A pipe fitting and method of making the same

Abstract

The application relates to the technical field of pipe manufacturing, and discloses a pipe and a manufacturing method thereof. The outer wall of a pipe body of the pipe is sequentially coated with a first heat preservation layer, a first aluminum foil layer, a heat tracing layer, a second aluminum foil layer and an outer layer. The heat tracing layer comprises a first insulating adhesive tape layer wound on the outer surface of the first aluminum foil layer, a heat tracing tape spirally wound on the outer surface of the first insulating adhesive tape layer at an interval, a plurality of smooth slopes used for filling steps formed between the edges of the heat tracing tape and the first insulating adhesive tape layer and forming a transition structure from the surface of the first insulating adhesive tape layer to the top surface of the heat tracing tape, a plurality of patches, each patch spanning the adjacent smooth slope and heat tracing tape and being attached to the smooth slope and the top surface of the heat tracing tape, and a second insulating adhesive tape layer wound on the outer surfaces of the heat tracing tape and the patches. The pipe and the manufacturing method thereof can realize uniform heating of the surface of the pipe body and condensation prevention through the synergistic cooperation of the multi-layer functional structure.

Description

Technical Field

[0001] This application relates to the field of pipe fitting manufacturing technology, and in particular to a pipe fitting and its manufacturing method. Background Technology

[0002] In the experimental and semiconductor packaging and testing industry, a large number of equipment and processes need to operate under low-temperature conditions. Environmental test chambers, thermostatic baths, and cryogenic reactors maintain low internal temperatures, and the circulating pipelines connected to them carry cryogenic media such as ethylene glycol solution, Freon, and liquid nitrogen. The surface temperature of these pipelines is often much lower than the ambient temperature. When the pipeline surface temperature is lower than the dew point temperature of the ambient air, water vapor in the air condenses into liquid water on the pipeline surface, resulting in condensation. Condensation not only makes the pipeline surface damp, affecting the cleanliness of the experimental environment, but more seriously, condensation dripping onto precision testing equipment, circuit boards, or chip samples can cause short circuits, corrosion, or distortion of measurement signals, leading to deviations in experimental data or even equipment damage, severely impacting the reliability and safety of the tests.

[0003] Various technical means to prevent condensation in pipelines have been proposed in the existing technology.

[0004] Technicians have already used large dehumidifiers or air conditioning systems to lower the dew point temperature of the entire laboratory environment below the surface temperature of the pipes, fundamentally eliminating the conditions for condensation. However, the high investment cost and energy consumption of such equipment make it difficult for small and medium-sized laboratories or chip packaging and testing laboratories to afford. Furthermore, due to limitations in building structure and spatial layout, some laboratories cannot install large dehumidification systems, making it even more difficult to implement in temporary testing or outdoor field testing scenarios.

[0005] Technicians also use insulation materials such as rubber and plastic sponge or polyurethane foam to wrap the outer wall of pipelines to reduce heat loss and increase the surface temperature, thereby reducing the risk of condensation. However, in low-temperature conditions or high-humidity environments, a single insulation layer is often insufficient to raise the surface temperature of the pipeline above the dew point, and condensation is still unavoidable. Furthermore, the insulation effect will further decrease when the insulation layer is insufficient in thickness or the material ages.

[0006] Technicians also use electrical heating to actively heat the pipes by wrapping them with heat tracing tape, thereby increasing the surface temperature of the pipes. However, using heat tracing tape alone can lead to uneven heat distribution, localized overheating or underheating, rapid heat loss, and high energy consumption. Summary of the Invention

[0007] Therefore, the purpose of this application is to overcome the shortcomings of existing pipe covering layers in terms of insufficient anti-condensation effect and uneven heat distribution under low temperature and high humidity conditions, and to provide a pipe fitting and its manufacturing method, which can achieve uniform heating and reliable anti-condensation of the pipe body surface through the synergistic effect of multi-layer functional structures. Specifically: a smooth slope is formed at the root of the heat tracing cable on both sides by a thermally conductive filling material to eliminate the steep changes at the step, and the heat tracing cable is mechanically locked by a patch spanning the smooth slope and the heat tracing cable to prevent it from shifting; a double insulation and double reflection structure is formed by the first aluminum foil layer and the second aluminum foil layer in combination with the first insulating tape layer and the second insulating tape layer, which sandwiches the heat tracing layer therein, ensuring electrical safety and forming an internal and external bidirectional heat reflection cavity to guide heat to the pipe body; at the same time, an elastic thermally conductive compensation layer is used to fill the surface unevenness formed by the spiral winding of the heat tracing cable, and in combination with the smooth interface layer of the longitudinal straight wrapping, so that the cold shrink tubing can be tightly attached to the surface of the elastic thermally conductive compensation layer without wrinkles after shrinkage.

