PE pipe flange strength test tool and method

Abstract

The application discloses a PE pipe flange strength test tool and method, and relates to the technical field of shipbuilding. The tool comprises a base, a stretching device and a jacking device arranged on the base. The stretching device comprises a left flange joint fixed on the base, a right flange joint arranged opposite to the left flange joint and slidingly arranged on the base, and a sliding driving device for driving the right flange joint to slide leftward and rightward. The left flange joint, the PE pipe and the right flange joint enclose a closed space. A water inlet pipe is arranged on the left flange joint and is connected with the closed space and the outside. The water inlet pipe is connected with a water tightness test device. The jacking device is arranged at the bottom of the PE pipe. The tool can effectively simulate the stress of the PE pipe caused by temperature and ship body deformation during the ship operation process, detect whether the ship pipe leaks, effectively verify the influence of the vertical arch on the flange strength during the ship operation process, and thus the construction can be advanced, and the delay of the ship delivery caused by the replacement and maintenance in the later period can be avoided.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a PE pipe flange strength testing fixture and method. Background Technology

[0002] In recent years, PE pipes have been increasingly used in the ballast systems of large ships. These systems are characterized by a long straight pipe section along the length of the ship and a large main pipe diameter. Because PE pipes have a large coefficient of thermal linear expansion, expansion joints are generally not installed. Therefore, the stress generated by temperature / ship deformation is absorbed by the PE pipe itself, and this stress is relatively large.

[0003] Currently, the strength testing method for PE pipe flanges generally adopts the GB / 15820-1995 standard. However, this method has the following problems: Using a tensile tester in GB / 15820-1995 is only suitable for small-diameter PE pipes; while marine ballast main pipes are larger, existing testing equipment cannot clamp them and cannot provide sufficient tensile force, making custom-made equipment very expensive. Furthermore, the tensile testing equipment cannot perform watertightness testing during the test, thus failing to verify whether the ship's pipes leak under stress. Additionally, the vertical arching during ship operation affects flange strength; and current verification methods can only verify PE pipe flange strength and bolt preload during sea trials. If the PE pipe flange strength is insufficient or the bolt preload is inadequate, the PE pipe flange needs to be replaced on-site or the bolt preload increased, which will delay delivery and affect shipyard profits. Summary of the Invention

[0004] The purpose of this invention is to provide a PE pipe flange strength testing fixture and method, which effectively simulates the stress caused by temperature / hull deformation during ship operation to detect whether the ship pipe is leaking. At the same time, it effectively verifies the influence of the vertical arch on the flange strength during ship operation, thereby enabling early construction and avoiding delays in ship delivery caused by later replacement and maintenance.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention discloses a PE pipe flange strength testing fixture, comprising a base, a tensioning device and a lifting device mounted on the base; the tensioning device includes a left flange joint fixed on the base, a right flange joint slidably mounted on the base opposite to the left flange joint, and a sliding drive device for driving the right flange joint to slide left and right; one end of the PE pipe to be tested is fixed on the left flange joint, and the other end is fixed on the right flange joint; the left flange joint, the PE pipe and the right flange joint form a sealed space; a water inlet pipe is provided on the left flange joint to connect the sealed space to the outside, and the water inlet pipe is connected to a water tightness testing device; the lifting device is located at the bottom of the PE pipe and is used to lift the PE pipe upward.

[0007] With the above structure, the PE pipe to be tested is installed on the left and right flange joints. The right flange joint is moved to the right by a sliding drive device, thereby stretching the PE pipe to simulate the stress tension caused by temperature / hull deformation after the PE pipe is installed on the ship. The PE pipe is lifted from the bottom by a jacking device, thereby simulating the impact on the flange strength caused by the ship's sag and arch after the PE pipe is installed on the ship. Then, high-pressure water is introduced into the sealed space formed by the left flange joint, the PE pipe, and the right flange joint to detect whether the ship's pipe is leaking. Based on the test results, the PE pipe flange can be replaced in advance or the bolt preload can be increased to prevent rework after the PE pipe is installed on the ship, which would cause delays in the construction period.

