A filler and a method for repairing pipeline defects

Abstract

The present invention provides a filler and a method for repairing pipeline defects, wherein the filler comprises: a first preparation, wherein the first preparation comprises a thermosetting material and an expansion monomer, wherein the expansion monomer is added to the thermosetting material at a weight ratio of 5%-15%; and a second preparation, wherein the second preparation comprises a curing agent and a cationic initiator, wherein the cationic initiator is added to the curing agent at a weight ratio of 3%-6%; wherein the first preparation and the second preparation are mixed and heated to generate an expansion copolymerization reaction. The filler proposed by the present invention expands in volume after solidification, and can abut against a cylinder and a pipeline, thereby fully transferring the stress of the pipeline defect to the cylinder.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline repair, and in particular to a filler and a method for repairing pipeline defects. Background Art

[0002] After long-term operation, oil and gas pipelines may have defects such as metal loss, interlayer, cracks, abnormal girth welds, and depressions that affect the safety of oil and gas pipeline transportation. In the prior art, two steel sleeves are used to cover the defects of the pipeline, and epoxy resin is filled in the gap between the steel sleeve and the pipeline to transfer the stress at the pipeline defect to the steel sleeve, so as to achieve the purpose of reinforcing and repairing the pipeline. However, the epoxy resin is filled into the gap between the steel sleeve and the pipeline in liquid state and then solidified. This process will cause volume shrinkage, resulting in the inability of the cured epoxy resin to completely fill the gap between the steel sleeve and the pipeline, and the density is not high, which makes the cured epoxy resin insufficient in its ability to transfer stress. Summary of the invention

[0003] The main purpose of the present invention is to provide a filler, which aims to solve the problem in the prior art that when the epoxy resin is filled in the gap between the steel sleeve and the pipe in liquid state, the volume shrinks after curing, resulting in the inability of the cured epoxy resin to completely fill the gap between the steel sleeve and the pipe, resulting in insufficient ability of the cured epoxy resin to transfer stress.

[0004] To achieve the above-mentioned purpose, the present invention proposes a filler, which includes: a first preparation, which includes a thermosetting material and an expansion monomer, and the expansion monomer is added to the thermosetting material at a weight ratio of 5%-15%; a second preparation, which includes a curing agent and a cationic initiator, and the cationic initiator is added to the curing agent at a weight ratio of 3%-6%; wherein the first preparation and the second preparation are mixed and heated to produce an expansion copolymerization reaction.

[0005] Optionally, the mixing ratio of the first preparation to the second preparation is 3:0.5 to 1:1.5.

[0006] Optionally, the temperature for the expansion copolymerization reaction between the first preparation and the second preparation is 100°C-150°C.

[0007] Optionally, vacuum degassing and defoaming treatment is performed when the first preparation and the second preparation undergo expansion copolymerization reaction.

[0008] Optionally, the thermosetting material is epoxy resin.

[0009] The present invention also proposes a method for repairing pipeline defects, which comprises the following steps: covering the defective part of the pipeline with a first sleeve and a second sleeve and docking them to form a cylinder; filling a filler into a sealed cavity enclosed by the cylinder and the pipeline; and closing a feed port, a discharge port and a pipe connection port on the cylinder.

[0010] Optionally, before the first sleeve and the second sleeve are covered on the defective part of the pipeline and connected to each other to form a cylinder, the method further includes: removing rust from the defective part of the pipeline.

[0011] Optionally, before the first sleeve and the second sleeve are covered on the defective part of the pipe and joined to each other to form a cylinder, the method further includes: applying a layer of resin-based primer on the surface of the defective part of the pipe.

[0012] Optionally, before the filler is filled into the sealed cavity enclosed by the cylinder and the pipe, the method further includes the step of evacuating the sealed cavity to a vacuum degree of 50 KPa-80 KPa.

[0013] Optionally, after closing the feed port, the discharge port and the connecting port on the cylinder, the method further includes: covering the area on the pipeline not covered by the cylinder with a viscoelastic body and / or a polypropylene cold wrapping tape.

