A flexible joint test tool and test method thereof

Abstract

The present invention relates to a flexible joint for an oil production platform, specifically a flexible joint test fixture and a test method thereof, wherein the flexible joint is installed in a fixed outer sleeve, a rotating shaft is provided on the fixed outer sleeve, and the rotating shaft is rotatably connected to a frame; the lower end of the flexible joint extends from the frame to form a flexible joint extension section, a cylinder connecting plate is installed on the flexible joint extension section, and a vertical cylinder is connected between the cylinder connecting plate and the bottom of the frame; a torque input balance wheel is installed on the rotating shaft, and the torque input balance wheel is connected to a torque input power source through a transmission mechanism; the top of the flexible joint body is sealed and connected to a cover, and a liquid circulation device is connected to the cover through a circulating liquid inlet pipe and a circulating liquid outlet pipe, and is connected to the inside of the flexible joint. The present invention realizes a deflection test of the flexible joint under an axial load, and at the same time places the elastomer in a high-temperature, high-pressure liquid environment to achieve a complete simulation of the working environment.

Description

Technical Field

[0001] The invention relates to a flexible joint for an oil production platform, in particular to a flexible joint test tool and a test method thereof. Background Art

[0002] Deepwater oil and gas exploration and production is the general trend of the development of the world's marine oil and gas industry. my country's South China Sea deepwater area has rich oil and gas resources. With the continuous increase in the depth of exploitation, offshore platforms and riser systems have developed rapidly. For deepwater production systems, the riser system is a conduit connecting the surface floating device and the seabed equipment. It is the "throat" for the transmission of various media and plays a very critical role. One of the important components of the riser system - the flexible joint is often the key component that is most likely to cause system damage and failure. Figure 1 As shown, the flexible joint 27 suspends the SCR riser 29 (steel catenary riser) on the side of the offshore platform 28, one end of the SCR riser 29 extends from the sea level 25 and is connected to the flexible joint 27, and the other end of the SCR riser 29 is located at the seabed mud surface 26; the flexible joint 27 suspends the SCR riser 29 (steel catenary riser) on the side of the offshore platform 28, which has the following outstanding advantages: significantly reducing the motion stress between the floating platform and the riser; can be used for the transmission of a variety of media; designed according to specific application requirements, can adapt to different connection methods, can provide a ±20° rotation angle, and can withstand an operating pressure of more than 50MPa and huge axial tension.

[0003] Because floating platforms often produce large motion responses under the influence of wind, waves, and currents, the flexible joint is located at the top of the riser and will bear large axial loads, rotation angles, high temperature, high pressure, and corrosion of the internal transmission medium. At the same time, the fatigue characteristics of the elastomer also need to be considered. Therefore, it is necessary to design simulation tests and fatigue tests for the flexible joints according to this working condition.

[0004] The most important test item for flexible joint elastomers is the deflection test under axial preload conditions. The diameter of the elastomer is about 1000mm, the axial preload is about 5000kN, and the moment of deflection of 3° is 106kN·m. It is impossible to conduct a combined loading test of axial and deflection on such an elastomer with large volume, large axial load and large deflection moment, while taking into account the pressure and high temperature in the joint cavity. Therefore, it is necessary to design a combined test device that can simultaneously apply large load axial tension and large moment deflection, and this test device must also meet the needs of fatigue testing. Summary of the invention

[0005] In order to meet the test requirements of flexible joints, the purpose of the present invention is to provide a flexible joint test tool and a test method thereof.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The test fixture of the present invention comprises a liquid circulation device, a torque input power source, a transmission mechanism, a frame, a vertical oil cylinder, a fixed sleeve, a cover and an oil cylinder connecting plate, wherein the flexible joint to be tested is installed in the fixed sleeve, the fixed sleeve is provided with a rotating shaft, and the rotating shaft is rotatably connected with the frame; the lower end of the flexible joint to be tested is extended from the frame to form a flexible joint extension section, the flexible joint extension section is provided with an oil cylinder connecting plate, a vertical oil cylinder for applying an axial load to the flexible joint extension section is connected between the oil cylinder connecting plate and the bottom of the frame, a displacement sensor is installed at the bottom of the frame, and a tension sensor is installed on the flexible joint extension section force sensor; a torque input balance wheel and a torque sensor are respectively installed on the rotating shaft, the torque input balance wheel is connected to the torque input power source through a transmission mechanism, the torque input power source drives the torque input balance wheel to swing through the transmission mechanism, and then drives the fixed sleeve and the flexible joint to swing through the rotating shaft, a counter is installed on the torque input balance wheel, and an inclination sensor is installed on the flexible joint body located above the fixed sleeve; the top of the flexible joint body is sealed with a cover, and the liquid circulation device is connected to the cover through a circulating liquid inlet pipe and a circulating liquid outlet pipe, and is connected with the inside of the flexible joint.

