Full-scale high pressure piping resonant bending fatigue pressurization and hold system and method

Abstract

The application provides a full-size high-pressure pipeline resonance bending fatigue pressure boosting and stabilizing system and method, which comprises obtaining pipeline size and target axial stress, a geometry-stress mapping formula determines target internal pressure P of a liquid filled in the pipeline according to the size and the target axial stress; sampling data of the pipeline is obtained, a pressure adjusting strategy outputs a pressure control value U according to the sampling data, and a pressure boosting pump connected with the pipeline is controlled to act based on the pressure control value U, so as to improve the stability of the liquid pressure in the pipeline. The application can automatically determine the target water pressure P according to the geometry size and the target axial stress of the pipeline, complete rapid pressurization and fine pressure stabilization, control the pressure fluctuation in a narrow band range under the long-time resonance excitation condition of the pipeline, realize high-fitting-degree reproduction of real working conditions, and improve the accuracy of test results.

Description

Technical Field

[0001] This invention relates to the field of fatigue performance measurement technology for full-size pipelines, specifically to a full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system and method. Background Technology

[0002] Full-scale resonant bending fatigue testing of pipelines is a key method for evaluating the fatigue life of marine risers, subsea oil and gas pipelines, long-distance pipeline joints, and pressure fittings. Resonant loading has the advantages of low power consumption, considerable stress amplitude, and high testing efficiency. Combined with fulcrum adjustment, flexible support, and control systems, it can reproduce long-term vibrations in the laboratory environment of ships / platforms.

[0003] However, existing tests mostly focus on bending loads, and the internal fluid pressure is often achieved through "initial static pressurization + passive monitoring". This makes it difficult to maintain stable internal pressure over a long period of time under the interference of small volume changes, temperature rise and leakage caused by resonant vibration, resulting in insufficient axial stress simulation and thus systematic deviations in fatigue life assessment. Summary of the Invention

[0004] In view of this, the problem to be solved by the present invention is to provide a full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization system and method, which can automatically determine the target water pressure based on the pipeline geometry and target axial stress, complete rapid pressurization and fine pressure stabilization, control pressure fluctuation within a narrow range under long-term resonant excitation conditions of the pipeline, achieve high-fit reproduction of real working conditions, and improve the accuracy of test results.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization method includes: calculating the target internal pressure, obtaining the pipeline size and target axial stress, and using a geometry-stress mapping formula to determine the target internal pressure P of the liquid filling the pipeline based on the size and target axial stress. Pressure stabilization control acquires sampling data from the pipeline, and the pressure regulation strategy outputs a pressure control value U based on the sampling data. Based on the pressure control value U, it controls the operation of the booster pump connected to the pipeline to improve the stability of the liquid pressure in the pipeline. The geometry-stress mapping formula is: ,in, σ a This indicates the target axial stress in the pipe. This represents the cross-sectional area of ​​the passageway within the pipe. This represents the area of ​​the annular cross-section of the pipe.

[0006] Furthermore, the sampling data includes a first internal pressure P1 representing the liquid pressure in the pipeline and a second internal pressure P2 representing the outlet pressure of the booster pump. The pressure regulation strategy includes: calculating a first difference between the first internal pressure P1 and the target internal pressure P, and the PID algorithm calculating the pressure control value U based on the first difference. Determine whether the second difference between the second internal pressure P2 and the first internal pressure P1 exceeds the second threshold. If yes, decrease the pressure control value U; otherwise, increase the pressure control value U.

[0007] Furthermore, the sampling data includes a temperature value T representing the pipe temperature, and the pressure regulation strategy includes optimizing the target internal pressure P: calculating the difference ΔT between the temperature value T and the preset base temperature T0, and calculating the compensation internal pressure ΔP through a compensation formula, which is: ΔP = α·ΔT, where α represents an empirical coefficient; The compensated internal pressure ΔP is added to the target internal pressure P to generate the optimized target internal pressure P.

[0008] Furthermore, the sampling data includes the vibration frequency f of the pipeline, and the pressure regulation strategy includes optimizing the differential coefficient Kd in the PID algorithm: including adjusting the differential coefficient Kd proportionally to the vibration frequency f.

[0009] A full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system includes a pipeline to be tested, a liquid supply and stabilizing pipeline for filling the pipeline with liquid, the liquid supply and stabilizing pipeline includes a water pump, the inlet of the pipeline is connected to a water storage tank through the water pump, and a booster pump for adjusting the liquid pressure in the pipeline is provided between the water pump and the inlet of the pipeline.

