LPG tank support seat segmented installation method

Abstract

The application relates to the technical field of shipbuilding, and discloses a segmented installation method of an LPG tank support seat, which takes an inner bottom plate as an upper tread of double-bottom segmented construction; after the double-bottom segmented construction is completed, the double-bottom segment is turned over, three-dimensional measurement is carried out, the datum on the double-bottom segment is corrected according to the measured data, and the accuracy of subsequent installation is ensured; the four corners of the double-bottom segment are used to draw horizontal datum points, the flatness of the installation position of the support seat on the inner bottom plate is measured by taking the horizontal plane where the corrected horizontal datum points are located as the datum, the web height of the support seat is pre-corrected according to the measured flatness data, the height is in place after installation, and repeated cutting after installation due to height deviation is reduced; after the support seat is preliminarily positioned, three-dimensional measurement is carried out on the support seat, adjustment is carried out according to the measured data, the installation of the support seat is completed only when the accuracy meets the requirements, and one-time complete work is realized.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for segmented installation of LPG tank support bases. Background Technology

[0002] The independent compartment of a certain LPG carrier is the core liquid cargo containment system of the LPG carrier. Its support base bears the weight of the LPG tank, the liquid cargo, and sway loads. The installation accuracy directly affects the stress distribution of the compartment, the reliability of the cryogenic sealing system, and the fatigue resistance. The LPG tank support base is installed on a cryogenic steel inner bottom plate. Because the inner bottom plate is made of cryogenic steel, the sensitivity of cryogenic steel to heat input means that the installation accuracy of the support base can only be achieved in one go. Moreover, the installation accuracy of the support base position is ≤5mm, and the height is +3mm to -2mm. The overall accuracy requirements are high. Existing technology cannot achieve one-time installation for this type of structure. The traditional method is to check the accuracy after welding. At this time, the cryogenic steel has already undergone irreversible thermal embrittlement, resulting in a vicious cycle of correction such as cutting and welding. At the same time, the existing technology does not effectively control the characteristics of cryogenic steel. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a segmented installation method for LPG tank support base with high installation accuracy.

[0004] To solve the above-mentioned technical problems, the present invention provides a segmented installation method for an LPG tank support, comprising the following steps:

[0005] S1: Lay multiple inner bottom plates on the jig frame, then splice and weld the multiple inner bottom plates together to form an inner bottom plate;

[0006] S2: Install the skeleton and frame onto the inner bottom plate, and then position and install the outer bottom plate onto the skeleton and frame to form a double-layer bottom segment;

[0007] S3: After loosening the double-layer bottom segment, measure its three-dimensional accuracy data, analyze and compare the deviation value between the measured data and the theoretical data, and then correct the position of the reference marks on the double-layer bottom segment according to the deviation value. The reference marks include the longitudinal center line, the rib line and the horizontal reference point. The horizontal reference point is marked at each of the four corners of the double-layer bottom segment. The theoretical height of the horizontal reference point from the inner bottom plate is a set value.

[0008] S4: Flip the double-layer bottom segment so that the inner bottom plate is at the top of the double-layer bottom segment, and then adjust the double-layer bottom segment to a horizontal state according to the four corrected horizontal reference points;

[0009] S5: Using the corrected longitudinal centerline and rib line as a reference, draw the installation outline and centerline of the support base;

[0010] S6: Based on the position of the installation outline and center line of the support seat, and taking the plane where the four horizontal reference points are located as the horizontal reference, measure the flatness of the installation position of the support seat on the inner bottom plate, and pre-correct the web height of the support seat based on the measured flatness data.

[0011] S7: After the support base is pre-repaired, hoist the support base onto the inner bottom plate, and perform preliminary positioning and spot welding on the support base according to the installation outline and center line of the support base;

[0012] S8: Perform three-dimensional measurement on the support base, fine-tune the support base according to the measured data, and measure again until the measured data meets the accuracy requirements. Then weld the web of the support base to the inner bottom plate to form a rigid connection.

[0013] As a preferred embodiment of the present invention, in S1, after laying the boards, the dimensions of the boards are checked and confirmed to be qualified before the tire is sealed and leveled to ensure that the gap between the inner bottom board and the tire frame is ≤2mm.

