Device and method for detecting bending resistance of steel cable for FPSO (floating production storage and offloading)

Abstract

The invention discloses a device and method for detecting the bending resistance of a steel cable for FPSO, and belongs to the technical field of metal product detection.The device for detecting the bending resistance of the steel cable comprises a bending wheel and a support used for supporting the bending wheel, the bending wheel can rotate relative to the support, and a winding cavity used for winding the steel cable is formed in the bending wheel; the steel cable is wound in the winding cavity by at least one circle, the rope end clamps at the two ends of the steel cable are fixed to the pre-tensioning equipment, so that after the steel cable is wound, loads are applied to the steel cable through the pre-tensioning equipment, and the invention further discloses a method for detecting the bending resistance of the steel cable for the FPSO. According to the invention, the actual state change in the steel cable installation process can be truly and effectively simulated, the influence on the sheath and structure of the steel cable when the steel cable is bent and loaded is verified, the steel cable is comprehensively evaluated through the bending resistance detection result, and a steel cable bending resistance evaluation report is obtained, so that the installation is guided, the damage problem in the installation and use processes is avoided, and the construction efficiency is improved. And the reliability and the safety of the steel cable in practical application are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal product detection, and in particular relates to a device and method for detecting the bending resistance of a steel cable for FPSO. Background Art

[0002] Currently, FPSO (floating production storage and offloading unit), TLP (tension leg platform) and SPAR are the most important offshore oil production equipment, and 75% of the world's offshore oil production is produced through the FPSO model.

[0003] FPSO is moored to the sea for a long time through a special positioning and mooring system. It is required to withstand environmental conditions that occur once in a hundred years. It has the characteristics of high investment, high risk and high return. It is an important facility for technology-intensive offshore oil production. It is fixed to the sea through a single-point mooring system and can rotate 360 ​​degrees freely in all directions with the action of wind, waves and currents. It is suitable for deepwater oil field development and the operating water depth can reach more than 2,000 meters. According to surveys, at a water depth of less than 500 meters, more than 80% of the world's FPSO positioning systems have steel cables.

[0004] With the development of technology, from the first generation of bare steel cables, to the second generation of single-layer plastic-coated steel cables, to today's double-layer plastic-coated steel cables, the size of the steel cable's outer sheath has increased, and its seawater corrosion resistance and wear resistance have become better and better, effectively extending its service life.

[0005] While the application performance of steel cables has been improved, more stringent requirements have been put forward for the installation process of steel cables. The steel cable installation process is to guide the manufacturer's steel cable into the installation winch, and then release it from the installation winch. One end of the steel cable is connected to the seabed anchor, and the other end is connected to the FPSO float. During the installation process of the cable, there must be no problems such as the breakage, damage of the steel cable sheath and damage to the wire rope structure. If the above problems occur, it will directly affect the normal use of the steel cable, resulting in the scrapping of the steel cable, and even affect the progress of the construction period.

[0006] In the early stage, the bending resistance of steel cables for FPSO was only calculated theoretically. Since there are certain deviations in parameters such as twist angle, twist reduction rate, twist radius, etc. during the twisting process, the theoretical calculation value will deviate from the actual value. If the deviation value exceeds a certain range, it will eventually affect the normal use of the steel cable. Therefore, theoretical calculation fully verifies the bending resistance of steel cables. At present, no method or device that can test the bending resistance of steel cables for FPSO has been found at home and abroad.

[0007] The user must require the steel cable manufacturer to test the bending resistance of the steel cable before it leaves the factory. Therefore, it is urgent to design a bending resistance testing device and method for FPSO steel cables to solve the above-mentioned problems. Summary of the invention

[0008] The purpose of the present invention is to provide a device and method for detecting the bending resistance of steel cables for FPSO, which has the advantages of being able to truly reflect the bending load conditions during the installation of the steel cables, making a scientific and reasonable evaluation of the performance of the steel cables, providing reliable test data support for the installation, and solving the problems of cracking and falling off of the steel cable sheath and reduced mechanical properties of the steel cables during the installation and application processes.

