A construction process for constant pressure connection of large-diameter ventilation ducts

Abstract

This application relates to the technical field of ventilation ducts and discloses a construction process for constant pressure connection of large-diameter ventilation ducts. The ventilation duct includes multiple sections, with adjacent sections connected by flanges and sealing rings. The flanges of the ducts have a rectangular ring structure. The process includes the following steps: S1, preparation; S2, duct treatment; S3, duct sealing, using plastic sheeting to seal the connection between the two ducts, with both sides of the plastic sheeting adhering to the outer wall of the duct, leaving a margin between the plastic sheeting and the duct; S4, inserting a steel plate, inserting a steel plate at the sealing ring of the two ducts, and observing the pressure fluctuations on the instruments; S5, installing the new duct; S6, resealing the duct; S7, removing the steel plate, which retracts non-uniformly and discontinuously along the original path; S8, fixing the new duct to the original duct. This application enables the connection or replacement of ducts without stopping the production line.

Description

Technical Field

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

[0002] Because there is a pressure difference between the ducts in the ventilation system of the high-precision air pressure manufacturing workshop and the external environment, when the ducts of the ventilation system need to be modified such as pipe connection, the preferred solution 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, where the temporary sealing plates are relatively light and can be quickly inserted and replaced manually without the aid of machinery, a rough plate replacement method is generally adopted. For situations where the internal and external pressure difference is low, and the temporary gaps generated during the switching process are insufficient to produce significant pressure fluctuations, and the plate deformation caused by the pressure difference is small, a rough plate replacement method can also be adopted.

[0004] Regarding the aforementioned technologies, it was found that installing large-size high-pressure differential pipelines without shutting down the production line presents significant construction difficulties. Summary of the Invention

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

[0006] This application provides a construction process for constant pressure connection of large-diameter ventilation ducts, employing the following technical solution:

[0007] A construction process for constant pressure connection of large-diameter ventilation ducts, the ventilation duct comprising multiple sections, with adjacent sections connected by flanges and sealing rings, the flanges of the ducts having a rectangular ring structure, including the following operational steps:

[0008] S1. Preparation work: Determine the location of pipe replacement, construction scope, construction tools, and erect duct support frame.

[0009] S2. Pipeline treatment: Replace the bolts on the bottom edge of the pipeline flange, replace short bolts with long bolts, and remove the bolts on both sides and the top edge of the pipeline.

[0010] S3. Pipe sealing: Use plastic sheeting to seal the connection between the two pipes. The two sides of the plastic sheeting in the width direction are respectively pasted to the outer wall of the pipe, and leave a margin between the plastic sheeting and the pipe.

[0011] S4. Inserting the steel plate: Insert the steel plate at the sealing ring of the two pipes. The steel plate tip should be sharpened. Before inserting the steel plate into the sealing ring, puncture the plastic sheet and attach the plastic sheet to the steel plate. The steel plate should be inserted into the pipe at a non-uniform and discontinuous speed. During the insertion process, the operator should continuously report the pressure inside the pipe. If the pressure deviates from the preset differential pressure value, the operation should be paused. When the pressure inside the pipe is stable, the steel plate tip should be paused every certain distance to observe the pressure fluctuations on the instrument.

[0012] After the steel plate is fully inserted between the two pipes, remove the plastic sheeting from the two pipes. The steel plate adheres to the pipe with negative pressure due to the pressure difference between the inside and outside of the pipe, and the other pipe can be removed.

[0013] S5. Install the new pipe. A sealing ring is installed on the flange of the new pipe. The new pipe moves along the support frame towards the steel plate, fitting snugly against it. As the new pipe fits against the steel plate, the sealing ring deforms. The bottom bolts of the original pipe are inserted into the flange of the new pipe, aligning the flanges of the new and original pipes.

[0014] S6. Pipe resealing: Re-install plastic sheeting between the new pipe and the original pipe for sealing, with the steel plate also located inside the plastic sheeting.

[0015] S7. Pull out the steel plate. The steel plate returns along the original path at a non-uniform speed and discontinuously. The plastic cloth is pressed tightly against the pipe due to the pressure difference. When the steel plate leaves the space between the two pipes, the sealing ring of the new pipe is attached to the flange of the original pipe.

[0016] S8. The new pipe is fixedly connected to the original pipe.