[0010] Furthermore, a pulsation suppression valve is provided at the water inlet of the pipeline.

[0011] Furthermore, a high-pressure return pipeline is provided between the water inlet of the pipeline and the water storage tank.

[0012] Furthermore, an air vent valve is installed at the highest point of the pipeline between the water pump and the water storage tank.

[0013] Furthermore, the drive port of the booster pump is connected to the air compressor, and a pressure regulating valve is provided between the air compressor and the booster pump.

[0014] Furthermore, an air storage tank is provided between the pressure regulating valve and the air compressor.

[0015] The beneficial effects of this invention are: A full-scale high-pressure pipeline resonant bending fatigue pressurization and stabilization method automatically determines the target internal pressure P by considering the pipeline's outer diameter, inner diameter, and target axial stress. This allows for the introduction of liquid at the target internal pressure P into the pipeline. During the test, a pressure regulation strategy ensures the stability of the liquid pressure within the pipeline or keeps it within a preset pressure fluctuation range. This method makes the composite load on the pipeline more closely resemble real marine operating conditions, achieving a high degree of fit to real operating conditions under long-term resonant excitation, thus improving the accuracy of the test results.

[0016] A full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system is implemented by incorporating a high-pressure return pipeline, a pulsation suppression valve, and a booster pump. When transient high pressure occurs in the pipeline, the high-pressure return pipeline is activated to allow some liquid to flow back to the storage tank, suppressing the transient high pressure. The pulsation suppression valve is used to suppress low-pressure waves generated by pipeline vibration. A pressure regulation strategy controls the booster pump's operation to suppress high-pressure waves and long-term pressure changes caused by equipment drift and pipeline leaks.

[0017] When the first difference is below the first threshold, the low-pressure wave is automatically suppressed by hardware (pulse suppression valve). When the first difference is above the first threshold, the booster pump is controlled by the control computer to efficiently and quickly suppress the high-pressure wave. Through the coordinated operation of software and hardware, using only a simple control algorithm, the liquid pressure in the pipeline can be accurately and quickly responded to and adjusted, keeping the steady-state pressure fluctuation within ±1–2% of the full scale (FS), thus improving the reliability of the test data. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system of the present invention; Figure 2 This is a flowchart of the full-size high-pressure pipeline resonant bending fatigue pressure boosting and stabilization method of the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise defined, 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 invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed terms.

[0021] This invention provides a full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system, such as... Figure 1 As shown, the test includes a pipe to be tested and a liquid supply and pressure stabilizing pipeline for filling the pipe with liquid. The liquid supply and pressure stabilizing pipeline includes a water pump. The inlet of the pipe is connected to a water storage tank through the water pump. A booster pump is installed between the water pump and the inlet of the pipe. The booster pump is used to adjust the liquid pressure in the pipe to keep the pressure in the pipe stable, so as to improve the stability of the test results.

[0022] The operation of the above pipeline is as follows: Before the test, liquid slightly below the preset pressure is filled into the pipeline through the liquid supply and pressure stabilization pipeline. Then, a booster pump increases the liquid pressure in the pipeline to equal the preset pressure. During the test, the pipeline is subjected to high-frequency vibration to test the fatigue resistance of the pipeline to vibration bending. Leakage caused by pipeline vibration and equipment drift can lead to frequent fluctuations or long-term deviations in the liquid pressure in the pipeline. The operation of the booster pump is controlled to adjust the liquid pressure in the pipeline, ensuring the stability of the liquid pressure during the test.

[0023] One embodiment of this application is: the water pump outlet is equipped with a safety valve to prevent liquid overpressure backflow, which would affect the use of the water pump.

[0024] A pulsation suppression valve is installed at the inlet of the pipeline. The elastic component (air bladder, spring or diaphragm, etc.) of the pulsation suppression valve converts the excessive pressure energy of the liquid into elastic energy, or converts the elastic energy into the pressure energy of the liquid, by compressing the pre-pressurized medium (gas or spring force). This is used to remove low-pressure fluctuations caused by pipeline vibration and improve the stability of the pressure inside the pipeline.

[0025] During the test, severe deformation caused by pipeline vibration or other malfunctions led to a sudden increase in liquid pressure within the pipeline. The pulsation suppression valve was unable to quickly and effectively eliminate this transient high-pressure interference. A high-pressure return pipeline is installed between the pipeline inlet and the water storage tank. When transient high pressure occurs at the inlet, the high pressure causes the return pipeline to open, allowing excess liquid to flow back to the water storage tank. This reduces the probability of transient high pressure occurring in the pipeline, facilitating the pulsation suppression valve to effectively suppress high-frequency pressure fluctuations and improve the stability of pressure within the pipeline.

