HDPE pipeline underwater flange butt joint system and butt joint method

Abstract

The invention relates to the technical field of HDPE pipeline butt joint, in particular to an HDPE pipeline underwater flange butt joint system and a butt joint method.The HDPE pipeline underwater flange butt joint system comprises a crane ship and a plurality of air sacs, the air sacs are bound to an installed HDPE pipeline and a to-be-installed HDPE pipeline, the crane ship comprises a first winch, a second winch and a crane, and the crane ship comprises a first winch, a second winch and a second winch. First cables of the first winch and the second winch are connected with the to-be-mounted HDPE pipeline, and the crane is connected with the to-be-mounted HDPE pipeline through a second cable; the first winch and the second winch are used for adjusting the horizontal position of the to-be-installed HDPE pipeline, and the crane is used for adjusting the elevation of the to-be-installed HDPE pipeline. According to the underwater flange butt joint system, the defects of a traditional underwater HDPE pipeline butt joint technology are overcome, the precision, efficiency and safety of butt joint of large-diameter and overweight HDPE pipeline underwater flanges are remarkably improved, high applicability and economical efficiency are achieved, and a reliable technical solution is provided for HDPE pipeline installation in ocean engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of HDPE pipeline butt joint, and particularly to an underwater flange butt joint system and a butt joint method for HDPE pipelines. Background Art

[0002] HDPE pipes (High Density Polyethylene pipes) can be well used as the seawater intake pipes of seawater cooling systems because they have a series of excellent properties, such as reliable connection, strong impact resistance of materials, outstanding anti-cracking ability, aging resistance, and corrosion resistance.

[0003] When large-diameter (inner diameter exceeding 3m) and overweight (pipe section length exceeding 5.5m, linear weight exceeding 0.9t / m) HDPE pipes reach the installation position and are sunk, underwater flange butt joint is required. Currently, the commonly used underwater pipeline butt joint methods mostly rely on ultrasonic detection devices (underwater three-dimensional systems) to cooperate with the guiding systems on land to assist in butt joint. This method has low butt joint accuracy, high operation difficulty, and requires repeated measurement, inspection, and calculation to achieve pipeline butt joint. Moreover, due to the long length, large diameter, and heavy weight of the HDPE pipes used for water intake, and being greatly affected by ocean currents, the above traditional methods are not applicable. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the existing underwater pipeline butt joint technology, such as low butt joint accuracy, high operation difficulty, low butt joint efficiency, and inapplicability to underwater butt joint of large-diameter and overweight HDPE pipes, and to provide an underwater flange butt joint system and a butt joint method for HDPE pipelines.

[0005] In the first aspect, the present invention provides an underwater flange butt joint system for HDPE pipelines, including a crane ship and a number of air bags. The air bags are tied to the installed HDPE pipeline and the HDPE pipeline to be installed. The crane ship includes a first winch, a second winch, and a crane. The first cables of the first winch and the second winch are both connected to the HDPE pipeline to be installed, and the crane is connected to the HDPE pipeline to be installed through a second cable. The first winch and the second winch are used to adjust the horizontal position of the HDPE pipeline to be installed, and the crane is used to adjust the elevation of the HDPE pipeline to be installed.

[0006] The HDPE pipeline underwater flange docking system provided by the present invention, through the precise control of the first winch, the second winch and the crane equipped on the lifting vessel, replaces the traditional manual repeated measurement and adjustment method, greatly reducing the operation difficulty and achieving the precise adjustment of the horizontal position and elevation of the HDPE pipeline to be installed underwater; the airbag is tied to the pipeline to provide buoyancy for auxiliary adjustment, which can effectively reduce the influence of ocean current on the pipeline attitude and keep the flange docking position stable, thus significantly improving the docking accuracy. The combined adjustment of the winch and the crane makes it faster to adjust the pipeline attitude during the docking process, without the need for multiple reworks, thus shortening the construction time of underwater docking and improving the overall efficiency. Since this system reduces the steps of repeated inspection and calculation in the traditional method and reduces the dependence on complex underwater detection equipment, the construction is more efficient.

[0007] The HDPE pipeline underwater flange docking system provided by the present invention, through the innovative combination of mechanical equipment and airbag binding technology, not only overcomes many deficiencies of the traditional underwater HDPE pipeline docking technology, significantly improves the accuracy, efficiency and safety of underwater flange docking of large-diameter and overweight HDPE pipelines, but also has strong applicability and economy, providing a reliable technical solution for the installation of HDPE pipelines in ocean engineering.

[0008] Preferably, the airbag is a 5T airbag.