[0008] Wherein: the fixed sleeve is in the shape of a hollow cylinder, and is divided into two parts with the same structure. The horizontal projection of each part is semicircular. A rotating shaft is provided on the outer surface of each part. The rotating shaft is rotatably connected to the frame through a bearing. The two parts are connected through sleeve fastening bolts, and the flexible joint is clamped inside the fixed sleeve.

[0009] The axial center lines of the two rotating shafts on the fixed sleeve are collinear and parallel to the horizontal plane, and the deflection center of the flexible joint intersects the axial center lines of the two rotating shafts perpendicularly.

[0010] The frame includes a bottom plate and two vertical plates. The two vertical plates are symmetrically located on both sides of the bottom plate and are perpendicular to the bottom plate. Each of the vertical plates is rotatably connected to a rotating shaft through the bearing.

[0011] The torque input power source is a gearbox, the transmission mechanism is a connecting rod, one end of the connecting rod is connected to the torque input balance wheel, and the other end is eccentrically connected to the output wheel of the gearbox.

[0012] The rotating shaft is provided with two limit blocks, which are symmetrically arranged on the left and right sides of the vertical section of the torque input balance wheel.

[0013] An extension section block is provided in the extension section of the flexible joint.

[0014] The test method of the flexible joint test tool of the present invention includes a static test method and a fatigue test method, wherein

[0015] The static test method includes the following steps:

[0016] A. Assemble the flexible joint to be tested;

[0017] B. fixing the fixed jacket to the flexible joint;

[0018] C. Rotate and install the fixed jacket and the flexible joint on the frame;

[0019] D. Installing a torque input balance wheel and a torque sensor on the rotating shaft respectively, and connecting the torque input balance wheel to a torque input power source through a transmission mechanism;

[0020] E. Connecting the extended section of the flexible joint with the vertical cylinder;

[0021] F. Connecting the cover to the liquid circulation device through the circulating liquid inlet pipe and the circulating liquid outlet pipe, and connecting the cover to the top of the flexible joint body of the flexible joint;

[0022] G. Install an inclination sensor on the flexible joint body, install a displacement sensor at the bottom of the frame, and install a tension sensor on the extended section of the flexible joint;

[0023] H. Start the liquid circulation device, inject the medium liquid with adjusted temperature into the inner cavity of the flexible joint, and after the temperature of the liquid in the cavity is constant, adjust the outlet pressure of the pump station in the liquid circulation device to the designed value;

[0024] I. Applying an axial load to the flexible joint elastic body through the vertical oil cylinder and the flexible joint extension section, and recording the displacement sensor value;

[0025] J. Start the torque input power source, apply torque to the fixed outer sleeve and the flexible joint through the torque input balance wheel according to the design requirements, and record the values ​​of the inclination sensor, torque sensor, displacement sensor, and tension sensor respectively;

[0026] The fatigue test method includes the following steps:

[0027] K. Install according to steps A to H of the static test method;

[0028] L. Apply axial load according to various working conditions according to the method in step I;

[0029] M. Control the torque input power source through the electro-hydraulic servo device to apply the cyclic torque;

[0030] N. Record the number of cycles through a counter.

[0031] Wherein: in the step B, an adjustment gasket is placed between the flexible joint shell and the bottom of the fixed sleeve to adjust the gap between the flexible joint and the bottom of the fixed sleeve, so that the deflection center of the flexible joint intersects the axial center line of the rotating shaft perpendicularly.

[0032] In the step D, a limit block is simultaneously installed on the rotating shaft.

