Large-diameter steel pipe inner wall continuous lining super-long PE pipe structure system

Abstract

The utility model discloses a large-diameter steel pipe inner wall continuous lining ultra-long PE pipe structure system, which belongs to the technical field of long-distance pressure pipeline corrosion prevention, and comprises outer protective steel pipes which are connected with each other, and lining PE pipes are arranged in the outer protective steel pipes in a penetrating manner; the ends of the outer protection steel pipes are fixedly connected with steel flanges, and the ends of the lining PE pipes are fixedly connected with PE flanges. A limiting steel ring is arranged on the outer side of the PE flange between the steel flanges; a pressure test hole is formed in the outer protective steel pipe at the joint between the outer protective steel pipes and on one side away from the liquid medium conveying direction, a pressure test pipe is welded outside the pressure test hole, and a pressure test valve is arranged at one end of the pressure test pipe away from the pressure test hole. The PE flanges are fixed to the ends of the lining PE pipes, the PE flanges are attached to the steel flanges in a matched mode, the PE flanges in butt joint are fastened to the inner sides of the limiting steel rings, the steel flanges are connected together, connection between the outer protection steel pipes is enhanced, and the sealing performance is better. A pressure test pipe and a pressure test valve are externally connected through the pressure test hole, and damage detection is carried out on the PE pipe of the segmented outer protection steel pipe.

Description

Technical Field

[0001] This utility model belongs to the field of corrosion protection technology for long-distance pressure pipelines, specifically relating to a structural system for continuous inner lining of ultra-long PE pipes on the inner wall of large-diameter steel pipes. Background Technology

[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.

[0003] Using steel pipes for long-distance (≥1000 meters) transport of liquid media is convenient for installation, but it has the disadvantage of being susceptible to corrosion; while using plastic pipes has the disadvantage of poor rigidity and being difficult to install.

[0004] To address the aforementioned issues, patent CN1785651A discloses an internally lined steel-plastic composite pipe technology. This technology uses a multi-U-shaped pipe reduction technique to reduce the diameter of a PE pipe (whose outer diameter is 1%-3% larger than the inner diameter of the steel pipe) by 2%-5%. The pipe is then pulled into the steel pipe by a traction machine. As the PE pipe recovers from its elastic deformation, its outer diameter gradually increases and it fits tightly against the inner wall of the steel pipe. A heating mold is then installed inside the PE pipe end to heat the end of the PE pipe. Once the end of the plastic pipe softens, the pressure of the mold is used to flip the plastic pipe wall outward and press it against the steel flange sealing surface of the original steel pipe end.

[0005] The above solution solves the technical problems of steel pipes being prone to corrosion and plastic pipes having poor rigidity when transporting liquid media by placing plastic pipes inside steel pipes. However, the above solution has the following problems:

[0006] 1. After softening the end of the PE pipe, it is pressed onto the sealing surface of the steel flange. When connecting steel pipes, bolt holes need to be made on the softened PE pipe. In addition, it will increase the distance between the flanges of the two steel pipes, resulting in poor sealing at the connection between the steel pipes.

[0007] 2. There is a lack of technical means to detect whether PE pipes are damaged, so it is impossible to know whether the PE pipe inside the steel pipe is damaged. Utility Model Content

[0008] To address the aforementioned problems, this utility model provides a structural system for a large-diameter steel pipe with a continuous inner lining of an ultra-long PE pipe. A PE flange is fixed to the end of the inner lining PE pipe, allowing it to fit closely to the steel flange. When connecting the outer protective steel pipes, the PE flanges are tightened inside a limiting steel ring, connecting the steel flanges together and strengthening the connection between the outer protective steel pipes, resulting in better sealing. Furthermore, by setting a pressure test hole on the outer protective steel pipe facing away from the liquid medium transport direction at the connection point between the outer protective steel pipes, and connecting it to a pressure test pipe and a pressure test valve, damage detection of the PE pipe in the segmented outer protective steel pipes can be performed.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A large-diameter steel pipe with a continuous inner lining of ultra-long PE pipe structure system includes interconnected outer protective steel pipes, each of which is lined with an inner PE pipe; steel flanges are fixedly connected to the ends of the outer protective steel pipes, and PE flanges are fixedly connected to the ends of the inner PE pipes; limiting steel rings are set between the steel flanges and on the outside of the PE flanges.