[0009] Preferably, the airbag is a 5T airbag (each can carry a weight of 5 tons), which can provide sufficient buoyancy for overweight HDPE pipelines and effectively reduce the influence of gravity on the pipelines in the underwater environment. The airbag's inflation and deflation adjustment function can flexibly adjust the buoyancy to adapt to the adjustment needs of the pipeline attitude, thus improving the flexibility and stability of underwater docking operations.

[0010] Preferably, the first winch and the second winch are 10T winches.

[0011] Preferably, both the first and second winches are 10T winches (the maximum pulling force of a single winch is 10 tons), which can meet the horizontal position adjustment needs of large-diameter (inner diameter exceeding 3m) and overweight (weight per meter exceeding 0.9t / m) HDPE pipelines. Even in the face of ocean current impacts in the ocean environment, they can provide sufficient pulling force for precise adjustment. The independent operation function of the first and second winches supports precise fine-tuning in the left and right directions of the pipeline, ensuring that the flange docking surfaces are accurately aligned, and further improving the docking accuracy.

[0012] In a second aspect, the present invention provides a method for underwater flange docking of HDPE pipelines, using the above-mentioned HDPE pipeline underwater flange docking system, including the following steps:

[0013] S1: Control the inflation degree of the airbag so that the butt joints of the HDPE pipe to be installed and the installed HDPE pipe are suspended at substantially the same height, and adjust the position of the HDPE pipe to be installed so that the butt joints of the HDPE pipe to be installed and the installed HDPE pipe maintain a safe distance;

[0014] S2: Connect the first cables of the first hoist and the second hoist to the butt joint of the HDPE pipe to be installed, and connect the second cable to the butt joint of the HDPE pipe to be installed; operate the first hoist and the second hoist to tighten the first cable at the same time, and pull the HDPE pipe to be installed closer to the installed HDPE pipe;

[0015] S3: operate the first winch and / or the second winch to jog, adjust the horizontal position of the HDPE pipe to be installed, operate the crane to adjust the elevation of the HDPE pipe to be installed, until the butt joint of the HDPE pipe to be installed fits with the butt joint of the installed HDPE pipe, and the holes of the first flange of the HDPE pipe to be installed and the second flange of the installed HDPE pipe are aligned, and the bolts are evenly inserted into the bolt holes of the first flange and the second flange to complete the flange bolt installation;

[0016] S4: Starting from the docking area between the HDPE pipe to be installed and the installed HDPE pipe, release the airbags to both sides to complete the bottom sinking of the HDPE pipe to be installed and the installed HDPE pipe.

[0017] The HDPE pipeline underwater flange docking method provided by the present invention makes the docking pipe head suspend and keep the suspension height consistent through the inflation and deflation adjustment of the air bag, thereby ensuring the stability of the pipeline in the water, reducing the docking deviation caused by gravity and ocean currents, and greatly improving the docking accuracy; before docking, the pipe head is kept at a safe distance, effectively preventing collision damage caused by unstable pipeline posture or external ocean currents, and ensuring the safety of pipelines and equipment;

[0018] The use of airbags to assist suspension and winch / crane precise adjustment avoids violent shaking and loss of control during the pipe docking process, reduces the risk of divers participating, and improves the safety of construction workers. The airbag inflation and deflation operation is simple and can be recycled many times, effectively reducing construction costs. The winch simultaneously tightens the first cable to ensure the accuracy of the HDPE pipe movement, avoids accidental tilting or movement of the pipe due to lack of coordination, and greatly reduces the probability of errors during the docking process.

[0019] The first winch, the second winch and the crane are adjusted in multiple dimensions, including precise control of the horizontal position and elevation, so that the pipe docking heads are seamlessly fitted, ensuring the precise alignment of the flange holes. After the flanges are aligned, bolts are immediately inserted for fixation. Without additional auxiliary equipment, the underwater operation procedure is simplified, the docking time is reduced, and the overall construction efficiency is improved. After the flange holes are aligned, bolts are evenly inserted for fixation, avoiding the problem of uneven local stress, improving the reliability of the flange connection, and ensuring the safety and stability of the pipeline during subsequent operation. The airbags are gradually released from the docking area to both sides, making the pipeline sinking process smooth and uniform, avoiding docking misalignment or equipment damage caused by sudden settlement, and ensuring the construction quality.

[0020] The underwater flange docking method for HDPE pipes provided by the present invention optimizes the operation process through systematic step-by-step design (such as S2 pulling closer, S3 fine-tuning, S4 releasing the airbag and sinking). The precise adjustment during the operation process reduces the steps of repeated probing and measurement in the traditional method, and improves the docking speed.

[0021] Preferably, in S1, the suspension height of the HDPE pipe to be installed and the installed HDPE pipe is 0.8 m - 1.2 m from the bottom of the pipe to the mud surface.