[0009] To achieve the above purpose, the specific technical scheme of the bending resistance detection device and method of the FPSO steel cable of the present invention is as follows: A device for testing the bending resistance of a steel cable for FPSO comprises a bending wheel and a bracket for supporting the bending wheel. The bending wheel can rotate relative to the bracket. A winding cavity for winding the steel cable is provided on the bending wheel. The steel cable is wound in the winding cavity for at least one circle. Rope end clamps at both ends of the steel cable are fixed to a pre-tensioning device so that a load can be applied to the steel cable through the pre-tensioning device after the steel cable is wound.

[0010] Furthermore, the bracket includes a support rod and a rotating shaft. The support rod is provided with a central shaft, and the central shaft is rotatably connected to the bending wheel.

[0011] Furthermore, the bending wheel includes a wheel body and a shaft sleeve, the wheel body is located outside the shaft sleeve, the shaft sleeve is rotatably connected to the rotating shaft, and the arc-shaped contour outside the wheel body is a winding cavity.

[0012] Furthermore, a connecting rod is fixedly connected between the wheel body and the shaft sleeve.

[0013] Furthermore, a baffle is fixedly connected to the wheel body, and the baffle is located at both ends of the winding cavity.

[0014] Further, the diameter of the bending wheel is the same as the diameter of the mounting drum.

[0015] Further, the surface roughness of the bending wheel is the same as the surface roughness of the mounting drum.

[0016] Furthermore, the magnitude of the load applied to the steel cable is the same as the maximum traction force generated when the steel cable is installed.

[0017] Furthermore, both ends of the bracket are fixed to the pile foundation by anchor bolts.

[0018] A method for detecting the bending resistance of a steel cable for FPSO, using the above-mentioned device for detecting the bending resistance of a steel cable for FPSO, comprises the following steps: S1. Wrap the steel cable around the bending wheel for at least one turn, put rope end clamps on both ends of the steel cable, and then clamp the rope end clamps on the pre-tensioning device; S2. Apply axial tension to the rope end clamp through the pre-tensioning equipment. The magnitude of the axial tension is consistent with the load on the steel cable during the installation process. When the load reaches the maximum value during the installation process, keep it for at least 2 minutes before unloading. S3. Check whether the steel cable sheath has any quality defects such as cracks, breaks, or damages, and keep records; S4. Cut the steel cable on the bending wheel and perform a static load test on the steel cable to detect the changes in the tension of the entire steel cable and the tension, bending and torsion values ​​of the steel wire of the cable body.

[0019] The present invention has the following advantages: it can truly and effectively simulate the actual state changes during the installation of the steel cable, verify the impact of the steel cable bending and loading on the steel cable sheath and structure, conduct a comprehensive evaluation of the steel cable through the bending test results, and obtain a steel cable bending performance evaluation report, thereby guiding the installation and avoiding damage problems that occur during installation and use, and improving the reliability and safety of the steel cable in actual applications. The device is simple and convenient to operate and can effectively simulate the performance changes of the steel cable when it is bent and loaded. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the bending resistance test of the steel cable of the present invention; Figure 2 It is a structural schematic diagram of the bending wheel of the present invention; Figure 3 It is a schematic diagram of the connection structure between the bending wheel and the bracket of the present invention; Figure 4 is a schematic cross-sectional view of the steel cable of the present invention; Explanation of the markings in the figure: 1. bending wheel; 11. wheel body; 12. connecting rod; 13. baffle; 2. bracket; 21. support rod; 22. central axis; 3. rope end clamp; 4. steel cable; 41. steel cable body; 42. first sheath; 43. second sheath. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0022] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0023] Please refer to the attached Figure 1 To Attachment Figure 4The invention describes a device and method for detecting the bending resistance of a steel cable for FPSO.

[0024] The steel cable for FPSO is composed of a steel cable body 41, a first sheath 42 and a second sheath 43. The steel cable body 41 is made of multiple high-quality carbon steel wires twisted according to certain rules, and mainly plays a positioning and stretching role in FPSO. The first sheath 42 and the second sheath 43 covering the steel cable body 41 are made of medium-density polyethylene material, which mainly prevents corrosion caused by seawater infiltration into the steel cable body and protects the steel cable body from wear and tear between the seabed sand.

[0025] In the early stage, the bending resistance of steel cables for FPSO was only calculated theoretically. Due to certain deviations in parameters such as twist angle, twist shrinkage, and twist radius during the twisting process, the theoretical calculation values ​​will deviate from the actual values. If the deviation exceeds a certain range, it will eventually affect the normal use of the steel cables. Therefore, theoretical calculations fully verify the bending resistance of steel cables.