[0014] As a preferred embodiment of the present invention, in S1, the tire frame includes multiple tire plates arranged laterally at intervals, the distance between two adjacent tire plates is less than 2m, and the flatness of the top surface of the tire plate is ≤2mm.

[0015] As a preferred embodiment of the present invention, in S1, the height of the frame gradually decreases from the middle to both sides in the lateral direction, and in S2, when installing the frame, the frame is installed gradually from the middle of the inner bottom plate to both sides in the lateral direction.

[0016] As a preferred embodiment of the present invention, in S2, before installing the ribs and frame, the installation positions of the mounting frame and ribs corresponding to the inner bottom plate are first ground, then the structural lines are drawn, and then the inner bottom plate structural pressure beam is installed according to the position of the structural lines.

[0017] As a preferred embodiment of the present invention, in S8, it is also necessary to measure the double-layer bottom segment and the reference mark on the double-layer bottom segment.

[0018] As a preferred embodiment of the present invention, in S8, at least six uniformly arranged measuring points are selected on the upper surface of the support.

[0019] As a preferred embodiment of the present invention, in S8, after welding is completed, data measurements are taken again on the support base and the double-layer bottom segment.

[0020] This invention discloses a segmented installation method for an LPG tank support base. Compared with existing technologies, its advantages are as follows: This method uses the inner bottom plate as the upper surface for the construction of the double-layer bottom segment, which ensures the flatness of the support base installation surface; after the double-layer bottom segment is constructed, it is flipped over and subjected to three-dimensional measurement. The reference on the double-layer bottom segment is corrected based on the measurement data to ensure the accuracy of subsequent installation; horizontal reference points are marked at the four corners of the double-layer bottom segment. Using the horizontal plane where the corrected horizontal reference points are located as the reference, the flatness of the installation position of the support base on the inner bottom plate is measured, and the web height of the support base is pre-adjusted based on the measured flatness data to ensure that the height is in place after installation, reducing the need for repeated cutting due to height deviation after installation; after the support base is initially positioned, three-dimensional measurement is performed on the support base, and adjustments are made based on the measurement data to ensure that the accuracy meets the requirements before the installation of the support base is completed, achieving a one-time completion and qualified result. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the double-layer bottom segmentation of the present invention;

[0022] Figure 2 This is a structural diagram of the support base of the present invention;

[0023] In the diagram, 1 is the double-layer bottom segment; 11 is the inner bottom plate; 12 is the outer bottom plate; 13 is the reference point; and 2 is the support base. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., used to indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] A preferred embodiment of the present invention provides a segmented installation method for an LPG tank support base, comprising the following steps:

[0027] S1: Multiple inner bottom plates are laid on the jig, and then the multiple inner bottom plates are spliced ​​and welded to form an inner bottom plate. The inner bottom plate is used as the upper jig surface for segmented construction. This ensures the flatness of the support base installation surface, making it the primary and key control element in the construction process. At the same time, this measure can ensure the accuracy and flatness of the spliced ​​plates.

[0028] S2: Install the skeleton and frame onto the inner bottom plate, that is, weld and fix the skeleton and frame onto the inner bottom plate respectively. Then, position and install the outer bottom plate onto the skeleton and frame, that is, weld and fix the outer bottom plate onto the outer bottom plate. At this time, the inner bottom plate 11, skeleton 14, frame 15, and outer bottom plate 12 are connected as a whole to form a double-layer bottom segment 1, as shown. Figure 1 As shown.

