A steel-plastic composite pipe connecting non-flange joint

Abstract

The present application relates to the field of steel pipeline lining repair, in particular to a flangeless joint structure for connecting steel-plastic composite pipeline. The flangeless joint structure for connecting steel-plastic composite pipeline comprises two PE lining pipes, the two PE lining pipes are placed in the disconnected steel pipeline to be repaired, the steel variable diameter threaded sleeve is welded on both sides of the fracture of the disconnected steel pipeline to be repaired, the opposite connecting part of the two PE lining pipes is welded with PE flange short connection, the sealing groove is pre-processed on the PE flange short connection, and the extrusion sealing and fixing are performed through the pre-processed matching external thread nut, after the sealing is installed, the two side ports are fixed in the form of welding, so that the two side ports form a whole, and the connection of the steel pipeline in the form of flangeless structure is completed. The composite pipeline port of the flangeless connection of the PE lining pipe provided by the present application is without connection flange, grouting and welding are not required on site, the structure is compact, the construction speed is fast, and high pressure can be resisted.

Description

Technical Field

[0001] This invention relates to the field of steel-plastic composite pipe joint technology, specifically a flangeless joint for connecting steel-plastic composite pipes. Background Technology

[0002] PE pipe equal-diameter reduction lining repair technology is one of the commonly used trenchless pipeline lining repair technologies at home and abroad. It is used to repair old buried pipelines of various medium and low pressures at normal temperature in the fields of oil and gas, municipal and industrial sectors, which transport water, gas and oil.

[0003] The connection at the break point in the composite pipeline formed by the PE-lined pipe is a crucial step affecting the normal operation of the pipeline after repair. Using flange connections to connect the PE-lined pipe increases the risk of future problems and is unsuitable for long-distance pipeline repairs. Using electrofusion fittings to connect the exposed PE pipe section to the outer reinforcement shell and then filling it with grout has drawbacks such as inconsistent on-site welding quality, large workload, incomplete grout filling, or the risk of the PE pipe section bursting due to internal pressure caused by grout shrinkage. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a flangeless joint structure for steel-plastic composite pipe connections that is scientific, economical, easy to use, improves construction efficiency, and ensures construction quality.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a flangeless joint structure for steel-plastic composite pipe connection, including a PE inner liner, a pipe to be repaired, a PE flange short joint, a steel reducing threaded sleeve, a venting fitting to ensure unobstructed interlayer space and prevent gas accumulation leading to corrosion or abnormal pressure, a fastening nut, and an O-ring.

[0006] Preferably, the two PE inner lining pipes are embedded in the broken pipe to be repaired, and a steel reducing threaded sleeve with the same diameter and wall thickness as the pipe to be repaired is welded to the break point of the broken pipe.

[0007] Preferably, the PE inner liner is welded to the welded PE flange short joint, and the PE flange short joint is machined with a groove sealing structure.

[0008] Preferably, the fastening nut is machined as a whole and used in conjunction with a steel reducing threaded sleeve for sealing. The end face is machined with a convex sealing structure for short-circuit sealing with a PE flange.

[0009] Preferably, the bottom of the steel reducing threaded sleeve is machined with a groove structure, which is used in conjunction with an O-ring for sealing to prevent fluid from entering the inside of the pipe to be repaired.

[0010] Preferably, after the steel reducing threaded sleeve is welded to the pipe to be repaired, a venting fitting is welded to the rear end of the steel reducing threaded sleeve to connect the interlayer space.

[0011] Compared with the prior art, the advantages of the present invention are: it is fixed by mechanical extrusion and welding, the structure is compact, no grouting is required on site, the construction speed is fast, and it can withstand high pressure. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the main cross-sectional structure of the present invention;

[0013] Figure 2 This is a schematic diagram of the steel variable diameter threaded sleeve structure of the present invention;

[0014] Figure 3 This is a schematic diagram of the fastening nut structure of the present invention;

[0015] Figure 4 This is a schematic diagram of the fastening nut structure of the present invention.

[0016] In the diagram: 1. PE inner lining pipe; 2. Pipe to be repaired; 3. PE flange short joint; 4. Steel reducing threaded sleeve; 5. Vent fitting; 6. Fastening nut; 7. O-ring seal. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1

[0019] Please see Figures 1-4 This invention provides a technical solution: a flangeless joint structure for connecting steel-plastic composite pipes. A steel reducing threaded sleeve is welded to both sides of the broken end of the steel pipe to be repaired. Vent fittings are welded to both ends of the steel reducing threaded sleeve, connecting it to a sandwich structure. A PE liner for the pipe to be repaired is placed inside the broken steel pipe. The PE liner is welded to a PE flange short-circuit. A pre-machined sealing groove is placed on the PE flange short-circuit, and a pre-made matching fastening nut is used for compression sealing and fixation. Simultaneously, an O-ring groove is machined at the bottom of the steel reducing threaded sleeve. After the O-ring is installed, compression sealing is performed. The two ends of the steel reducing threaded sleeve are fixed by welding to form a whole, thus completing the flangeless connection of the steel pipe.