[0022] Controlling the suspension height within the range of 0.8 m - 1.2 m can effectively avoid the frictional resistance that may be caused by the contact between the bottom of the pipe and the mud surface, and also avoid the problem of unstable attitude caused by too high suspension; within this height range, the HDPE pipe can be in a relatively stable water flow area near the seabed, reducing the interference of ocean currents on the pipeline docking accuracy, thereby further improving the reliability of flange docking.

[0023] Preferably, in S1, the safety distance is 4.5 m - 5.5 m.

[0024] Setting the safety distance to 4.5 m - 5.5 m ensures that there is enough adjustment space for the pipe to be installed during the approaching process. The position of the pipe can be precisely controlled by the winch and the crane, and the residual deviation can be gradually eliminated, improving the accuracy of flange docking.

[0025] Preferably, before the first cable is connected to the docking head of the HDPE pipe to be installed, the diver first removes the blind plate at the docking head end of the HDPE pipe to be installed and the sand plate at the docking head end of the installed HDPE pipe.

[0026] Removing the blind plate and the sand plate before the connection of the first cable prepares for the subsequent flange docking, avoiding construction inconvenience caused by the interference of the subsequent blind plate and sand plate, and saving time and labor costs.

[0027] Preferably, in S3, the order of evenly inserting bolts into the bolt holes of the first flange and the second flange is to evenly insert GRP bolts from the high position to the low position of the first flange and the second flange.

[0028] Inserting GRP bolts evenly from the high position to the low position can effectively prevent the flange from tilting or deforming caused by the bolts being inserted on one side first, ensure that the flange remains horizontal during the butt joint process, avoid stress concentration affecting the flange sealing surface, and make the force on the flange gradually uniform by evenly inserting GRP bolts, thus avoiding local warping or sealing failure of the flange caused by excessive force at a single point, and further improving the airtightness and watertightness of the butt joint.

[0029] Preferably, after evenly inserting bolts into the bolt holes of the first flange and the second flange in S3, check whether there is a wedge-shaped gap between the first flange and the second flange. When the tops of the first flange and the second flange are in contact but there is a gap at the bottom, first tighten the bolts at the upper part of the first flange and the second flange, then lift the HDPE pipeline to be installed or the installed HDPE pipeline to make the bottoms of the first flange and the second flange in contact; when the bottoms of the first flange and the second flange are in contact but there is a gap at the top, first tighten the bolts at the bottom of the first flange and the second flange, then reduce the tension of the first cable and lower the height of the first flange to make the tops of the first flange and the second flange in contact; after confirming that there is no wedge-shaped gap between the first flange and the second flange, tighten all the bolts to complete the installation of the flange bolts.

[0030] By observing whether there is a wedge-shaped gap at the top or bottom of the flange and adopting different adjustment strategies (such as tightening the bolts at the corresponding positions, lifting or lowering the pipeline height), the contact surfaces of the flanges can be accurately aligned to ensure the flatness and sealing performance of the flanges. Tightening all the bolts after eliminating the wedge-shaped gap can make the force at each position of the flange uniform, avoiding problems such as sealing failure or flange deformation caused by excessive local force.

[0031] Preferably, it further includes the following steps:

[0032] S5: 24 hours after completing the installation of the flange bolts, the diver goes underwater to tighten the bolts for the second time and uses a 2-mm feeler gauge to detect the gap between the first flange and the second flange. If the detection is qualified, the underwater flange butt joint of the HDPE pipeline ends; if the detection is unqualified, tighten the bolts again until the detection is qualified.

[0033] Affected by factors such as ocean currents and temperature differences in the underwater environment, the flange bolts of HDPE pipes may experience a decrease in bolt pre-tightening force due to material stress relaxation or uneven installation stress after installation. Secondary tightening can effectively compensate for the loss of pre-tightening force and ensure the stable fit of the flange contact surface. By means of secondary tightening, the flange gap is adjusted within the design specifications (detected using a 2 mm feeler gauge), which can minimize the risk of seal material aging or interface cracking and meet the usage requirements in the long-term marine environment.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. The underwater flange docking system for HDPE pipes provided by the present invention, through the precise control of the first winch, the second winch and the crane equipped on the crane ship, replaces the traditional method of manual repeated measurement and adjustment, greatly reducing the operation difficulty and achieving the precise adjustment of the horizontal position and elevation of the HDPE pipes to be installed underwater; the airbag is tied to the pipe to provide buoyancy for auxiliary adjustment, which can effectively reduce the influence of ocean current on the pipe attitude and keep the flange docking position stable, thus significantly improving the docking accuracy. The combined adjustment of the winch and the crane enables the adjustment of the pipe attitude during the docking process to be faster, without the need for multiple reworks, thus shortening the construction time of underwater docking and improving the overall efficiency. Since this system reduces the steps of repeated inspection and calculation in the traditional method and reduces the dependence on complex underwater detection equipment, the construction is more efficient;

[0036] 2. The underwater flange docking system for HDPE pipes provided by the present invention, through the innovative combination of mechanical equipment and airbag tying technology, not only overcomes many deficiencies of the traditional underwater HDPE pipe docking technology, significantly improves the accuracy, efficiency and safety of underwater flange docking of large-diameter and overweight HDPE pipes, but also has strong applicability and economy, providing a reliable technical solution for the installation of HDPE pipes in ocean engineering.

