Polyurethane thermal insulation pipe with polyvinyl chloride outer sheath and production process

Abstract

According to the polyvinyl chloride outer sheath polyurethane thermal insulation pipe and the production process, the effects of high strength and light weight are achieved, meanwhile, it is further guaranteed that the thickness of a thermal insulation layer is consistent through a T-shaped support structure, the heat loss rate of a thermal pipeline is reduced, connection between adjacent working pipes is more convenient and faster through different flange plate connection modes, and the production efficiency is improved. According to the specific technical scheme, the heat preservation pipe with the support comprises a working pipe, a polyvinyl chloride outer protective sleeve, a heat preservation layer and a T-shaped supporting block; the T-shaped supporting blocks are evenly bound to the outer wall of the working pipe through steel wires in the heat preservation pipe with the support. Or the support-free thermal insulation pipe comprises a working pipe, a polyvinyl chloride outer sheath pipe and a thermal insulation layer; the working pipe is sleeved in the polyvinyl chloride outer sheath pipe, and the thermal insulation layer is filled in an interlayer of the working pipe and the polyvinyl chloride outer sheath pipe; a flange plate is arranged at one end of the working pipe, and the flange plate is sleeved near a port of the working pipe.

Description

Technical Field

[0001] The invention relates to the technical field of thermal insulation pipes, in particular to a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe and a production process. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] At present, the existing prefabricated direct buried thermal insulation pipes are all high-density polyethylene outer protective pipes and hard polyurethane foam plastic prefabricated direct buried thermal insulation pipes. The high-density polyethylene outer protective pipe is used as the outer protective pipe after being placed for a period of time after production.

[0004] Due to the low strength of the polyethylene body and stress, the pipe will have a large out-of-roundness and obvious shrinkage. Compared with the working pipe, the out-of-roundness of the high-density polyethylene outer sheath pipe is larger. During the production of pipe threading and foaming, the outer sheath pipe has low bonding strength with the insulation layer, poor process stability, and low product quality consistency. Especially after foaming, it is easy to cause inconsistent thickness of the insulation layer, which leads to reduced insulation effect of the insulation pipe and increased heat loss rate of the thermal pipeline.

[0005] In view of the above situation, an insulation pipe and production process that can solve the above problems are developed. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe and a production process. The polyvinyl chloride outer sheath pipe solves the problem of uneven thickness of the insulation layer caused by filling the foaming material in the traditional outer sheath pipe, and the polyvinyl chloride outer sheath pipe is used to achieve the effect of high strength and light weight. At the same time, the T-shaped bracket structure is used to further ensure the consistency of the thickness of the insulation layer, thereby reducing the heat loss rate of the thermal pipeline. Different flange connection forms make the connection between adjacent working pipes more convenient.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a polyvinyl chloride outer sheath polyurethane insulated pipe, including an insulated pipe with a bracket, wherein the insulated pipe with a bracket is composed of a first working pipe, a first polyvinyl chloride outer sheath pipe, a first insulation layer, and a T-shaped support block;

[0009] The T-shaped support block is arranged on the outer wall of the first working tube and is evenly tied and fixed with steel wire; the first working tube is inserted into the first polyvinyl chloride outer sheath tube, and the first insulation layer is filled into the interlayer formed by the first working tube and the first polyvinyl chloride outer sheath tube;

[0010] Or, a support-free insulated pipe, wherein the support-free insulated pipe is composed of a second working pipe, a second polyvinyl chloride outer sheath pipe, and a second insulation layer;

[0011] The second working tube is inserted into the second polyvinyl chloride outer sheath tube, and the second thermal insulation layer is filled into the sandwich formed by the second working tube and the second polyvinyl chloride outer sheath tube.

[0012] Further, a first flange is provided at one end of the first working pipe, the first flange is inserted near the port of the first working pipe, the port of the first working pipe has a flared opening larger than the pipe diameter, and the first working pipe and the first flange can rotate relative to each other;

[0013] A second flange is provided at one end of the second working tube, and the second flange is welded to one end of the second working tube.