[0008] To address the aforementioned technical problems, the present invention provides a pipe fitting, comprising: a pipe body, the outer wall of which is sequentially covered from the inside out with a first insulation layer, a first aluminum foil layer, a heat tracing layer, a second aluminum foil layer, and an outer layer; wherein the heat tracing layer comprises: a first insulating tape layer wound around the outer surface of the first aluminum foil layer; a heat tracing cable spirally wound around the outer surface of the first insulating tape layer at a tape spacing; a plurality of smooth ramps spaced apart along the axial direction of the pipe body, used to fill the steps formed between the two sides of the heat tracing cable and the first insulating tape layer, and to form a transition structure from the surface of the first insulating tape layer to the top surface of the heat tracing cable; a plurality of patches spaced apart along the axial direction of the pipe body, each patch spanning an adjacent smooth ramp and the heat tracing cable, and adhering to the smooth ramp and the top surface of the heat tracing cable; and a second insulating tape layer wound around the outer surface of the heat tracing cable and the patches.

[0009] Preferably, the outer layer comprises: an elastic thermally conductive compensation layer covering the second aluminum foil layer; a cold-shrink adhesive layer covering the elastic thermally conductive compensation layer; and a textile layer covering the cold-shrink adhesive layer.

[0010] Preferably, the elastic thermally conductive compensation layer includes a foamed tape, which is wrapped on the outer surface of the second aluminum foil layer in a longitudinal straight wrapping manner; the length direction of the foamed tape is parallel to the axial direction of the pipeline body, the wrapping direction is along the circumference of the pipeline body, and the joint is a flat joint.

[0011] Preferably, the first insulation layer includes an insulation tape, which is spirally wound along the length of the pipe body at a 1 / 4 to 1 / 3 overlap. The spacing between adjacent winding loops of the heat tracing tape is 1 to 2 times the width of the heat tracing tape. The angle between the smooth slope surface and the surface of the first insulating tape layer is 45° to 60°. The two edge portions of each patch are respectively attached to the first insulating tape layer, and the middle portion of the patch is sequentially attached to the smooth slope on one side, the top surface of the heat tracing tape, and the smooth slope on the other side.

[0012] Preferably, the material of the smooth slope is thermally conductive silicone rubber putty or thermally conductive sealant; the patch is glass cloth tape or polyimide fiber tape; the insulation tape is polytetrafluoroethylene insulation tape; and the heat tracing tape is a self-regulating heat tracing tape.

[0013] On the other hand, the present invention provides a method for manufacturing a pipe fitting. After sequentially covering the pipe body of the pipe fitting with a first insulation layer, a first aluminum foil layer, a heat tracing layer, and a second aluminum foil layer, the manufacturing method includes: Step SS11: On the outer surface of the second aluminum foil layer, an elastic thermally conductive compensation layer, a smooth transition film, and a smooth isolation film are sequentially wrapped in a longitudinal straight wrapping manner; Step SS12: A rigid bushing is fitted onto the outer surface of the second end of the smooth isolation film; Step SS13: The second end of the smooth transition film and the second end of the smooth isolation film are folded outward together, wrapped around the rigid bushing, and then tied and fixed to form a pull-out ring; Step SS14: The cold-shrink tubing is pulled from the first end of the smooth isolation film... The cold shrink tubing is inserted into and fitted onto the outer surface of the smooth insulating membrane; wherein the length of the cold shrink tubing is less than the axial distance from the first end to the second end of the smooth insulating membrane; Step SS15: By pulling the pull ring, the smooth transition membrane and the smooth insulating membrane are pulled out from between the cold shrink tubing and the elastic thermally conductive compensation layer; Step SS16: The cold shrink tubing is shrunk and shaped, so that the inner wall of the cold shrink tubing adheres to the outer surface of the elastic thermally conductive compensation layer; Step SS17: An adhesive layer is coated on the outer surface of the shrunk and shaped cold shrink tubing, and before the adhesive layer cures, a textile tube is fitted onto the cold shrink tubing, so that the textile tube is bonded and fixed to the cold shrink tubing through the adhesive layer.

[0014] Preferably, the first end of the smooth transition membrane and the first end of the smooth isolation membrane are flush with the first end of the elastic thermally conductive compensation layer; the second end of the smooth transition membrane and the second end of the smooth isolation membrane extend axially along the pipeline body beyond the second end of the elastic thermally conductive compensation layer.

[0015] Preferably, the length of the cold shrink tubing is at least 20 mm less than the axial distance.

[0016] Preferably, the seams of the smooth transition membrane, the smooth isolation membrane, and the elastic thermally conductive compensation layer are staggered in the circumferential direction of the pipeline body.

[0017] Preferably, the smooth transition membrane is an expanded polytetrafluoroethylene film; the smooth isolation membrane is a polyester film or a polytetrafluoroethylene film; and the elastic thermally conductive compensation layer is a thermally conductive silicone rubber foam layer.