[0033] The advantages and positive effects of the present invention are:

[0034] 1. The present invention realizes the deflection test of the flexible joint under axial load, and at the same time places the elastomer in a high-temperature, high-pressure liquid environment, thereby achieving a complete simulation of the working environment, solving the problem that the existing test equipment can only perform a single tensile or deflection test but cannot perform a combined test; at the same time, high-temperature circulating liquid is added to the flexible joint test, solving the problem that the elastomer material test at room temperature cannot fully simulate the actual high-temperature working conditions.

[0035] 2. The present invention directly inputs the torque through the torque input shaft. The prior art uses the oil cylinder to apply force, and the offset distance between the oil cylinder and the rotation center of the flexible joint is used as the lever arm. The error of the indirect input torque includes: the error of the force applied by the oil cylinder and the error of the offset distance, and the measurement result has a large deviation. The present invention directly inputs the torque, which greatly reduces the error and outputs more accurate test results.

[0036] 3. The extension section of the flexible joint of the present invention is relatively fixed to the rotation center of the flexible joint body, and no additional force will be generated on the extension section of the flexible joint due to the deflection of the flexible joint body. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the application state structure of the flexible joint;

[0038] Figure 2 This is a structural front view of the test tooling of the present invention;

[0039] Figure 3 It is a right side cross-sectional view of the test tool of the present invention;

[0040] Figure 4 A top view of the structure of the test tooling of the present invention;

[0041] Among them: 1 is a liquid circulation device, 2 is a torque input balance wheel, 3 is a gearbox, 4 is a connecting rod, 5 is a frame, 6 is a vertical cylinder, 7 is a flexible joint extension section, 8 is a jacket fastening bolt, 9 is a fixed jacket, 10 is a counter, 11 is a flexible joint body, 12 is an inclination sensor, 13 is a cover, 14 is a bearing, 15 is a torque sensor, 16 is a cylinder connecting plate, 17 is a protruding section plug, 18 is a flexible joint elastomer, 19 is a flexible joint shell, 20 is a flexible joint flange, 21 is a circulating liquid inlet pipe, 22 is a displacement sensor, 23 is a limit block, 24 is a circulating liquid outlet pipe, 25 is a sea level, 26 is a seabed mud surface, 27 is a flexible joint, 28 is an offshore platform, 29 is an SCR riser, and 30 is a rotating shaft. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings.

[0043] like Figures 2 to 4 As shown, the test fixture of the present invention includes a liquid circulation device 1, a torque input power source, a transmission mechanism, a frame 5, a vertical cylinder 6, a fixed sleeve 9, a cover 13 and a cylinder connecting plate 16, wherein the flexible joint to be tested is installed in the fixed sleeve 9, and the fixed sleeve 9 is provided with a rotating shaft 30, and the rotating shaft 30 is rotatably connected to the frame 5; the lower end of the flexible joint to be tested is extended from the frame 5 to form a flexible joint extension section 7, and the flexible joint extension section 7 is provided with an extension section plug 17, and a cylinder connecting plate 16 is installed on the flexible joint extension section 7, and a vertical cylinder 6 for applying an axial load to the flexible joint extension section 7 is connected between the cylinder connecting plate 16 and the bottom of the frame 5, and the cylinder body or piston of the vertical cylinder 6 is fixedly connected to the frame 5, and the piston or cylinder body of the vertical cylinder 6 is fixedly connected to the cylinder connecting plate 16, and a displacement sensor 22 is installed at the bottom of the frame 5 to observe the axial displacement of the flexible joint, and the flexible joint is extended. A tension sensor is installed on the segment 7 to measure and control the applied axial tensile load; a torque input balance wheel 2 and a torque sensor 15 are installed on the rotating shaft 30 respectively, the torque sensor 15 is used to measure the torque of the deflection of the flexible joint elastic body 18, the torque input balance wheel 2 is connected to the torque input power source through a transmission mechanism, and the torque input power source drives the torque input balance wheel 2 to swing through the transmission mechanism, and then drives the fixed sleeve 9 and the flexible joint to swing through the rotating shaft 30, a counter 10 is installed on the torque input balance wheel 2, and an inclination sensor 12 is installed on the flexible joint body 11 located above the fixed sleeve 9 of the flexible joint to measure the deflection angle of the flexible joint body 11 under the action of the torque; the top of the flexible joint body 11 is sealed and connected to the cover 13, and the liquid circulation equipment 1 is connected to the cover 13 through the circulating liquid inlet pipe 21 and the circulating liquid outlet pipe 24, and is connected to the inside of the flexible joint.