[0026] One embodiment of this application is as follows: the high-pressure return pipeline includes a back pressure valve, and the conduction pressure of the back pressure valve is adjustable. When the pressure at the inlet exceeds the conduction pressure, the back pressure valve is activated; when the pressure at the inlet of the pipeline is lower than the conduction pressure, the back pressure valve is deactivated.

[0027] A first filter is installed between the water pump and the water storage tank to prevent particles from entering the water pump and the high-pressure pipeline at the back end, thus affecting the normal operation of the water pump and the high-pressure pipeline at the back end.

[0028] Under resonant conditions, the pipeline exhibits a small but high-frequency effective volume change during first-order or higher-order modal vibration. If unexpelled free gas enters the pipeline, it significantly reduces the equivalent bulk modulus of the liquid within, intensifying pressure ripple (making pressure fluctuations more frequent). The output of the first filter is connected to both the water storage tank and a communicating vessel via a bypass valve. The communicating vessel is located at the highest point of the pipeline and connected to an exhaust valve. When the first filter draws in and filters the liquid, gas within the liquid easily precipitates and accumulates at the highest point of the pipeline. Exhausting this gas through the exhaust valve effectively reduces the probability of gas entering the pipeline.

[0029] The booster pump's drive port is connected to the air supply pipeline, which includes an air compressor. A pressure regulating valve is installed between the air compressor and the booster pump to provide high-pressure gas at a set pressure to the booster pump. An air storage tank is installed between the air compressor and the pressure regulating valve. When the air compressor's output pressure is higher than a threshold, the air storage tank stores excess gas; when the air compressor's output pressure is lower than the threshold, the air storage tank releases gas to provide a stable high-pressure gas supply. In one embodiment of this application, the pressure regulating valve is a proportional air source pressure regulating valve, which is connected to a control system to adjust the output pressure.

[0030] A second filter, an air dryer, and a third filter are connected in series between the air compressor and the air tank to remove water, oil, water vapor, and solid impurities from the air, protect valves and booster pumps, and extend their service life.

[0031] A full-size high-pressure pipeline resonant bending fatigue pressure boosting and stabilization method, such as... Figure 2 As shown, the process includes calculating the target internal pressure P, obtaining the pipe size and target axial stress, and using a geometry-stress mapping formula to determine the target internal pressure P of the liquid filling the pipe based on the size and target axial stress.

[0032] The geometry-stress mapping formula is: , in, σ a This indicates the target axial stress in the pipe. This represents the cross-sectional area of ​​the passageway within the pipe. This represents the area of ​​the annular cross-section of the pipe.

[0033] and The calculation formula is: Where D represents the outer diameter of the pipe and d represents the inner diameter of the pipe.

[0034] One embodiment of this application is a marine pipeline specimen with a diameter D=168mm, a wall thickness of 18mm, and an inner diameter d=132mm, and a target axial stress. =100MPa. A can be calculated. i =π(66)2≈13685mm², A r =π[(84)2−(66)2]≈8495mm²; The target internal pressure P calculated by the geometry-stress mapping formula is: P=σa⋅Ar / Ai≈100×8495 / 13685≈62.1MPa.

[0035] Pressure stabilization control acquires sampling data from the pipeline, and the pressure regulation strategy outputs a pressure control value U based on the sampling data. Based on the pressure control value U, the booster pump connected to the pipeline is controlled to improve the stability of the liquid pressure in the pipeline.

[0036] The sampling data includes the first internal pressure P1, which represents the liquid pressure inside the pipeline; the second internal pressure P2, which represents the outlet pressure of the booster pump; the temperature value T, which represents the pipeline temperature; and the vibration frequency f of the pipeline.

[0037] A pressure sensor is installed near the inlet of the pipeline to obtain the first internal pressure P1. In one embodiment of this application, the target internal pressure P is 62.1 MPa. The allowable fluctuation range of the first internal pressure P1 is controlled within P ± 1% of full scale (FS), i.e., 62.1 ± 0.621 MPa. If the pressure fluctuation is between P ± 1% FS and P ± 2% FS, the pressure regulation strategy is not activated, and only the pulsation suppression valve filters out the low-pressure wave; if the pressure fluctuation exceeds P ± 2% FS (i.e., 62.1 ± 1.242 MPa), the system triggers an alarm and forcibly activates the pressure regulation strategy to adjust the first internal pressure P1.