[0014] The technical solution of the present invention forms a first preparation by adding an expansion monomer into the thermosetting material at a weight ratio of 5%-15%, and forms a second preparation by adding a cationic initiator into the curing agent at a weight ratio of 3%-6%. The first preparation and the second preparation are then mixed and heated to generate an expansion copolymerization reaction, thereby obtaining a filler with expansion properties. After solidification, the filler expands in volume and can abut against a cylinder and a pipe, thereby fully transferring the stress of the defective part of the pipe to the cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of the application of the filler of the present invention;

[0017] Figure 2 It is a schematic diagram of the application of the filler of the present invention under another visual perspective;

[0018] Figure 3 for Figure 1 Schematic diagram of the structure of the middle cylinder;

[0019] Figure 4 for Figure 1 Schematic diagram of the structure of the middle cylinder under another visual perspective;

[0020] Figure 5 A schematic diagram of a process of an embodiment of a pipeline defect repair method of the present invention;

[0021] Figure 6 It is a schematic flow chart of a second embodiment of the pipeline defect repairing method of the present invention;

[0022] Figure 7 It is a schematic flow chart of a third embodiment of the pipeline defect repairing method of the present invention;

[0023] Figure 8 It is a schematic flow chart of a third embodiment of the pipeline defect repairing method of the present invention;

[0024] Fig. 9 This is a schematic flow chart of a fourth embodiment of the pipeline defect repairing method of the present invention.

[0025] Description of Figure Numbers:

[0026] Label name Label name 10 pipeline 22 Second sleeve 11 Defective parts 221 Feed port 20 Cylinder 23 Sealing ring 21 First sleeve 231 Seals 211 Take-over port 30 Insulation sealing sleeve 212 Discharge port 40 Filler

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0030] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] The present invention proposes a filler 40, which includes: a first preparation, which includes a thermosetting material and an expansion monomer, and the expansion monomer is added to the thermosetting material at a weight ratio of 5%-15%; a second preparation, which includes a curing agent and a cationic initiator, and the cationic initiator is added to the curing agent at a weight ratio of 3%-6%; wherein the first preparation and the second preparation are mixed and heated to produce an expansion copolymerization reaction.

[0032] In this embodiment, the expansion monomer is added to the thermosetting material at a weight ratio of 5%-15% and stirred evenly to form a first preparation. The greater the proportion of the expansion monomer added, the more obvious the volume expansion of the thermosetting material after solidification; in order to ensure the smooth solidification of the thermosetting material, a second preparation consisting of a curing agent and a cationic initiator needs to be added to the first preparation, and the cationic initiator is added to the curing agent at a weight ratio of 3%-6% and stirred evenly; the first preparation and the second preparation are mixed and heated to undergo expansion copolymerization to form a liquid filler 40 with expansion characteristics. The liquid filler 40 expands in volume after solidification, and the volume after expansion is equal to the volume of the liquid filler 40, or greater than the volume of the liquid filler 40, or there is a certain degree of shrinkage but greater than the volume of solidification without the addition of the expansion monomer, such as shrinkage of 1%.

[0033] like Figure 1-4 As shown, the liquid filler 40 with expansion characteristics abuts against the cylinder 20 and the pipe 10 after solidifying in the sealed cavity, and can fully transfer the stress of the defective part of the pipe 10 to the cylinder 20.

[0034] The defective part 11 on the pipe 10 is equipped with a defect repair structure, which includes: a first sleeve 21 and a second sleeve 22, the first sleeve 21 and the second sleeve 22 are joined to form a cylinder 20 and form a joining line in the axial direction, the first sleeve 21 and the second sleeve 22 are both provided with sealing members 231 at both ends, and the sealing members 231 are located on the inner side surfaces of the first sleeve 21 and the second sleeve 22, wherein the sealing members 231 at the same end of the cylinder 20 are joined to each other to form a sealing ring 23; the cylinder 20 covers the surface of the defective part 11 of the pipe 10 to surround the pipe 10, and an insulating sealing sleeve 30 is provided between the sealing ring 23 and the pipe 10; the sealing cavity formed by the surface of the pipe 10 and the cylinder 20 is filled with a filler 40.

