Large-diameter ventilation pipeline constant-pressure pipe connecting construction technology

Abstract

The invention relates to the technical field of ventilation pipelines, and discloses a large-diameter ventilation pipeline constant-pressure pipe connecting construction technology, a ventilation pipeline comprises multiple sections of pipelines, every two adjacent pipelines are connected through flanges and sealing rings, the flanges of the pipelines are of a rectangular annular structure, and the construction technology comprises the following operation steps that S1, preparation work is conducted; s2, pipeline treatment; s3, pipeline sealing is conducted, specifically, the joint of the two pipelines is sealed through plastic cloth, the two side edges, in the width direction, of the plastic cloth are pasted to the outer walls of the pipelines correspondingly, and allowance is reserved between the plastic cloth and the pipelines; s4, steel plates are inserted, specifically, the steel plates are inserted in the sealing rings of the two pipelines, and the pressure fluctuation condition of the instrument is observed; s5, a new pipeline is installed; S6, the pipeline is sealed again; s7, the steel plate is pulled out, and the steel plate retracts in an original way in a non-uniform-speed and discontinuous mode; and S8, the new pipeline and the original pipeline are fixedly connected. According to the invention, pipe connection or pipe replacement can be realized without shutdown of a production line.

Description

Technical Field

[0001] The present application relates to the technical field of ventilation duct connection, and in particular to a construction process for a constant pressure connection pipe for a large-diameter ventilation duct. Background Art

[0002] Since there is a pressure difference between the air duct in the ventilation system of the high-precision wind pressure manufacturing workshop and the external environment, when the air duct of the ventilation system needs to be connected and modified, the preferred option is to find a shutdown window or shut down the corresponding production line in the workshop to deal with the risk of sudden pressure changes during the construction process.

[0003] In addition, for small-sized air vents, the temporary blocking plate of the air vent is overall light and can be quickly plugged in and replaced manually without the help of machinery. In this case, a rough plug-in plate replacement method is generally adopted. For situations where the internal and external pressure difference is low, the short gap generated during the switching process is not enough to produce obvious pressure difference fluctuations, and the deformation of the plug-in plate is small due to the pressure difference, a rough plug-in plate replacement method can generally be used.

[0004] With respect to the above-mentioned related technologies, it is found that it is very difficult to construct large-size high-pressure differential pipelines without stopping the production line. Summary of the invention

[0005] In order to achieve constant pressure connection of large-size, high-pressure differential pipelines without stopping the production line, the present application provides a constant pressure connection construction process for large-diameter ventilation ducts.

[0006] The present application provides a large-diameter ventilation duct constant pressure pipe construction process, which adopts the following technical solution: A construction process for constant pressure pipe connection of a large-diameter ventilation duct, wherein the ventilation duct comprises multiple sections of ducts, two adjacent ducts are connected by flanges and sealing rings, and the flanges of the ducts are rectangular ring structures, comprising the following steps: S1. Preparation work: determine the pipeline replacement location, construction scope, construction tools, and set up the duct support frame; S2. Pipeline processing: replace the bolts on the bottom of the pipeline flange, replace the short bolts with long bolts, and remove the bolts on both sides and the top of the pipeline; S3, Pipeline sealing: Use plastic sheeting to seal the joint of the two pipes. The two sides of the plastic sheeting in the width direction are respectively attached to the outer wall of the pipe, leaving a margin between the plastic sheeting and the pipe; S4. Insert the steel plate. Insert the steel plate at the sealing ring of the two pipes. The front edge of the steel plate is sharpened. Before inserting the steel plate into the sealing ring, the plastic sheet is first pierced and the plastic sheet is pasted on the steel plate. The steel plate is inserted into the pipe at a non-uniform and discontinuous speed. During the insertion of the steel plate, the staff continuously reports the pressure in the pipe. If the pressure difference deviates from the preset value, the operation is suspended. When the pressure in the pipe is stable, the front edge of the steel plate needs to pause once every time it is extended to a certain distance to observe the pressure fluctuation of the instrument. After the steel plate is fully inserted between the two pipes, the plastic sheets on the two pipes are removed. The steel plate is attached to the pipe with negative pressure due to the pressure difference between the inside and outside of the pipes, and the other pipe can be removed. S5. Install the new pipeline. A sealing ring is installed on the flange of the new pipeline. The new pipeline moves closer to the steel plate along the support frame. The new pipeline fits on the steel plate. When the new pipeline fits on the steel plate, the sealing ring is deformed. The bottom bolts of the original pipeline are inserted into the flange of the new pipeline. The flange of the new pipeline is aligned with the flange of the original pipeline. S6. Pipeline resealing: reinstall plastic sheeting between the new pipeline and the original pipeline for sealing, with the steel plate also inside the plastic sheeting; S7. Pull out the steel plate, and the steel plate returns non-uniformly and discontinuously along the original path. The plastic sheet is pressed against the pipe due to the pressure difference. When the steel plate leaves between the two pipes, the sealing ring of the new pipe fits against the flange of the original pipe. S8. The new pipeline and the original pipeline are fixedly connected.