[0018] The advantages of the above-mentioned technical solution of this application compared with the prior art include at least the following: the pipe fitting described in this application can achieve uniform heating and reliable anti-condensation of the pipe body surface through the synergistic effect of the multi-layer functional structure. Specifically: a smooth slope is formed at the root of the heat tracing cable on both sides by a heat-conducting filling material, eliminating the steep change at the step, and the heat tracing cable is mechanically locked by a patch spanning the smooth slope and the heat tracing cable to prevent it from shifting; a double insulation and double reflection structure is formed by the first aluminum foil layer and the second aluminum foil layer in combination with the first insulating tape layer and the second insulating tape layer, which sandwiches the heat tracing layer therein, ensuring electrical safety and forming an internal and external bidirectional heat reflection cavity to guide heat to the pipe body; at the same time, the surface unevenness formed by the spiral winding of the heat tracing cable is filled by an elastic heat-conducting compensation layer, combined with a smooth interface layer with a longitudinal straight wrap, so that the cold shrink tubing can be tightly attached to the surface of the elastic heat-conducting compensation layer without wrinkles after shrinkage.

[0019] Furthermore, the spiral winding of the heat tracing cable creates a wavy, uneven surface, preventing the subsequent covering layers from fitting evenly and resulting in numerous air gaps between layers. Simultaneously, the uneven substrate surface and high frictional resistance make it difficult to smoothly insert the cold-shrink tubing, and wrinkles and air bubbles are more likely to occur during heat shrinkage. If a liquid lubricant is used to assist insertion, the residue after shrinkage forms an isolation layer, hindering a tight fit between the cold-shrink tubing and the covered layer. The tubing manufacturing method described in this application uses a longitudinal straight wrapping method to cover an elastic thermally conductive compensation layer, utilizing the adaptive deformation of the elastic material to fill and smooth the surface unevenness formed by the winding of the heat tracing cable, providing a flat substrate for the cold-shrink tubing. By covering the elastic layer with a smooth transition film and a smooth isolation film, and using a rigid liner-reinforced pull-out ring to pull out the entire tube before shrinkage, it ensures smooth, undamaged insertion of the cold-shrink tubing and avoids the problem of the isolation film being unable to be pulled out due to radial pressure after shrinkage. Simultaneously, the uniform radial pressure generated by the shrinkage of the cold-shrink tubing compresses and compacts the internal layers, effectively eliminating interlayer gaps. Attached Figure Description

[0020] To make the content of this application easier to understand, the following detailed description is provided based on specific embodiments of this application and in conjunction with the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of a pipe fitting in one embodiment of this application.

[0022] Figure 2 This is a schematic diagram of one structure of the heat tracing layer in an embodiment of this application.

[0023] Figure 3 This is a schematic diagram of the outer layer structure in an embodiment of this application.

[0024] Figure 4 This is a schematic diagram of a process flow for manufacturing pipe fittings in an embodiment of this application.

[0025] Explanation of reference numerals in the accompanying drawings: 1. Pipe body; 2. First insulation layer; 3. First aluminum foil layer; 4. Heat tracing layer; 41. First insulating tape layer; 42. Heat tracing tape; 43. Smooth slope; 44. Patch; 45. Second insulating tape layer; 5. Second aluminum foil layer; 6. Outer layer; 61. Elastic thermally conductive compensation layer; 62. Cold shrink adhesive layer; 63. Textile layer; 64. Smooth transition film; 65. Smooth isolation film; 66. Cold shrink tubing; 67. Rigid bushing; 68. Pull-out ring. Detailed Implementation

[0026] The present application will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present application, but the embodiments are not intended to limit the present application.

[0027] Example 1: This example provides a pipe fitting.

[0028] The pipe fittings in this embodiment include: a pipe body 1 and a covering layer covering the outer wall of the pipe body 1.

[0029] In application, the pipeline body 1 is used to transport cryogenic media. The covering layer is used to insulate the pipeline body 1 and to provide uniform heating.

[0030] refer to Figure 1 The covering layer includes a first insulation layer 2, a first aluminum foil layer 3, a heat tracing layer 4, a second aluminum foil layer 5, and an outer layer 6, which are sequentially covered from the inside to the outside of the outer wall of the pipeline body 1.

[0031] The first insulation layer 2 includes an insulation tape, which can be a polytetrafluoroethylene (PTFE) insulation tape, spirally wound along the axial direction of the pipe body 1 using an overlapping method. Furthermore, the insulation tape is spirally wound along the length of the pipe body 1 on the outer wall of the pipe body 1 with a 1 / 4 to 1 / 3 overlap, ensuring complete coverage at the overlap and no spiral gaps while controlling the total thickness of the first insulation layer 2 within a reasonable range, thus balancing insulation and heat conduction.