[0038] A pressure sensor is installed at the outlet of the booster pump to obtain a second internal pressure P2. This second internal pressure P2 serves as an auxiliary parameter, maintaining the difference between the second internal pressure P2 and the first internal pressure P1 within the range of 0.5-1.0 MPa to ensure effective pumping. If P2-P1 < 0.5 MPa, it indicates a decrease in the pumping efficiency. Possible causes include: leakage between the booster pump and the pipeline; inaccurate sampling due to sensor drift; and reduced pressure stabilization efficiency due to drift of other pressure-regulating devices. It is necessary to check for leaks or device drift.

[0039] The temperature of the pipe wall or the liquid inside the pipe is collected in real time by a temperature sensor to obtain the pipe temperature value T. In one embodiment of this application, the pipe temperature value T is controlled between 15-35℃ under normal operating conditions. If the temperature rises by more than 5℃, the target internal pressure P is increased to offset the volume change caused by the thermal expansion of the pipe, which would otherwise cause a drop in the liquid pressure inside the pipe.

[0040] The vibration frequency f is obtained through a resonant excitation system. One embodiment of this application involves setting the vibration frequency f to 5-20Hz to simulate long-term vibration under marine conditions. If the vibration causes pressure waves in the liquid to be within ±1~2% of full scale (FS), initial hardware suppression is performed using a pulsation suppression valve and a high-frequency return pipeline. If the pressure ripple exceeds ±2% of full scale (FS), a pressure regulation strategy is activated, and the differential coefficient Kd of the PID algorithm is adjusted based on the vibration frequency f to prioritize the suppression of high-pressure waves.

[0041] The pressure regulation strategy includes: calculating the first difference between the first internal pressure P1 and the target internal pressure P, determining whether the first difference exceeds the first threshold; if no, no action is taken; if yes, the PID algorithm calculates the pressure control value U based on the first difference.

[0042] The formula for the PID algorithm is: u(t)=Kp·e(t) + Ki·∫e(t)dt + Kd·de(t) / dt, Where Kp represents the proportional coefficient, Ki represents the integral coefficient, Kd represents the derivative coefficient, e(t) represents the first difference at time t, and u(t) represents the pressure control value at time t. In one embodiment of this application, the first threshold is set to the target internal pressure P ± 2%FS.

[0043] One embodiment of this application is as follows: Kp = 0.5-1.0, Ki = 0.1-0.2, and Kd = 0.05-0.1. The proportional gain Kp can quickly increase the liquid pressure in the pipeline, preventing the liquid in the pipeline from being in a low-pressure state for a long time, which would lead to gas precipitation; the integral gain Ki is used to eliminate steady-state errors, such as pressure drift caused by long-term leakage; and the differential gain Kd is used to suppress high-pressure fluctuations. u(t) directly acts on the proportional gas source pressure regulating valve to adjust the driving gas pressure of the booster pump, thereby dynamically regulating the output pressure of the booster pump.

[0044] Determine whether the second difference between the second internal pressure P2 and the first internal pressure P1 exceeds the second threshold. If yes, decrease the pressure control value U; otherwise, increase the pressure control value U.

[0045] The second difference is used to represent the pressure change between the booster pump and the pipeline. In one embodiment of this application, the second threshold is 0.5 MPa. When the second difference exceeds the second threshold, it indicates that there is a leak between the booster pump and the pipeline. The pressure loss caused by the leak is offset by increasing u(t). When the second difference is lower than the second threshold, it indicates that the booster pump is adjusting the pressure too quickly, posing a risk of overpressure. The operating speed of the booster pump is reduced by decreasing u(t), thereby reducing the probability of overpressure.

[0046] The pressure regulation strategy includes optimizing the target internal pressure P: calculating the difference ΔT between the temperature value T and the preset base temperature T0, and calculating the compensation internal pressure ΔP using the compensation formula: ΔP = α·ΔT, where α represents an empirical coefficient; the compensation internal pressure ΔP is added to the target internal pressure P to generate the optimized target internal pressure P.

