Heat tracing pipe, method for processing heat tracing pipe, and heat tracing pipe system

Abstract

The present disclosure relates to the technical field of fluid delivery, and particularly relates to a heat tracing pipe, a processing method of the heat tracing pipe and a heat tracing pipe system. The heat tracing pipe provided by the present disclosure comprises a pipe body, which is a stainless steel seamless coil pipe or a stainless steel welded coil pipe; an anti-corrosion layer is arranged on the outer surface of the pipe body, which is a zirconium ceramic coating or a hydrophobic non-woven fabric, and is used for blocking the corrosion of chloride ions; a thermal insulation layer is wrapped on the outer surface of the anti-corrosion layer, which is an integrated glass fiber aerogel felt (glass fiber needle punching blanket) or pure aerogel; a Mylar tape is wrapped on the outer surface of the thermal insulation layer, which is made of aluminum plated on a polyethylene film, a polypropylene film or a polyester film, and is used for reflecting heat radiation and compressing the air in the thermal insulation layer through the wrapping tension to inhibit heat convection; a heat insulation non-woven fabric layer is coated on the outer surface of the Mylar tape; and an external protective layer is coated on the outer surface of the heat insulation non-woven fabric layer.

Description

Technical Field

[0001] This disclosure relates to the field of fluid transport technology, and in particular to a heat tracing pipe, a method for processing the heat tracing pipe, and a heat tracing pipeline system. Background Technology

[0002] In industries such as energy, petrochemicals, and coal chemicals, heat tracing and insulation of process pipelines, instrumentation, and analytical sampling systems are crucial for ensuring production safety, maintaining media flow, and preventing freezing. Traditional heat tracing and insulation systems typically employ a split construction model of "pipeline + on-site insulation," which involves first laying carbon steel or stainless steel heat tracing pipelines, then wrapping them with insulation materials such as rock wool or perlite on-site, and finally adding an outer protective layer of aluminum or iron sheet. Traditional heat tracing and insulation systems suffer from drawbacks such as high heat loss and short lifespan. Summary of the Invention

[0003] This disclosure provides a heat tracing pipe, a method for processing the heat tracing pipe, and a heat tracing pipeline system to at least solve the above-mentioned technical problems existing in the prior art.

[0004] The first aspect of this disclosure provides a heat tracing pipe, comprising, from the inside to the outside: The pipe body is a seamless stainless steel coil or a welded stainless steel coil. An anti-corrosion layer is provided on the outer surface of the pipe body. The anti-corrosion layer is a zirconium ceramic coating or a hydrophobic non-woven fabric, which is used to block chloride ion corrosion. A thermal insulation layer is wrapped around the outer surface of the anti-corrosion layer. The thermal insulation layer is an integrated glass fiber aerogel felt (glass fiber needle-punched blanket) or pure aerogel. Mylar tape is wrapped around the outer surface of the thermal insulation layer. The Mylar tape is made of aluminum plated on polyethylene film, polypropylene film or polyester film (PET). It is used to reflect heat radiation and to suppress heat convection by compressing the air inside the thermal insulation layer through wrapping tension. The Mylar tape (4) is wrapped around the thermal insulation layer (3) with a tension of 5N~10N. The overlap rate of the Mylar tape (4) is greater than or equal to 50%. The Mylar tape (4) compresses the thermal insulation layer (3) so that the air content inside the thermal insulation layer (3) is less than or equal to 10%. A heat-insulating non-woven fabric layer is wrapped around the outer surface of the Mylar tape; An external protective layer is wrapped around the outer surface of the heat-insulating nonwoven fabric layer.

[0005] Furthermore, when the anti-corrosion layer is a zirconium ceramic coating, the thickness of the anti-corrosion layer is 0.1mm~0.3mm, and the adhesion of the zirconium ceramic coating is greater than or equal to 5MPa; The anti-corrosion layer is a hydrophobic nonwoven fabric with a water repellency of ≥95% and a chloride ion permeability of ≤0.01mg / (m²·d).

[0006] Furthermore, the thickness of the insulation layer is 12mm~40mm; When the insulation layer is an integrated glass fiber aerogel felt (glass fiber needled blanket), the thermal conductivity of the integrated glass fiber aerogel felt (glass fiber needled blanket) is 0.031 W / (m·K). When the insulation layer is pure aerogel, the thermal conductivity of the pure aerogel is 0.025 W / (m·K).

[0007] Furthermore, the proportion of aerogel added to the glass fiber aerogel felt is greater than or equal to 60%, so that the heat conduction blocking efficiency of the insulation layer is greater than or equal to 90%, and the outer surface temperature of the insulation layer is less than or equal to 50°C.

[0008] Furthermore, the wrapping tension of the Mylar tape is 5N~10N, the wrapping overlap rate is greater than or equal to 50%, and the internal air volume ratio of the insulation layer is less than or equal to 10% by compressing the tension of the Mylar tape.

[0009] Furthermore, the aluminum coating thickness of the Mylar tape is greater than or equal to 0.01 mm, and the thermal radiation reflectivity is greater than or equal to 85%.