[0017] By adopting the above technical solution, through the main steps of sealing before plate insertion, plate insertion, replacement of old and new pipe fittings, sealing before plate removal, and steel plate removal, the negative pressure difference in the pipeline fluctuates little, enabling pipe connection or replacement without stopping the production line. Plastic sheeting seals the two pipelines. When the steel plate is not inserted into the pipeline, the leading edge of the steel plate is located within the sealed cavity formed by the plastic sheeting, while the trailing edge is outside the plastic sheeting. The pressure inside the plastic sheeting is the same as the external pressure, and the plastic sheeting does not adhere to the pipeline. When the steel plate is inserted between the two pipelines, a gap appears. The plastic sheeting, due to the internal and external pressure difference, adheres tightly to both the pipeline and the steel plate, sealing the gap and creating a sealed state. After the steel plate is partially inserted into the pipeline, it seals one side of the pipeline. The plastic sheeting can be removed from the steel plate without affecting the sealing effect at the pipeline connection.

[0018] The pipeline replacement process allows for replacement without shutting down the production line, thereby enabling constant pressure connection of large-size high-pressure differential pipelines.

[0019] Optionally, in step S4, a reinforcement assembly is used to reinforce the connection between the steel plate and the pipe. The reinforcement assembly includes a machined bolt and a reinforcement nut. The machined bolt passes through the steel plate and the machined nut is threaded together, with the nut abutting against the flange.

[0020] The effect of temporarily reinforcing the steel plate by adopting the above technical solution.

[0021] Optionally, the reinforcement assembly further includes a reinforcement rod with its two ends forming an included angle. The reinforcement rod has a through hole for a screw to pass through. The reinforcement nut abuts against the reinforcement rod. One end of the reinforcement rod abuts against a steel plate, and the other end of the reinforcement rod abuts against a flange.

[0022] By adopting the above technical solution, the structure of the reinforcing rod forms a three-point fixation, which fixes the steel plate and the flange.

[0023] Optionally, the reinforcing nut is located near the flange.

[0024] By adopting the above technical solution, it is convenient to disassemble the fixed components.

[0025] Optionally, in step S5, the bottom edge of the steel plate contacts the long bolt.

[0026] By adopting the above technical solution, the long bolts provide guidance and support for the steel plate.

[0027] Optionally, the sealing ring of the new pipe is fixedly installed on the flange, and adhesive tape is used to bond the flange and the sealing ring.

[0028] By adopting the above technical solution, the steel plate pulling process creates friction on the sealing ring, which may cause the sealing ring to be pulled. The tape can reinforce the sealing ring.

[0029] Optionally, the steel plate tip should be paused once every 50mm of penetration and once every 50mm of withdrawal.

[0030] By adopting the above technical solutions, we can ensure that the negative pressure fluctuations in the pipeline are small and that the pipeline switching process is stable and orderly.

[0031] During the optional steel plate movement, if the pressure inside the pipeline deviates by more than 15Pa, the operation is paused every 5 seconds and waits for 20 seconds to stabilize before resuming. If the deviation is ±20Pa, the operation is stopped, the cause is analyzed and measures are taken, and construction can only continue 20 seconds after the fluctuation is under control.

[0032] By adopting the above technical solutions and controlling specific data and time, the pressure inside the pipeline is stabilized, ensuring that the pipeline switching process is carried out stably and orderly.

[0033] In summary, this application includes at least one of the following beneficial effects:

[0034] 1. During the switching process of large-diameter pipelines, the pressure fluctuation inside the pipeline can be stabilized within ±20pa (normal operating fluctuation range), and the production line can be replaced without stopping the machine;

[0035] 2. During pipeline switching, the pressure difference between the inside and outside of the pipeline allows the plastic sheet to provide a local seal at the pipeline connection, which is simple to operate and can save costs. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the construction process of an embodiment of this application;

[0037] Figure 2 This is a schematic diagram illustrating the location of the pipeline and the initial position of the steel plate in an embodiment of this application;

[0038] Figure 3 This is a schematic diagram illustrating the structure of the pipeline with only the bottom edge bolts remaining, as shown in the embodiments of this application.

[0039] Figure 4 This is a cross-sectional view of an embodiment of this application showing plastic sheeting pasted on the outer periphery of two pipes;

[0040] Figure 5 This is a cross-sectional view illustrating the application of this invention, showing a plastic sheet being adhered to a steel plate.

[0041] Figure 6 This is a schematic diagram illustrating the insertion of a steel plate into a pipe and its engagement with a long bolt, as described in an embodiment of this application.