[0026] The user must require the steel cable manufacturer to test the bending performance of the steel cable before it leaves the factory. Based on the characteristics that the test bending wheel must be consistent with the diameter of the installation drum, and the tensile load of the steel cable is the same as the installation cable release load, the steel cable manufacturer conducts a bending test. After passing the test, it can be considered as qualified for the bending test if it meets the application requirements. The steel cable manufacturer installs a bending wheel with the same diameter as the installation equipment drum in the middle of the pre-tensioning equipment. After the steel cable is wound around the bending wheel for at least one circle, the two ends of the steel cable are fixed on the clamping device that can apply tension, and the maximum tension applied by the device is not less than 5000kN. After the two ends of the steel cable are clamped and fixed, the steel cable is tensioned at a loading speed of 5kN per second. When the load reaches the set tension, it is kept unloaded for at least 1 minute, and the surface state of the steel cable sheath is visually inspected; repeat the above steps to apply a certain load and then unload, and at the same time, the steel cable at the lower bending part is cut off, the surface state of the steel cable is visually inspected, and the static load test of the steel cable is performed.

[0027] Since the steel cables used in FPSO are all large-sized single-strand steel wire ropes, it is impossible to complete the bending test on ordinary bending fatigue equipment. It is necessary to design a bending wheel, wrap the steel cable around it, and use tensioning equipment to test it. The diameter and roughness characteristics of the designed bending wheel are consistent with the installation drum. Combined with the operating characteristics of the 5000kN pre-tensioning equipment, the two ends of the steel cable are clamped on the pre-tensioning equipment to apply load to test the bending performance of the steel cable. This test can not only truly detect and reflect the bending performance of the steel cable, but also play a great preventive role in the installation evaluation of the steel cable, eliminating problems caused by the application process after the installation of the steel cable. At the same time, the device is simple in design and easy to assemble.

[0028] Therefore, the bending performance detection device for the steel cable for FPSO includes a bending wheel 1 and a bracket 2 for supporting the bending wheel 1. The bending wheel 1 can rotate relative to the bracket 2. A winding cavity for winding the steel cable 4 is opened on the bending wheel 1. The steel cable 4 is wound in the winding cavity for at least one circle. The rope end clamps 3 at both ends of the steel cable 4 are fixed to the pre-tensioning device so that after the steel cable 4 is wound, a load can be applied to the steel cable 4 through the pre-tensioning device.

[0029] Preferably, the bracket 2 includes a support rod 21 and a rotating shaft, the support rod 21 is provided with a central shaft 22, and the central shaft 22 is rotatably connected to the bending wheel 1. In other embodiments of the present invention, the central shaft 22 can be fixedly connected to the bending wheel 1, and the central shaft 22 can be rotatably connected to the support rod 21, as long as it can be ensured that the bending wheel 1 can rotate relative to the bracket 2.

[0030] Specifically, the bending wheel 1 includes a wheel body 11 and a sleeve. The wheel body 11 is located outside the sleeve. The sleeve is rotatably connected to the rotating shaft. The arc-shaped contour outside the wheel body 11 is a winding cavity.

[0031] Preferably, a connecting rod 12 is fixedly connected between the wheel body 11 and the shaft sleeve, and the rigidity of the bending wheel 1 is strengthened by the connecting rod 12, so that the bearing capacity of the bending wheel 1 is not deformed or damaged when subjected to the maximum applied load.

[0032] Specifically, a baffle 13 is fixedly connected to the wheel body 11 , and the baffle 13 is located at both ends of the winding cavity to prevent the steel cable 4 from slipping out of the winding cavity on the wheel body 11 .

[0033] In order to ensure the accuracy of the inspection, the diameter of the bending wheel 1 is the same as the diameter of the installation drum, the surface roughness of the bending wheel 1 is the same as the surface roughness of the installation drum, and the magnitude of the load applied to the steel cable 4 is the same as the maximum traction force generated when the steel cable 4 is installed.

[0034] Furthermore, both ends of the bracket 2 are fixed on the pile foundation by anchor bolts.