[0029] S3: After loosening the double-layer bottom segment, measure its three-dimensional accuracy data, analyze and compare the deviation between the measured data and the theoretical data, and then correct the positions of the reference marks on the double-layer bottom segment based on the deviation value. The reference marks include the longitudinal center line, rib inspection line, and horizontal reference points. Horizontal reference points are marked at the four corners of the double-layer bottom segment, and the theoretical height of the horizontal reference points from the inner bottom plate is a set value. Specifically, after the overall welding of the double-layer bottom segment is completed, the next step is to cut off all connection points between the jig and the segment. This process ensures that the double-layer bottom segment is in a completely free state, without any external force or support interference. Only under such conditions can comprehensive and accurate three-dimensional accuracy measurements be performed. This measurement method ensures the accuracy of unconstrained segmented measurement data, guaranteeing the overall accuracy and reliability of the data. Based on the measurement data, the longitudinal centerline (longitudinal section line) and main rib inspection lines (transverse section line) of the segments are corrected and clearly re-marked. These corrected lines serve as the length and width references for subsequently marking the support installation position lines on the segments. At the four corners (or key rib corner points) of the double-layer bottom segment, horizontal reference points are precisely marked at a set value (e.g., 1000mm) from the theoretical height of the inner bottom plate. Based on the free-state measurement data, these horizontal reference points are corrected (calculating the deviation between the actual height and the theoretical value). The plane formed by these four corrected horizontal reference points serves as the horizontal adjustment reference after the segment is flipped (adjusting the segment so that the four horizontal reference points are on the same horizontal plane) and the reference for controlling the support installation height.

[0030] S4: Turn the double-bottom segment over so that the inner bottom plate is at the top of the double-bottom segment, that is, the support mounting surface is facing upward. Then, based on the corrected four horizontal reference points, use tools such as jacks to adjust the segment posture and adjust the double-bottom segment to a horizontal state. This is the prerequisite for the support to obtain the correct levelness.

[0031] S5: Using the corrected longitudinal centerline and rib inspection line as a reference, draw the installation outline and centerline of the support base; specifically, based on the corrected longitudinal section line and rib inspection line, use a total station to check the perpendicularity of the rib inspection line and longitudinal section line. After confirming that there are no errors, open and mark the line in the middle position. Then, the precision control personnel accurately draw the installation outline and centerline of the support base on the inner bottom plate according to the baseline and by using a measuring tape.

[0032] S6: Based on the position of the support's installation outline and center line, and using the plane containing the four horizontal reference points as the horizontal reference, measure the flatness of the support's installation position on the inner base plate. Based on the measured flatness data, pre-adjust the web height of the support. Specifically, based on the position of the support's installation structural lines (outline and center line), and using the plane containing the four horizontal reference points as the horizontal reference, measure the flatness of the installation position. Based on the measured flatness data of the inner base plate, simulate and pre-adjust the web height of the support. The height of the support web from the inner base plate is confirmed based on the data, and the flatness data is marked on the support's installation position. Based on the flatness and floor height requirements, the construction team conducts advance inspections and pre-repairs of the incoming support materials according to the floor height data. For example, if the height of the inner bottom plate at the support location is +4mm, corresponding to a theoretical support distance of 272mm from the inner bottom plate, the height of the support web is adjusted in advance to ensure that its actual size is within the range of 269mm-271mm. After pre-repairing and passing the inspection, the support is installed. This ensures that the support is accurately pre-repaired according to the flatness data of the inner bottom plate installation location before installation. By matching the inner bottom plate height deviation with the support web cutting data, the height is ensured to be in place after installation, reducing the impact on the performance of low-temperature steel caused by repeated cutting and adjustment due to height deviation after installation.

[0033] S7: After the support base is pre-repaired, hoist the support base 2 onto the inner bottom plate 11. Based on the installation outline and center line of the support base, perform preliminary positioning and spot welding to fix the support base. After hoisting the support base into place, adjust the position of the support base to ensure that the position error of the panel is ≤5mm, the position error of the web plate is ≤3mm, and the height deviation of the four corners of a single support base from the simulation data is ≤2mm. Perform preliminary spot welding to fix the support base.

[0034] S8: Perform three-dimensional measurement on the support base. Based on the measured data, fine-tune the support base and measure again until the measured data meets the accuracy requirements. Then, weld the web plate of the support base to the inner bottom plate to form a rigid connection. Figure 2As shown; specifically, a high-precision total station was used to comprehensively inspect the support base during precise three-dimensional measurement. First, a detailed three-dimensional measurement of the upper surface position and height of the support base was conducted. The measured data was then analyzed using precision analysis software (position tolerance ≤ 5mm, height tolerance +3mm / -2mm, levelness requirements) and strictly compared. If the data did not meet the requirements, the support base was fine-tuned using jacks, supports, and hand-operated hoists while still in a spot-welded fixed state, until all measurement data fully met the accuracy requirements and the adjustment status was confirmed by precision control personnel. Only after the three-dimensional measurement data confirmed that the position, height, and levelness of the support base strictly met the standards could formal welding proceed. A low-temperature steel-specific welding process that had passed process evaluation was adopted, with strict control over: welding materials (matching low-temperature welding rods / wires), preheating temperature (if required) and interpass temperature, heat input (voltage, current, welding speed), and welding sequence (symmetrical welding, segmented back welding, etc.) to minimize welding deformation and residual stress.