[0011] At the connection between the outer protective steel pipes, a test pressure hole is opened on the outer protective steel pipe on the side away from the direction of liquid medium transportation. A test pressure pipe is welded to the outside of the test pressure hole, and a test pressure valve is installed at the end of the test pressure pipe away from the test pressure hole.

[0012] Preferably, the outer diameter of the PE flange is smaller than the outer diameter of the steel flange.

[0013] Preferably, the inner diameter of the limiting steel ring is equal to the outer diameter of the PE flange.

[0014] Preferably, the thickness of the limiting steel ring is equal to twice the thickness of the PE flange.

[0015] Preferably, the outer ring edge of the limiting steel ring is located inside the bolt hole on the steel flange.

[0016] Preferably, the inner wall of the PE flange is provided with creep-resistant reinforcing ribs.

[0017] Preferably, the inner wall of the steel flange is provided with an annular groove, and the outer wall of the PE flange is provided with a tapered flange, so that a mechanical interlock can be formed when the PE flange and the steel flange are connected.

[0018] Preferably, the outer protective steel pipe is composed of several welded steel pipes.

[0019] Preferably, the inner PE pipe inserted inside the outer protective steel pipe has retractable sections at both ends extending out of the outer protective steel pipe.

[0020] Preferably, the retracted sections at both ends of the PE-lined pipe are connected to the PE flanges by hot-melt welding.

[0021] Compared with the prior art, the advantages and positive effects of this utility model are:

[0022] 1. This utility model fixes a PE flange at the end of the inner PE pipe, so that the PE flange and the steel flange fit closely together. When connecting the outer steel pipes, the steel flanges are connected together by fastening the butt PE flanges to the inside of the limiting steel ring, which strengthens the connection between the outer steel pipes and improves the sealing performance.

[0023] 2. This utility model enables the detection of damage to the PE pipe of the segmented outer protective steel pipe by setting a test pressure hole on the outer protective steel pipe away from the direction of liquid medium transportation at the connection between the outer protective steel pipes and the outer protective steel pipe, and connecting an external test pressure pipe and a test pressure valve. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0025] Figure 1 This is a schematic diagram of the connection structure system of Embodiment 1 or 2 of this utility model;

[0026] Figure 2 This is a schematic diagram of the connection between the steel flange and the PE flange in Embodiment 2 of this utility model;

[0027] In the picture:

[0028] 1. Limiting steel ring; 2. Inner PE pipe; 21. PE flange; 3. Outer steel pipe; 31. Steel flange; 4. Test pressure hole; 5. Test pressure pipe; 6. Test pressure valve. Detailed Implementation

[0029] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] The present invention will now be described in detail with reference to the accompanying drawings.

[0031] Example 1

[0032] This embodiment discloses a structural system for a large-diameter steel pipe with a continuous inner lining of an ultra-long PE pipe, such as... Figure 1 As shown, the system includes interconnected outer steel pipes 3, each of which is fitted with an inner PE pipe 2. Steel flanges 31 are fixedly connected to the ends of the outer steel pipes 3, and the outer steel pipes 3 are connected to each other via steel flanges 31. PE flanges 21 are fixedly connected to the ends of the inner PE pipes 2, and when the outer steel pipes 3 are connected to each other, the ends of the inner PE pipes 2 are also joined together, with the PE flanges 21 of the two inner PE pipes 2 joined together.

[0033] like Figure 1As shown, the outer diameter of the PE flange 21 is smaller than the outer diameter of the steel flange 31. A limiting steel ring 1 is provided on the outside of the PE flange 21 between the two steel flanges 31. The inner diameter of the limiting steel ring 1 is equal to the outer diameter of the PE flange 21, and the thickness of the limiting steel ring 1 is twice the thickness of the PE flange 21. Its function is to secure the PE flange 21 between the limiting steel rings 1, increasing the sealing performance of the connection. The thickness mentioned here does not refer to the distance between the inner and outer rings of the limiting steel ring 1, but rather to the thickness located between the steel flanges 31. In this embodiment, when the steel flanges 31 are connected by bolts, a hydraulic pre-tightening device is used to apply a pre-tightening force of 120kN to ensure a tight connection; for example, a bolt hydraulic tensioner (bolt tensioner) can be used.

