Plastic-coated steel pipe welding joint structure

Abstract

The utility model relates to a plastic-coated steel pipe welding joint structure, which belongs to the technical field of pipeline connection, and comprises two sections of plastic-coated steel pipe main bodies, a thermal shrinkage elastic sleeve and a detachable welding thermal isolation pipe, and a metal transition connecting part is arranged at the connecting end between the two sections of plastic-coated steel pipe main bodies. One sides of the two sections of plastic-coated steel pipes are in a convex step shape, the metal transition connecting part is in a concave step shape, the sizes of the concave step and the convex step are matched with each other, the concave step and the convex step are meshed in the axial direction after being inserted, a sealing ring is embedded in a groove, and the sealing ring is extruded to deform after being inserted to fill a gap, so that the sealing performance is further enhanced. The detachable welding thermal isolation pipe is used for reducing conduction of welding heat to a plastic layer, a thermal shrinkage lining sleeve is preset, an external stepped structure and an internal thermal shrinkage elastic sleeve form an internal and external synergistic effect, the mechanical strength is guaranteed, sealed connection of the plastic layer is achieved, the sealing performance and low-temperature adaptability of a welding connector are improved, and the welding quality and consistency are improved.

Description

Technical Field

[0001] This utility model relates to the field of pipeline connection technology, specifically to a welded joint structure for plastic-coated steel pipes. Background Technology

[0002] Plastic-coated steel pipes are widely used in water supply, fire protection, and HVAC systems. To enhance corrosion resistance, they often employ internal and external anti-corrosion coatings. However, traditional welded joints present several problems in low-temperature construction environments. Temperature directly damages the plastic coating on the surface or inner wall of the steel pipe, causing the plastic layer to peel off. The inner plastic lining at the joint becomes unstable during thermal expansion and contraction, resulting in voids or leaks at the joint. Welded joints are rigid and subject to concentrated thermal stress, making them prone to cracking and corrosion. Furthermore, the weld seam is prone to cracking or leakage, requiring extensive manual grinding, repair, and sealing after welding, which increases the difficulty of construction. Utility Model Content

[0003] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a plastic-coated steel pipe welding joint structure that can withstand welding heat load and maintain the integrity of the plastic layer seal.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A welded joint structure for plastic-coated steel pipe includes: a plastic-coated steel pipe body and a metal transition connection part. The metal transition connection part is provided between two sections of the plastic-coated steel pipe body. One or both ends of the two sections of the plastic-coated steel pipe body are respectively provided with plastic-coated steel pipe connecting ends. The plastic-coated steel pipe connecting ends are concave steps, and the metal transition connection part is a convex step. The dimensions of the plastic-coated steel pipe connecting ends and the concave and convex steps of the metal transition connection part are matched to form an axial engagement.

[0006] Preferably, the length of the metal transition connection is greater than or equal to the length of the insertion section at the end of the plastic-coated steel pipe, and the stepped surface layer of the metal transition connection is provided with a high-temperature resistant rubber sealing ring to enhance the axial displacement resistance of the metal transition connection.

[0007] Preferably, a heat-shrinkable elastic sleeve is provided inside the connection between the two ends of the plastic-coated steel pipe. The material of the heat-shrinkable elastic sleeve is cross-linked polyolefin or PVDF. After being heated, the heat-shrinkable elastic sleeve automatically shrinks and firmly presses the inner end face of the two plastic-coated steel pipe bodies, so as to achieve a tight connection and seal between the heat-shrinkable elastic sleeve and the two plastic-coated steel pipe bodies.

[0008] Preferably, the dimensions of the convex step at one end of the metal transition connection are consistent with the step dimensions, roundness, and coaxiality of the plastic-coated steel pipe connection end.