[0014] Furthermore, the first working tube and the second working tube are both steel tube structures, and the inner walls of the first working tube and the second working tube are coated with an anti-corrosion layer.

[0015] Furthermore, the end surface of the first flange is in contact with the end surface of the first polyvinyl chloride outer sheath tube; and the end surface of the second flange is in contact with the end surface of the second polyvinyl chloride outer sheath tube.

[0016] Furthermore, the first polyvinyl chloride outer sheath tube and the second polyvinyl chloride outer sheath tube are provided with a plurality of holes for injecting foaming material.

[0017] In a second aspect, the present invention provides a production process for a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe, the production process for the thermal insulation pipe with a bracket comprising the following steps:

[0018] S1. Prepare a first polyvinyl chloride outer sheath tube, prepare a high-performance polyvinyl chloride outer sheath tube, use high mixing to knead the material evenly and then process it through extrusion, sizing, cooling, cutting and other processes;

[0019] S2. Prepare a matching first working pipe, and use a shot blasting machine to remove rust, dirt and oil stains adhering to the inner and outer walls of the steel pipe;

[0020] S3. Spraying an anti-corrosion layer on the inner wall, selecting an anti-corrosion coating antiseptic according to the properties of the medium, and injecting it into the first working tube in a pressurized form, so that the anti-corrosion coating is evenly distributed on the inner wall of the first working tube;

[0021] S4. Arrange T-shaped support blocks, and evenly arrange T-shaped support blocks along the circumferential direction of the first working tube; then use a pipe threading machine to penetrate the first polyvinyl chloride outer sheath pipe, and ensure that a certain distance is reserved at both ends of the first working tube;

[0022] S5. The end of the first working pipe in the first polyvinyl chloride outer sheath pipe is inserted into the first flange, and then the port of the first working pipe is expanded to achieve the connection between the first flange and the first working pipe;

[0023] S6. Use isocyanate and polyether polyol as foaming raw materials, add a catalyst therein, and then use a foaming injection device to inject the foaming raw materials into the cavity between the first working tube and the first polyvinyl chloride outer sleeve through the holes on the first polyvinyl chloride outer sleeve to form a foam insulation layer.

[0024] Furthermore, the T-shaped support block is fixed on the outer side of the first working tube by binding with steel wire.

[0025] Furthermore, the first working tube and the second working tube are sealed by a foam sealing ring when connected.

[0026] In a third aspect, the present invention provides another production process for a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe, wherein the production process for the support-free thermal insulation pipe comprises the following steps:

[0027] S1. Prepare the second polyvinyl chloride outer sheath; use high mixing to knead the material evenly and then process it through extrusion, sizing, cooling, cutting and other processes;

[0028] S2. Prepare a second working tube that matches the requirements; use a shot blasting machine to remove rust, dirt and oil from the inner and outer walls of the steel pipe;

[0029] S3. Spray an anti-corrosion layer on the inner wall of the second working tube, select an anti-corrosion agent for the anti-corrosion coating according to the properties of the medium, and inject it into the second working tube under pressure so that the anti-corrosion coating is evenly distributed on the inner wall of the second working tube;

[0030] S4. Use a pipe threading machine to insert the second working pipe into the second polyvinyl chloride outer sheath pipe, and ensure that a certain distance is reserved at both ends of the second working pipe;

[0031] S5. The end of the second working tube in the second PVC outer sheath pipe is inserted into the second flange, and then the connecting seam between the second working tube and the second flange is welded; the end face of the second flange is closely fitted with the end face of the second PVC outer sheath pipe;

[0032] S6. The outer sheath tube is clamped by a clamping block to fix and position the second polyvinyl chloride outer sheath tube, and arc grooves are provided on both sides, and the arc matches the second polyvinyl chloride outer sheath tube;

[0033] S7. Use isocyanate and polyether polyol as foaming raw materials, add a catalyst therein, and then use a foaming injection device to inject the foaming raw materials into the cavity between the second working tube and the second polyvinyl chloride outer sheath tube through the holes on the second polyvinyl chloride outer sheath tube to form a foam insulation layer.