[0042] Figure 7 This is a schematic diagram illustrating the structure of the steel plate when it acts as a sealant for the pipeline, according to an embodiment of this application.

[0043] Figure 8 This is a schematic diagram illustrating the application of this application in which tape is adhered to a flange and a sealing ring.

[0044] Figure 9 This is a schematic diagram illustrating the structure of the reinforcement component installed between the steel plate and the flange in an embodiment of this application.

[0045] Explanation of reference numerals in the attached drawings: 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 sheet; 70, tape; 80, reinforcing component; 81, reinforcing bolt; 82, reinforcing nut; 83, reinforcing rod. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 1-9 This application will be described in further detail.

[0047] This application discloses a construction process for constant pressure connection of large-diameter ventilation ducts.

[0048] A constant pressure connection construction process for large-diameter ventilation ducts is disclosed for online constant pressure connection of 1.2m*1.4m rectangular ventilation ducts 10. The internal pressure of the ventilation duct 10 is controlled at -113±2mmAg. The ventilation duct 10 consists of multiple sections 10, with adjacent sections connected by flanges 11 and sealing rings 13. The main steps include: sealing before plate insertion, plate insertion, replacement of old and new pipe fittings, sealing before plate removal, and plate removal. This process overcomes challenges such as sealing during connection, pressure difference between the inside and outside of the duct, plate insertion, and plate fixing, ultimately achieving constant pressure switching construction.

[0049] Specifically, refer to Figure 1 A construction process for constant pressure connection of large-diameter ventilation ducts includes the following steps.

[0050] S1. Preparation work: Determine the replacement location of pipe 10, the scope of construction, construction tools, and erect the duct support frame 30.

[0051] S2, Pipeline 10 treatment: Replace the bolts on the bottom edge of flange 11 of pipeline 10, replace the short bolts with long bolts 12, and remove the bolts on both sides and the top edge of pipeline 10.

[0052] S3. Pipe 10 is sealed by using 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 pasted to the outer wall of the pipe 10, and a slack is left between the plastic sheet 60 and the pipe 10.

[0053] S4, Insertion steel plate 20;

[0054] S5. Install new pipe 10;

[0055] S6. Reseal pipe 10 by reinstalling plastic sheeting 60 between the new pipe 10 and the original pipe 10 for sealing.

[0056] S7. Pull out 20 mm of steel plate;

[0057] S8, the new pipe 10 and the original pipe 10 are fixedly connected.

[0058] More specifically, refer to Figure 2In step S1, steel pipe support frames 30 are installed around the replacement position of pipe 10 to support the duct. In this embodiment, a ventilation duct is connected to the end of the blind flange of pipe 10. A jack bracket 40 is installed, and the installation position of steel plate 20 is determined. 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 a certain distance. To solve the problem of the jack 50's travel distance, an H-beam and a stepping base can be installed on the jack bracket 40. The stepping base continuously adjusts forward along the H-beam. Alternatively, the travel distance of the jack 50 can be solved by replacing the piston rod with an extension rod of varying lengths. The above two techniques for increasing the travel distance of the jack 50 are conventional techniques and will not be elaborated upon in this application, nor are they specifically shown in the figures.

[0059] The steel plate 20 in this embodiment measures 1500*1250*6mm, is made of Q235 steel, and weighs approximately 90kg. The steel plate 20 has a sharpened front edge with chamfered top and bottom corners. A top support plane is provided at the tail of the steel plate 20, and the piston rod of the jack 50 is connected to the tail top support plane.

[0060] Reference Figure 3 In step S2, the bolts at the connection between the two pipes 10 are partially disassembled to maintain the connection and negative pressure between the two pipes 10. First, the bottom bolts of the flange 11 of pipe 10 are replaced, with short bolts replaced by long bolts 12 (φ8×40, grade 4.8, galvanized). The long bolts 12 are replaced one at a time, with the nuts facing outwards and fitting against the outer wall of the flange 11. Then, the bolts on both sides and the top of the flange 11 of pipe 10 are removed. All bolts are loosened first, and then the bolts are removed from the middle to the corners. After the partial bolt removal of pipe 10, due to the negative pressure inside pipe 10, the two pipes 10 remain in contact through the sealing ring 13.