[0035] In this embodiment, the first sleeve 21 and the second sleeve 22 cover the surface of the defective portion 11 of the pipe 10, and the first sleeve 21 and the second sleeve 22 are connected to form a cylinder 20 to surround the pipe 10. The joining line (not shown in the figure) formed at the joint can be a straight line or a curve, as long as the first sleeve 21 and the second sleeve 22 can form a closed cylinder 20, and the joining line extends toward the axial direction of the pipe 10 or the cylinder 20.

[0036] The first sleeve 21 and the second sleeve 22 are both provided with sealing members 231 on the inner side. After the first sleeve 21 and the second sleeve 22 are joined, the sealing members 231 are butted against each other at both ends of the cylinder 20 to form sealing rings 23, so as to ensure that the sealed cavity can form a cavity with a certain vacuum degree and that there will be no leakage when the filler 40 is filled. An insulating sealing sleeve 30 is spaced between the sealing ring 23 and the pipeline 10 to prevent the cylinder 20 from contacting the pipeline 10. The insulating sealing sleeve 30 is made of a material with good insulation, so that the cylinder 20 will not form a corrosion circuit with the pipeline, and can protect the pipeline 10, the first sleeve 21 and the second sleeve 22. At the same time, when the defect is further expanded to a leak, it can also play a role in sealing and stopping leakage of the transmission liquid in the pipeline 10.

[0037] The filler 40 can transfer the stress of the defective part of the pipe 10 to the cylinder 10 to prevent the defect from further spreading.

[0038] In a preferred embodiment, the first sleeve 21 and the second sleeve 22 are semi-cylinders 20, and the joints are welded to form a cylinder 20 surrounding the pipeline 10. Since the pipeline 10 is not directly involved in the welding, it is not necessary to reduce the pressure of the pipeline 10, so it will not affect the normal transportation of the pipeline 10. The pipeline 10 does not have the risk of welding through or generating new cracks during welding, and the quality requirements for welding are reduced; the pipeline 10 can be an oil and gas pipeline 10 for transporting natural gas or oil, and the defective part 11 of the pipeline 10 is located in the middle of the cylinder 20. Among them, the first sleeve 21 and the second sleeve 22 can be steel sleeves, and the sealing ring 23 is a steel ring.

[0039] In this embodiment, the filler 40 (not shown in the figure) is a thermosetting filler 40 (ie, a solidified filler 40 ), and the thermosetting filler 40 fills the sealing cavity.

[0040] The sealing cavity is filled with a liquid thermosetting filler 40, which is bonded to the inner side surfaces of the first sleeve 21 and the second sleeve 22 after solidification. The stress generated by the impact of the material transmitted in the pipe on the defective portion 11 is transferred to the cylinder 20 through the solidified filler 40, thereby achieving the purpose of protecting the pipeline 10.

[0041] Furthermore, the mixing ratio of the first preparation and the second preparation is 3:0.5 to 1:1.5.

[0042] To ensure that the filler 40 can be successfully solidified and fill the sealed cavity after expansion, to avoid gaps between the filler 40 and the cylinder 20, so that the filler 40 can transfer stress to the cylinder 20 to the greatest extent, and to prevent the volume shrinkage of the solid filler 40 after solidification, the mixing ratio of the first preparation and the second preparation is 3:0.5 to 1:1.5. Any value within this ratio range can achieve the purpose, such as 3:1 or 1:1, which are not listed here one by one.

[0043] Specifically, the temperature for the expansion copolymerization reaction between the first preparation and the second preparation is 100°C-150°C.

[0044] Only when the temperature reaches a certain level can the cationic initiator decompose to produce a sufficient number of free radicals to initiate the polymerization reaction between the expansion monomer and the thermosetting material. As the temperature increases, the reaction rate accelerates, the condensation rate increases, and the conversion rate improves. However, when the temperature is too high, the reaction is difficult to control. Therefore, in this embodiment, the temperature of the expansion copolymerization reaction is 100°C-150°C to ensure that the reaction of the preparation is stable and controllable.

