Three-machine stress-free piping construction method for ethylene unit

Abstract

The invention provides an ethylene unit three-machine stress-free piping construction method which comprises the following steps: dividing a connecting pipeline into a horizontal section, a vertical pipe section and an adjusting section according to a pipeline diagram, and respectively prefabricating the horizontal section, the vertical pipe section and the adjusting section; the adjusting section, the horizontal section and the vertical pipe section are assembled and spliced in sequence by means of hanging a dial indicator and assisting a rack; the welded junction of the pipeline is moved to the final welded junction position and welded through symmetrical welders, pipeline installation and connection are in a free vertical state, stress caused by pipeline installation is eliminated, and the installation precision and the construction progress of connection of equipment and the pipeline are effectively guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of chemical equipment installation, and in particular to a three-machine stress-free piping construction method for an ethylene device. Background Art

[0002] The ethylene plant is the core plant of the petrochemical industry and the main facility for producing ethylene. The three machines in the ethylene plant (cracking gas compressor, ethylene compressor, and propylene compressor) are the key equipment of the entire plant, providing power for the flow of materials. The stable operation of the three machines requires that the stress of the pipeline system cannot be transmitted to the three machines. Therefore, the stress-free piping construction of the pipeline system is a key link.

[0003] In traditional piping construction, stress often occurs when the pipeline is connected to the three machines. When the pipeline expands and contracts due to temperature changes during operation, the expansion or contraction of the pipeline will produce tension or pressure on the interface of the three equipment because traditional piping does not fully consider this change. This additional stress may cause deformation and damage at the equipment interface, and even affect the mechanical structure and sealing performance of the equipment. In the high temperature and high pressure environment of the ethylene device, this damage may further cause leakage, increased vibration and other problems, seriously affecting the service life and safety of the equipment. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a stress-free piping construction method for three machines in an ethylene device, which realizes the installation of stress-free piping of equipment port pipelines, reduces high-altitude operations, and ensures high-precision installation of pipelines.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for constructing three-machine stress-free piping of an ethylene device, comprising the steps of: Step 1: According to the pipeline diagram, the connecting pipeline is divided into a horizontal section, a vertical pipe section, and an adjustment section, and prefabricated respectively; Step 2: a stand is arranged around the compressor, a plurality of hoists are arranged on the top of the stand, the hoists are connected to the outer wall of the riser section through the sling, and the prefabricated riser section is delivered to the bottom of the installation position by using the hoists and the sling; The stand comprises a hanging frame, which comprises a plurality of columns arranged around the compressor, a top hanging frame is arranged on the top of the columns, an operating hanging frame is arranged in the middle of the columns, a lifting hoist is arranged on the top hanging frame, and a supporting frame is arranged on the upper part of the operating hanging frame; Step 3: Remove the hoist and slings, place the vertical pipe on the shim on the support frame, and then use a feeler gauge to measure the gap and non-parallelism between the two flanges of the compressor and the main pipe. According to the measured values, adjust the shim and move the pipe section for alignment; then add formal gaskets between the flanges and install bolts; Step 4: Assemble and weld the horizontal section, adjustment section and riser section.

[0006] Furthermore, in step one, when the riser section is prefabricated, it is lengthened by 20 mm as an adjustment cutting allowance.

[0007] Furthermore, in step one, when the horizontal section, the riser section and the adjustment section are prefabricated, the stand is used as a processing platform.

[0008] Furthermore, in step one, before the riser is formally installed, the flange port of the riser is pre-connected with the flange port of the compressor, a temporary gasket is inserted between the riser flange and the compressor flange, the parallelism of the flange is checked, and a dial indicator is set on the coupling to test the radial and axial displacements of the body.

[0009] Furthermore, in step 2, the lifting hoists are hung on the top hanger to connect the riser sections, and the riser sections are lifted by the lifting hoists to 5 to 10 mm away from the compressor flange. The centers of the bolt holes of the upper and lower flanges are preliminarily aligned, and the connecting bolts are inserted. The bolts are only used as centering guides and do not bear the weight of the riser sections.

[0010] Furthermore, in step three, by adjusting the shims and moving the riser section for alignment, the gap between the riser flange and the compressor flange is made to be 3 mm and the non-parallelism is within 0.1 mm.

[0011] Furthermore, in step four, during the assembly welding, check the parallelism between the compressor flange and the riser flange and whether the inserted bolts can loosen freely. If any non-compliance is found, it shall be processed and adjusted to the specified requirements. Install a dial indicator on the supports on both sides of the compressor and the axial flexible legs to monitor whether the compressor has radial and axial displacements due to the force.