[0061] Reference Figure 4 In step S3, before inserting the steel plate 20, the connection between the two pipes 10 is sealed using a transparent plastic sheet 60. The plastic sheet 60 is applied around the outer wall of the pipe 10, sealing the connection between its sides and the outer wall. Because the two pipes 10 are still sealed, the air pressure inside the plastic sheet 60 is the same as the external air pressure. The width of the plastic sheet 60 is greater than the distance between the two pipes 10, ensuring that the plastic sheet 60, except for its sides which are sealed to the pipes 10, leaves space between it and the pipes 10; the plastic sheet 60 is not directly attached to the pipes 10.

[0062] Reference Figure 5Before inserting the steel plate 20 at the connection of the pipe 10, the plastic sheet 60 is first broken through the steel plate 20, and then the broken part of the plastic sheet 60 is pasted onto the steel plate 20 with tape so that the steel plate 20 does not affect the sealing treatment of the pipe 10 by the plastic sheet 60.

[0063] Since the original flange 11 is still tightly fitted due to the adhesive of the sealing ring 13, a pry bar is needed to loosen it. During this process, the plastic sheet 60 will inevitably be slightly damaged; any leaks should be repaired with tape immediately.

[0064] During insertion, the side of the steel plate 20 should ideally be flush against the pipe 10 to be retained, while the sealing ring 13 is primarily adhered to the pipe 10 to be removed. The steel plate 20 creates a gap between the sealing ring 13 and the pipe 10. The pressure difference between the inside and outside of the pipe 10 causes the plastic sheet 60 to adhere to the pipe 10, sealing the gap and providing a localized auxiliary seal. This significantly reduces the risk of pressure fluctuations within the pipe 10.

[0065] After the steel plate 20 is inserted into the pipe 10, the tape holding the plastic sheet 60 to the steel plate 20 needs to be removed before further insertion. The plastic sheet 60 should remain naturally adhered to the surface of the steel plate 20 due to the negative pressure inside the pipe 10. During subsequent insertion, the plastic sheet 60 should be adjusted in a timely manner to prevent it from being pulled into gaps by the steel plate 20. At this point, the connection between the steel plate 20 and the pipe 10 also provides a certain degree of sealing for the pipe 10.

[0066] The steel plate 20 is inserted into the pipe 10 at a non-uniform and discontinuous speed, and the staff continuously reports the pressure inside the pipe 10. When moving the steel plate 20, if the pressure inside the duct deviates by more than 15 Pa every 5 seconds, the operation is paused and waits for 20 seconds for it to stabilize before resuming. If the pressure deviates by ±20 Pa, the operation is immediately stopped, the cause is analyzed, and measures are taken. Construction can only continue after 20 seconds when the fluctuation is controllable. When the pressure inside the duct is stable, the steel plate 20 tip must be paused every 50 mm of penetration.

[0067] Reference Figure 6 During the insertion process, the steel plate 20 comes into contact with the long bolt 12. The bolt at the bottom of the pipe 10 is always in a properly loose installation state. The long bolt 12 acts as a lower limit stop for the steel plate 20 during its movement.

[0068] Reference Figure 7 The side wall of the steel plate 20 can be fitted with positioning bolts 21. When the steel plate 20 is fully inserted between the two pipes 10, the thread of the positioning bolt 21 contacts the outer wall of the flange 11 of the pipe 10, indicating that the steel plate 20 does not need to be moved.

[0069] After the steel plate 20 is fully inserted between the two pipes 10, the steel plate 20 is pressed tightly against the pipes 10 by the pressure inside and outside the pipes 10. Remove the plastic sheet 60 from the two pipes 10, and remove the other pipe 10. The old sealing ring 13 is also removed along with the pipe 10.

[0070] Begin step S5 by installing the new pipe 10. A sealing ring 13 is fixedly affixed to the flange 11 of the new pipe 10. Use an electric hoist to lift the new pipe 10. The new pipe 10 moves along the steel pipe support frame 30 towards the steel plate 20. The flange 11 of the new pipe 10 is connected to the long bolt 12. The long bolt 12 also ensures that the two pipes 10 are not misaligned when connected.

[0071] Reference Figure 8 The new pipe 10 is attached to the steel plate 20 via a sealing ring 13. Force can be applied to the new pipe 10 manually or using equipment, causing the sealing ring 13 to adhere tightly to the steel plate 20 and deform appropriately. During the removal process, there is significant friction between the steel plate 20 and the sealing ring 13. To secure the sealing ring 13, tape 70 is applied to both the flange 11 and the sealing ring 13, with the sealing ring 13 positioned away from the removal direction of the steel plate 20. When the steel plate 20 is removed and there is a pulling sensation on the sealing ring 13, the tape 70 helps the sealing ring 13 overcome the pull and remain stably positioned on the pipe 10.