[0045] Optionally, vacuum degassing and defoaming treatment is performed when the first preparation and the second preparation undergo expansion copolymerization reaction.

[0046] The tightness of the filler 40 is the key to whether the stress of the defective part 11 can be fully transferred to the cylinder 20. The denser the filler 40 is, the better the performance of transferring stress is. Therefore, vacuum degassing and defoaming treatment are performed during the expansion copolymerization reaction of the first preparation and the second preparation to prevent bubbles from affecting the tightness of the filler 40.

[0047] As an embodiment, the thermosetting material is epoxy resin.

[0048] Under the action of the cationic initiator, the epoxy resin undergoes an expansion polymerization reaction with the expansion monomer to form an expansion filler 40. It is understandable that the epoxy resin is not the only thermosetting material that can undergo an expansion polymerization reaction with the expansion monomer, such as polyurethane or phenolic resin, which are not listed here one by one.

[0049] The cylinder 20 is provided with a feed port 221 , a discharge port 212 and a pipe connection port 211 .

[0050] The feed port 221 is used to charge the filler 40, and the discharge port 212 is used to discharge the excess filler 40 when the filler 40 solidifies and expands. The calibers of the feed port 221 and the discharge port 212 can be designed according to the filling equipment or the amount of the filler 40, and are determined according to the needs. In a preferred embodiment, the feed port 221 and the discharge port 212 are not located at the first sleeve 21 or the second sleeve 22 at the same time.

[0051] Optionally, the concave parts on the surface of the pipe 10 are filled with putty powder to make the surface of the pipe 10 smooth.

[0052] The concave parts of the surface of the pipe 10 are filled with putty powder to make the surface of the pipe 10 smooth, ensuring that the stress of the defective part 11 is fully transferred to the cylinder 20.

[0053] Furthermore, the roughness of the surface of the pipe 10 is greater than or equal to 30 μm.

[0054] The roughness helps to increase the friction between the pipe 10 and the insulating sealing sleeve 30, reduce the shear strength between the surface of the pipe 10 and the insulating sealing sleeve 30, further ensure the reliability of application transmission, and increase the axial tensile resistance of the pipe 10. The putty powder can be a special filling putty powder, which has a certain strength and is polished after hardening, so that the roughness of the surface of the pipe 10 is greater than or equal to 30μm.

[0055] Specifically, a layer of resin-based primer is applied on the surface of the pipe 10 .

[0056] The resin-based primer can improve the adhesion of the surface of the pipe 10 and ensure that the filler 40 and the pipe 10 are tightly bonded together.

[0057] The end surfaces where the first sleeve 21 and the second sleeve 22 are joined to each other are inclined surfaces, and the inclined surfaces of the first sleeve 21 and the second sleeve 22 form a welding groove.

[0058] The inclined surface of the first sleeve 21 and the inclined surface of the second sleeve 22 form a welding groove for welding. The welding rod is melted into liquid and filled into the welding groove, and the first sleeve 21 and the second sleeve 22 are welded together to form a cylinder 20. Alternatively, the end surfaces of the first sleeve 21 and the second sleeve 22 that are joined to each other may not be set as inclined surfaces, but a connecting piece may be added at the joint, and then the connecting piece may be welded to the first sleeve 21 and the second sleeve 22.

[0059] It is understandable that the joining of the first sleeve 21 and the second sleeve 22 is not limited to the above-mentioned welding method, for example, using an adhesive with strong bonding properties.

[0060] Furthermore, the insulating sealing sleeve 30 is made of hard polyurethane.

[0061] The hard polyurethane has good insulation properties, which can prevent the cylinder 20 and the pipe 10 from forming a corrosion circuit and provide axial protection for the pipe 10 .

[0062] like Figure 3 , 4 As shown, the seal 231 is 3 mm to 5 mm away from the end of the cylinder 20, the ring height of the seal 231 is 5 mm to 10 mm, and the ring thickness of the seal 231 is 2 mm to 5 mm.