[0037] 3. The underwater flange docking method for HDPE pipes provided by the present invention adjusts the inflation and deflation of the airbag to make the docking pipe head float and keep the floating height consistent, ensuring the stable attitude of the pipe in water, reducing the docking deviation caused by the influence of gravity and ocean currents, and greatly improving the docking accuracy; maintaining a safe distance between the pipe heads before docking can effectively prevent collision damage caused by unstable pipe attitude or external ocean current influence, ensuring the safety of the pipes and equipment;

[0038] 4. The HDPE pipe underwater flange docking method provided by the present invention uses airbags to assist suspension and winch / crane precise adjustment, which avoids violent shaking and loss of control during pipe docking, reduces the risk of divers participating, and improves the safety of construction personnel. The airbag inflation and deflation operation is simple and can be recycled for multiple times, effectively reducing construction costs; the winch synchronously tightens the first cable to ensure the accuracy of the HDPE pipe movement, avoids accidental tilting or movement of the pipe due to incoordination, and greatly reduces the probability of errors during docking;

[0039] 5. The HDPE pipe underwater flange docking method provided by the present invention, the first winch, the second winch and the crane are adjusted in multiple dimensions, including precise control of the horizontal position and elevation, so that the pipe joints can be seamlessly fitted together, ensuring the precise alignment of the flange holes. After the flanges are aligned, the bolts are immediately inserted to complete the fixation, without the need for additional auxiliary equipment, which simplifies the underwater operation procedures, reduces the docking time, and improves the overall construction efficiency. After the flange holes are aligned, the bolts are evenly inserted for fixation, avoiding the problem of uneven local force, improving the reliability of the flange connection, and ensuring the safety and stability of the pipeline in subsequent operation. The airbags are gradually released from the docking area to both sides, so that the pipeline sinking process is smooth and uniform, avoiding docking misalignment or equipment damage caused by sudden settlement, and ensuring the construction quality;

[0040] 6. The HDPE pipe underwater flange docking method provided by the present invention optimizes the operation process through a systematic step-by-step design (such as S2 pulling closer, S3 fine-tuning, and S4 releasing the airbag to sink). The precise adjustment during the operation reduces the steps of repeated trial and measurement in the traditional method, thereby improving the docking speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the position of the HDPE pipe to be installed before docking with the installed HDPE pipe;

[0042] Figure 2 is a schematic diagram of first cable pulling;

[0043] Figure 3 is a schematic diagram of tightening the first cable;

[0044] Figure 4 Schematic diagram of adjusting the elevation of the HDPE pipe to be installed for the crane;

[0045] Figure 5 Schematic diagram of the first winch and the second winch for adjusting the horizontal position of the HDPE pipe to be installed;

[0046] Figure 6 This is a schematic diagram when there is a gap between the bottom ends of the first flange and the second flange;

[0047] Figure 7 Schematic diagram when there is a gap at the top of the first flange and the second flange.

[0048] Markings in the figure:

[0049] 1 - Crane ship, 11 - First winch, 12 - Second winch, 13 - Crane, 14 - First cable, 15 - Second cable, 2 - Airbag, 100 - HDPE pipeline to be installed, 101 - First flange, 200 - Installed HDPE pipeline, 201 - Second flange. Specific implementation manner

[0050] The present invention will be further described in detail below in conjunction with specific embodiments. However, this should not be construed as limiting the scope of the above - mentioned subject matter of the present invention to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0051] In the description of the specific embodiments of the present invention, without special explanation, the expression terms indicating the orientation or position relationship such as "upper", "lower", "left", "right", "center", "inner", "outer", etc. are all based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the invention product / device / equipment is usually used. These orientation or position relationship terms are only for facilitating the description of the present invention solution or simplifying the description in the specific embodiments, facilitating technicians to quickly understand the solution, rather than indicating or implying that a specific device / component / element must have a specific orientation or be constructed and operated in a specific position relationship. Therefore, it cannot be understood as a limitation to the present invention.