[0034] like Figure 1 As shown, the outer ring of the limiting steel ring 1 is located inside the bolt holes on the steel flange 31 to prevent the limiting steel ring 1 from obstructing the passage of bolts when the steel flanges 31 are connected. In this embodiment, both the steel flange 31 and the PE flange 21 are prefabricated. To prevent the PE flange 21 from undergoing slow and irreversible plastic deformation, anti-creep reinforcing ribs are provided on the inner wall of the PE flange 21. The reinforcing ribs are mainly in the form of annular corrugations, threaded ribs, or longitudinal reinforcing ribs. In this application, annular corrugations are used.

[0035] In this embodiment, the outer protective steel pipe 3 is ≥1000 meters long and is composed of several welded steel pipes. After the welding between the steel pipes is completed, a weld grinding robot is used to grind the weld beads on the inner wall of the steel pipe. For example, the submersible pipe weld grinding robot based on modular design disclosed in patent CN106514662B can be used. In this embodiment, the weld beads on the inner wall of the steel pipe must be ground to Ra≤12.5μm to prevent them from being scratched during the installation of the inner PE lining pipe 2. In this embodiment, the inner PE lining pipe 2 is connected by hot melt welding, for example, a fully automatic hot melt welding machine disclosed in patent CN114834056A can be used.

[0036] The method of inserting the inner PE pipe 2 into the outer sheath steel pipe 3 involves using a necking machine to radially compress the inner PE pipe 2 (compression rate 3-5%), and then using a traction unit to pull the end of the inner PE pipe 2 into the outer sheath steel pipe 3. The single insertion length is ≥1000 meters, which can reduce the number of on-site joints. The outer diameter of the inner PE pipe 2 is slightly larger than the inner diameter of the outer sheath steel pipe 3, generally by 1%-3%.

[0037] Taking DN800 steel pipe as an example, a steel flange 31 is welded to the starting end of the outer protective steel pipe 3. Then, after a certain length of steel pipe welding is completed, a weld grinding robot is started to process the weld beads, such as 300 meters. An SJ-1200 necking machine is used to compress the Φ812mm inner PE-lined pipe 2 to Φ788mm; one end of the inner PE-lined pipe 2 is connected to the traction unit, and the traction speed of the traction unit is controlled at 0.8-1.2m / min.

[0038] After the inner PE pipe 2 of the outer steel pipe 3 is installed, a steel flange 31 is welded to the end of the outer steel pipe 3. Then, the two ends of the inner PE pipe 2 are cleaned and the PE flange 21 is welded to the inner PE pipe 2 by hot-melt welding.

[0039] It should be noted that before the formal installation of the PE-lined pipe 2, its shrinkage rate needs to be verified by the manufacturer. This means that after the PE-lined pipe 2 has undergone diameter reduction and stretching within the steel pipe for a certain distance, its length changes after 24 hours. In this embodiment, due to the long installation length (≥1000 meters), after installation within the outer protective steel pipe 3, a shrinkage section of one to two meters needs to be reserved at both ends of the PE-lined pipe 2 to ensure that the length of the PE-lined pipe after shrinkage within 24 hours is equal to that of the outer protective steel pipe after connecting the steel flange. Therefore, after the PE-lined pipe 2 is installed, a certain length of shrinkage section is reserved first, and then the PE flange 21 is connected to the PE-lined pipe 2 by hot-melt welding.

[0040] like Figure 1 As shown, at the connection between the outer protective steel pipes 3 and the outer protective steel pipe 3, a test pressure hole 4 is provided on the outer protective steel pipe 3 on the side away from the direction of liquid medium transportation. A test pressure pipe 5 is welded to the outside of the test pressure hole 4. A test pressure valve 6 is provided at the end of the test pressure pipe 5 away from the test pressure hole 4. The test pressure hole 4 is provided on the outer protective steel pipe 3 and cannot be provided on the inner PE lining pipe.

[0041] At the connection between the outer protective steel pipes 3 and 3, PE flanges 21 and 21 are tightly pressed between steel flanges 31 and 31, and are tightly bound at the connection by limiting steel rings 1. Since the liquid medium passes through the PE pipe, when a section of the PE pipe is damaged, the liquid medium will fill the space between the outer protective steel pipe 3 and the PE pipe in that section, but cannot pass through the connection formed by PE flanges 21, limiting steel rings 1, and steel flanges 31; when the pressure test valve 6 on the current section of the outer protective steel pipe 3 is opened, the liquid medium will rush out from the pressure test hole 4 of the current section and act on the pressure test valve 6, causing the pressure test valve 6 to feel the pressure.

