buried pipeline (7); and at the same time, the data acquisition device (3) transmits the data measured by the sensor assembly to the computer (1) for analysis and processing.

10. The buried pipeline corrosion fatigue coupling test method according to claim 9, characterized in that: The step 4 further includes: The fatigue loading system (9) establishes a time matching relationship of the corrosion-fatigue coupling action according to the power function followed by the metal atmospheric exposure, predicts the time and load value when the buried pipeline (7) reaches a certain corrosion depth, and thus realizes fatigue loading of the buried pipeline (7).

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