[0052] In addition, if terms such as "horizontal", "vertical", "hanging", "parallel" etc. appear, it does not mean that the corresponding device / component / element is required to be absolutely horizontal or vertical or hanging or parallel, but can be slightly inclined or have a deviation. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Or, it can be simply understood that the corresponding device / component / element is arranged in the directions of "horizontal", "vertical", "hanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still play its role in the solution of the present invention.

[0053] In addition, the expressions such as "first", "second", "third", etc. in the terms are only used to distinguish the description of the same or similar components, and should not be understood as emphasizing or implying the relative importance of specific components.

[0054] In addition, in the description of the embodiments of the present invention, "several", "multiple", and "a number of" represent at least two. It can be any situation such as 2, 3, 4, 5, 6, 7, 8, 9, etc., and even more than 9.

[0055] In addition, in the description of the technical solutions of the present invention, unless otherwise clearly specified / defined / restricted, where the terms "set", "installed", "connected", "connected", "provided with", "laid", and "arranged" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be commonly used connection means in the art such as welding, riveting, bolting, and threaded connection. Such a connection can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components.

[0056] Embodiment 1

[0057] This embodiment provides an underwater flange docking system for HDPE pipes, which is used for underwater flange docking of HDPE pipes with large diameters (inner diameter exceeding 3m) and ultra-heavy weights (pipe section length exceeding 5.5m, weight per linear meter exceeding 0.9t / m).

[0058] Specifically, as Figures 1 - 4 shown, the underwater flange docking system for HDPE pipes includes a crane ship 1 and a number of airbags 2. The airbags 2 are tied to the installed HDPE pipe 200. Specifically, for example Figure 2 shown, the airbags 2 can be tied near the docking pipe head of the installed HDPE pipe 200. For example, they can be tied within the range of 0 - 40m of the docking pipe head of the installed HDPE pipe 200.

[0059] The airbags 2 are tied to the HDPE pipe 100 to be installed. Specifically, the entire pipe section of the HDPE pipe 100 to be installed is tied with airbags 2.

[0060] The crane ship 1 includes a first winch 11, a second winch 12, and a crane 13. The first cable 14 of the first winch 11 is connected to the HDPE pipe 100 to be installed. The first cable 14 of the second winch 12 is also connected to the HDPE pipe 100 to be installed. The crane 13 is located above the HDPE pipe 100 to be installed, and the crane 13 is connected to the HDPE pipe 100 to be installed through a second cable 15.

[0061] The first winch 11 and the second winch 12 are used to adjust the horizontal position of the HDPE pipe 100 to be installed, and the crane 13 is used to adjust the elevation of the HDPE pipe 100 to be installed.

[0062] Preferably, the air bags 2 used in this embodiment are all 5T air bags. The preferred air bag 2 is a 5T air bag (each can bear a weight of 5 tons), which can provide sufficient buoyancy for overweight HDPE pipes and effectively reduce the influence of the pipe gravity in the underwater environment. The inflation and deflation adjustment function of the air bag 2 can flexibly adjust the buoyancy to meet the adjustment requirements of the pipe attitude, thus improving the flexibility and stability of the underwater docking operation.

[0063] Preferably, the first winch 11 and the second winch 12 in this embodiment are both 10T winches. The preferred first and second winches are both 10T winches (the maximum pulling force of a single winch is 10 tons), which can meet the horizontal position adjustment requirements of large-diameter (inner diameter exceeding 3m) and overweight (weight per meter exceeding 0.9t / m) HDPE pipes. Even in the face of ocean current impacts in the marine environment, sufficient pulling force can be provided for precise adjustment. The independent operation function of the first and second winches supports precise fine-tuning of the pipe in the left and right directions, ensuring that the flange docking surfaces are accurately aligned, and further improving the docking accuracy.

[0064] The HDPE pipe underwater flange docking system provided in this embodiment, through the precise control of the first winch 11, the second winch 12 and the crane 13 equipped on the crane ship 1, replaces the traditional manual repeated measurement and adjustment method, greatly reducing the operation difficulty and achieving precise adjustment of the horizontal position and elevation of the HDPE pipe 100 to be installed underwater; the air bag 2 is tied to the pipe to provide buoyancy for auxiliary adjustment, which can effectively reduce the influence of ocean current action on the pipe attitude and keep the flange docking position stable, thus significantly improving the docking accuracy.

[0065] The combined adjustment of the winch and the crane makes it faster to adjust the pipe attitude during the docking process, without the need for multiple reworks, thus shortening the construction time of underwater docking and improving the overall efficiency. Since this system reduces the steps of repeated inspection and calculation in the traditional method and reduces the dependence on complex underwater detection equipment at the same time, the construction is more efficient.