[0044] The fixed sleeve 9 of this embodiment is in the shape of a hollow cylinder and is divided into two parts with the same structure. The horizontal projection of each part is semicircular. A rotating shaft 30 is provided on the outer surface of each part. The rotating shaft 30 is rotatably connected to the frame 5 through a bearing 14. The two parts are connected through a sleeve fastening bolt 8 to clamp the flexible joint inside the fixed sleeve 9. The frame 5 of this embodiment includes a bottom plate and two vertical plates. The two vertical plates are symmetrically located on both sides of the bottom plate and are perpendicular to the bottom plate. Each vertical plate is rotatably connected to a rotating shaft 30 through a bearing 14. The axial center lines of the two rotating shafts 30 on the fixed sleeve 9 are collinear and parallel to the horizontal plane. The deflection center of the flexible joint intersects the axial center lines of the two rotating shafts 30 perpendicularly.

[0045] The torque input power source of this embodiment is the gearbox 3, and the transmission mechanism is the connecting rod 4, one end of the connecting rod 4 is connected to the torque input balance wheel 2, and the other end is eccentrically connected to the output wheel of the gearbox 3. The gearbox 3 of this embodiment can be replaced by an oil cylinder, and the piston of the oil cylinder is extended and retracted to drive the connecting rod 4. The torque input balance wheel 2 of this embodiment can be replaced by a gear or a sprocket.

[0046] The torque sensor 15 of this embodiment is arranged between the torque input balance wheel 2 and the bearing 14 to reduce the deviation introduced by the friction resistance.

[0047] In this embodiment, a limit block 23 is installed on the rotating shaft 30. There are two limit blocks 23, which are symmetrically arranged on the left and right sides of the vertical section of the torque input balance wheel 2. They are used to control the torsion angle of the flexible joint and serve as a safety device to prevent the elastic body of the flexible joint from being excessively twisted.

[0048] The liquid circulation device 1 of this embodiment is a prior art, has heating and pressurizing functions, and is equipped with a pressure sensor and a temperature sensor, which can simulate high temperature (70°C) and high pressure (57MPa) transmission media to ensure that the pressure and temperature of the liquid (i.e., the transmission medium) entering the inner cavity of the flexible joint are stable.

[0049] The gearbox 3 of this embodiment is connected to an electro-hydraulic servo device, which is used to control the input size and frequency of the torque and cooperate with the counter 10 to perform fatigue characteristic tests; the counter is used for fatigue characteristic tests of the flexible joint and cooperates with the electro-hydraulic servo device to record the number of fatigue cycles.

[0050] The test method of the flexible joint test tool of the present invention includes a static test method and a fatigue test method, wherein:

[0051] The static test method includes the following steps:

[0052] A. Assemble the flexible joint to be tested; that is, the flexible joint flange 20 and the flexible joint shell 19 are fixedly connected by bolts to form the flexible joint body 11, the upper end of the hemispherical tube is located inside the flexible joint shell 19, and the flexible joint elastomer 18 is installed between the upper end of the hemispherical tube and the inner wall of the flexible joint shell 19, and the lower end of the hemispherical tube is the flexible joint extension section 7;

[0053] B. Fix the fixed sleeve 9 on the flexible joint, and use an adjustment gasket placed between the flexible joint housing 19 and the bottom of the fixed sleeve 9 to adjust the gap between the flexible joint and the bottom of the fixed sleeve 9, so that the deflection center of the flexible joint intersects the axial center line of the rotating shaft 10 perpendicularly;

[0054] C. Rotate and install the fixed jacket 9 and the flexible joint on the frame 5;

[0055] D. Install the torque input balance wheel 2, the torque sensor 15 and the limit block 23 on the rotating shaft 5, respectively, and connect the torque input balance wheel 2 to the torque input power source (i.e., the gearbox 3) through the transmission mechanism (i.e., the connecting rod 4);