[0009] Preferably, a detachable welding heat insulation tube is provided on the outside of the metal transition connection. The detachable welding heat insulation tube is installed on the outside of the welding area. The detachable welding heat insulation tube has a multi-layer structure, with an inner layer of ceramic fiber felt, a middle layer of silicone composite pad, and an outer layer of heat reflective coating shell to reduce the conduction of welding heat to the plastic layer.

[0010] Beneficial effects: In the plastic-coated steel pipe welded joint structure disclosed in this utility model, the metal transition connection part is concave and stepped. The dimensions of the concave and convex steps are matched to form an axial interlock, which enhances the resistance to axial displacement and disperses welding thermal stress. The detachable welding heat isolation pipe can avoid direct damage to the plastic layer by the high temperature of welding, prevent the plastic lining from bulging due to thermal expansion and the joint from falling off, and assist in positioning and sealing. The high-temperature resistant rubber sealing ring is used to fill the gap and further enhance the sealing performance. The metal transition connection part and the internal heat-shrinkable elastic sleeve form an internal and external synergistic effect, which not only ensures mechanical strength, but also realizes the sealed connection of the plastic layer, improves the sealing performance and low temperature adaptability of the welded joint, simplifies the construction process, and improves the welding quality and consistency. Attached Figure Description

[0011] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0012] In the attached diagram:

[0013] Figure 1 This is a schematic diagram of the overall structure of the welded joint of the plastic-coated steel pipe of this utility model;

[0014] Figure 2 This is a perspective view and a front view of one end of the metal transition connection part of the welded joint of the plastic-coated steel pipe of this utility model;

[0015] Figure 3 This is a schematic diagram of the connection end of the plastic-coated steel pipe of this utility model.

[0016] The following are the labels in the diagram: 1. Plastic-coated steel pipe body; 2. Detachable welded heat insulation pipe; 3. Heat-shrinkable elastic sleeve; 4. Plastic-coated steel pipe connection end; 5. Metal transition connection part; 6. High-temperature resistant rubber sealing ring; 7. Concave step; 8. Convex step. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of the embodiments. The following text is only used to describe a plastic-coated steel pipe welding joint structure of the present utility model, and does not strictly limit the protection scope of the specific claims of the present utility model.

[0018] Example: Figures 1-3 As shown, a welded joint structure for a plastic-coated steel pipe includes:

[0019] A type of welded joint structure for plastic-coated steel pipes, such as Figure 1 As shown, it includes: a plastic-coated steel pipe body 1 and a metal transition connection part 5. The metal transition connection part 5 is provided between two sections of the plastic-coated steel pipe body 1. One or both ends of the two sections of the plastic-coated steel pipe body 1 are respectively provided with plastic-coated steel pipe connecting ends 4. The plastic-coated steel pipe connecting ends 4 are concave steps 7, and the metal transition connection part 5 is a convex step. The dimensions of the plastic-coated steel pipe connecting ends 4 and the concave steps 7 and convex steps of the metal transition connection part 5 are matched to form an axial engagement.

[0020] In an embodiment, such as Figure 2 As shown, the length of the metal transition connection 5 is greater than or equal to the length of the insertion section at the end of the plastic-coated steel pipe, and the stepped surface layer of the metal transition connection 5 is provided with a high-temperature resistant rubber sealing ring 6 to enhance the axial displacement resistance of the metal transition connection 5.

[0021] In an embodiment, such as Figure 1 As shown, a heat-shrinkable elastic sleeve 3 is provided inside the connection between the two ends of the plastic-coated steel pipe. The material of the heat-shrinkable elastic sleeve 3 is cross-linked polyolefin or PVDF. After being heated, the heat-shrinkable elastic sleeve 3 automatically shrinks and firmly presses the inner end face of the two plastic-coated steel pipe bodies 1, so as to realize the tight connection and sealing between the heat-shrinkable elastic sleeve 3 and the two plastic-coated steel pipe bodies 1.

[0022] In an embodiment, such as Figure 2 and Figure 3 As shown, the dimensions of the convex step at one end of the metal transition connection 5 are consistent with the step dimensions, roundness, and coaxiality of the plastic-coated steel pipe connection end 4.