[0007] By adopting the above technical scheme, through the main steps of sealing before plugging plate construction, plugging plate, replacing old and new pipe fittings, sealing before pulling plate construction, and pulling steel plate, the negative pressure difference in the pipeline fluctuates little, so that the pipe can be connected or replaced without stopping the production line; the plastic sheet is used to seal the two pipelines. When the steel plate does not enter the pipeline, the front end of the steel plate is located in the sealing cavity formed by the plastic sheet, and the tail of the steel plate is located outside the plastic sheet. The pressure in the plastic sheet is the same as the external pressure, and the plastic sheet does not fit the pipeline; when the steel plate is inserted between the two pipelines, a gap appears between the two pipelines, and the plastic sheet is tightly attached to the pipeline and the steel plate due to the internal and external pressure difference. The plastic sheet seals the gap in the pipeline, so that the two pipelines form a sealed state. After the steel plate is partially inserted into the pipeline, the steel plate seals one side of the pipeline, and the plastic sheet pasted on the steel plate can be removed without affecting the sealing effect of the plastic sheet on the pipeline connection; The process of pipeline replacement enables the production line to be replaced without stopping, thereby achieving constant pressure connection of large-size, high-pressure differential pipelines.

[0008] Optionally, in step S4, a reinforcement assembly is used to reinforce the connection between the steel plate and the pipeline, and the reinforcement assembly includes a processing bolt and a reinforcement nut. The processing bolt passes through the steel plate and is threadedly connected with the processing nut, and the nut abuts against the flange.

[0009] By adopting the above technical solution, the steel plate can be temporarily reinforced.

[0010] Optionally, the reinforcement assembly also includes a reinforcement rod, the two ends of the reinforcement rod form an angle, the rod portion of the reinforcement rod is provided with a through hole for screws to pass through, the reinforcement nut abuts against the rod portion of the reinforcement rod, one end of the reinforcement rod abuts against the steel plate, and the other end of the reinforcement rod abuts against the flange.

[0011] By adopting the above technical solution, the structure of the reinforcement rod forms a three-point fixation, so that the steel plate and the flange are fixedly connected.

[0012] Optionally, the reinforcement nut is close to the flange.

[0013] By adopting the above technical solution, the disassembly of the fixed components is facilitated.

[0014] Optionally, in step S5, the bottom edge of the steel plate is in contact with the long bolt.

[0015] By adopting the above technical solution, the long bolts have the effect of guiding and supporting the steel plates.

[0016] Optionally, the sealing ring of the new pipe is fixedly installed on the flange, and adhesive tape is bonded between the flange and the sealing ring.

[0017] By adopting the above technical solution, there is friction on the sealing ring during the steel plate pulling process, and the sealing ring may be pulled, and the tape can reinforce the sealing ring.

[0018] Optionally, the steel plate forward needs to pause every time it penetrates 50 mm, and the steel plate forward needs to pause every time it is pulled out 50 mm.

[0019] By adopting the above technical solution, it is ensured that the negative pressure fluctuation in the pipeline is small and the pipeline switching process is carried out stably and orderly.

[0020] During the optional steel plate movement process, when the pressure deviation in the pipeline exceeds 15Pa, 5s / time, the operation is suspended and waits for stabilization for 20s before continuing. If ±20pa appears, the operation is stopped, the cause is analyzed and measures are taken + construction can be continued 20s after the fluctuation is controllable.