[0056] E. Connect the flexible joint extension section 7 and the vertical cylinder 6;

[0057] F. Connect the cover 13 to the liquid circulation device 1 through the circulating liquid inlet pipe 21 and the circulating liquid outlet pipe 24, and connect the cover 13 to the top of the flexible joint body 11 of the flexible joint;

[0058] G. Install an inclination sensor on the flexible joint body 11, install a displacement sensor 22 at the bottom of the frame 5, and install a tension sensor on the flexible joint extension section 7;

[0059] H. Start the liquid circulation device 1, inject the medium liquid with adjusted temperature into the inner cavity of the flexible joint, and after the temperature of the liquid in the cavity is constant, adjust the outlet pressure of the pump station in the liquid circulation device 1 to the design value;

[0060] I. Apply axial load to the flexible joint elastic body 18 through the vertical oil cylinder 6 and the flexible joint extension section 7, and record the value of the displacement sensor 22;

[0061] J. Start the torque input power source, apply torque to the fixed outer sleeve 9 and the flexible joint through the torque input balance wheel 2 according to the design requirements, and record the values ​​of the inclination sensor 12, the torque sensor 15, the displacement sensor 22, and the tension sensor respectively;

[0062] The fatigue test method includes the following steps:

[0063] K. Install according to steps A to H of the static test method;

[0064] L. Apply axial load according to various working conditions according to the method in step I;

[0065] M. Control the torque input power source through the electro-hydraulic servo device to apply the cyclic torque;

[0066] N. The number of cycles is recorded by counter 10.

[0067] The above method is used to measure the deflection angle-torque of the flexible joint under high temperature and high pressure liquid environment and axial load, and the deflection stiffness curve is drawn based on this.

[0068] The present invention can simulate the actual working condition more realistically, connect the flexible joint extension section 7 with the vertical cylinder 6, and apply an axial load to the flexible joint extension section 7 through the vertical cylinder 6. The flexible joint housing 19 is locked by the fixed sleeve 9, and the fixed sleeve 9 is installed on the frame 5 through the rotating shaft 30. Then the torque input power source applies torque to the flexible joint body 11 through the torque sensor 15, and the angle change of the flexible joint body 11 is measured using the inclination sensor 12, so as to obtain a torque-angle curve, and further obtain a torsional stiffness curve. By injecting circulating high-temperature and high-pressure liquid into the flexible joint, the environment of the flexible joint under working conditions is simulated. By controlling the input direction of the torque input end and the frequency of change of the torque magnitude, the fatigue test of the flexible joint is realized.

Claims

1. A flexible joint test tool, characterized in that: The invention comprises a liquid circulation device (1), a torque input power source, a transmission mechanism, a frame (5), a vertical oil cylinder (6), a fixed sleeve (9), a cover (13) and an oil cylinder connecting plate (16), wherein a flexible joint to be tested is installed in the fixed sleeve (9), the fixed sleeve (9) is provided with a rotating shaft (30), and the rotating shaft (30) is rotatably connected to the frame (5); the lower end of the flexible joint to be tested extends from the frame (5) to form a flexible joint extension section (7), the flexible joint extension section (7) is provided with an oil cylinder connecting plate (16), a vertical oil cylinder (6) for applying an axial load to the flexible joint extension section (7) is connected between the oil cylinder connecting plate (16) and the bottom of the frame (5), a displacement sensor (22) is installed at the bottom of the frame (5), and a tension sensor (22) is installed on the flexible joint extension section (7). force sensor; a torque input balance wheel (2) and a torque sensor (15) are respectively mounted on the rotating shaft (30); the torque input balance wheel (2) is connected to a torque input power source via a transmission mechanism; the torque input power source drives the torque input balance wheel (2) to swing via the transmission mechanism, and then drives the fixed sleeve (9) and the flexible joint to swing via the rotating shaft (30); a counter (10) is mounted on the torque input balance wheel (2); a tilt sensor (12) is mounted on a flexible joint body (11) of the flexible joint located above the fixed sleeve (9); the top of the flexible joint body (11) is sealedly connected to a cover (13); the liquid circulation device (1) is connected to the cover (13) via a circulating liquid inlet pipe (21) and a circulating liquid outlet pipe (24), and is communicated with the interior of the flexible joint; The fixed outer sleeve (9) is in the shape of a hollow cylinder and is divided into two parts with the same structure. The horizontal projection of each part is semicircular. A rotating shaft (30) is provided on the outer surface of each part. The rotating shaft (30) is rotatably connected to the frame (5) via a bearing (14). The two parts are connected via outer sleeve fastening bolts (8) to clamp the flexible joint inside the fixed outer sleeve (9). The axial center lines of the two rotating shafts (30) on the fixed sleeve (9) are collinear and parallel to the horizontal plane, and the deflection center of the flexible joint intersects the axial center lines of the two rotating shafts (30) perpendicularly; The frame (5) comprises a bottom plate and two vertical plates, wherein the two vertical plates are symmetrically located on both sides of the bottom plate and are perpendicular to the bottom plate, and each of the vertical plates is rotatably connected to a rotating shaft (30) via the bearing (14).