[0023] In an embodiment, such as Figure 1 As shown, a detachable welding heat insulation tube is provided on the outside of the metal transition connection part 5. The detachable welding heat insulation tube is installed on the outside of the welding area. The detachable welding heat insulation tube has a multi-layer structure, with an inner layer of ceramic fiber felt, a middle layer of silicone composite pad, and an outer layer of heat reflective coating shell to reduce the conduction of welding heat to the plastic layer.

[0024] In use, the two plastic-coated steel pipes are connected at their ends 4, which are processed into concave steps 7. A sealing ring is embedded in the convex step 8 of the metal transition connection 5. The dimensions of the concave and convex steps match each other to form an axial engagement, enhancing the resistance to axial displacement and dispersing welding thermal stress. The high-temperature resistant rubber sealing ring 6 is used to fill the gap and further enhance the sealing performance. A heat-shrinkable elastic sleeve 3 is built into the connection section between the plastic-coated steel pipe end 4 and the metal transition connection 5 to ensure axial alignment. The two ends of the plastic-coated steel pipe are butt-welded to the metal transition connection 5 respectively. After welding, the pipes are cooled naturally or with the assistance of hot air. The detachable welding heat isolation pipe 2 is then removed. The detachable welding heat isolation pipe can prevent the high temperature of welding from directly damaging the plastic layer, prevent the plastic lining from bulging due to thermal expansion, and prevent the joint from falling off. It also assists in positioning and sealing. The metal transition connection 5 and the internal heat-shrinkable elastic sleeve 3 work together to ensure mechanical strength and achieve a sealed connection of the plastic layer, improve the sealing performance and low-temperature adaptability of the welded joint, simplify the construction process, and improve the welding quality and consistency.

[0025] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. For those skilled in the art, after learning the contents of the present utility model, they can make several equivalent changes and substitutions without departing from the principle of the present utility model. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present utility model.

Claims

1. A welded joint structure for plastic-coated steel pipes, comprising two plastic-coated steel pipe bodies, characterized in that: include: A metal transition connection is provided between the two sections of the plastic-coated steel pipe body. One or both ends of the two sections of the plastic-coated steel pipe body are respectively provided with plastic-coated steel pipe connection ends. The plastic-coated steel pipe connection ends are concave steps, and the metal transition connection parts are convex steps. The dimensions of the plastic-coated steel pipe connection ends and the concave and convex steps of the metal transition connection parts are matched to form an axial engagement.

2. The structure of a welded joint for a plastic-coated steel pipe according to claim 1, characterized in that: The length of the metal transition connection is greater than or equal to the length of the insertion section at the end of the plastic-coated steel pipe, and the stepped surface layer of the metal transition connection is provided with a high-temperature resistant rubber sealing ring to enhance the anti-axial displacement performance of the metal transition connection.

3. The structure of a welded joint for a plastic-coated steel pipe according to claim 1, characterized in that: The interior of the connection between the two plastic-coated steel pipes is provided with a heat-shrinkable elastic sleeve. The material of the heat-shrinkable elastic sleeve is cross-linked polyolefin or PVDF. After being heated, the heat-shrinkable elastic sleeve automatically shrinks and firmly presses the inner end face of the two plastic-coated steel pipe bodies.

4. The structure of a welded joint for a plastic-coated steel pipe according to claim 1, characterized in that: The dimensions of the convex step at one end of the metal transition connection are consistent with the step dimensions, roundness, and coaxiality of the plastic-coated steel pipe connection end.

5. The structure of a welded joint for a plastic-coated steel pipe according to claim 1, characterized in that: A detachable weldable heat insulation tube is installed on the outside of the metal transition connection. The detachable weldable heat insulation tube has a multi-layer structure, with an inner layer of ceramic fiber felt, a middle layer of silicone composite pad, and an outer layer of heat-reflective coating shell.

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