[0021] By adopting the above technical solution, the pressure in the pipeline can be stabilized through specific data and time control, so that the pipeline switching process can be carried out in a stable and orderly manner.

[0022] In summary, the present application includes at least one of the following beneficial effects: 1. During the switching process of large-diameter pipelines, the pressure fluctuation in the pipeline can be stabilized at ±20pa (normal operating fluctuation range), and the production line can be replaced without stopping; 2. During the pipeline switching process, the pressure difference between the inside and outside of the pipeline is used to make the plastic sheet partially seal the pipeline connection, which is simple to operate and can save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the construction process flow of an embodiment of the present application; Figure 2 This is a schematic diagram of the pipeline position and the initial position of the steel plate in the embodiment of the present application; Figure 3 This is a schematic diagram of the structure of an embodiment of the present application in which only the long bolts on the bottom side of the pipeline are left; Figure 4 This is a cross-sectional view of an embodiment of the present application showing that plastic sheets are attached to the outer circumference of two pipes; Figure 5 This is a cross-sectional view of an embodiment of the present application showing a plastic sheet being attached to a steel plate; Figure 6 It is a schematic diagram of an embodiment of the present application showing the steel plate being inserted into a pipe and cooperating with a long bolt; Figure 7 This is a schematic diagram of the structure of the embodiment of the present application when the steel plate plays a role in blocking the pipeline; Figure 8 This is a schematic diagram of an embodiment of the present application showing that the tape is attached to the flange and the sealing ring; Fig. 9 It is a structural schematic diagram of an embodiment of the present application in which a reinforcement component is installed between a steel plate and a flange.

[0024] Explanation of the reference numerals: 10. Pipe; 11. Flange; 12. Long bolt; 13. Sealing ring; 20. Steel plate; 21. Positioning bolt; 30. Support frame; 40. Jack bracket; 50. Jack; 60. Plastic sheeting; 70. Tape; 80. Reinforcement assembly; 81. Reinforcement bolt; 82. Reinforcement nut; 83. Reinforcement rod. DETAILED DESCRIPTION

[0025] The following is combined with Figure 1-9 This application is described in further detail.

[0026] The embodiment of the present application discloses a construction process for a constant pressure pipe connection for a large-diameter ventilation duct.

[0027] A large-diameter ventilation duct constant pressure pipe connection construction process is used for online constant pressure pipe connection of 1.2m*1.4m rectangular ventilation duct 10, and the pressure in the ventilation duct 10 is controlled at -113±2mmAg. The ventilation duct 10 includes multiple sections of pipes 10, and the adjacent pipes 10 are connected by flanges 11 and sealing rings 13. The main steps are: sealing before plug-in construction, plug-in, replacement of old and new pipe fittings, sealing before pulling out the plate, pulling out the plate, overcoming the sealing problems during the connection process, the pressure difference between the inside and outside of the duct, plug-in pushing, plug-in fixing and other problems, and finally realizing constant pressure switching construction.

[0028] Specifically, refer to Figure 1 A large-diameter ventilation duct constant pressure pipe construction process includes the following steps: S1. Preparation work: determine the replacement position of the pipeline 10, the construction scope, construction tools, and set up the air duct support frame 30; S2, processing the pipeline 10, replacing the bolts on the bottom side of the flange 11 of the pipeline 10, replacing the short bolts with the long bolts 12, and removing the bolts on both sides and the top side of the pipeline 10; S3, sealing the pipe 10, using a plastic sheet 60 to seal the connection between the two pipes 10, the two sides of the plastic sheet 60 in the width direction are respectively attached to the outer wall of the pipe 10, and a margin is left between the plastic sheet 60 and the pipe 10; S4, plug-in steel plate 20; S5, installing new pipeline 10; S6, the pipeline 10 is resealed, and the plastic sheet 60 is reinstalled between the new pipeline 10 and the original pipeline 10 for sealing; S7, pull out the steel plate 20; S8. The new pipeline 10 and the original pipeline 10 are fixedly connected.