[0008] Preferably, a left mounting plate and a right mounting plate are fixedly installed on the base, facing each other. The left flange joint is fixed to the left mounting plate, and the right flange joint is slidably installed on the right mounting plate. A limiting post is set on the base on both the front and rear sides of the PE pipe. A sliding rod is fixed between each limiting post and the right mounting plate. The axis of the sliding rod is in the left-right direction, and the right flange joint is slidably installed on the sliding rod. This design ensures that the right flange joint can slide smoothly.

[0009] Preferably, the sliding drive device includes a worm gear jack and a stepper motor that drives the worm gear jack, with the output shaft of the worm gear jack fixed to the right flange joint. This design allows for precise control of the sliding distance of the right flange joint, thereby controlling the tensile distance of the PE pipe and resulting in more accurate test data.

[0010] Preferably, two sliding rods are fixed between each limiting post and the right mounting plate, and the two sliding rods are arranged parallel to each other vertically. This design provides sufficient support points for the right flange joint, thereby reducing the possibility of deformation caused by stress on a single sliding rod, and ensuring the sliding stability of the right flange joint.

[0011] Preferably, the lifting device includes a lifting platform mounted on the base that moves up and down, and a lifting drive device that drives the lifting platform to move up and down. With this design, the lifting platform pushes the PE pipe upward from the bottom, thereby simulating the sag and arch state of the PE pipe.

[0012] Preferably, the lifting platform includes a V-shaped support frame; the PE pipe is supported on the front and rear inclined surfaces of the V-shaped support frame. This design increases the contact area between the PE pipe and the lifting platform, ensuring balanced force on the PE pipe and preventing deformation.

[0013] Preferably, support wheels are rotatably mounted on the front and rear inclined surfaces of the V-shaped support frame. The support wheels support the bottom of the PE pipe and rotate in the left-right direction. This design avoids friction between the V-shaped support frame and the PE pipe during the lifting or stretching process, thus preventing damage to the PE pipe.

[0014] Preferably, there are two lifting devices, located on the left and right sides of the PE pipe respectively. This design makes the PE pipe more stable in shape and more evenly stressed when simulating a sag or arch, thus avoiding damage to the PE pipe caused by uneven stress.

[0015] A method for conducting experiments using the aforementioned PE pipe flange strength testing fixture includes the following steps: S1: Calculate the maximum deformation of the PE pipe ΔL1 caused by temperature differences; S2: Calculate the maximum deformation of the PE pipe along the ship's length ΔL2 and the sag and camber caused by hull deformation during ship operation; S3: Fabricate the test PE pipe and clamp the flange of the PE pipe onto the tensioning device of the PE pipe flange strength testing fixture; S4: Stretch the PE pipe using the tensioning device for a stretching length of ΔL, where ΔL = ΔL1 + ΔL2; S5: Lift the PE pipe using a jacking device to ensure that the sag and camber of the PE pipe are consistent with the sag and camber calculated in S2; Step S6: Perform a pressure tightness test by filling the inlet pipe with water using a water tightness testing device to check for leaks in the PE pipe.

[0016] By adopting the above method, it is possible to effectively simulate the situation where PE pipes are subjected to stress caused by temperature / hull deformation during ship operation, and detect whether the ship pipes are leaking. At the same time, it is possible to effectively verify the impact of the vertical arch on the flange strength during ship operation, so as to carry out construction in advance and avoid the delay in ship delivery caused by later replacement and maintenance.

[0017] Preferably, the formula for calculating the maximum deformation ΔL1 of the PE pipe in S1 is: ΔL1=Δt*α*L; where Δt is the highest temperature difference estimated from the installation to the use stage of the PE pipe based on historical temperatures; α is the linear expansion coefficient of the PE pipe; and L is the total length of the PE pipe. This design allows for accurate calculation of the deformation of the PE pipe due to temperature, thus making the simulation data more accurate.

[0018] After adopting the above technical solution, the beneficial effects of the present invention are:

[0019] This invention provides a PE pipe flange strength testing fixture and method, which solves the technical problem in the prior art where PE pipes in large ship ballast systems cannot be simulated in advance, leading to rework after assembly and affecting the construction period. This invention effectively simulates the stress caused by temperature / hull deformation during ship operation, detecting whether the ship's pipes are leaking. At the same time, it effectively verifies the impact of the vertical arch on the flange strength during ship operation, thereby enabling early construction and avoiding delays in ship delivery caused by later replacement and maintenance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a PE pipe flange strength testing fixture and method according to the present invention;

[0021] Figure 2 yes Figure 1 A schematic diagram of the tooling structure without the PE pipe assembled in the middle;

[0022] Figure 3 yes Figure 1 Side view;

[0023] Figure 4 This is a schematic diagram of the lifting device.