[0035] This method uses the inner bottom plate as the upper tread for the double-layer bottom segment construction, which ensures the flatness of the support base installation surface. After the double-layer bottom segment construction is completed, the segment is turned over and three-dimensionally measured. The reference on the double-layer bottom segment is corrected based on the measurement data to ensure the accuracy of subsequent installation. Horizontal reference points are marked at the four corners of the double-layer bottom segment. Using the horizontal plane where the corrected horizontal reference points are located as the reference, the flatness of the installation position of the support on the inner bottom plate is measured. The web height of the support is pre-adjusted based on the measured flatness data to ensure the height is in place after installation, reducing the need for repeated cutting due to height deviation after installation. After the support is initially positioned, three-dimensional measurement is performed on the support. Adjustments are made based on the measurement data to ensure that the accuracy meets the requirements before the support installation is completed, achieving a one-time completion and qualified result.

[0036] For example, in S1, the height of the jig gradually decreases laterally from the middle to both sides. In S2, when installing the frame, the installation starts from the middle of the inner bottom plate and proceeds laterally to both sides. The frame installation must follow a specific assembly sequence to ensure the stability of the entire structure and avoid unnecessary deformation. Frame assembly should begin in the middle and gradually expand to both sides. This sequence helps to disperse the stress generated during assembly, thereby reducing frame deformation caused by stress concentration. Based on the frame installation sequence and according to the method for controlling segmented welding deformation, a counter-deformation amount equal in magnitude and opposite in direction to the welding deformation is pre-added during jig fabrication. For example, through experience or calculation, when the jig dimensions meet specific conditions, an empirical formula can be applied to determine the counter-deformation value. The anti-deformation process is implemented based on the on-site frame welding conditions. Laterally, it involves fillet welds, while longitudinally it's a continuous structure of a single longitudinal girder. The anti-deformation is applied with the center of the transverse jig as the highest horizontal point, and is performed every 1mm. This measure helps to counteract potential horizontal warping deformation on both sides that may occur during subsequent welding. The precision control personnel check the anti-deformation level on both sides from the highest point of the jig and use a string line to check the overall flatness of the jig, ensuring the jig height meets the ±1mm requirement. To ensure welding quality and reduce welding deformation, the current and voltage parameters during the welding process must be strictly controlled according to the welding procedure specifications.

[0037] For example, in S2, before installing the ribs and frame, the installation positions of the mounting frame and ribs corresponding to the inner bottom plate are first ground, and then the structural lines are marked. Then, the inner bottom plate structural beams are installed according to the position of the structural lines. During the splicing and beam installation process, the work is carried out directly on the jig, and the jig is used to effectively level and constrain the inner bottom plate, thereby ensuring the first-pass yield rate after welding.

[0038] As a preferred embodiment of the present invention, in S8, the double-layer bottom segment and the reference marks on the double-layer bottom segment also need to be measured. To further ensure the integrity of the data and the accuracy of subsequent analysis, the segment body, frame, and baseline also need to be measured synchronously. This method ensures that the data of the support base and other related structures are collected at the same time, thereby making the subsequent data analysis more synchronous and accurate.

[0039] For example, in S8, at least six evenly distributed measurement points are selected on the upper surface of the support. To ensure the accuracy and reliability of the measurement results, according to the standard operating procedure for total station measurement, at least six measurement points are selected on the upper surface panel of a single support, and these points need to be evenly distributed on the panel. Such a distribution ensures that comprehensive data on the support surface is obtained, thereby more accurately assessing its structure and location.

[0040] For example, in S8, after welding is completed, the support base and the double-layer bottom segment are measured again. After the overall welding is completed, the support base and the segment body are measured again for integrity and the measured data is analyzed to ensure that complete and qualified transfer data is provided to the subsequent process.