[0042] In other words, during the pressure testing phase, the pressure testing valve 6 on a certain section of the outer protective steel pipe 3 is opened. When the pressure testing valve 6 has pressure, it proves that the inner PE lining pipe 2 of the current section is damaged and needs repair. In this embodiment, the maximum diameter of the pressure testing hole 4 is 2mm, the diameter of the pressure testing pipe 5 is 15mm, and the height is 100mm. The pressure testing process is divided into three stages: First, a pressure of 0.6MPa is maintained for 30 minutes, and the pressure testing valve 6 is observed to see if there is a pressure change; if not, the next stage is performed: a pressure of 1.0MPa is maintained for 60 minutes, and the pressure testing valve 6 is observed to see if there is a pressure change; if not, the final stage is performed: a pressure of 1.5MPa is maintained for 15 minutes, and the pressure testing valve 6 is observed to see if there is a pressure change; if not, it proves that the inner PE lining pipe of the current section is not damaged.

[0043] In this embodiment, a PE flange is fixed at the end of the inner PE pipe, so that the PE flange fits closely with the steel flange. When connecting the outer steel pipes, the steel flanges are connected together by tightening the butt-jointed PE flanges inside the limiting steel ring, which strengthens the connection between the outer steel pipes and improves the sealing performance. By setting a pressure test hole on the outer steel pipe opposite to the direction of liquid medium transportation at the connection between the outer steel pipes, and connecting a pressure test pipe and a pressure test valve, damage detection of the PE pipe of the segmented outer steel pipe can be performed.

[0044] Example 2

[0045] This embodiment differs from Embodiment 1 in that it features an annular groove on the inner wall of the steel flange 31 and a tapered flange on the outer wall of the PE flange 21. When the PE flange 21 and the steel flange 31 are connected, they form a mechanical interlock, strengthening the connection and enhancing the sealing effect. In this embodiment, the gap between the PE flange 21 and the steel flange 31 is ≤0.3mm.

[0046] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A large-diameter steel pipe inner wall continuous lining ultra-long PE pipe structural system, characterized in that, The outer steel pipe is internally provided with a PE pipe, and the end of the outer steel pipe is fixedly connected with a steel flange, and the end of the PE pipe is fixedly connected with a PE flange. A pressure test hole is formed on the outer steel pipe away from the liquid medium conveying direction, and a pressure test pipe is welded outside the pressure test hole.

2. A large-diameter steel pipe inner wall continuous lining ultra-long PE pipe structural system according to claim 1, characterized in that, The outer diameter of the PE flange is smaller than that of the steel flange.

3. A large-diameter steel pipe inner wall continuous lining ultra-long PE pipe structural system according to claim 1, characterized in that, The inner diameter of the limiting steel ring is equal to the outer diameter of the PE flange.

4. A large-diameter steel pipe inner wall continuous lining super-long PE pipe structural system according to claim 1, characterized in that, The thickness of the limiting steel ring is equal to twice the thickness of the PE flange.

5. A large-diameter steel pipe inner wall continuous lining super-long PE pipe structural system according to claim 1, characterized in that, The outer ring edge of the limiting steel ring is located inside the bolt hole of the steel flange.

6. A large diameter steel pipe inner wall continuous lining ultra-long PE pipe structural system according to claim 1, characterized in that, The inner wall of the PE flange is provided with an anti-creep reinforcing rib.

7. A large diameter steel pipe inner wall continuous lining super-long PE pipe structural system according to claim 1, characterized in that, An annular groove is formed on the inner wall of the steel flange, and a tapered flange is formed on the outer wall of the PE flange, and mechanical interlocking can be formed when the PE flange is connected with the steel flange.

8. A large diameter steel pipe inner wall continuous lining ultra-long PE pipe structural system according to claim 1, characterized in that, The outer steel pipe is composed of several steel pipes.

9. A large diameter steel pipe inner wall continuous lining super-long PE pipe structural system according to claim 1, characterized in that, The PE pipe internally provided in the outer steel pipe is provided with a reserved retraction section at both ends of the outer steel pipe.

10. A large diameter steel pipe inner wall continuous lining super-long PE pipe structural system according to claim 9, characterized in that, The reserved retraction sections at both ends of the PE pipe are connected with the PE flange through hot melting welding.

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