[0032] The first aluminum foil layer 3 is made of aluminum foil paper tightly wrapped around the outer surface of the first insulation layer 2 along the circumference of the pipeline, with overlapping at the seams. Furthermore, the first aluminum foil layer 3 utilizes the high reflectivity of the metallic material to reflect a portion of the heat lost from the heat tracing layer 4 back towards the pipeline, improving thermal efficiency. When the heat generated by the heat tracing layer 4 radiates towards the pipeline body 1, this heat is reflected back towards the heat tracing layer 4 by the highly reflective aluminum foil layer at the interface of the first aluminum foil layer 3.

[0033] refer to Figure 2 The heat tracing layer 4 includes: a first insulating tape layer 41, a heat tracing cable 42, multiple smooth ramps 43, multiple patches 44, and a second insulating tape layer 45.

[0034] The first insulating tape layer 41 forms an electrical insulation barrier between the conductive first aluminum foil layer 3 and the heat tracing layer 4. Furthermore, the first insulating tape layer 41 can be formed using a high-temperature resistant insulating tape such as polyimide. Specifically, the first insulating tape layer 41 is formed by wrapping a high-temperature resistant insulating tape around the outer surface of the first aluminum foil layer 3.

[0035] The heating cable 42 can be a self-regulating heating cable 42, spirally wound with spacing around the outer surface of the first insulating tape layer 41. Specifically, the long side of the flat cross-section of the heating cable 42 is attached to the pipe wall to obtain a larger heat transfer contact area. To ensure a uniform axial temperature field distribution on the surface of the pipe body 1, the spacing between adjacent winding loops of the heating cable 42 is 1 to 2 times the bandwidth of the heating cable 42, and the heat-affected zones of adjacent heating cables 42 form a smooth overlap on the surface of the pipe body 1. When the spacing is less than 1 times the bandwidth of the heating cable 42, the heat-affected zones of adjacent heating cables 42 overlap severely, resulting in a temperature increase in the overlapping area and causing local overheating; when the spacing is greater than 2 times the bandwidth of the heating cable 42, a low-temperature blind zone appears between adjacent heat-affected zones, which cannot meet the requirement of uniform heating.

[0036] Multiple smooth ramps 43 are spaced apart along the axial direction of the pipeline body 1 to fill the steps formed between the two sides of the heat tracing cable 42 and the first insulating tape layer 41, forming a transition structure from the surface of the first insulating tape layer 41 to the top surface of the heat tracing cable 42. When the angle between the slope surface of the smooth ramp 43 and the surface of the first insulating tape layer 41 is less than 45°, the ramp transition is too gentle, the spacing between adjacent smooth ramps 43 is insufficient to accommodate the effective bonding area of ​​the patch, and the material is prone to flow and deformation during scraping construction. When the angle between the slope surface of the smooth ramp 43 and the surface of the first insulating tape layer 41 is greater than 60°, the ramp transition is abrupt, the patch experiences bending stress concentration when crossing the ramp, and there is a tendency for peeling between the patch edge and the ramp surface, resulting in a decrease in mechanical locking effect. In this embodiment, the angle between the slope surface of the smooth ramp 43 and the surface of the first insulating tape layer 41 can be between 45° and 60°.

[0037] Furthermore, the material of the smooth slope 43 is thermally conductive silicone rubber putty or thermally conductive sealant. For example, a scraper is used to evenly apply thermally conductive silicone rubber putty to the junction between the roots of both sides of the heat tracing cable 42 and the first insulating tape layer 41, and an arc-shaped scraper is used to smooth it along the length of the heat tracing cable 42 to form a smooth slope 43 from the surface of the first insulating tape layer 41 to the top surface of the heat tracing cable 42. The angle between the slope surface and the surface of the first insulating tape layer 41 is 45° to 60°. Then, it is left to cure at room temperature for 4 to 8 hours, or heated and cured at 60°C to 80°C for 30 to 60 minutes.

[0038] Multiple patches 44 are spaced apart along the axial direction of the pipeline body 1. Each patch 44 spans the adjacent smooth slope 43 and the heat tracing cable 42 and is attached to the top surface of the smooth slope 43 and the heat tracing cable 42.

[0039] To effectively save construction time and suppress the movement of the heat tracing cable 42, multiple patches 44 are distributed at 200mm to 500mm intervals along the axial direction of the pipeline body 1. Each patch 44 must simultaneously cover the smooth slope 43, the top surface of the heat tracing cable 42, and the slope on the other side. If the width of the patch 44 is too small, it cannot provide sufficient bonding area and peel strength; if the width of the patch 44 is too large, it will interfere with adjacent smooth slopes 43. Furthermore, one patch 44 is applied at the location of each smooth slope 43, and the width of the patch 44 is greater than the width of the smooth slope 43. In this embodiment, the width of the patch 44 is 20mm to 50mm. Furthermore, the patch 44 is made of glass cloth tape or polyimide fiber tape. The two edges of each patch 44 are respectively attached to the first insulating tape layer 41, and the middle portion of the patch 44 is sequentially attached to a smooth slope 43 on one side, the top surface of the heating cable 42, and the smooth slope 43 on the other side, adhering tightly to each surface. The patch 44 mechanically locks the heating cable 42 to the first insulating tape layer 41, preventing the heating cable 42 from shifting due to its own elasticity or thermal stress during subsequent operations and long-term operation.