[0029] More specifically, see Figure 2 In step S1, a steel pipe support frame 30 is installed around the replacement position of the pipe 10 to support the air duct. In the embodiment of the present application, the ventilation duct is connected to the blind plate end of the pipe 10. The jack bracket 40 is implemented, and the installation position of the steel plate 20 is implemented. The jack bracket 40 is fixedly installed on the steel pipe support frame 30, and the jack 50 is installed on the jack bracket 40. The jack 50 pushes the steel plate 20 to move a certain distance. In order to solve the stroke problem of the jack 50, an H-shaped steel beam and a stepping base can be installed on the jack bracket 40. The stepping base can be continuously adjusted forward along the H-shaped steel beam. The stroke problem of the jack 50 can also be solved by replacing extension rods of different lengths on the piston rod. The above two technical means to increase the stroke of the jack 50 are conventional technologies, which will not be elaborated in this application and are not specifically shown in the figure.

[0030] The steel plate 20 of the embodiment of the present application has a size of 1500*1250*6mm, a material of Q235, and a weight of about 90kg. The front edge of the steel plate 20 is sharpened, and the upper and lower corners of the front edge are chamfered. A supporting plane is set at the rear of the steel plate 20, and the piston rod of the jack 50 is connected to the rear supporting plane.

[0031] Reference Figure 3 In step S2, the bolts at the connection of the two pipes 10 are partially disassembled so that the two pipes 10 can still maintain connectivity and negative pressure. First, replace the bolts at the bottom of the flange 11 of the pipe 10, and replace the short bolts with long bolts 12 (φ8×40, 4.8 grade, galvanized), remove one and replace one, and the nuts of the long bolts 12 face outward and fit the outer wall of the flange 11. Then remove the bolts on both sides and the top of the flange 11 of the pipe 10, first loosen all the bolts, and then remove the bolts from the middle to the corners. After the partial bolts of the pipe 10 are removed, due to the negative pressure in the pipe 10, the two pipes 10 are still in a fit state through the sealing ring 13.

[0032] Reference Figure 4 In step S3, before inserting the steel plate 20, the connection between the two pipes 10 is sealed. The two pipes 10 are sealed with a transparent plastic sheet 60. After the side of the plastic sheet 60 is pasted along the outer wall of the pipe 10, the side of the plastic sheet 60 is sealed and connected with the outer wall of the pipe 10. Since the two pipes 10 are still in a sealed connection state, the air pressure in the space inside the plastic sheet 60 is the same as the external air pressure. The width of the plastic sheet 60 is larger than the size between the pasting positions of the two pipes 10, so that in addition to the side of the plastic sheet 60 being sealed and connected with the pipe 10, there is space between the plastic sheet 60 and the pipe 10, and the plastic sheet 60 does not fit on the pipe 10.

[0033] Reference Figure 5 Before inserting the steel plate 20 at the connection of the pipe 10, the steel plate 20 first breaks the plastic sheet 60, and then the broken position of the plastic sheet 60 is taped to the steel plate 20, so that the steel plate 20 does not affect the sealing treatment of the plastic sheet 60 on the pipe 10.

[0034] Since the original flange 11 is still in a tightly fitted state due to the adhesion of the sealing ring 13, a crowbar is needed to assist in loosening. In this process, the plastic sheet 60 will inevitably be slightly damaged, and the leak should be repaired with adhesive tape in time.

[0035] During the insertion of the steel plate 20, the side of the steel plate 20 is preferably attached to the pipe 10 to be retained, and the sealing ring 13 is mainly bonded to the pipe 10 to be removed. The sealing ring 13 between the two pipes 10 is stretched open by the steel plate 20 to form a gap, and the pressure difference between the inside and outside of the pipe 10 causes the plastic sheet 60 to fit on the pipe 10, and the plastic sheet 60 blocks the gap of the pipe 10. The plastic sheet 60 has a local auxiliary sealing effect on the pipe 10, which greatly reduces the risk of pressure fluctuation in the pipe 10.

[0036] After the steel plate 20 is inserted into the pipe 10, the tape of the plastic sheet 60 on the steel plate 20 needs to be removed for further insertion. The plastic sheet 60 remains naturally attached to the surface of the steel plate 20 due to the negative pressure in the pipe 10. In the subsequent insertion process, the plastic sheet 60 should be adjusted in time to keep the plastic sheet 60 attached to the steel plate 20 from being carried into the gap by the steel plate 20. At this time, the connection between the steel plate 20 and the pipe 10 also has a certain blocking effect on the pipe 10.