[0041] The present invention has the following advantages:

[0042] 1. Traditional deformation control relies on heat treatment after welding. The innovative advantage of this invention is that it achieves source control of deformation by using a pre-set anti-deformation jig, a template jig, an upper jig assembly plate, and a pressure beam constraint.

[0043] 2. Traditional installation methods often result in inconsistent installation benchmarks, leading to misalignment with the structure and asynchronous overall state of the sections after installation. The innovative advantage of this invention is that it measures and corrects deviations based on the benchmark lines of the secondary marking on the bottom plate within each section. A unified benchmark is used from the structural marking to the installation of the support base on the reverse side.

[0044] 3. Traditional methods only use two-dimensional control in the pre-welding stage. The innovative advantage of this invention is that it achieves three-dimensional data measurement and analysis in the baseline correction before turning over, the pre-welding installation positioning, and the complete measurement after completion, ensuring accurate overall data analysis.

[0045] 4. Traditional support bases are adjusted after installation based on deviations, while this invention innovatively adds three-dimensional pre-installation technology, enabling accurate simulation and pre-installation of the horizontal deviation between the web height and the inner bottom plate, ensuring precise horizontal accuracy after installation.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method of installing a LPG tank support pedestal in sections, characterized by: Includes the following steps: S1: Lay multiple inner bottom plates on the jig frame, then splice and weld the multiple inner bottom plates together to form an inner bottom plate. The jig frame includes multiple jig plates arranged laterally at intervals. The distance between two adjacent jig plates is less than 2m. The flatness of the top surface of the jig plate is ≤2mm. The height of the jig frame gradually decreases from the middle to both sides laterally. S2: Install the skeleton and frame on the inner bottom plate, and then position and install the outer bottom plate on the skeleton and the frame to form a double bottom segment. When installing the frame, start from the middle of the inner bottom plate and install it gradually from the side to both sides. S3: After loosening the double-layer bottom segment, measure its three-dimensional accuracy data, analyze and compare the deviation value between the measured data and the theoretical data, and then correct the position of the reference marks on the double-layer bottom segment according to the deviation value. The reference marks include the longitudinal center line, the rib line and the horizontal reference point. The horizontal reference point is marked at each of the four corners of the double-layer bottom segment. The theoretical height of the horizontal reference point from the inner bottom plate is a set value. S4: Flip the double-layer bottom segment so that the inner bottom plate is at the top of the double-layer bottom segment, and then adjust the double-layer bottom segment to a horizontal state according to the four corrected horizontal reference points; S5: Using the corrected longitudinal centerline and rib line as a reference, draw the installation outline and centerline of the support base; S6: Based on the position of the installation outline and center line of the support seat, and taking the plane where the four horizontal reference points are located as the horizontal reference, measure the flatness of the installation position of the support seat on the inner bottom plate, and pre-correct the web height of the support seat based on the measured flatness data. S7: After the support base is pre-repaired, hoist the support base onto the inner bottom plate, and perform preliminary positioning and spot welding on the support base according to the installation outline and center line of the support base; S8: Perform three-dimensional measurement on the support base, fine-tune the support base according to the measured data, and measure again until the measured data meets the accuracy requirements. Then weld the web of the support base to the inner bottom plate to form a rigid connection.

2. The LPG tank support pad segmental installation method according to claim 1, characterized in that: In S1, after laying the boards, the dimensions of the boards are checked and confirmed to be qualified before the tire is sealed and leveled to ensure that the gap between the inner bottom board and the tire frame is ≤2mm.

3. The LPG tank support pad segmental installation method according to claim 1, characterized in that: In S2, before installing the ribs and frame, the installation positions of the mounting frame and ribs corresponding to the inner bottom plate are first ground, then the structural lines are marked, and then the inner bottom plate structural pressure beams are installed according to the position of the structural lines.

4. The LPG tank support pad segmental installation method according to claim 1, characterized in that: In S8, the double-bottom segment and the reference marks on the double-bottom segment also need to be measured.

5. The LPG tank support pad segmental installation method according to claim 1, characterized in that: In S8, at least six evenly arranged measurement points are selected on the upper surface of the support.

6. The LPG tank support pad segmental installation method of claim 1, wherein: In S8, after welding is completed, data measurements are taken again for the support base and the double-layer bottom segment.

Images