[0047] One embodiment of this application is as follows: α is set to 0.15 MPa / ℃, and the normal temperature T of the pipeline is 35℃. If temperature (T) increases by 5°C, the compensated internal pressure (ΔP) calculated according to the compensation formula is 0.75 MPa. The sum of the compensated internal pressure (ΔP) and the target internal pressure (P) is the optimized target internal pressure (P). The PID algorithm calculates u(t) based on the optimized target internal pressure (P), which can reduce the impact of temperature expansion on pressure and improve the stability of axial stress in the pipeline.

[0048] The pressure regulation strategy includes optimizing the derivative coefficient Kd in the PID algorithm: this involves adjusting Kd proportionally to the vibration frequency f. By dynamically adjusting Kd based on pressure wave fluctuations, the filtering accuracy is improved while prioritizing the suppression of high-pressure waves, thus enhancing the efficiency of software and hardware collaboration.

[0049] One embodiment of this application is as follows: when the pressure fluctuation is below P±2%FS, the pulsation suppression valve suppresses low-frequency pressure waves; when the pressure fluctuation exceeds P±2%FS, the high-pressure return pipeline and pressure regulation strategy are activated to ensure that the overall pressure fluctuation of the liquid in the pipeline is controlled within ±1-2%FS. This improves the pressure stability during the test.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for boosting and stabilizing pressure in full-size high-pressure pipelines due to resonant bending fatigue, characterized in that: include, Calculate the target internal pressure, obtain the pipe size and target axial stress, and use the geometry-stress mapping formula to determine the target internal pressure P of the liquid filling the pipe based on the size and target axial stress. Pressure stabilization control acquires sampling data from the pipeline, and the pressure regulation strategy outputs a pressure control value U based on the sampling data. Based on the pressure control value U, it controls the operation of the booster pump connected to the pipeline to improve the stability of the liquid pressure in the pipeline. The geometry-stress mapping formula is: ,in, σ a This indicates the target axial stress in the pipe. This represents the cross-sectional area of ​​the passageway within the pipe. This represents the area of ​​the annular cross-section of the pipe.

2. The full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization method according to claim 1, characterized in that, The sampled data includes a first internal pressure P1 representing the liquid pressure in the pipeline and a second internal pressure P2 representing the outlet pressure of the booster pump. The pressure regulation strategy includes: calculating a first difference between the first internal pressure P1 and the target internal pressure P, determining whether the first difference exceeds a first threshold; if no, no action is taken; if yes, the PID algorithm calculates the pressure control value U based on the first difference. Determine whether the second difference between the second internal pressure P2 and the first internal pressure P1 exceeds the second threshold. If yes, decrease the pressure control value U; otherwise, increase the pressure control value U.

3. The full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization method according to claim 2, characterized in that, The sampling data includes a temperature value T representing the pipe temperature, and the pressure regulation strategy includes optimizing the target internal pressure P: calculating the difference ΔT between the temperature value T and the preset base temperature T0, and calculating the compensation internal pressure ΔP through a compensation formula, which is: ΔP = α·ΔT, where α represents an empirical coefficient; The compensated internal pressure ΔP is added to the target internal pressure P to generate the optimized target internal pressure P.

4. The full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization method according to claim 2, characterized in that, The sampled data includes the vibration frequency f of the pipeline, and the pressure regulation strategy includes optimizing the differential coefficient Kd in the PID algorithm: including adjusting the differential coefficient Kd proportionally to the vibration frequency f.

5. A full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization system, comprising the full-size high-pressure pipeline resonant bending fatigue pressurization and stabilization method according to any one of claims 1-4, characterized in that, The system includes a pipe to be tested, a liquid supply and pressure stabilizing pipeline for filling the pipe with liquid, the liquid supply and pressure stabilizing pipeline including a water pump, the inlet of the pipe being connected to a water storage tank via the water pump, and a booster pump for adjusting the liquid pressure inside the pipe being provided between the water pump and the inlet of the pipe.

6. The full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system according to claim 5, characterized in that, A pulsation suppression valve is installed at the inlet of the pipeline.

7. The full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system according to claim 5, characterized in that, A high-pressure return pipeline is installed between the water inlet of the pipeline and the water storage tank.

8. The full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system according to claim 5, characterized in that, An air vent valve is installed at the highest point of the pipeline between the water pump and the water storage tank.

9. The full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system according to claim 5, characterized in that, The booster pump's drive port is connected to the air compressor, and a pressure regulating valve is provided between the air compressor and the booster pump.

10. The full-size high-pressure pipeline resonant bending fatigue boosting and stabilizing system according to claim 9, characterized in that, An air storage tank is provided between the pressure regulating valve and the air compressor.

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