[0037] The steel plate 20 is inserted into the pipe 10 at a non-uniform and discontinuous speed, and the staff continuously reports the pressure in the pipe 10. When the steel plate 20 is moved, if the pressure in the air duct deviates by more than 15Pa, 5s / time, the operation is suspended and waits for stabilization for 20s before continuing. If it is ±20pa, the operation is stopped immediately, the cause is analyzed and measures are taken. Construction can only be continued 20s after the fluctuation is controllable. When the pressure in the air duct is stable, the steel plate 20 front needs to pause every time it penetrates 50mm.

[0038] Reference Figure 6 During the plugging process, the steel plate 20 contacts the long bolts 12, and the bolts at the bottom of the pipe 10 are always in a properly loose installation state. The long bolts 12 act as the lower limit stopper of the steel plate 20 during its movement.

[0039] Reference Figure 7 The side wall of the steel plate 20 may be plugged with a positioning bolt 21. When the steel plate 20 is fully inserted between the two pipes 10, the screw of the positioning bolt 21 contacts the outer side wall of the flange 11 of the pipe 10, indicating that the steel plate 20 does not need to be moved any more.

[0040] After the steel plate 20 is completely inserted between the two pipes 10, the steel plate 20 is tightly attached to the pipes 10 due to the pressure relationship between the inside and outside of the pipes 10. The plastic sheets 60 on the two pipes 10 are removed, and the other pipe 10 is removed, and the old sealing ring 13 is also removed with the pipes 10.

[0041] Step S5 begins, installing the new pipe 10, with a sealing ring 13 fixedly attached to the flange 11 of the new pipe 10. The new pipe 10 is hoisted by an electric hoist, and the new pipe 10 is moved toward the steel plate 20 along the steel pipe support frame 30, and the flange 11 of the new pipe 10 is connected with the long bolts 12, which can also ensure that the two pipes 10 are not misaligned when connected.

[0042] Reference Figure 8, the new pipe 10 is attached to the steel plate 20 through the sealing ring 13. The new pipe 10 can be manually or by equipment to apply force. The sealing ring 13 is tightly attached to the steel plate 20 and deformed appropriately. There is a large friction between the steel plate 20 and the sealing ring 13 during the withdrawal process. In order to stabilize the sealing ring 13, the adhesive tape 70 is pasted on the flange 11 and the sealing ring 13. The sealing ring 13 is away from the withdrawal direction of the steel plate 20 and the adhesive tape 70 is pasted. When the steel plate 20 is pulled on the sealing ring 13 during the withdrawal process, the adhesive tape 70 allows the sealing ring 13 to overcome the pulling and stably stay on the pipe 10.

[0043] In order to partially seal the new pipe 10 and the original pipe 10 during the process of pulling out the steel plate 20, a plastic sheet 60 is re-wrapped between the new pipe 10 and the original pipe 10. Both sides of the plastic sheet 60 are respectively pasted on the outer peripheral side of the new pipe 10 and the outer peripheral side of the original pipe 10. After the plastic sheet 60 is pasted and fixed, a closed space is left between it and the pipe 10. The steel plate 20 is also located in the plastic sheet 60, and the piston rod and the plastic sheet 60 are sealed and connected.

[0044] Reference Figure 8 When the steel plate 20 is non-uniformly and discontinuously retracted along the original path, a gap appears at the connection of the two pipes 10. The plastic sheet 60 is pressed against the pipe 10 by the pressure difference. The contact part between the steel plate 20 and the sealing ring 13 also has a blocking effect on the connection of the pipe 10. Part of the plastic sheet 60 is also attached to the steel plate 20. Then the plastic sheet 60 is removed from the piston rod. When the steel plate 20 leaves between the two pipes 10, the sealing ring 13 of the new pipe 10 is pressed against the flange 11 of the original pipe 10 by the pressure difference between the inside and outside of the pipe 10.