[0012] Furthermore, in step four, the last pair of pipe openings are formed into horizontal welding joints, and the welding is performed by two welders simultaneously and symmetrically.

[0013] The present invention realizes the construction method of stress-free piping of high-power and large-diameter equipment pipelines by adopting the method of hanging meters and setting up benches. Compared with the traditional piping construction method of piping from the far end of the pipe section to the equipment end of the moving equipment, it saves the cost of erecting and dismantling scaffolds, reduces high-altitude operations, shortens the construction period, and saves costs. Through the actual measurement of hanging meters, the pipeline installation connection is placed in a free vertical state, eliminating the stress caused by the pipeline installation, and effectively ensuring the installation accuracy and construction progress of the equipment and pipeline connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings herein are used to provide further explanation of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their description are used for explanation and do not constitute improper limitation of the present invention.

[0015] Figure 1is a schematic diagram of the pipeline weld according to the present invention; Figure 2 The steel operating platform of the present invention; Figure 3 Final fixed port welding sequence diagram.

[0016] In the figure, 1-compressor flange, 2-guide bolt, 3-lifting hoist, 4-positioning top screw, 5-operating hanger, 6-riser section, 7-shim, 8-gasket feeler gauge, 9-support frame, 10-top hanger, 11-riser flange. DETAILED DESCRIPTION

[0017] The main inlet and outlet pipelines of the cracking gas compressor, ethylene compressor and propylene compressor of the ethylene device are arranged relatively concentratedly and have a relatively high installation height. The connection between the compressor unit and the pipeline system requires that the stress of the pipeline system cannot be transmitted to the compressor equipment, and the unit must achieve stress-free connection. The basic concept of the present invention is to first divide the connecting pipeline into horizontal section, vertical pipe section and adjustment section according to the pipeline diagram, do a good job of numbering, use the equipment body flange as a reference point, use a stand to fix the pipeline, hang a dial indicator to adjust the verticality and horizontality of the pipeline, and the gap of the flange surface of the pipe mouth, ensure free verticality to achieve stress-free connection of the pipeline, ensure that the equipment pipe mouth is not subjected to the weight and tension of the pipeline, thereby ensuring stress-free operation of the equipment, and making the operation convenient during piping installation.

[0018] Taking the ethylene compressor K1650 as an example, the technical solution to be protected by the present invention is further explained clearly and completely. The connecting pipe section of the ethylene compressor K1650 includes: K1650 three-level G3702 inlet: 48"-RE16012-A71KEO-AC K1650 three-level G3702 outlet: 24"-RE16013-A71KEO-AC K1650 low pressure inlet: 30"-RE16001-A71KEO-AC K1650 High Pressure Inlet: 24"-RE16170-A71KEO-AC K1650 High Pressure Outlet: 16"-RE16115-A71KEO-AH.

[0019] Step 1: According to the pipeline diagram, divide the connecting pipeline into horizontal section, vertical pipe section and adjustment section, and prefabricate them separately.

[0020] Before the formal installation of the riser, pre-connect the flange of the riser with the flange of the compressor, add a temporary gasket between the riser flange 11 and the compressor flange 1, check the parallelism of the flanges and set up a dial indicator on the coupling to test the radial and axial displacement of the machine body.

[0021] For example, Figure 1 As shown, taking the middle pipeline 24"-RE16010-A81KEO-AC as an example, the section between 1# and 4# welds is the riser section 6, the section between 4# and 6# welds is the horizontal section, the adjustment section is placed on the horizontal pipe between 4# and 6# welds, and the last weld of the entrance is set at 4# weld. It should be noted that this exemplary pipeline does not include a span section, but other pipelines include a span section. For pipelines below this type, the pipeline at the equipment port should be divided into the adjustment section, horizontal section, riser section and span section of the pipeline in advance according to the single-line diagram.

[0022] When the adjustment section is prefabricated, the hanging line measurement should be carried out according to the actual position and actual elevation of the body interface flange. When prefabricating the horizontal pipe, the level of the powder line must be checked with a level meter. Only after passing the test can the length be measured and cut. The vertical pipe section should be lengthened by 20mm as the adjustment cutting allowance. After the allowance is cut, the inside of the pipe should be cleaned.