[0063] With d1 being the distance from the seal 231 to the end of the cylinder 20, 3mm≤d1≤5mm, with d2 being the ring height of the seal 231, 5mm≤d2≤10mm, with d3 being the ring thickness of the seal 231, 2mm≤d3≤5mm, the seals 231 on the first sleeve 21 and the second sleeve 22 are butted together to form a sealing ring 23, and the size of d1, d2, and d3 determines the volume of the sealing cavity. The seal 231 can increase the strength of the first sleeve 21 and the second sleeve 22, and play the role of a reinforcing rib to prevent the first sleeve 21 and the second sleeve 22 from deforming before installation. At the same time, since the two sealing rings 23 at both ends of the cylinder 20 have the same size, it can ensure that the gap between the cylinder 20 and the pipe 10 is consistent everywhere, so that the stress of the defective part 11 of the pipe 10 can be fully transferred to the cylinder 20.

[0064] Specifically, the area on the pipe 10 not covered by the cylinder 20 is provided with a viscoelastic body and / or a polypropylene cold wrapping tape (not shown in the figure).

[0065] The viscoelastic and / or polypropylene cold wrap tape has anti-corrosion properties and is wrapped around the area of ​​the pipe 10 that is not covered by the cylinder 20 to protect the pipe 10 from corrosion.

[0066] Please refer to Figure 1-5 The present invention also provides a method for repairing defects of a pipeline 10, and the method for repairing defects of the pipeline 10 comprises the following steps:

[0067] S10: Cover the defective part 11 of the pipe 10 with the first sleeve 21 and the second sleeve 22 and connect them to form a cylinder 20;

[0068] S20: Filling a filler 40 into the sealed cavity formed by the cylinder 20 and the pipe 10;

[0069] S30: Close the feed port 221, the discharge port 212 and the connecting port 211 on the cylinder 20.

[0070] In this embodiment, the first sleeve 21 and the second sleeve 22 cover the defective part 11 of the pipe 10, and the first sleeve 21 and the second sleeve 22 are welded with a seal 231. The first sleeve 21 and / or the second sleeve 22 are provided with a feed port 221, a discharge port 212 and a pipe connection port 211. The ends of the first sleeve 21 and the second sleeve 22 that are butt-jointed with each other are polished or punched into a bevel, and an insulating sealing sleeve 30 is provided on the seal 231. The first sleeve 21 and the second sleeve 22 are then butt-jointed with each other to form a cylinder 20, and the defective part 11 of the pipe 10 is located in the middle of the cylinder 20.

[0071] Then, a filler 40 is filled into the sealed cavity enclosed by the cylinder 20 and the pipe 10. The filler 40 has expansion properties and abuts against the cylinder 20 and the pipe 10 after solidifying in the sealed cavity, and can fully transfer the stress of the defective part of the pipe 10 to the cylinder 20, thereby achieving the purpose of protecting the pipe 10.

[0072] In the step of closing the feed port 221, the discharge port 212 and the connecting port 211 on the cylinder 20, it can be judged whether the filler 40 has filled the entire sealing cavity by the length of the filler 40 overflowing from the discharge port 212 (the filler 40 overflowing from the discharge port 212 will solidify when it is cold).

[0073] Furthermore, if Figure 6 As shown, before the first sleeve 21 and the second sleeve 22 are covered on the defective part 11 of the pipe 10 and connected to each other to form the cylinder 20, the method further includes:

[0074] S11: Derusting the defective portion 11 of the pipeline 10.

[0075] Rust will reduce the friction between the insulating sealing sleeve 30 and the pipe 10, which is not conducive to reducing the shear strength between the surface of the pipe 10 and the insulating sealing sleeve 30. Therefore, before the first sleeve 21 and the second sleeve 22 are covered on the defective part 11 of the pipe 10 and welded into the cylinder 20, the defective part 11 of the pipe 10 needs to be rusted. In a preferred embodiment, the rust removal level reaches ST3 or higher.