[0066] The HDPE pipe underwater flange docking system provided in this embodiment, through the innovative combination of mechanical equipment and air bag tying technology, not only overcomes many deficiencies of the traditional underwater HDPE pipe docking technology, significantly improves the accuracy, efficiency and safety of underwater flange docking of large-diameter and overweight HDPE pipes, but also has strong applicability and economy, providing a reliable technical solution for the installation of HDPE pipes in ocean engineering.

[0067] Embodiment 2

[0068] This embodiment provides an HDPE pipe underwater flange docking method. This docking method uses the HDPE pipe underwater flange docking system provided in Embodiment 1 and includes the following steps:

[0069] S1: As shown in Figure 1 , control the inflation degree of the airbag 2 to make the docking pipe heads of the HDPE pipe 100 to be installed and the HDPE pipe 200 already installed suspended and the suspension heights are basically the same. Specifically, the suspension height D of the HDPE pipe 100 to be installed and the HDPE pipe 200 already installed is 0.8 m - 1.2 m from the pipe bottom to the mud surface. Controlling the suspension height within the range of 0.8 m - 1.2 m can effectively avoid the frictional resistance that may be caused by the contact between the pipe bottom and the mud surface, and also avoid the problem of unstable attitude caused by too high suspension. And within this height range, the HDPE pipe can be in a relatively stable water flow area near the seabed, reducing the interference of ocean currents on the pipe docking accuracy, thereby further improving the reliability of flange docking.

[0070] Adjust the position of the HDPE pipe 100 to be installed to keep a safe distance between the docking pipe head of the HDPE pipe 100 to be installed and the HDPE pipe 200 already installed. In this embodiment, the safe distance L between the docking pipe head of the HDPE pipe 100 to be installed and the HDPE pipe 200 already installed is 4.5 m - 5.5 m. Setting the safe distance to 4.5 m - 5.5 m ensures that there is enough adjustment space for the pipe to be installed during the approaching process, and the position of the pipe can be precisely controlled by the winch and the crane 13 to gradually eliminate the residual deviation and improve the accuracy of flange docking.

[0071] S2: As shown in Figure 2 , the diver dives into the water and first removes the blind plate at the docking pipe head end of the HDPE pipe 100 to be installed and the sand plate at the docking pipe head end of the HDPE pipe 200 already installed. The diver connects the first cable 14 of the first winch 11 and the second winch 12 to the docking pipe head of the HDPE pipe 100 to be installed, and also connects the second cable 15 to the docking pipe head of the HDPE pipe 100 to be installed. As shown by the hollow arrow in Figure 3 , the staff operates the first winch 11 and the second winch 12 to tighten the first cable 14 simultaneously, pulling the HDPE pipe 100 to be installed closer to the HDPE pipe 200 already installed;

[0072] S3: As shown in Figure 5 , the staff can operate the first winch 11 and / or the second winch 12 to jog to adjust the horizontal position of the HDPE pipe 100 to be installed.

[0073] As shown in Figure 4As shown by the hollow arrow in the middle, the staff can operate the crane 13 to adjust the elevation of the HDPE pipe 100 to be installed until the docking pipe heads of the HDPE pipe 100 to be installed fit with the docking pipe heads of the installed HDPE pipe 200, and the hole positions of the first flange 101 of the HDPE pipe 100 to be installed and the second flange 201 of the installed HDPE pipe 200 are aligned. Subsequently, bolts are evenly inserted into the bolt holes of the first flange 101 and the second flange 201.

[0074] In this embodiment, the order of bolt insertion is to evenly insert GRP bolts from the high position to the low position of the first flange 101 and the second flange 201. Inserting GRP bolts evenly from the high position to the low position can effectively prevent the flange from tilting or deforming due to the bolts being inserted on one side first, ensure that the flange remains horizontal during docking, avoid stress concentration affecting the flange sealing surface, and make the force on the flange gradually uniform by evenly inserting GRP bolts, avoiding local warping or sealing failure of the flange caused by excessive force at a single point, and further improving the airtightness and watertightness of the docking.

[0075] After bolts are evenly inserted into the bolt holes of the first flange 101 and the second flange 201, check whether there is a wedge-shaped gap between the first flange 101 and the second flange 201.

[0076] As Figure 6 shown, when the tops of the first flange 101 and the second flange 201 are in contact but there is a gap at the bottom, first tighten the bolts at the upper part of the first flange 101 and the second flange 201, and then lift the HDPE pipe 100 to be installed or the installed HDPE pipe 200 to make the bottoms of the first flange 101 and the second flange 201 in contact.