[0045] Similarly, the steel plate 20 leaves the pipe 10 at a non-uniform and discontinuous speed, and the staff continuously reports the pressure in the pipe 10. When moving the steel plate 20, when the pressure in the air duct deviates by more than 15Pa, 5s / time, the operation is suspended and waits for stabilization for 20s before continuing. If ±20pa appears, the operation is stopped immediately, the cause is analyzed and measures are taken. Construction can only be continued 20s after the fluctuation is controllable. When the pressure in the air duct is stable, the steel plate 20 needs to be paused every time the front end is pulled out 50mm.

[0046] The initial 3-6cm of the plugging and unplugging process is the key process for controlling pressure fluctuations, and the travel speed is strictly controlled.

[0047] When all the steel plates 20 are pulled out, the plastic sheet 60 is also removed from the pipe 10 , and finally the new pipe 10 and the original pipe 10 are fixedly and sealedly connected using bolts and nuts.

[0048] Further, refer to Fig. 9In step S4, when the steel plate 80 completely blocks the pipeline 10, the reinforcement assembly 80 is used to strengthen the connection between the steel plate 20 and the pipeline 10. The reinforcement assembly 80 includes a reinforcement bolt 81 and a reinforcement nut 82. The top of the steel plate 20 located outside the pipeline 10 is provided with a through hole for the reinforcement bolt 81 to pass through. The reinforcement bolt 81 passes through the steel plate 20 and is threadedly connected with the reinforcement nut 82. The reinforcement assembly 80 also includes a reinforcement rod 83. The two ends of the reinforcement rod 83 form an angle. The angle between the two ends of the reinforcement rod 83 of the embodiment of the present application is preferably 90°, and the reinforcement rod 83 is L-shaped. A through hole for the screw to pass through is provided on the longer rod portion of the reinforcement rod 83. The screw first passes through the reinforcement rod 83 and then is threadedly connected with the nut. The shorter rod end of the reinforcement rod 83 abuts on the steel plate 20, and the longer rod end of the reinforcement rod 83 abuts on the flange 11 of the pipeline 10. The reinforcement assembly 80 is provided in multiple groups, and the addition of the reinforcement rod 83 further strengthens the connection relationship between the steel plate 20 and the pipeline 10.

[0049] The implementation principle of a large-diameter ventilation duct constant pressure pipe construction process in the embodiment of the present application is: Mainly in the process of inserting and removing the plates, the pressure relationship is fully considered and a phased, non-uniform speed operation plan is formulated; the plate insertion process is divided into: the breaking stage (first remove the plastic sheet 60, and stick the plastic sheet 60 and the steel plate 20), the insertion stage (inserting the steel plate 20 into the connection between the two pipes 10), and the finishing stage (fixing the steel plate 20 after inserting the plate); the removal process is divided into: the connection stage (first use the plastic sheet 60 to re-seal the new pipe 10 and the original pipe 10), the removal stage (non-uniform speed removal of the steel plate 20), and the finishing stage. In addition, according to actual needs, a local auxiliary sealing method is adopted for the connection of the pipe 10, and the large-diameter pipe 10 is replaced without stopping the production line, which greatly reduces the risk of internal pressure fluctuations of the large-diameter pipe 10.