[0023] First, connect the riser section 6 from the 1# to 4# ports on the pipeline 24"-RE16010-A81KEO-AC to the compressor flange 1. Prefabricate the reducer welds 2# and 3# in advance. Add temporary gaskets between the riser flange 11 and the compressor flange 1. The bolts do not need to be too tight. At the same time, check the parallelism of the flanges. Weld four fixtures symmetrically around the 4# and 6# welds, then assemble the 6# weld, spot weld, and each weld is welded symmetrically by two welders. While welding, pay close attention to the misalignment of the pipe at the 4# weld, and adjust it by symmetrical welding. Finally, two welders symmetrically assemble the 4# weld. While welding, the fitter sets up a dial indicator on the coupling to test the radial and axial displacement of the body. If it exceeds the standard, the welder should stop welding immediately, and then adjust the welding position according to the nature of the deviation until the welding is completed and the inspection is qualified, and finally remove the fixture.

[0024] After the weld is completed, loosen the fastening bolts and remove the temporary gasket, which is 10# steel with a surface finish of 6.3. Use a gasket feeler gauge to check the flange parallel deviation, radial deviation, and sealing surface spacing. If it is unqualified, re-grind one side and adjust the welding to meet the measurement standard.

[0025] In this step, the compressor inlet pipeline must be cleaned before installation. When removing impurities, it can be done manually (sandblasting) or manually rusted, and then sealed with plastic cloth. After cleaning, the pipe section is confirmed by the workshop before installation. Before installing the adjustment section, it is necessary to check whether the sealing surface of the body flange and the pipe flange are parallel and whether the bolt holes are concentric. Only after the quality inspection personnel have passed the inspection can the installation be carried out. When piping the compressor, it should be done from the outside to the body, and the head should be shaken at the weld close to the body.

[0026] Step 2: a stand is set up around the compressor, and multiple lifting hoists 3 are set up on the top of the stand. The lifting hoists 3 are connected to the outer wall of the vertical pipe section 6 through the lifting slings. The prefabricated vertical pipe section 6 is sent to the bottom of the installation position by using the lifting hoists 3 and the lifting slings.

[0027] like Figure 2 As shown, the stand includes a hanging frame, which includes a plurality of columns arranged around the compressor, a top hanger 10 is arranged on the top of the columns, an operating hanger 5 is arranged in the middle of the columns, a lifting hoist 3 is arranged on the top hanger 10, and a support frame 9 is arranged on the upper part of the operating hanger 5.

[0028] Use a temporary stand as an installation and adjustment platform, pre-connect the flange port of the pipeline with the equipment port, hang a dial indicator for inspection, and handle the equipment without stress, so as to ensure that the pipeline is welded together without stress. Use the stand to ensure the horizontality and verticality of the pipeline, set up the lifting ears and auxiliary tools in advance to ensure the horizontality of the pipeline assembly, and ensure the high-altitude installation work of stress-free connection of the equipment flange port.

[0029] In this step, since the main inlet and outlet pipelines of the compressor are arranged relatively concentratedly and have a relatively high installation height, in order to facilitate the operation during piping installation and not to add the weight of hoisting and positioning to the compressor body, firstly, a two-layer steel operating platform is set at an appropriate height of the compressor unit, and a top hanger 10 is set at the top position of the platform. Then, the prefabricated riser section 6 is delivered to the bottom of the installation position by using the lifting hoist 3 and the lifting sling.

[0030] Exemplarily, four lifting hoists 3 are hung on the top hanger 10 to connect the riser section 6. The lifting hoists 3 are used to lift the riser section 6 to 5 to 10 mm away from the compressor flange. The centers of the bolt holes of the upper and lower flanges are preliminarily aligned, and the connecting guide bolts 2 are inserted. The guide bolts 2 are only used for centering guides and do not bear the weight of the riser section 6.

[0031] Step three, when the vertical pipe section 6 is delivered to the bottom of the installation position, set up the support frame 9 on the operating hanger 5 and set the shim 7 on the support frame 9, remove the lifting hoist 3 and the lifting sling, put the vertical pipe in place on the shim 7 on the support frame 9, and then use the shim feeler gauge 8 to measure the gap and non-parallelism between the two flanges of the compressor and the main pipe. The measurement should be carried out symmetrically at four points. According to the measured values, adjust the shim 7 and move the pipe section for alignment so that the gap is 3mm and the non-parallelism is within 0.1mm.

[0032] Then add the formal gasket between the flanges and install bolt 2. The bolts in the inserted bolt holes can be loosened freely. Add the formal gasket before inserting the bolts. Before adding the formal gasket, check that the sealing surfaces of the two flanges and the gasket are free of damage and defects. After the vertical pipe is aligned, it is necessary to prevent arbitrary movement and keep it in a free state.