[0077] As Figure 7 shown, when the bottoms of the first flange 101 and the second flange 201 are in contact but there is a gap at the top, first tighten the bolts at the bottom of the first flange 101 and the second flange 201, and then reduce the tension of the first cable 14 and lower the height of the first flange 101 to make the tops of the first flange 101 and the second flange 201 in contact.

[0078] After confirming that there is no wedge-shaped gap between the first flange 101 and the second flange 201, tighten all the bolts to complete the installation of the flange bolts.

[0079] By observing whether there is a wedge-shaped gap at the top or bottom of the flange and adopting different adjustment strategies (such as tightening the bolts at the corresponding position, lifting or lowering the pipe height), the contact surface of the flange can be accurately aligned to ensure the flatness and sealing performance of the flange. Tightening all the bolts after the wedge-shaped gap is eliminated can make the force at each position of the flange uniform, avoiding problems such as sealing failure or flange deformation caused by excessive local force.

[0080] S4: Starting from the butt joint area of ​​the HDPE pipe 100 to be installed and the installed HDPE pipe 200, the airbags 2 are released to both sides. Specifically, the order of releasing the airbags 2 can be synchronously performed on both sides in sequence, or can be performed alternately on both sides. The HDPE pipe 100 to be installed and the installed HDPE pipe 200 are placed on the bottom.

[0081] S5: 24 hours after the flange bolts are installed, the diver goes into the water to tighten the bolts for the second time, and uses a 2mm feeler gauge to detect the gap between the first flange 101 and the second flange 201. If the test is qualified, the underwater flange docking of the HDPE pipe is completed. If the test is unqualified, the bolts are tightened again until the test is qualified. HDPE pipes are affected by ocean currents, temperature differences and other factors in the underwater environment. After the flange bolts are installed, the bolt preload may decrease due to material stress relaxation or uneven installation stress. Secondary tightening can effectively compensate for the loss of preload and ensure the stable fit of the flange contact surface. Through secondary tightening, the flange gap is adjusted to the design specification (using a 2mm feeler gauge for detection), which can minimize the risk of aging of sealing materials or cracking of interfaces and meet the requirements of long-term use in marine environments.

[0082] The HDPE pipe underwater flange docking method provided in this embodiment suspends the docking pipe head and keeps the suspension height consistent through the inflation and deflation adjustment of the airbag 2, thereby ensuring the stability of the pipeline in the water, reducing the docking deviation caused by gravity and ocean currents, and greatly improving the docking accuracy; maintaining a safe distance between the pipe heads before docking effectively prevents collision damage caused by unstable pipeline posture or external ocean currents, and ensures the safety of pipelines and equipment.

[0083] The use of airbag 2 to assist suspension and precise adjustment of winch / crane avoids severe shaking and loss of control during pipeline docking, reduces the risk of divers' participation, and improves the safety of construction workers. The airbag 2 is easy to inflate and deflate and can be recycled many times, effectively reducing construction costs. The two winches synchronously tighten the first cable 14 to ensure the accuracy of the movement of the HDPE pipe, avoid accidental tilting or movement of the pipe due to incoordination, and greatly reduce the probability of errors during the docking process.

[0084] The first hoist 11, the second hoist 12 and the crane 13 are adjusted in multiple dimensions, including precise control of the horizontal position and elevation, so that the pipe docking heads are seamlessly fitted, ensuring the accurate alignment of the flange holes. Immediately after the flanges are aligned, bolts are inserted to complete the fixation. Without additional auxiliary equipment, the underwater operation procedure is simplified, the docking time is reduced, and the overall construction efficiency is improved. After the flange holes are aligned, bolts are evenly inserted for fixation, avoiding the problem of uneven local stress, improving the reliability of the flange connection, and ensuring the safety and stability of the pipeline during subsequent operation.

[0085] The air bags 2 are gradually released from the docking area to both sides, making the pipe sinking process smooth and uniform, avoiding docking misalignment or equipment damage caused by sudden settlement, and ensuring the construction quality.

[0086] The underwater flange docking method for HDPE pipes provided by the present invention optimizes the operation process through systematic step-by-step design. The precise adjustment during the operation process reduces the steps of repeated probing and measurement in the traditional method, improving the docking speed.

[0087] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A HDPE pipe underwater flange docking system, characterized in that: The invention comprises a crane vessel (1) and a plurality of airbags (2), wherein the airbags (2) are tied to an installed HDPE pipe (200), and the airbags (2) are tied to an HDPE pipe (100) to be installed. The crane vessel (1) comprises a first winch (11), a second winch (12) and a crane (13), wherein first cables (14) of the first winch (11) and the second winch (12) are both connected to the HDPE pipe (100) to be installed, and the crane (13) is connected to the HDPE pipe (100) to be installed via a second cable (15); the first winch (11) and the second winch (12) are used to adjust the horizontal position of the HDPE pipe (100) to be installed, and the crane (13) is used to adjust the elevation of the HDPE pipe (100) to be installed.