[0024] In the diagram, 1. Base, 11. Limiting post, 2. Tensioning device, 21. Left flange joint, 211. Left mounting plate, 22. Right flange joint, 221. Right mounting plate, 222. Slide rod, 23. Sliding drive device, 231. Worm gear jack, 232. Stepper motor, 3. Lifting device, 31. Lifting platform, 311. V-shaped support frame, 312. Lifting drive device, 313. Support wheel, 314. Telescopic column, 4. PE pipe, 41. Flange, 5. Water inlet pipe. Detailed Implementation

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] The orientations mentioned in this specification are based on the orientation of the PE pipe flange strength testing fixture and method of this invention during normal operation, and do not limit the orientation during storage and transportation. They only represent relative positional relationships and do not represent absolute positional relationships.

[0027] like Figure 1 , Figure 2 and Figure 3 As shown in the figure, a PE pipe flange strength testing fixture includes a base 1, a tensioning device 2 and a lifting device 3 disposed on the base 1.

[0028] The tensile device 2 includes a left flange joint 21 fixed on the base 1, a right flange joint 22 slidably mounted on the base 1 and arranged opposite to the left flange joint 21, and a sliding drive device 23 for driving the right flange joint 22 to slide left and right. Flanges 41 are fixed to both ends of the PE pipe 4 to be tested, with one flange 41 fixed to the left flange joint 21 and the other flange 41 fixed to the right flange joint 22. The flanges 41 are bolted to the left flange joint 21 / right flange joint 22 on the same side, forming a sealed space with the left flange joint 21, the PE pipe, and the right flange joint 22.

[0029] The sliding installation method of the right flange joint 22 can be a variety of structures, such as a slide rail on the base 1 and a slider fixedly installed on the right flange joint 22, with the slider slidingly installed in the slide rail to realize the sliding installation of the right flange joint 22.

[0030] In this embodiment, to facilitate the installation of the left flange joint 21 and the right flange joint 22, a left mounting plate 211 and a right mounting plate 221 are fixedly installed on the base 1, respectively, with their left and right sides facing each other. To maintain the stability of the device, the four corners of the left mounting plate 211 and the right mounting plate 221 are connected by connecting rods to form a stable frame structure. The left flange joint 21 is fixed on the left mounting plate 211, and the right flange joint 22 is slidably installed on the right mounting plate 221. The sliding installation method of the right mounting plate 221 is as follows: a limiting post 11 is set on the base 1 on both the front and rear sides of the PE pipe 4, and a sliding rod 222 is fixed between each limiting post 11 and the right mounting plate 221. The axis of the sliding rod 222 is in the left and right direction. The right flange joint 22 is provided with a sliding hole for the sliding rod 222 to pass through. By fitting the right flange joint 22 onto the sliding rod 222, the right flange joint 22 is slidably installed on the sliding rod 222.

[0031] To ensure smoother sliding, a sliding sleeve is installed inside the sliding hole. Furthermore, to improve the guiding effect of the sliding of the right flange joint 22, in this embodiment, two sliding rods 222 are fixed between each limiting post 11 and the right mounting plate 221. The two sliding rods 222 are arranged parallel to each other vertically, thereby ensuring that the right flange joint 22 is more stable.

[0032] The sliding drive device 23 can be an electric cylinder, a pneumatic cylinder, or an electric push rod. To achieve precise control of the stretching, in this embodiment, the sliding drive device 23 includes a worm gear jack 231 and a stepper motor 232 that drives the worm gear jack 231. The output shaft of the worm gear jack 231 is fixed to the right flange joint 22. The stepper motor 232 drives the movement of the worm gear jack 231, thereby controlling the left and right sliding of the right flange joint 22, thus achieving the stretching of the PE pipe 4. The left flange joint 21 is provided with a water inlet pipe 5 connecting the sealed space to the outside world. The water inlet pipe 5 is connected to a watertightness testing device.