[0040] The second insulating tape layer 45 is made of the same material as the first insulating tape layer 41. Furthermore, the second insulating tape layer 45 is wrapped around the outer surfaces of the heat tracing tape 42 and the patch 44 to form an outer insulating covering.

[0041] The second aluminum foil layer 5 is made by wrapping aluminum foil paper around the outer surface of the second insulating tape layer 45.

[0042] It is worth noting that the first aluminum foil layer 3 and the second aluminum foil layer 5 are located on the inner and outer sides of the heat tracing layer 4, respectively, forming parallel reflective walls. Of the heat generated by the heat tracing cable 42, the portion radiated outwards is reflected back to the direction of the heat tracing layer 4 by the second aluminum foil layer 5, while the portion radiated inwards through the gaps in the heat tracing cable 42 is reflected back to the direction of the heat tracing layer 4 by the first aluminum foil layer 3. This creates a bidirectional heat reflection effect, reducing unnecessary heat loss to the environment and uneven, rapid heat transfer to the pipeline body before heat is conducted to the pipeline body, thus improving heat utilization efficiency. Therefore, the first aluminum foil layer 3 and the second aluminum foil layer 5, as well as the first insulating tape layer 41 and the second insulating tape layer 45, constitute an integrated structure of double insulation and double reflection. The heat tracing layer 4 is sandwiched between this integrated structure of double insulation and double reflection, ensuring electrical safety and forming a bidirectional heat reflection cavity, effectively guiding heat to the pipeline body 1.

[0043] In some embodiments, when only the first aluminum foil layer 3 is provided and the second aluminum foil layer 5 is not provided, the surface temperature uniformity of the pipe fitting is poor; specifically, the maximum circumferential temperature difference of the pipe fitting surface is 12°C to 18°C. In some embodiments, when only the second aluminum foil layer 5 is provided and the first aluminum foil layer 3 is not provided, the surface temperature uniformity of the pipe fitting is poor; specifically, the maximum circumferential temperature difference of the pipe fitting surface is 15°C to 20°C. In some embodiments, when both the first aluminum foil layer 3 and the second aluminum foil layer 5 are provided, the surface temperature uniformity of the pipe fitting is good; specifically, the maximum circumferential temperature difference of the pipe fitting surface is less than or equal to 5°C.

[0044] refer to Figure 3 The outer layer 6 includes: an elastic thermally conductive compensation layer 61, a cold-shrink adhesive layer 62, and a textile layer 63.

[0045] The elastic thermally conductive compensation layer 61 can be a thermally conductive silicone rubber foam layer, covering the second aluminum foil layer 5. Further, the elastic thermally conductive compensation layer 61 includes a foamed tape, such as a thermally conductive silicone rubber foamed tape. The foamed tape is wrapped longitudinally on the outer surface of the second aluminum foil layer 5. Specifically, the length direction of the foamed tape is parallel to the axial direction of the pipe body 1, the wrapping direction is along the circumference of the pipe body 1, and the joint is a flat joint.

[0046] It is worth noting that the elastic thermally conductive compensation layer 61 can be compressed to fill the surface unevenness formed by the spiral winding of the heat tracing tape 42, making the base of the outer layer 6 a smooth cylindrical surface, ensuring that each layer can be uniformly compacted when the subsequent cold-shrink adhesive layer 62 shrinks.

[0047] The cold-shrink adhesive layer 62 covers the elastic thermally conductive compensation layer 61. Further, the cold-shrink adhesive layer 62 is formed by heating and shrinking a silicone rubber cold-shrink tubing 66 fitted onto the elastic thermally conductive compensation layer 61, tightly covering the outer surface of the elastic thermally conductive compensation layer 61. The radial compression force of the cold-shrink adhesive layer 62 is used to eliminate interlayer air gaps.

[0048] The textile layer 63 covers the cold-shrink adhesive layer 62. Furthermore, the textile layer 63 is formed by bonding and fixing a wear-resistant and flame-retardant textile tube sleeved over the cold-shrink adhesive layer 62 to the cold-shrink adhesive layer 62 via an adhesive layer.

[0049] Example 2: Based on Example 1, this example provides a method for manufacturing a pipe fitting.

[0050] The manufacturing method of the pipe fitting in this embodiment involves sequentially covering the pipe body 1 of the pipe fitting with the first insulation layer 2, the first aluminum foil layer 3, the heat tracing layer 4, the second aluminum foil layer 5, and the outer layer 6.

[0051] In application, the following steps are performed sequentially on the pipe body 1 of the fitting: spiral winding of the first insulation layer 2, wrapping of the first aluminum foil layer 3, winding of the first insulating tape layer 41, spiral winding and adhesive positioning of the heat tracing tape 42, coating and trimming of the smooth slope 43, application of the patch 44, winding of the second insulating tape layer 45, and wrapping of the second aluminum foil layer 5.