[0034] Furthermore, the second working tube and the adjacent second working tube ports are sealed by a sealing ring.

[0035] The beneficial effects of the present invention are as follows:

[0036] The present invention adopts a thermal insulation pipe with a polyvinyl chloride outer sheath pipe. The strength and rigidity of the polyvinyl chloride material are high, and the wear resistance of the polyvinyl chloride is better. Under the condition of the same outer diameter and the same wall thickness, the polyvinyl chloride has a better roundness, is easier to process during the foaming process, and the foamed insulation layer is uniform. The product molding consistency is high and the stability is good. In order to further ensure the uniformity of the insulation layer, a T-shaped support block is introduced and tied to the side of the working pipe with steel wire, which not only realizes the fixation of the support block, but also does not affect the anti-corrosion performance of the working pipe. The T-shaped bracket structure further ensures the uniformity of the insulation layer, thereby reducing the heat loss rate of the thermal pipeline. Adjacent working tubes are connected by flanges, and the insulation layer can be directly filled to the end face of the flange, which not only reduces the heat loss but also allows the two adjacent working tubes to be directly connected by bolts, minimizing the exposed area of ​​the working tube. At the same time, the flange is inserted into the working tube and the port of the working tube is expanded so that the flange and the working tube can rotate relative to each other, so as to solve the problem that the bolt holes of the flange at the final interface do not correspond and cannot be installed. The present invention also designs a bracket-free insulation pipe. On the one hand, the outer sheath of the polyvinyl chloride has a certain strength, and the foaming uniformity of the insulation layer can be guaranteed to a certain extent through its own performance. At the same time, the flange and the working tube are welded, and the processing is convenient, which is suitable for application scenarios of long-distance heat transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0038] Figure 1 This is a cross-sectional view of the thermal insulation pipe with a bracket of the present invention;

[0039] Figure 2 It is a cross-sectional view of the support-free thermal insulation pipe of the present invention.

[0040] In the figure: 1 is the first working pipe, 2 is the first polyvinyl chloride outer sheath pipe, 3 is the first thermal insulation layer, 4 is the T-shaped support block, 5 is the second working pipe, 6 is the second polyvinyl chloride outer sheath pipe, and 7 is the second thermal insulation layer. DETAILED DESCRIPTION

[0041] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0043] Embodiment 1

[0044] The present embodiment discloses a polyvinyl chloride outer sheath polyurethane insulation pipe, including an insulation pipe with a bracket, which is composed of a first working pipe, a first polyvinyl chloride outer sheath pipe, a first insulation layer, and a T-shaped support block; the T-shaped support block is arranged on the outer wall of the first working pipe and is evenly tied and fixed with steel wire; the first working pipe is inserted into the first polyvinyl chloride outer sheath pipe, and the first insulation layer is filled into the interlayer formed by the first working pipe and the first polyvinyl chloride outer sheath pipe; a first flange is arranged at one end of the first working pipe, and the first flange is inserted near the port of the first working pipe, and the port of the first working pipe has an expansion larger than the pipe diameter, and the first working pipe and the first flange can rotate relative to each other; the first working pipe is a steel pipe structure and the inner wall is coated with an anti-corrosion layer. The first working pipe needs to be passed through a high-temperature or low-temperature medium. In order to ensure the service life of the first working pipe and avoid corrosion damage, an anti-corrosion coating is pre-brushed inside the first working pipe, and the outer layer is provided with a first polyvinyl chloride outer sheath pipe 2. In order to further avoid a large amount of heat exchange between the medium and the external environment during the transportation process, the first thermal insulation layer 3 is formed by filling with thermal insulation material polyurethane.