[0033] A lifting device 3 is installed at the bottom of the PE pipe 4 to lift the PE pipe 4 upwards. The lifting device 3 includes a lifting platform 31 that is mounted vertically on the base 1 and located at the bottom of the PE pipe 4 to be tested, and a lifting drive device 312 that drives the lifting platform 31 to rise and fall. The lifting drive device 312 can be a hydraulic lifting device, which drives the lifting platform 31 to rise and fall. The rising and falling of the lifting platform 31 causes the middle of the PE pipe 4 to bulge upwards, thereby simulating the mid-sag and arch state of a ship during navigation. In order to make the mid-sag and arch shape of the PE pipe 4 more stable, two lifting platforms 31 are provided in this embodiment, located on the left and right sides of the PE pipe 4 respectively.

[0034] like Figure 4 As shown, the lifting platform 31 includes a V-shaped support frame 311; the PE pipe 4 is clamped between the front and rear inclined surfaces of the V-shaped support frame 311, which is welded from steel pipes.

[0035] To prevent the V-shaped support frame 311 from causing wear to the PE pipe 4 during stretching and lifting, support wheels 313 are rotatably installed on the front and rear inclined surfaces of the V-shaped support frame 311. The support wheels 313 support the bottom of the PE pipe 4 and rotate in the left and right direction.

[0036] In order to make the lifting platform 31 more stable, telescopic columns 314 are provided on the front and rear sides of the V-shaped support frame 311. The fixed end of the telescopic column 314 is fixed on the base 1, and the telescopic end of the telescopic column 314 is fixed on the V-shaped support frame 311.

[0037] A method for conducting experiments using the aforementioned PE pipe flange strength testing fixture includes the following steps:

[0038] S1: Calculate the maximum deformation of the PE pipe ΔL1 caused by temperature difference;

[0039] Based on the historical temperatures of the shipyard's location, the maximum temperature difference Δt from the installation of the PE pipe to its service stage is estimated, and the maximum deformation ΔL1 of the PE pipe due to temperature is calculated. The formula for calculating ΔL1 is: ΔL1=Δt*α*L, where α is the linear expansion coefficient of the PE pipe, which can be found in the PE pipe material certificate; the linear expansion coefficient refers to the amount of linear expansion of a unit length of PE pipe along its length when the temperature changes by 1℃; the specific value is 1.1 to 1.3 multiplied by 10 to the power of negative 4 per Kelvin (10^-4 / K), meaning that if the temperature rises by 1K (or 1℃), each meter of PE pipe will increase in length by approximately 0.00011 to 0.00013 meters (i.e., 1.1 to 1.3 micrometers) due to thermal expansion. L is the total length of PE pipe 4.

[0040] S2: Calculate the maximum deformation ΔL2 and mid-sag and camber of the PE pipe in the longitudinal direction caused by the ship's hull structure during ship operation;

[0041] The maximum deformation ΔL2 of the PE pipe in the longitudinal direction caused by the hull structure during ship operation, and the maximum structural sagging and camber of the PE pipe are calculated through structural finite element analysis (software analysis software includes PKPM, 3D3S, MTS, MST, Tongji Qimingxing, ETABS, SAP2000, SAFE, PERFORM-3D, MIDAS, STAAD PRO, ROBOT, EASY, FORTEN, ANSYS, ABAQUS, NASTRAN, MARC, LS-DYNA, etc.).

[0042] S3: Fabricate the test PE pipe 4 and clamp the flange of the PE pipe 4 onto the tensile device 2 of the PE pipe flange strength test fixture.

[0043] Fabricate the test PE pipe and assemble PE pipe 4 with the aforementioned PE pipe flange strength test fixture. It is particularly important to note that the length L + △L1 + △L2 should be less than the maximum left-right distance between the left flange joint 21 and the right flange joint 22. The flange on one side of PE pipe 4 is fixed to the left flange joint 21 with bolts, and the flange on the other side is fixed to the right flange joint 22 with studs. The PE pipe consists of multiple pipes that are joined together laterally, with adjacent pipes fixedly connected by flanges and clamped with sealing rings.

[0044] S4: The PE pipe is stretched by the stretching device 2, and the stretching length is △L, where △L=△L1+△L2.

[0045] The sliding drive device 23 drives the right flange joint 22 to slide to the right, thereby stretching the PE pipe 4.

[0046] S5: Lift the PE pipe using the lifting device 3 to make the sag and arch of the PE pipe consistent with the sag and arch calculated in S2.