[0035] The method for detecting the bending resistance of the steel cable for FPSO uses the bending resistance detection device for the steel cable for FPSO 4 according to any one of claims 1 to 9, and comprises the following steps: S1, wrap the steel cable 4 around the bending wheel 1 for at least one circle, sleeve the rope end clamps 3 at both ends of the steel cable 4, and then clamp the rope end clamps 3 on the pre-tensioning device; S2. Apply axial tension to the rope end clamp 3 through the pre-tensioning device. The magnitude of the axial tension is consistent with the load on the steel cable 4 during the installation process. When the load reaches the maximum value during the installation process, keep it for at least 2 minutes before unloading. S3. Check whether the sheath of the steel cable 4 has any quality defects such as cracks, breaks, or damages, and keep records; S4. Cut the steel cable 4 on the bending wheel 1, perform a static load test on the steel cable 4, and detect the changes in the tension of the entire rope of the steel cable 4 and the tension, bending and torsion values ​​of the steel wire of the cable body of the steel cable 4.

[0036] This method can effectively simulate the actual state changes of the steel cable 4 during installation, and verify the impact of the bending load on the sheath and structure of the steel cable 4. The steel cable 4 is comprehensively evaluated through the bending test results to obtain a bending performance evaluation report of the steel cable 4, thereby guiding the installation and avoiding damage problems during installation and use, and improving the reliability and safety of the steel cable 4 in actual application.

[0037] Regardless of the size of the FPSO steel cable 4, this method can be used to detect the bending resistance of the steel cable 4, thereby ensuring the safe use of the FPSO steel cable 4.

[0038] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A bending resistance detection device for a steel cable for FPSO, characterized in that: It includes a bending wheel and a bracket for supporting the bending wheel. The bending wheel can rotate relative to the bracket. A winding cavity for winding a steel cable is provided on the bending wheel. The steel cable is wound in the winding cavity for at least one circle. The rope end clamps at both ends of the steel cable are fixed to the pre-tensioning device so that after the steel cable is wound, a load can be applied to the steel cable through the pre-tensioning device.

2. The bending resistance detection device for FPSO steel cable according to claim 1, characterized in that: The bracket comprises a support rod and a rotating shaft. The support rod is provided with a central shaft, and the central shaft is rotatably connected with the bending wheel.

3. The bending resistance detection device for FPSO steel cable according to claim 2 is characterized in that: The bending wheel comprises a wheel body and a shaft sleeve, wherein the wheel body is located outside the shaft sleeve, the shaft sleeve is rotatably connected to the rotating shaft, and the arc profile outside the wheel body is a winding cavity.

4. The bending resistance detection device for FPSO steel cable according to claim 3 is characterized in that: A connecting rod is fixedly connected between the wheel body and the shaft sleeve.

5. The bending resistance detection device for FPSO steel cable according to claim 3 is characterized in that: The wheel body is fixedly connected with baffles, which are located at two ends of the winding cavity.

6. The bending resistance detection device for FPSO steel cable according to claim 1, characterized in that: The diameter of the bending wheel is the same as the diameter of the mounting drum.

7. The bending resistance detection device for FPSO steel cable according to claim 1, characterized in that: The surface roughness of the bending wheel is the same as the surface roughness of the mounting drum.

8. The bending resistance detection device for FPSO steel cable according to claim 1, characterized in that: The magnitude of the load applied to the cable is the same as the maximum traction force generated when the cable is installed.

9. The bending resistance detection device for FPSO steel cable according to claim 1, characterized in that: Both ends of the bracket are fixed to the pile foundation by anchor bolts.

10. A method for detecting the bending resistance of a steel cable for FPSO, characterized in that: The device for detecting the bending resistance of the FPSO steel cable according to any one of claims 1 to 9 comprises the following steps: S1. Wrap the steel cable around the bending wheel for at least one turn, put rope end clamps on both ends of the steel cable, and then clamp the rope end clamps on the pre-tensioning device; S2. Apply axial tension to the rope end clamp through the pre-tensioning equipment. The magnitude of the axial tension is consistent with the load on the steel cable during the installation process. When the load reaches the maximum value during the installation process, keep it for at least 2 minutes before unloading. S3. Check whether the steel cable sheath has any quality defects such as cracks, breaks, or damages, and keep records; S4. Cut the steel cable on the bending wheel and perform a static load test on the steel cable to detect the changes in the tension of the entire steel cable and the tension, bending and torsion values ​​of the steel wire of the cable body.

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