[0033] Step 4: assemble and weld the horizontal section, the adjustment section and the vertical pipe section 6.

[0034] The assembly and splicing of the horizontal section, riser section and cross section in the single-line drawing is the key to ensure that the pipeline does not generate stress on the compressor unit. In particular, the final connection and fixing weld will directly affect the non-parallelism between the two flanges of the compressor and the riser section and the centering of the bolt holes, thereby affecting the concentricity of the unit.

[0035] When installing the cross section and splicing it with the horizontal pipe section, the vertical pipe must be used as a reference to check the verticality and parallelism of the vertical pipe. The result should be correct. The cross section and the vertical pipe section should be pre-assembled and the assembly welds should be adjusted to ensure that the gap around the pipe opening is uniform and the misalignment meets the requirements.

[0036] In principle, the final assembly of the pipe mouth is set as a horizontal welding joint to reduce welding deformation. The spot welding of the pipe mouth must be carried out symmetrically and staggered by two qualified welders at the same time (such as Figure 3 ) When welding, the welding current and speed of the two people should be basically the same. Spot welding should be carried out. At the same time, full-time personnel should be arranged to measure the parallelism between the compressor and the flange at the end of the vertical pipe, and check whether the inserted bolts can be loosened freely. Install a dial indicator on the supports on both sides of the compressor and the axial flexible legs. Through the changes in the dial indicator readings, monitor whether the compressor has radial and axial displacement due to force. Timely adjust the welding position, sequence, time and speed, adjust the stress caused by welding, and ensure that the monitoring data are within the specified requirements.

[0037] In this embodiment, precise installation guidance and dynamic construction monitoring are achieved by hanging a dial indicator. (1) During the pipeline installation process, the dial indicator can display the displacement changes at the pipeline interface in real time, providing construction personnel with accurate adjustment basis. When the pipeline is connected to the equipment, by observing the data of the dial indicator, the construction personnel can adjust the position and angle of the pipeline in time to ensure that the pipeline is docked with the equipment in a stress-free state and avoid stress concentration caused by forced docking. (2) During the pipeline welding process, the dial indicator is used to monitor the slight displacement of the pipeline to determine the impact of welding thermal stress on the pipeline. If it is found that the displacement exceeds the allowable range, the welding sequence or parameters can be adjusted in time to ensure the welding quality and the stability of the pipeline.

[0038] In this embodiment, segmentation makes pipeline installation more systematic and controllable. Each segment has a clear installation position and interface requirements. Construction personnel can operate according to the pre-established installation sequence and standards, reducing confusion and errors during the installation process. In the key segments where the pipeline is connected to the equipment, the installation deviation is controlled within a very small range (such as ±1mm) through precise measurement and positioning, ensuring that the interface between the pipeline and the equipment fits tightly, improving the installation quality and sealing of the pipeline system.

[0039] Each segmented pipeline can be processed and pre-assembled with high precision during the prefabrication stage, including pipeline cutting, groove production and pipe fitting assembly, with a processing accuracy of ±0.5mm. In this way, each segment can be quickly and accurately connected during on-site installation, reducing the workload of on-site adjustment and correction, which is conducive to ensuring the overall straightness and concentricity of the pipeline system, thereby improving the fluid transportation efficiency and operation stability of the pipeline.

[0040] In this embodiment, the stand can be equipped with a variety of auxiliary tools, which can facilitate the fixing and positioning of the pipeline during the prefabrication process, and facilitate construction workers to weld and process from different angles, thereby reducing the labor intensity of construction workers and improving the prefabrication quality.

[0041] During the pipeline installation phase, the stand can be used as a temporary support and adjustment platform for the pipeline. Through the height and angle adjustment functions of the stand, the pipeline can be accurately adjusted to a position that matches the equipment interface or adjacent pipelines, making it easier to dock and connect the pipelines.

[0042] The stand is a temporary support structure for the pipeline, providing stable support for the pipeline. The stand can ensure the safety of the pipeline during installation and prevent the pipeline from being deformed due to its own weight or external force. When hoisting large pipelines, the pipeline is placed on the stand for adjustment and docking, which reduces the time the pipeline stays in the air and improves installation efficiency and safety.

[0043] The stand can help construction workers accurately adjust the position and angle of the pipeline through its own adjustment function. Through the positioning device and measuring tools on the stand, construction workers can control the installation deviation of the pipeline within a very small range and achieve accurate docking of the pipeline with equipment or adjacent pipelines. This high-precision installation method can effectively reduce the installation stress of the pipeline and extend the service life of the pipeline.