[0052] In practical applications, after sequentially covering the pipeline body 1 with the first insulation layer 2, the first aluminum foil layer 3, the heat tracing layer 4, and the second aluminum foil layer 5, the manufacturing method includes steps SS11 to SS17, as described above. Figure 4 .

[0053] Step SS11: On the outer surface of the second aluminum foil layer 5, an elastic thermally conductive compensation layer 61, a smooth transition film 64, and a smooth isolation film 65 are sequentially wrapped in a longitudinal straight wrapping manner.

[0054] In application, the smooth transition film 64 is an expanded polytetrafluoroethylene (ePTFE) film with a thickness of 0.05 mm to 0.15 mm. The smooth transition film 64 needs to withstand tensile stress during the pulling process while possessing sufficient flexibility to accommodate the microscopic deformation of the elastic thermally conductive compensation layer 61. If the thickness of the smooth transition film 64 is less than 0.05 mm, it is prone to breakage during pulling; if the thickness is greater than 0.15 mm, its own stiffness is high, resulting in significant frictional resistance between it and the elastic thermally conductive compensation layer 61 during extraction. The smooth isolation film 65 is a polyester film or ePTFE film with a thickness of 0.03 mm to 0.10 mm, providing a low-friction surface while possessing sufficient stiffness to resist wrinkling during insertion. The elastic thermally conductive compensation layer 61 is a thermally conductive silicone rubber foam layer.

[0055] When applying the elastic thermally conductive compensation layer 61: Cut the thermally conductive silicone rubber foam tape into rectangular sheets that match the axial length of the pipe body 1. Wrap the cut thermally conductive silicone rubber foam tape circumferentially along the width of the pipe body 1, with the length parallel to the axial direction of the pipe body 1. During application, peel off the release paper from the back of the foam tape and, starting from one side of the pipe body 1, press it evenly circumferentially to ensure a tight fit with the second aluminum foil layer 5. The joints are joined using a flat joint method, that is, the two long sides of the foam tape are joined together and filled with thermally conductive silicone or sealed with a thin tape of the same material or with a smooth surface.

[0056] Furthermore, the thickness of the thermally conductive silicone rubber foam tape is selected based on the surface unevenness depth formed by the winding of the heat tracing tape 42. After the heat tracing tape 42 is wound, the height of the protrusion depends on the thickness of the heat tracing tape 42 itself, and a depression is formed between two adjacent turns of heat tracing tape 42. The difference in the depth of the depression is the height difference between the top surface of the heat tracing tape 42 and the lowest point of the depression. Since the elastic thermally conductive compensation layer 61 needs to provide at least 20% additional compression margin under pressure; if the thickness of the elastic thermally conductive compensation layer 61 is less than 0.8 times the thickness of the heat tracing tape 42, it cannot completely cover the protruding area; if the thickness of the elastic thermally conductive compensation layer 61 is more than 1.5 times the thickness of the heat tracing tape 42, it will waste material and may also increase the radial shrinkage load of the cold shrink tubing; the thickness of the elastic thermally conductive compensation layer 61 needs to meet the following requirements: 0.8 to 1.5 times the thickness of the heat tracing tape 42, and / or the thickness of the elastic thermally conductive compensation layer 61 is not less than 1.2 times the difference in the depth of the depression. When covering the smooth transition membrane 64: Expanded PTFE film is used, and it is also wrapped on the outer surface of the elastic thermally conductive compensation layer 61 in a longitudinal straight wrapping manner. The cut width of the expanded PTFE film is equal to the perimeter of the pipe body 1 after the elastic thermally conductive compensation layer 61 is wrapped plus a small allowance, and the length direction is parallel to the axial direction of the pipe body 1. The joint is also treated with a flat joint.

[0057] When covering the smooth isolation membrane 65: use polyester film or polytetrafluoroethylene film, still wrapping it in a longitudinal straight wrapping manner on the outer surface of the smooth transition membrane 64, with the seam flush.

[0058] In practical applications, the seams of the smooth transition membrane 64, the smooth isolation membrane 65, and the elastic thermally conductive compensation layer 61 are staggered in the circumferential direction of the pipeline body 1. Specifically, the axial seams of the elastic thermally conductive compensation layer 61, the smooth transition membrane 64, and the smooth isolation membrane 65 are staggered by 60° in the circumferential direction of the pipeline body 1, so that the seams are evenly distributed in the circumferential direction, avoiding seam overlap that could cause local bulging or concentrated film extraction resistance.

[0059] In actual implementation, the first end of the smooth transition membrane 64 and the first end of the smooth isolation membrane 65 are flush with the first end of the elastic thermal compensation layer 61; the second end of the smooth transition membrane 64 and the second end of the smooth isolation membrane 65 extend along the axial direction of the pipeline body 1 to exceed the second end of the elastic thermal compensation layer 61 by more than 80mm, so as to reserve sufficient folding operation margin.