[0050] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A constant pressure pipe construction process for a large-diameter ventilation duct, wherein the ventilation duct (10) comprises a plurality of ducts (10), two adjacent ducts (10) are connected via flanges (11) and sealing rings (13), and the flanges (11) of the ducts (10) are rectangular ring structures, characterized in that: The steps include: S1. Preparation work, determining the replacement position of the pipeline (10), the construction scope, construction tools, and setting up the air duct support frame (30); S2, processing the pipeline (10), replacing the bolts on the bottom side of the flange (11) of the pipeline (10), replacing the short bolts with the long bolts (12), and removing the bolts on both sides and the top side of the pipeline (10); S3, sealing the pipe (10), using a plastic sheet (60) to seal the connection between the two pipes (10), with both sides of the plastic sheet (60) in the width direction being adhered to the outer wall of the pipe (10) respectively, leaving a margin between the plastic sheet (60) and the pipe (10); S4, inserting the steel plate (20), inserting the steel plate (20) at the sealing rings (13) of the two pipes (10), sharpening the front edge of the steel plate (20), breaking the plastic sheet (60) before inserting the steel plate (20) into the sealing ring (13), and sticking the plastic sheet (60) on the steel plate (20), and inserting the steel plate (20) into the pipe (10) at a non-uniform speed and discontinuously. During the insertion of the steel plate (20), the staff continuously reports the pressure in the pipe (10). If the pressure difference deviates from the preset value, the operation is suspended. When the pressure in the pipe (10) is stable, the front edge of the steel plate (20) needs to pause once every time it is extended to a certain distance to observe the pressure fluctuation of the instrument. After the steel plate (20) is completely inserted between the two pipes (10), the plastic sheet (60) on the two pipes (10) is removed, and the steel plate (20) is attached to the pipe (10) with negative pressure due to the pressure difference between the inside and outside of the pipes (10), and the other pipe (10) can be removed; S5. Install the new pipeline (10). A sealing ring (13) is installed on the flange (11) of the new pipeline (10). The new pipeline (10) is moved closer to the steel plate (20) along the support frame (30). The new pipeline (10) is attached to the steel plate (20). When the new pipeline (10) is attached to the steel plate (20), the sealing ring (13) is deformed. The bottom bolts of the original pipeline (10) are inserted into the flange (11) of the new pipeline (10). The flange (11) of the new pipeline (10) is aligned with the flange (11) of the original pipeline (10). S6, the pipeline (10) is resealed, and the plastic sheet (60) is reinstalled between the new pipeline (10) and the original pipeline (10) for sealing, and the steel plate (20) is also located inside the plastic sheet (60); S7, the steel plate (20) is pulled out, and the steel plate (20) is returned non-uniformly and discontinuously along the original path, and the plastic sheet (60) is pressed against the pipe (10) due to the pressure difference, and when the steel plate (20) leaves between the two pipes (10), the sealing ring (13) of the new pipe (10) is pressed against the flange (11) of the original pipe (10); S8, the new pipeline (10) and the original pipeline (10) are fixedly connected.

2. A large-diameter ventilation duct constant pressure pipe construction process according to claim 1, characterized in that: In step S4, a reinforcement assembly (80) is used to reinforce the connection between the steel plate (20) and the pipe (10). The reinforcement assembly (80) includes a processing bolt and a reinforcement nut (82). The processing bolt passes through the steel plate (20) and is threadedly connected to the processing nut, and the nut abuts against the flange (11).

3. A large-diameter ventilation duct constant pressure pipe construction process according to claim 2, characterized in that: The reinforcement assembly (80) further comprises a reinforcement rod (83), two ends of the reinforcement rod (83) form an angle, a rod portion of the reinforcement rod (83) is provided with a through hole for a screw to pass through, the reinforcement nut (82) abuts against the rod portion of the reinforcement rod (83), one end of the reinforcement rod (83) abuts against the steel plate (20), and the other end of the reinforcement rod (83) abuts against the flange (11).

4. A large-diameter ventilation duct constant pressure pipe construction process according to claim 3, characterized in that: The reinforcing nut (82) is close to the flange (11).

5. A large-diameter ventilation duct constant pressure pipe construction process according to claim 1, characterized in that: In step S5, the bottom edge of the steel plate (20) is in contact with the long bolt (12).

6. A large-diameter ventilation duct constant pressure pipe construction process according to claim 1, characterized in that: The sealing ring (13) of the new pipe (10) is fixedly mounted on the flange (11), and a tape (70) is bonded between the flange (11) and the sealing ring (13).

7. A large-diameter ventilation duct constant pressure pipe construction process according to claim 1, characterized in that: The forward of the steel plate (20) needs to pause once for every 50mm of penetration, and the forward of the steel plate (20) needs to pause once for every 50mm of extension.

8. The large-diameter ventilation duct constant pressure pipe construction process according to claim 1 is characterized by: During the movement of the steel plate (20), when the pressure in the pipeline (10) deviates by more than 15Pa, 5s / time, the operation is suspended and waited for stabilization for 20s before continuing. If it exceeds ±20pa, the operation is stopped, the cause is analyzed and measures are taken. Construction can be continued only after the fluctuation is controllable for 20s.

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