[0020] Specifically, the PE flange short joint and the fastening nut are sealed with grooves, the fastening nut and the steel reducing threaded sleeve are sealed with an O-ring structure, the PE inner liner and the PE flange short joint are welded together to make them a whole, and the steel reducing threaded sleeve is made of special duplex steel material, which effectively reduces corrosion and extends the service life of the pipeline.

[0021] Specifically, a venting fitting is installed in the annular gap between the PE inner liner and the steel slip-on fitting to release internal gas and other impurities.

[0022] Specifically, the steel reducing threaded joint has the same diameter and wall thickness as the inner wall of the pipe to be repaired.

[0023] Example 2

[0024] Please see Figures 1-4 The flangeless joint structure for steel-plastic composite pipe connection provided in Embodiment 2 of the present invention achieves flangeless connection through the following methods and steps:

[0025] First, determine the location of the disconnection in the pipeline to be repaired, cut the reserved space according to the specified length, assemble and weld the pipeline to be repaired with the steel reducing threaded sleeve, and weld the vent fitting at the same time to ensure that the interlayer space is unobstructed;

[0026] Secondly, after the steel reducing threaded sleeve is welded to a qualified standard, the position of the pipe end to be repaired is adjusted to meet the requirements of the inner lining operation. After the inner lining is completed, the inner lining pipe is welded to the PE flange short joint. After the welding is completed, a pre-tightening force is applied to the PE flange short joint to ensure that it is assembled in place.

[0027] Then, by pre-reserving the groove, install the O-ring seal, and use a special torque wrench to tighten the fastening nuts in sequence, so that they are squeezed inside and out to achieve good sealing performance.

[0028] Then, after completing the above steps, perform the assembly operation, install PE gaskets between the fastening nuts, and squeeze the two fasteners together to complete the seal, prevent fluid penetration, form a double-seal structure, and enhance safety performance.

[0029] Finally, the steel reducing threaded sleeve is welded together to form a single unit, preventing misalignment caused by geological subsidence and other factors that could affect the pipeline's service life. Corrosion protection is then applied to the pipe joints, creating a composite pipeline with a flangeless PE-lined pipe. The PE lining can be installed using methods such as folded reducing lining, equal-diameter stretching lining, or sliding-in insertion lining.

Claims

1. A flangeless joint structure for connecting steel-plastic composite pipes, characterized in that: Includes PE inner lining pipe (1), pipe to be repaired (2), PE flange short joint (3), steel reducing threaded sleeve (4), venting fitting (5) to ensure unobstructed interlayer space and avoid gas accumulation leading to corrosion or abnormal pressure, fastening nut (6) and O-ring seal (7).

2. The flangeless joint structure for steel-plastic composite pipe connection according to claim 1, characterized in that: The two PE inner lining pipes (1) are embedded in the broken pipe (2) to be repaired. A steel reducing threaded sleeve (4) with the same diameter and wall thickness as the pipe (2) to be repaired is welded to the broken end of the pipe (2).

3. The flangeless joint structure for steel-plastic composite pipe connection according to claim 1, characterized in that: The PE inner liner (1) is welded to the welded PE flange short joint (3), and the PE flange short joint (3) is machined with a groove sealing structure.

4. The flangeless joint structure for steel-plastic composite pipe connection according to claim 1, characterized in that: The fastening nut (6) is machined as a whole and is used in conjunction with the steel reducing threaded sleeve (4) for sealing. The end face is machined with a convex sealing structure and is used in conjunction with the PE flange short-connection (3) for sealing.

5. The flangeless joint structure for steel-plastic composite pipe connection according to claim 1, characterized in that: The bottom of the steel reducing threaded sleeve (4) is machined with a groove structure, which is used in conjunction with an O-ring to seal and prevent the fluid in the pipeline from entering the interior of the pipeline to be repaired (2).

6. The flangeless joint structure for steel-plastic composite pipe connection according to claim 1, characterized in that: After the steel reducing threaded sleeve (4) is welded to the pipe (2) to be repaired, a venting fitting (5) is welded to the rear end of the steel reducing threaded sleeve (4) to connect the interlayer space.

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