[0010] Furthermore, the outer protective layer is formed of modified polyvinyl chloride, wherein the oxygen index of the modified polyvinyl chloride is less than or equal to 30%, the operating temperature range is -40℃ to 105℃, and the elongation at break is greater than or equal to 200%.

[0011] Furthermore, the heat tracing pipe is a single continuous rolled cable with a total length of not less than 200 meters and a wall thickness error of ≤3%.

[0012] The second aspect of this disclosure provides a processing method for a heat tracing pipe as described in the first aspect, comprising the following steps: pre-treating the pipe body, the purpose of which is to: eliminate cold working stress, reduce work hardening, reshape a uniform austenitic structure, improve the plasticity and toughness of the pipe, and ensure that the heat tracing pipe is not easily deformed or cracked during bending installation and long-term use, and has a uniform and stable wall thickness.

[0013] 1050~1100℃: Within the complete austenitizing temperature range of stainless steel, it can fully dissolve carbides and eliminate processing texture. Holding for 20~30 minutes: Ensures uniform temperature inside and outside the pipe wall, completely eliminating work hardening and preventing residual stress from causing later cracking. Bright annealing: Performed under a protective atmosphere, ensuring no oxidation or decarburization on the surface, guaranteeing stronger adhesion of subsequent anti-corrosion coatings / non-woven fabrics. Remodeling the austenitic structure: Refines and homogenizes the grains, improving toughness, fatigue resistance, and corrosion resistance, especially suitable for high-salt-spray marine environments.

[0014] When the anti-corrosion layer is a zirconium ceramic coating, it is formed by plasma spraying; when the anti-corrosion layer is a hydrophobic nonwoven fabric, it is formed by spiral wrapping. The insulation layer is formed by unidirectional cotton covering or bidirectional spiral winding process, with a winding angle of 25°~50°. The Mylar tape is wound synchronously at a winding speed of 7m / min to 10m / min, and the winding tension is gradually increased to 5N to 10N; The outer protective layer is formed by hot melt extrusion using an extruder, with an extrusion temperature of 160℃~180℃.

[0015] A third aspect of this disclosure provides a heat tracing piping system, including the heat tracing pipe described in the first aspect.

[0016] The technical solution provided in this disclosure has the following advantages compared with the prior art: The heat tracing pipe provided in this embodiment uses a seamless stainless steel coil or a welded stainless steel coil as the pipe body, which has high structural strength and stable medium transportation, and is suitable for the long-term operation requirements of industrial heat tracing systems. The anti-corrosion layer uses a zirconium ceramic coating or hydrophobic non-woven fabric, which can effectively block the corrosion of the stainless steel pipe body by chloride ions, significantly improving the service life and reliability in high salt spray and high corrosion environments such as ships, islands, and seashores. The insulation layer uses an integrated glass fiber aerogel felt (glass fiber needle-punched blanket) or pure aerogel, which has a low thermal conductivity and excellent heat insulation effect, can efficiently block heat conduction, greatly reduce heat loss, improve heat tracing efficiency, and reduce energy consumption. The Mylar tape has both heat radiation reflection and air compression functions. On the one hand, it can reflect internal heat and block heat radiation; on the other hand, it can squeeze out the air in the insulation layer through the wrapping tension, which can significantly suppress heat convection, achieving triple blocking of heat conduction, heat convection, and heat radiation. The heat insulation effect is significantly better than that of traditional single-layer or simple composite structures. The heat insulation non-woven fabric layer can protect the Mylar tape from high temperature damage, while strengthening the overall wrapping tension, further improving the structural stability and convection blocking effect. The outer protective layer provides overall mechanical protection, weather protection, and insulation protection, enabling the heat tracing pipe to adapt to complex working conditions such as outdoor, high temperature, low temperature, and ultraviolet radiation. The overall structure is stable, the service life is long, and it is applicable to a wide range of scenarios.

[0017] The heat tracing pipe provided in this embodiment comprehensively blocks heat diffusion from three dimensions: heat conduction (insulation layer + anti-corrosion layer), heat convection (insulation non-woven fabric layer), and heat radiation (Mylar tape), through the synergistic effect of a multi-layer composite structure, thus solving the pain points of poor insulation and short life of traditional heat tracing pipes and cables.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0019] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0020] Figure 1 A schematic diagram of the structure of the heat tracing pipe provided in an embodiment of this disclosure is shown; Figure 2 A flowchart illustrating the processing method of the heat tracing pipe provided in the embodiments of this disclosure is shown.

[0021] The labels in the diagram are as follows: 1. Pipe body; 2. Anti-corrosion layer; 3. Insulation layer; 4. Mylar tape; 5. Thermal insulation non-woven fabric layer; 6. External protective layer. Detailed Implementation

[0022] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0023] The heat tracing pipe provided in this embodiment includes, from the inside out, a pipe body 1, an anti-corrosion layer 2, a heat insulation layer 3, a Mylar tape 4, a heat-insulating non-woven fabric layer 5, and an external protective layer 6.