[0060] Step SS12: Fit the rigid bushing 67 onto the outer surface of the second end of the smooth isolation membrane 65.

[0061] In application, the rigid bushing 67 is inserted from the second end of the smooth insulating film 65 and placed on the outer surface of the smooth insulating film 65 so that the inner end face of the rigid bushing 67 is kept 10mm to 15mm from the second end face of the elastic thermally conductive compensation layer 61 for subsequent folding.

[0062] Step SS13: Fold the second end of the smooth transition membrane 64 and the second end of the smooth isolation membrane 65 outward together, wrap them around the rigid bushing 67, and then tie them in place to form a pull-out ring 68.

[0063] In application, the second end of the smooth transition membrane 64 and the second end of the smooth isolation membrane 65 are folded outward together to wrap around the rigid bushing 67. Then, heat-resistant pressure-sensitive tape is used to tightly bind and fix the folded root on the side of the rigid bushing 67 near the first end of the pipe body 1 to form a pull-out ring 68. The rigid bushing 67 provides rigid support for the pull-out ring 68, so that the pull-out ring 68 maintains its shape during subsequent pull-out operations, making it easy to clamp and pull.

[0064] Step SS14: Insert the cold shrink tubing 66 into the first end of the smooth release film 65 and place it on the outer surface of the smooth release film 65.

[0065] In application, the length of the cold-shrink tubing 66 is less than the axial distance between the first and second ends of the smooth release diaphragm 65. Furthermore, the length of the cold-shrink tubing 66 is at least 20 mm shorter than the axial distance to provide axial movement space for the operation of the pull-out ring 68. In practical application, the axial distance between the inner end face of the pull-out ring 68 and the first end face of the smooth release diaphragm 65 is measured, and the cold-shrink tubing 66 is cut so that its length is at least 20 mm shorter than the axial distance. The cut cold-shrink tubing 66 is then inserted from the first end of the tubing body 1 and fitted onto the outer surface of the smooth release diaphragm 65. Because the surface of the smooth release diaphragm 65 is smooth, no liquid lubricant is required during the insertion process.

[0066] Step SS15: By pulling the pull ring 68, the smooth transition film 64 and the smooth isolation film 65 are pulled out from between the cold shrink tubing 66 and the elastic thermally conductive compensation layer 61.

[0067] In application, the pull ring 68 is clamped by a clamping tool and pulled outward smoothly along the axial direction of the pipe body 1, so that the smooth transition film 64 and the smooth isolation film 65 are pulled out together from between the cold shrink tubing 66 and the elastic thermally conductive compensation layer 61. After being pulled out, a gap is formed between the inner wall of the cold shrink tubing 66 and the outer surface of the elastic thermally conductive compensation layer 61.

[0068] In practical applications, when the pull ring 68 pulls out the smooth transition film 64 and the smooth isolation film 65, an auxiliary fixing force is applied to the cold shrink tubing 66 near the first end to prevent the cold shrink tubing 66 from moving to the second end along with the isolation film, thus ensuring that the cold shrink tubing 66 remains in the predetermined position.

[0069] In actual implementation, the pull-out ring 68 detaches from the pipe fitting as the smooth transition membrane 64 and smooth isolation membrane 65 are pulled out. At this point, the binding straps are loosened, and the rigid liner ring 67 is removed from the folded membrane material for recycling.

[0070] Step SS16: The cold shrink tubing 66 is shrunk and shaped so that the inner wall of the cold shrink tubing 66 adheres to the outer surface of the elastic thermally conductive compensation layer 61.

[0071] When used, the cold shrink tubing 66 shrinks and sets at room temperature.

[0072] Step SS17: Apply an adhesive layer to the outer surface of the cold-shrink tubing 66 after shrinking and shaping, and before the adhesive layer cures, put the textile tube on the cold-shrink tubing 66 so that the textile tube is bonded and fixed to the cold-shrink tubing 66 through the adhesive layer.

[0073] In application, an adhesive material is evenly coated onto the outer surface of the shrunken tubing 66 after shrinkage and shaping. Before the adhesive material is surface dry and cured, the textile tube is placed on the shrunken tubing 66 and smoothed out. After the adhesive material is completely cured, an adhesive layer is formed, and the textile tube is bonded and fixed to the outside of the shrunken tubing 66.

[0074] In practical applications, the adhesive layer is room temperature curing silicone rubber.

[0075] In actual implementation, a heat-shrinkable retaining ring is wrapped around each end of the textile tube. After being heated and shrunk, the heat-shrinkable retaining ring further locks the ends of the textile tube.