[0045] Or, a non-support insulated pipe, which is composed of a second working pipe 5, a second polyvinyl chloride outer sheath pipe 6, and a second insulation layer 7; the second working pipe 5 is inserted into the second polyvinyl chloride outer sheath pipe 6, and the second insulation layer is filled into the interlayer formed by the second working pipe 5 and the second polyvinyl chloride outer sheath pipe 6; a second flange is provided at one end of the second working pipe 5, and the second flange is welded to one end of the second working pipe 5; the second working pipe 5 is a steel pipe structure and the inner wall is coated with an anti-corrosion layer. High-temperature or low-temperature medium needs to be passed into the second working pipe 5. In order to ensure the service life of the second working pipe 5 and avoid corrosion damage, the anti-corrosion coating is pre-brushed inside the second working pipe 5. In order to further avoid a large amount of heat exchange between the medium and the external environment during transportation, the second insulation layer is filled with the insulation material polyurethane.

[0046] Embodiment 2

[0047] This embodiment discloses a production process of a thermal insulation pipe with a bracket, comprising the following steps:

[0048] S1, prepare a first polyvinyl chloride outer sheath tube 2, the manufacturing process is to use high mixing to knead the materials evenly and then process them through extrusion, sizing, cooling, cutting and other processes to prepare a first polyvinyl chloride outer sheath tube 2 of required size and required strength.

[0049] S2, prepare a matching first working tube 1. Use a shot blasting machine to remove rust, dirt and oil adhered to the inner and outer walls of the first working tube 1, increase the adhesion of the first thermal insulation layer 3 to the outer side of the first working tube 1, and ensure the adhesion of the anti-corrosion layer to the inner wall of the first working tube 1, so as to avoid the anti-corrosion layer being damaged during the process of conveying the medium, resulting in corrosion of the inner wall of the first working tube 1 and reducing the service life of the first working tube 1.

[0050] S3, spraying an anti-corrosion layer on the inner wall of the first working tube 1, selecting an anti-corrosion agent for the anti-corrosion coating according to the properties of the medium, and injecting it into the first working tube 1 in a pressurized form, so that the anti-corrosion coating is evenly distributed on the inner wall of the first working tube 1.

[0051] S4, on the outer surface of the first working tube 1, T-shaped support blocks 4 are evenly arranged along the circumferential direction of the first working tube 1. When arranging, the T-shaped support blocks 4 are tied and fixed on the outer side of the first working tube 1 in the form of steel wires to avoid damage to the inner surface coating of the first working tube 1 caused by welding or screw fixation; then a pipe threading machine is used to penetrate into the first polyvinyl chloride outer sheath pipe 2, and a certain distance is reserved at both ends of the first working tube 1 for setting flanges at both ends of the first working tube 1.

[0052] S5, the end of the first working tube 1 in the first polyvinyl chloride outer sheath tube 2 is inserted into the first flange, and then the diameter of the first working tube 1 is expanded to achieve the connection between the first flange and the first working tube 1, which can effectively achieve the sealing and reliable connection between adjacent first working tubes 1. By inserting the first flange into the first working tube 1 and expanding the port of the first working tube 1, the first flange and the first working tube 1 can be relatively rotated, so as to solve the problem that the bolt holes of the first flange at the final interface do not correspond and cannot be installed. The first working tube 1 and the adjacent first working tube 1 are sealed with a foam sealing ring. The first flange is in close contact with the outer wall of the working tube 1, and the end face of the first flange is in close contact with the end face of the first polyvinyl chloride outer sheath tube 2.

[0053] S6, using isocyanate and polyether polyol as foaming raw materials, adding a catalyst therein, and then spraying them into the cavity between the first working tube 1 and the polyvinyl chloride outer sleeve through a foaming spray device to form a foam first thermal insulation layer 3.

[0054] Embodiment 3

[0055] This embodiment discloses a production process of a support-free thermal insulation pipe, comprising the following steps:

[0056] S1, prepare a second polyvinyl chloride outer sheath tube 6. The manufacturing process is to use high mixing to knead the materials uniformly and then process them through extrusion, sizing, cooling, cutting and other processes to prepare a polyvinyl chloride outer sheath tube 2 of required size and required strength.