2. The HDPE pipe underwater flange docking system according to claim 1, characterized in that: The airbag (2) is a 5T airbag.

3. The HDPE pipe underwater flange docking system according to claim 1, characterized in that: The first hoist (11) and the second hoist (12) are 10T hoists.

4. A method for connecting underwater flanges of HDPE pipes, characterized in that: The HDPE pipe underwater flange docking system according to any one of claims 1 to 3 comprises the following steps: S1: controlling the inflation degree of the airbag (2) so that the butt joints of the HDPE pipe to be installed (100) and the installed HDPE pipe (200) are suspended and the suspension heights are substantially the same, and adjusting the position of the HDPE pipe to be installed (100) so that the butt joints of the HDPE pipe to be installed (100) and the installed HDPE pipe (200) maintain a safe distance; S2: connecting the first cables (14) of the first hoist (11) and the second hoist (12) to the butt joint of the HDPE pipe (100) to be installed, and connecting the second cable (15) to the butt joint of the HDPE pipe (100) to be installed; operating the first hoist (11) and the second hoist (12) to simultaneously tighten the first cable (14), and pull the HDPE pipe (100) to be installed closer to the installed HDPE pipe (200); S3: operate the first hoist (11) and / or the second hoist (12) to jog, adjust the horizontal position of the HDPE pipe (100) to be installed, operate the crane (13) to adjust the elevation of the HDPE pipe (100) to be installed, until the butt joint of the HDPE pipe (100) to be installed fits with the butt joint of the installed HDPE pipe (200), and the holes of the first flange (101) of the HDPE pipe (100) to be installed and the second flange (201) of the installed HDPE pipe (200) are aligned, and bolts are evenly inserted into the bolt holes of the first flange (101) and the second flange (201), thereby completing the installation of flange bolts; S4: Starting from the butt joint area between the HDPE pipe to be installed (100) and the installed HDPE pipe (200), the airbag (2) is released to both sides to complete the bottom sinking of the HDPE pipe to be installed (100) and the installed HDPE pipe (200).

5. A method for underwater flange docking of HDPE pipes according to claim 4, characterized in that: The suspension height of the HDPE pipe (100) to be installed and the installed HDPE pipe (200) in S1 is 0.8m-1.2m from the bottom of the pipe to the mud surface.

6. A method for connecting underwater flanges of HDPE pipes according to claim 4, characterized in that: The safety distance in S1 is 4.5m-5.5m.

7. The method for underwater flange connection of a HDPE pipeline according to claim 4, characterized in that: Before the first cable (14) in S2 is connected to the butt joint of the HDPE pipe (100) to be installed, the diver first removes the blind plate at the butt joint end of the HDPE pipe (100) to be installed and the sand plate at the butt joint end of the installed HDPE pipe (200).

8. The method for underwater flange docking of HDPE pipes according to claim 4, characterized in that: In S3, the order of uniformly inserting bolts into the bolt holes of the first flange (101) and the second flange (201) is to uniformly insert the GRP bolts from the high position to the low position of the first flange (101) and the second flange (201).

9. The method for underwater flange connection of a HDPE pipeline according to claim 4, characterized in that: In S3, after bolts are uniformly inserted into the bolt holes of the first flange (101) and the second flange (201), it is observed whether there is a wedge-shaped gap between the first flange (101) and the second flange (201). When the top ends of the first flange (101) and the second flange (201) are tightly attached but there is a gap at the bottom ends, first tighten the bolts on the top of the first flange (101) and the second flange (201), and then lift the HDPE pipe (100) to be installed or the installed HDPE pipe (200) to make the bottom ends of the first flange (101) and the second flange (201) tightly attached; When the bottom ends of the first flange (101) and the second flange (201) are tightly attached but there is a gap at the top ends, first tighten the bolts at the bottom of the first flange (101) and the second flange (201), then reduce the tension of the first cable (14), lower the height of the first flange (101), and make the top ends of the first flange (101) and the second flange (201) tightly attached; After confirming that there is no wedge-shaped gap between the first flange (101) and the second flange (201), tighten all bolts to complete the flange bolt installation.

10. The method for underwater flange connection of a HDPE pipeline according to claim 4, characterized in that: The following steps are also included: S5: 24 hours after the flange bolts are installed, the diver goes into the water to tighten the bolts for a second time and uses a 2 mm feeler gauge to detect the gap between the first flange (101) and the second flange (201). If the test is qualified, the HDPE pipe underwater flange docking is completed. If the test is unqualified, the bolts are tightened again until the test is qualified.

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