[0072] In order to achieve a partial seal between the new pipe 10 and the original pipe 10 during the process of removing the steel plate 20, a plastic sheet 60 is re-wrapped between the new pipe 10 and the original pipe 10. The two sides of the plastic sheet 60 are respectively pasted to the outer periphery of the new pipe 10 and the outer periphery of the original pipe 10. After the plastic sheet 60 is pasted and fixed, it also leaves a closed space with the pipe 10. The steel plate 20 is also located inside the plastic sheet 60, and the piston rod is sealed and connected to the plastic sheet 60.

[0073] Reference Figure 8 During the non-uniform and discontinuous retraction of the steel plate 20 along the original route, after a gap appears at the connection between the two pipes 10, the plastic sheet 60 adheres tightly to the pipe 10 due to the pressure difference. The contact area between the steel plate 20 and the sealing ring 13 also has a sealing effect on the connection between the pipes 10, and part of the plastic sheet 60 also adheres to the steel plate 20. Then, the plastic sheet 60 is removed from the piston rod. When the steel plate 20 leaves the space between the two pipes 10, the sealing ring 13 of the new pipe 10 adheres to the flange 11 of the original pipe 10 due to the pressure difference between the inside and outside of the pipe 10.

[0074] Similarly, the steel plate 20 leaves the pipe 10 at a non-uniform and discontinuous speed, and the staff continuously reports the pressure inside the pipe 10. When moving the steel plate 20, if the pressure inside the duct deviates by more than 15 Pa every 5 seconds, the operation is paused and waits for 20 seconds for it to stabilize before resuming. If the pressure deviates by ±20 Pa, the operation is immediately stopped, the cause is analyzed, and measures are taken. Construction can only continue after 20 seconds when the fluctuation is controllable. When the pressure inside the duct is stable, the steel plate 20 tip must be pulled out every 50 mm, requiring a pause.

[0075] The insertion and removal process, specifically the initial 3-6cm, is a critical phase for pressure fluctuation control, and the travel speed is strictly controlled.

[0076] After all the steel plates 20 are pulled out, the plastic sheet 60 is also removed from the pipe 10. Finally, bolts and nuts are used to fix and seal the new pipe 10 and the original pipe 10.

[0077] Furthermore, refer to Figure 9 In step S4, when the steel plate 80 completely seals the pipe 10, a reinforcing component 80 is used to strengthen the connection between the steel plate 20 and the pipe 10. The reinforcing component 80 includes a reinforcing bolt 81 and a reinforcing nut 82. The top of the steel plate 20 outside the pipe 10 has a through hole for the reinforcing bolt 81 to pass through. The reinforcing bolt 81 passes through the steel plate 20 and is threadedly connected to the reinforcing nut 82. The reinforcing component 80 also includes a reinforcing rod 83. The two ends of the reinforcing rod 83 form an included angle. In this embodiment, the included angle of the two ends of the reinforcing rod 83 is preferably 90°, and the reinforcing rod 83 is L-shaped. The longer part of the reinforcing rod 83 has a through hole for a screw to pass through. The screw passes through the reinforcing rod 83 first and then is threadedly connected to the nut. The shorter end of the reinforcing rod 83 abuts against the steel plate 20, and the longer end of the reinforcing rod 83 abuts against the flange 11 of the pipe 10. Multiple sets of reinforcement components 80 are provided, and the addition of reinforcement rods 83 further enhances the connection between steel plate 20 and pipe 10.

[0078] The implementation principle of the constant pressure connection construction process for large-diameter ventilation ducts in this application embodiment is as follows:

[0079] The pressure relationship was fully considered during the insertion and removal of the steel plate, and a phased, non-uniform speed operation plan was formulated. The insertion process is divided into: the breaking stage (first breaking the plastic sheet 60 and then pasting the plastic sheet 60 and the steel plate 20), the insertion stage (the steel plate 20 is inserted into the connection between the two pipes 10), and the finishing stage (the steel plate 20 is fixed after insertion). The removal process is divided into: the connection stage (first sealing the new pipe 10 and the original pipe 10 with the plastic sheet 60), the removal stage (the steel plate 20 is removed at a non-uniform speed), and the finishing stage. In addition, according to actual needs, a local auxiliary sealing method was adopted for the connection of the pipes 10, and the large-diameter pipes 10 were replaced without stopping the production line, which greatly reduced the risk of internal pressure fluctuations in the large-diameter pipes 10.