[0057] S2, prepare a matching second working tube 5. Use a shot blasting machine to remove rust, dirt and oil stains adhered to the inner and outer walls of the second working tube 5, increase the adhesion between the second thermal insulation layer 3 and the outer side of the second working tube 5, and ensure the adhesion between the anti-corrosion layer and the inner wall of the second working tube 5, so as to avoid the anti-corrosion layer being damaged during the process of conveying the medium, resulting in corrosion of the inner wall of the second working tube 5 and reducing the service life of the second working tube 5.

[0058] S3, spraying an anti-corrosion layer on the inner wall of the second working tube 5, selecting an anti-corrosion coating antiseptic according to the properties of the medium, and injecting it into the second working tube 5 in a pressurized form, so that the anti-corrosion coating is evenly distributed on the inner wall of the second working tube 5.

[0059] S4, using a pipe threading machine to thread the second working pipe 5 into the second polyvinyl chloride outer sheath pipe 6, and ensuring that a certain distance is reserved between the two ends of the second working pipe 5.

[0060] S5, the end of the second working tube 5 in the second polyvinyl chloride outer sheath tube 6 is inserted into the second flange, and then the connection seam between the second working tube 5 and the second flange is welded. Since the polyvinyl chloride outer sheath has a certain strength, the foaming uniformity of the second thermal insulation layer 3 can be guaranteed to a certain extent through its own performance. At the same time, the second flange and the second working tube 5 are welded, which is convenient for processing and suitable for application scenarios of long-distance heat transmission. The end face of the second flange is tightly fitted with the end face of the second polyvinyl chloride outer sheath tube 6.

[0061] S6, the outer sheath tube is clamped by a clamping block to fix and position the second polyvinyl chloride outer sheath tube 6, and arc grooves are set on both sides, and the arc matches the second polyvinyl chloride outer sheath tube 6 to ensure the uniformity between the second polyvinyl chloride outer sheath tube 6 and the second working tube 5, that is, to ensure the uniformity of the polyurethane layer along the circumferential direction.

[0062] S7, using isocyanate and polyether polyol as foaming raw materials, adding a catalyst therein, and then spraying them into the cavity between the second working tube 5 and the glass fiber reinforced plastic outer casing through a foaming spray device to form a foam second thermal insulation layer 3.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polyvinyl chloride outer sheathed polyurethane insulation pipe, characterized in that: It comprises a heat-insulating pipe with a bracket, wherein the heat-insulating pipe with a bracket consists of a first working pipe, a first polyvinyl chloride outer sheath pipe, a first heat-insulating layer, and a T-shaped support block; The T-shaped support block is arranged on the outer wall of the first working tube and is evenly tied and fixed with steel wire; the first working tube is inserted into the first polyvinyl chloride outer sheath tube, and the first insulation layer is filled into the interlayer formed by the first working tube and the first polyvinyl chloride outer sheath tube; Or, a support-free insulated pipe, wherein the support-free insulated pipe is composed of a second working pipe, a second polyvinyl chloride outer sheath pipe, and a second insulation layer; The second working tube is inserted into the second polyvinyl chloride outer sheath tube, and the second thermal insulation layer is filled into the sandwich formed by the second working tube and the second polyvinyl chloride outer sheath tube.

2. A polyvinyl chloride outer sheathed polyurethane thermal insulation pipe as claimed in claim 1, characterized in that: A first flange is provided at one end of the first working pipe, the first flange is inserted near a port of the first working pipe, the port of the first working pipe has an expanded opening larger than the pipe diameter, and the first working pipe and the first flange can rotate relative to each other; A second flange is provided at one end of the second working tube, and the second flange is welded to one end of the second working tube.

3. The polyvinyl chloride outer sheath polyurethane insulation pipe according to claim 1, characterized in that: The first working tube and the second working tube are both steel tube structures, and the inner walls of the first working tube and the second working tube are both coated with an anti-corrosion layer.

4. A polyvinyl chloride outer sheathed polyurethane thermal insulation pipe as claimed in claim 2, characterized in that: The end surface of the first flange is in contact with the end surface of the first polyvinyl chloride outer sheath tube; the end surface of the second flange is in contact with the end surface of the second polyvinyl chloride outer sheath tube.