2. The flexible joint test tool according to claim 1, characterized in that: The torque input power source is a gearbox (3), the transmission mechanism is a connecting rod (4), one end of the connecting rod (4) is connected to the torque input balance wheel (2), and the other end is eccentrically connected to the output wheel of the gearbox (3).

3. The flexible joint test tool according to claim 1, characterized in that: A limit block (23) is mounted on the rotating shaft (30), and there are two limit blocks (23) which are symmetrically arranged on the left and right sides of the vertical cross section of the torque input balance wheel (2).

4. The flexible joint test tool according to claim 1, characterized in that: An extension section seal (17) is provided in the extension section (7) of the flexible joint.

5. A test method for the flexible joint test tool according to any one of claims 1 to 4, characterized in that: Including static test methods and fatigue test methods, The static test method includes the following steps: A. Assemble the flexible joint to be tested; B. Fixing the fixed sleeve (9) on the flexible joint; C. Rotate and install the fixed sleeve (9) and the flexible joint on the frame (5); D. installing a torque input balance wheel (2) and a torque sensor (15) on the rotating shaft (30), and connecting the torque input balance wheel (2) to a torque input power source through a transmission mechanism; E. Connecting the flexible joint extension section (7) to the vertical cylinder (6); F. Connecting the cover (13) to the liquid circulation device (1) through the circulating liquid inlet pipe (21) and the circulating liquid outlet pipe (24), and connecting the cover (13) to the top of the flexible joint body (11) of the flexible joint; G. Installing an inclination sensor on the flexible joint body (11), installing a displacement sensor (22) on the bottom of the frame (5), and installing a tension sensor on the extended section (7) of the flexible joint; H. Start the liquid circulation device (1), inject the medium liquid whose temperature has been adjusted into the inner cavity of the flexible joint, and after the temperature of the liquid in the cavity becomes constant, adjust the outlet pressure of the pump station in the liquid circulation device (1) to the designed value; I. Apply an axial load to the flexible joint elastic body (18) through the vertical oil cylinder (6) and the flexible joint extension section (7), and record the value of the displacement sensor (22); J. Start the torque input power source, apply torque to the fixed outer sleeve (9) and the flexible joint through the torque input balance wheel (2) according to the design requirements, and record the values ​​of the inclination sensor (12), the torque sensor (15), the displacement sensor (22) and the tension sensor respectively; The fatigue test method includes the following steps: K. Install according to steps A to H of the static test method; L. Then apply axial load according to various working conditions according to the method in step I; M. Control the torque input power source through the electro-hydraulic servo device to apply the cyclic torque; N. The number of cycles is recorded by a counter (10).

6. The test method according to claim 5, characterized in that: In step B, an adjustment gasket is placed between the flexible joint housing (19) and the bottom of the fixed sleeve (9) to adjust the gap between the flexible joint and the bottom of the fixed sleeve (9) so that the deflection center of the flexible joint intersects perpendicularly with the axial center line of the rotating shaft (30).

7. The test method according to claim 5, characterized in that: In the step D, a limit block (23) is simultaneously installed on the rotating shaft (30).

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