[0080] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A construction process for constant pressure connection of a large-diameter ventilation duct, wherein the ventilation duct (10) comprises multiple sections of duct (10), and adjacent ducts (10) are connected by flanges (11) and sealing rings (13), wherein the flanges (11) of the ducts (10) have a rectangular ring structure, characterized in that: The following steps are included: S1. Preparation work: Determine the location of the pipeline (10) replacement, the scope of construction, construction tools, and erect the duct support frame (30). S2, Pipeline (10) treatment: Replace the bolts on the bottom edge of the flange (11) of the pipeline (10), replace the short bolts with long bolts (12), and remove the bolts on both sides and the top edge of the pipeline (10). S3. Pipe (10) sealing: Use plastic cloth (60) to seal the connection between the two pipes (10). The two sides of the plastic cloth (60) in the width direction are respectively pasted to the outer wall of the pipe (10). There is a margin between the plastic cloth (60) and the pipe (10). S4. Insert the steel plate (20). Insert the steel plate (20) at the sealing ring (13) of the two pipes (10). The steel plate (20) is sharpened at the tip. Before inserting the steel plate (20) into the sealing ring (13), first puncture the plastic cloth (60) and stick the plastic cloth (60) on the steel plate (20). The steel plate (20) is inserted into the pipe (10) at a non-uniform speed and discontinuously. During the insertion process, the staff continuously reports the pressure in the pipe (10). If the pressure deviates from the preset pressure difference value, the operation is suspended. When the pressure in the pipe (10) is stable, the steel plate (20) needs to be paused once every time it extends a certain distance to observe the pressure fluctuation of the instrument. During the movement of the steel plate (20), when the pressure in the pipe (10) deviates by more than 15Pa, the operation is suspended every 5 seconds. After 20 seconds of stabilization, the operation is resumed. If ±20Pa occurs, the operation is stopped, the cause is analyzed and measures are taken. Construction can continue 20 seconds after the fluctuation is controllable. After the steel plate (20) is fully inserted between the two pipes (10), the plastic sheet (60) on the two pipes (10) is removed. The steel plate (20) is attached to the pipe (10) with negative pressure inside due to the pressure difference between the inside and outside of the pipe (10), and the other pipe (10) can be removed. S5. Install the new pipe (10). A sealing ring (13) is installed on the flange (11) of the new pipe (10). The new pipe (10) moves along the support frame (30) toward the steel plate (20). The new pipe (10) fits against the steel plate (20). When the new pipe (10) fits against the steel plate (20), the sealing ring (13) deforms. The bottom bolts of the original pipe (10) are inserted into the flange (11) of the new pipe (10). The flange (11) of the new pipe (10) is aligned with the flange (11) of the original pipe (10). S6. Reseal the pipe (10). Reinstall a plastic sheet (60) between the new pipe (10) and the original pipe (10) for sealing. The steel plate (20) is also located inside the plastic sheet (60). S7. Pull out the steel plate (20). The steel plate (20) returns along the original path at a non-uniform speed and discontinuously. The plastic cloth (60) is pressed tightly against the pipe (10) by the pressure difference. When the steel plate (20) leaves the two pipes (10), the sealing ring (13) of the new pipe (10) is attached to the flange (11) of the original pipe (10). S8, the new pipe (10) and the original pipe (10) are fixedly connected.

2. The construction process for constant pressure connection of large-diameter ventilation ducts 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 reinforcement bolt (81) and a reinforcement nut (82). The reinforcement bolt (81) passes through the steel plate (20) and the reinforcement nut (82) is threaded together. The reinforcement nut (82) abuts against the flange (11).

3. The construction process for constant pressure connection of large-diameter ventilation ducts according to claim 2, characterized in that: The reinforcement component (80) also includes a reinforcement rod (83), the two ends of the reinforcement rod (83) form an included angle, the rod part of the reinforcement rod (83) has a through hole for screws to pass through, the reinforcement nut (82) and the rod part of the reinforcement rod (83) abut against each other, 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. The construction process for constant pressure connection of large-diameter ventilation ducts according to claim 3, characterized in that: The reinforcing nut (82) is located near the flange (11).

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

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

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

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