[0076] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A pipe fitting, characterized in that, include: The pipeline body, the outer wall of which is sequentially covered from the inside out with a first insulation layer, a first aluminum foil layer, a heat tracing layer, a second aluminum foil layer, and an outer layer; wherein, the heat tracing layer includes: The first insulating tape layer is wrapped around the outer surface of the first aluminum foil layer; The heat tracing tape is spirally wound around the outer surface of the first insulating tape layer with a spacing; Multiple smooth ramps are spaced apart along the axial direction of the pipeline body to fill the steps formed between the two sides of the heat tracing cable and the first insulating tape layer, and to form a transition structure from the surface of the first insulating tape layer to the top surface of the heat tracing cable. Multiple patches are spaced apart along the axial direction of the pipeline body, each patch spanning the adjacent smooth slope and the heat tracing cable, and adhering to the top surface of the smooth slope and the heat tracing cable; A second insulating tape layer is wrapped around the outer surface of the heat tracing tape and the patch.

2. The pipe fitting according to claim 1, characterized in that, The outer layer includes: An elastic thermally conductive compensation layer is wrapped around the second aluminum foil layer; A cold-shrink adhesive layer is applied over the elastic thermally conductive compensation layer. A textile layer is wrapped around the cold-shrink adhesive layer.

3. The pipe fitting according to claim 2, characterized in that, The elastic thermally conductive compensation layer includes a foamed tape, which is wrapped on the outer surface of the second aluminum foil layer in a longitudinal straight wrapping manner; the length direction of the foamed tape is parallel to the axial direction of the pipeline body, the wrapping direction is along the circumference of the pipeline body, and the joint is a flat joint.

4. The pipe fitting according to claim 1, characterized in that, The first insulation layer includes an insulation strip, which is spirally wound along the length of the pipe body at a 1 / 4 to 1 / 3 overlap. The spacing between adjacent winding loops of the heat tracing cable is 1 to 2 times the width of the heat tracing cable; The angle between the smooth slope surface and the surface of the first insulating tape layer is 45° to 60°. The two edge portions of each patch are respectively attached to the first insulating tape layer, and the middle portion of the patch is sequentially attached to a smooth slope on one side, the top surface of the heat tracing cable, and a smooth slope on the other side.

5. The pipe fitting according to claim 4, characterized in that, The material of the smooth slope is thermally conductive silicone rubber putty or thermally conductive sealant. The patch is made of glass cloth tape or polyimide fiber tape; The insulation tape is a tetrafluoroethylene insulation tape; The heating cable is a self-regulating heating cable.

6. A method for manufacturing a pipe fitting, characterized in that, After sequentially covering the pipe body of the pipe fitting as described in any one of claims 1 to 5 with the first insulation layer, the first aluminum foil layer, the heat tracing layer, and the second aluminum foil layer, the manufacturing method includes: Step SS11: On the outer surface of the second aluminum foil layer, an elastic thermally conductive compensation layer, a smooth transition film, and a smooth insulating film are sequentially wrapped in a longitudinal straight wrapping manner; Step SS12: Fit the rigid bushing onto the outer surface of the second end of the smooth insulating membrane; Step SS13: Fold the second end of the smooth transition membrane and the second end of the smooth isolation membrane outward together, wrap them around the rigid bushing, and then tie them in place to form a pull-out ring; Step SS14: Insert the cold shrink tubing into the first end of the smooth release film and place it on the outer surface of the smooth release film; wherein the length of the cold shrink tubing is less than the axial distance from the first end to the second end of the smooth release film; Step SS15: By pulling the pull ring, the smooth transition film and the smooth isolation film are pulled out from between the cold shrink tubing and the elastic thermally conductive compensation layer; Step SS16: The cold shrink tubing is shrunk and shaped so that the inner wall of the cold shrink tubing adheres to the outer surface of the elastic thermally conductive compensation layer; Step SS17: Apply an adhesive layer to the outer surface of the cold-shrink tubing after shrinkage and shaping, and before the adhesive layer cures, put the textile tube on the cold-shrink tubing so that the textile tube is bonded and fixed to the cold-shrink tubing through the adhesive layer.

7. The method for manufacturing pipe fittings according to claim 6, characterized in that, The first end of the smooth transition membrane and the first end of the smooth isolation membrane are both flush with the first end of the elastic thermally conductive compensation layer. The second end of the smooth transition membrane and the second end of the smooth isolation membrane both extend axially along the pipeline body to the second end beyond the elastic thermal compensation layer.

8. The method for manufacturing the pipe fitting according to claim 6, characterized in that, The length of the cold shrink tubing is at least 20 mm less than the axial distance.

9. The method for manufacturing the pipe fitting according to claim 6, characterized in that, The seams of the smooth transition membrane, the smooth isolation membrane, and the elastic thermally conductive compensation layer are staggered in the circumferential direction of the pipeline body.

10. The method for manufacturing the pipe fitting according to claim 6, characterized in that, The smooth transition membrane is an expanded polytetrafluoroethylene film. The smooth insulating membrane is a polyester film or a polytetrafluoroethylene film. The elastic thermally conductive compensation layer is a thermally conductive silicone rubber foam layer.

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