[0047] Step S6: Fill the inlet pipe 5 with water using a water tightness tester to perform a pressure tightness test and check for leaks in the PE pipe.

[0048] Perform a 1-hour leak test on PE pipe 4 at 1.5 times the design pressure to check for leaks in the pipeline.

[0049] This invention provides a PE pipe flange strength testing fixture and method, which solves the technical problem in the prior art where PE pipes in large ship ballast systems cannot be simulated in advance, leading to rework after assembly and affecting the construction period. This invention effectively simulates the stress caused by temperature / hull deformation during ship operation, detecting whether the ship's pipes are leaking. At the same time, it effectively verifies the impact of the vertical arch on the flange strength during ship operation, thereby enabling early construction and avoiding delays in ship delivery caused by later replacement and maintenance.

[0050] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method of conducting an experiment using a PE pipe flange strength test fixture, characterized by: The method utilizes a PE pipe flange strength test tool, the test tool comprising a base, a stretching device and a jacking device arranged on the base; the stretching device comprises a left flange joint fixed on the base, a right flange joint arranged opposite to the left flange joint and slidingly installed on the base, and a sliding driving device driving the right flange joint to slide left and right; the PE pipe to be tested is fixed at one end on the left flange joint and at the other end on the right flange joint; the left flange joint, the PE pipe and the right flange joint enclose a closed space; a water inlet pipe is arranged on the left flange joint and communicates the closed space with the outside, and the water inlet pipe is connected to a water tightness test device; the jacking device is arranged at the bottom of the PE pipe and is used to jacking the PE pipe upward; The method comprises the following steps: S1: calculating the maximum deformation amount of the PE pipe caused by temperature difference △L1; S2: calculating the maximum deformation amount of the PE pipe in the length direction of the ship caused by the deformation of the ship body and the sag amount of the middle vertical arch; S3: manufacturing a test PE pipe and clamping the flange plate of the PE pipe to the stretching device of the PE pipe flange strength test tool; S4: stretching the PE pipe by the stretching device, and the stretching length is △L, wherein △L=△L1+△L2; S5: jacking the PE pipe by the jacking device, so that the sag amount of the middle vertical arch of the PE pipe is consistent with the sag amount of the middle vertical arch calculated in S2; Step S6: filling water into the water inlet pipe by the water tightness test device to perform pressure tightness test, and checking whether the PE pipe leaks.

2. The method of claim 1, wherein the method is characterized by: The left and right installation plates are fixed on the base in opposite directions; the left flange joint is fixed on the left installation plate, and the right flange joint is slidingly installed on the right installation plate; a limiting column is arranged on the base at the front and back of the PE pipe, and a slide rod is fixed between each limiting column and the right installation plate, the axial direction of the slide rod being left and right, and the right flange joint being slidingly installed on the slide rod.

3. The method of claim 1, wherein the method is characterized by: The sliding driving device comprises a worm gear elevator and a stepping motor driving the worm gear elevator to operate, and the output shaft of the worm gear elevator is fixed on the right flange joint.

4. The method of claim 2, wherein the method is characterized by: Two slide rods are fixed between each limiting column and the right installation plate, and the two slide rods are arranged in parallel in the up and down direction.

5. The method of claim 1, wherein the method is characterized by: The jacking device comprises a lifting platform moving up and down on the base and a lifting driving device driving the lifting platform to lift.

6. The method of testing with the PE pipe flange strength test tooling according to claim 5, characterized in that: The lifting platform comprises a V-shaped support frame, and the PE pipe is supported on the front and back inclined surfaces of the V-shaped support frame.

7. The method of claim 6, wherein the method is characterized by: Support wheels are rotatably installed on the front and back inclined surfaces of the V-shaped support frame, and the support wheels are supported on the bottom of the PE pipe and rotate in the left and right direction.

8. The method of claim 5, wherein the method is characterized by: The jacking device is provided with two jacking devices, which are respectively arranged on the left and right sides of the PE pipe.

9. The method of claim 1, wherein The calculation formula of the maximum deformation amount AL1 of the PE pipe of the S1 is: AL1=AL*alpha*L; wherein, AL is the temperature difference from the installation of the PE pipe to the highest temperature in the use stage according to the temperature in the past years; alpha is the linear expansion coefficient of the PE pipe; and L is the total length of the PE pipe.

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