[0044] The bench is seamlessly connected with the entire stress-free piping construction process. In the pipeline prefabrication stage, the bench serves as a high-precision processing platform for pipeline segments. During the pipeline installation process, the bench can quickly and accurately transport the pipeline segments to the installation location, and provide stable support and positioning, which is convenient for construction personnel to carry out pipeline docking and welding operations; in the pipeline stress adjustment stage, the bench can also be used as an operating platform for stress monitoring and adjustment, and closely cooperates with the dial indicator monitoring system to achieve precise control and optimization of pipeline segment stress. This makes the entire stress-free piping construction process smoother and more efficient, reduces the errors and stress changes caused by the conversion of construction links, and further improves the construction quality and stability of the pipeline system.

[0045] In summary, this embodiment realizes the construction method of stress-free piping for high-power and large-diameter equipment pipelines by using the hanging meter and setting up a bench method. Compared with the traditional piping construction method of moving equipment from the far end of the pipe section to the equipment end, it saves the cost of scaffolding erection and dismantling, shortens the construction period, and saves costs. It changes the previous construction method of piping that cannot achieve installation accuracy and eliminate stress, and provides a technical reference for the construction of similar projects in the future. Through the actual measurement of the hanging meter, the pipeline installation connection is placed in a free vertical state, and the stress caused by the pipeline installation is eliminated through the auxiliary facilities, which effectively ensures the pipeline construction quality and construction progress.

Claims

1. A method for constructing three-machine stress-free piping in an ethylene plant, characterized in that: Includes steps: Step 1: According to the pipeline diagram, the connecting pipeline is divided into a horizontal section, a vertical pipe section, and an adjustment section, and prefabricated respectively; Step 2: a stand is arranged around the compressor, a plurality of hoists are arranged on the top of the stand, the hoists are connected to the outer wall of the riser section through the sling, and the prefabricated riser section is delivered to the bottom of the installation position by using the hoists and the sling; The stand comprises a hanging frame, which comprises a plurality of columns arranged around the compressor, a top hanging frame is arranged on the top of the columns, an operating hanging frame is arranged in the middle of the columns, a lifting hoist is arranged on the top hanging frame, and a supporting frame is arranged on the upper part of the operating hanging frame; Step 3: Remove the hoist and slings, place the vertical pipe on the shim on the support frame, and then use a shim feeler gauge to measure the gap and non-parallelism between the two flanges of the compressor and the main pipe. According to the measured values, adjust the shim and move the pipe section for alignment; then add formal gaskets between the flanges and install bolts; Step 4: Assemble and weld the horizontal section, adjustment section and riser section.

2. The method according to claim 1, characterized in that: In step 1, when prefabricating the vertical pipe section, add 20 mm to adjust the cutting allowance.

3. The method according to claim 1 or 2, characterized in that: In step 1, when the horizontal section, the riser section and the adjustment section are prefabricated, the above-mentioned stand is used as a processing platform.

4. The method according to claim 3, characterized in that: In step one, before the riser is formally installed, pre-connect the flange of the riser with the flange of the compressor, insert a temporary gasket between the flange of the riser and the flange of the compressor, check the parallelism of the flanges, and set up a dial indicator on the coupling to test the radial and axial displacement of the machine body.

5. The method according to claim 1 or 4, characterized in that: In step 2, hang the lifting hoist on the top hanger to connect the vertical pipe section, use the lifting hoist to lift the vertical pipe section to 5 to 10 mm away from the compressor flange, preliminarily align the center of the bolt holes of the upper and lower flanges, and insert the connecting bolts. The bolts are only used as centering guides and do not bear the weight of the vertical pipe section.

6. The method according to claim 5, characterized in that: In step three, by adjusting the shims and moving the riser section for alignment, the gap between the riser flange and the compressor flange is made to be 3 mm and the non-parallelism is within 0.1 mm.

7. The method according to claim 1 or 6, characterized in that: In step 4, during assembly welding, check the parallelism between the compressor flange and the riser flange and whether the inserted bolts can loosen freely. If any non-compliance is found, handle it and adjust it to the specified requirements. Install a dial indicator on the supports on both sides of the compressor and the axial flexible legs to monitor whether the compressor has radial and axial displacement due to force.

8. The method according to claim 7, characterized in that: In step 4, the last pair of pipe ends are assembled into horizontal welding joints, and welding is performed simultaneously and symmetrically by two welders.

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