[0076] The roughness helps to increase the friction between the pipe 10 and the insulating sealing sleeve 30, reduce the shear strength between the surface of the pipe 10 and the insulating sealing sleeve 30, so as to further ensure the reliability of application transmission and increase the axial tensile resistance of the pipe 10. Therefore, after rust removal, the surface of the pipe 10 can be roughened with a grinder so that the roughness of the surface of the pipe 10 is greater than or equal to 30μm, and putty powder is filled in the concave parts of the surface of the pipe 10 to make the surface of the pipe 10 smooth.

[0077] like Figure 7 As shown, before the first sleeve 21 and the second sleeve 22 are covered on the defective part 11 of the pipe 10 and joined to each other to form the cylinder 20, the method further includes:

[0078] S12: Apply a layer of resin-based primer on the surface of the defective part 11 of the pipeline 10.

[0079] The resin-based primer can improve the adhesion of the surface of the cylinder 20 and ensure that the filler 40 and the inner wall of the cylinder 20 are tightly bonded together.

[0080] like Figure 8 As shown, before the filler 40 is filled into the sealed cavity enclosed by the cylinder 20 and the pipe 10, the following steps are also included:

[0081] S21: Evacuate the sealed cavity to a vacuum degree of 50KPa-80KPa.

[0082] To ensure that the filler 40 fills the sealing cavity and prevent bubbles from existing in the filler 40, the sealing cavity needs to be evacuated to a vacuum degree of 50KPa-80KPa before the filler 40 is filled into the sealing cavity. The connection port 211 is used to connect the vacuum equipment to facilitate vacuuming.

[0083] like Fig. 9 As shown, after closing the feed port 221, the discharge port 212 and the pipe connection port 211 on the cylinder 20, the method further includes:

[0084] S40: Covering the area on the pipe 10 not covered by the cylinder 20 with viscoelastic and / or polypropylene cold wrap tape.

[0085] The viscoelastic and / or polypropylene cold wrap tape has anti-corrosion properties and is wrapped around the area of ​​the pipe 10 that is not covered by the cylinder 20 to protect the pipe 10 from corrosion.

[0086] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for repairing pipeline defects, characterized in that: The pipeline defect repair method comprises the following steps: Adding an expandable monomer to a thermosetting material at a weight ratio of 5% to 15% and stirring evenly to form a first preparation, adding a second preparation consisting of a curing agent and a cationic initiator to the first preparation, and heating and mixing the first preparation and the second preparation to undergo an expansion copolymerization reaction to form a liquid filler with expansion properties; wherein the mixing ratio of the first preparation to the second preparation is 3:0.5 to 1:1.5; The first sleeve and the second sleeve are covered on the defective part of the pipeline and connected to each other to form a cylinder; wherein the first sleeve and the second sleeve are both provided with sealing members on the inner side, and the sealing members are connected to each other at both ends of the cylinder to form a sealing ring, and an insulating sealing sleeve is interposed between the sealing ring and the pipeline; Evacuate the sealed chamber to a vacuum degree of 50KPa-80KPa; Filling a filler into the sealed cavity formed by the cylinder and the pipe; Close the feed port, the discharge port and the pipe connection port on the cylinder; The step of filling a filler into the sealed cavity formed by the cylinder and the pipe comprises: Filling the sealing cavity with a liquid thermosetting filler, which is bonded to the inner side surfaces of the first sleeve and the second sleeve after solidification; Before the first sleeve and the second sleeve are covered on the defective part of the pipeline and connected to each other to form a cylinder, the method further includes: Derusting defective parts of the pipeline; Before the first sleeve and the second sleeve are covered on the defective part of the pipeline and joined to each other to form a cylinder, the method further includes: Apply a layer of resin-based primer on the surface of the defective part of the pipeline; After closing the feed port, the discharge port and the connecting port on the cylinder, the method further comprises: The areas on the pipe not covered by the cylinder are covered with viscoelastic and / or polypropylene cold wrap tape.

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