5. The polyvinyl chloride outer sheath polyurethane insulation pipe according to claim 1, characterized in that: The first polyvinyl chloride outer sheath tube and the second polyvinyl chloride outer sheath tube are provided with a plurality of holes for injecting foaming material.

6. The production process of a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe as described in claims 1-5, characterized in that: The production process of the thermal insulation pipe with a support comprises the following steps: S1. Prepare the first polyvinyl chloride outer sheath tube, prepare high-performance polyvinyl chloride outer sheath tube, use high mixing to knead the material evenly and then process it through extrusion, sizing, cooling, cutting and other processes; S2. Prepare a matching first working pipe, and use a shot blasting machine to remove rust, dirt and oil stains adhering to the inner and outer walls of the steel pipe; S3, spraying an anti-corrosion layer on the inner wall, selecting an anti-corrosion agent for the anti-corrosion coating according to the properties of the medium, and injecting it into the first working tube in a pressurized manner, so that the anti-corrosion coating is evenly distributed on the inner wall of the first working tube; S4. Arrange T-shaped support blocks, and evenly arrange T-shaped support blocks along the circumferential direction of the first working tube; then use a pipe threading machine to penetrate the first polyvinyl chloride outer sheath pipe, and ensure that a certain distance is reserved at both ends of the first working tube; S5. The end of the first working pipe in the first polyvinyl chloride outer sheath pipe is inserted into the first flange, and then the port of the first working pipe is expanded to achieve the connection between the first flange and the first working pipe; S6. Use isocyanate and polyether polyol as foaming raw materials, add a catalyst therein, and then use a foaming injection device to inject the foaming raw materials into the cavity between the first working tube and the first polyvinyl chloride outer sleeve through the holes on the first polyvinyl chloride outer sleeve to form a foam insulation layer.

7. The production process of a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe as claimed in claim 6, characterized in that: The T-shaped support block is fixed on the outer side of the first working tube by binding with steel wire.

8. The production process of a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe as claimed in claim 6, characterized in that: The first working tube and the second working tube are connected and sealed by a foam sealing ring.

9. The production process of a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe as described in claims 1-5, characterized in that: The production process of the support-free thermal insulation pipe comprises the following steps: S1. Prepare the second polyvinyl chloride outer sheath; use high mixing to knead the material evenly and then process it through extrusion, sizing, cooling, cutting and other processes; S2. Prepare a second working tube that matches the requirements; use a shot blasting machine to remove rust, dirt and oil from the inner and outer walls of the steel pipe; S3. Spray an anti-corrosion layer on the inner wall of the second working tube, select an anti-corrosion agent for the anti-corrosion coating according to the properties of the medium, and inject it into the second working tube under pressure so that the anti-corrosion coating is evenly distributed on the inner wall of the second working tube; S4. Use a pipe threading machine to insert the second working pipe into the second polyvinyl chloride outer sheath pipe, and ensure that a certain distance is reserved at both ends of the second working pipe; S5. The end of the second working tube in the second PVC outer sheath pipe is inserted into the second flange, and then the connecting seam between the second working tube and the second flange is welded; the end face of the second flange is closely fitted with the end face of the second PVC outer sheath pipe; S6. The outer sheath tube is clamped by a clamping block to fix and position the second polyvinyl chloride outer sheath tube, and arc grooves are provided on both sides, and the arc matches the second polyvinyl chloride outer sheath tube; S7. Use isocyanate and polyether polyol as foaming raw materials, add a catalyst therein, and then use a foaming injection device to inject the foaming raw materials into the cavity between the second working tube and the second polyvinyl chloride outer sheath tube through the holes on the second polyvinyl chloride outer sheath tube to form a foam insulation layer.

10. The production process of a polyvinyl chloride outer sheathed polyurethane thermal insulation pipe according to claim 9, characterized in that: The second working tube and the adjacent second working tube port are sealed by a sealing ring.

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