[0024] Pipe body 1 is made of stainless steel seamless coil or stainless steel welded coil; using stainless steel seamless coil or stainless steel welded coil as pipe body 1 has strong pressure bearing capacity and good sealing performance, which can meet the long-term and stable medium transportation needs of industrial heat tracing systems.

[0025] The anti-corrosion layer 2 is set on the outer surface of the pipe body 1. The anti-corrosion layer 2 is a zirconium ceramic coating or a hydrophobic non-woven fabric, which is used to block chloride ion corrosion. The anti-corrosion layer 2 formed by the zirconium ceramic coating or hydrophobic non-woven fabric can effectively block the corrosion of chloride ions and salt spray on the stainless steel pipe body 1, avoid the pipe from rusting and being damaged, and at the same time help to block heat conduction, significantly improving the corrosion resistance and service life of the heat tracing pipe in highly corrosive scenarios such as ships, vessels, seaside, and islands.

[0026] The insulation layer 3 is wrapped around the outer surface of the anti-corrosion layer 2. The insulation layer 3 is made of integrated glass fiber aerogel felt (also known as glass fiber needled blanket) or pure aerogel. The integrated glass fiber aerogel felt (glass fiber needled blanket) or pure aerogel has an extremely low thermal conductivity and excellent thermal insulation performance. It can significantly reduce heat loss to the outside through conduction, improve heat tracing efficiency, and reduce energy consumption. Optionally, the insulation layer 3 adopts a unidirectional cotton covering or a double-sided spiral winding process with a spiral angle of 25°–50°. This ensures that the insulation layer 3 is evenly spread and tightly adhered to the pipe body 1 in both the circumferential and axial directions. This effectively avoids defects such as wrapping deviation, local excessive thickness / thinness, voids, and gaps, ensuring that the overall structure of the insulation layer is uniform and dense, thereby achieving a stable and consistent heat conduction blocking effect.

[0027] Mylar tape 4 is wrapped around the outer surface of the insulation layer 3. Mylar tape 4 is made of aluminum plated on polyethylene, polypropylene, or polyester (PET) film. It is used to reflect heat radiation and suppress heat convection by compressing the air inside the insulation layer 3 through wrapping tension. Mylar tape 4 is wrapped around the insulation layer 3 with a tension of 5N~10N, and the overlap rate of Mylar tape 4 is greater than or equal to 50%. Mylar tape 4 compresses the insulation layer 3 so that the air content inside the insulation layer 3 is less than or equal to 10%, actively suppressing heat convection. Mylar tape 4, made of aluminum plated on polyethylene, polypropylene, or polyester (PET) film, can have the dual functions of heat radiation reflection and air compression to suppress convection. Mylar tape 4 is wrapped around insulation layer 3 with a constant tension of 5N~10N, with an overlap rate of ≥50%. Through uniform tension compression, the air content inside insulation layer 3 is controlled to ≤10%, actively suppressing thermal convection. Simultaneously, it efficiently reflects radiated heat from the tube body, achieving thermal radiation blocking. This synergistic effect of radiation and convection enhances the thermal insulation performance, significantly reducing heat loss. The overlap rate is the percentage of the width of one overlapping loop of Mylar tape 4 relative to the total bandwidth.

[0028] A heat-insulating nonwoven fabric layer 5 is wrapped around the outer surface of the Mylar tape 4; an outer protective layer 6 is wrapped around the outer surface of the heat-insulating nonwoven fabric layer 5. The heat-insulating nonwoven fabric layer 5 effectively protects the Mylar tape 4, preventing it from being burned when the material of the outer protective layer 6 melts; it further strengthens the overall wrapping tension, compresses residual air, and helps block heat convection. The outer protective layer 6 provides mechanical protection for the entire cable, preventing impact, moisture, and salt spray corrosion. It also assists in heat insulation and electrical insulation; extending the overall service life of the cable, enabling the heat tracing pipe to adapt to complex working conditions such as outdoor use, high temperature, low temperature, and ultraviolet radiation, resulting in a longer overall service life and a wider range of applications.

[0029] The insulation layer 3 and the anti-corrosion layer 2 form a heat conduction layer, the heat insulation non-woven fabric layer 5 forms a convection layer, and the Mylar tape 4 forms a heat radiation layer. Through the synergistic effect of the multi-layer composite structure, heat diffusion can be completely blocked.

[0030] The heat tracing pipe provided in this embodiment uses a multi-layer composite structure to comprehensively block heat diffusion from three dimensions: heat conduction (insulation layer 3 + anti-corrosion layer 2), heat convection (insulation non-woven fabric layer 5), and heat radiation (Mylar belt 4), thus solving the problems of poor insulation and short lifespan of traditional heat tracing pipes and cables.

[0031] The heat tracing pipe provided in this embodiment uses a seamless stainless steel coil or a welded stainless steel coil as the pipe body 1, which has high structural strength and stable medium transportation, and is suitable for the long-term operation requirements of industrial heat tracing systems. The anti-corrosion layer 2 uses a zirconium ceramic coating or hydrophobic non-woven fabric, which can effectively block the corrosion of the stainless steel pipe body 1 by chloride ions, significantly improving the service life and reliability in high salt spray and high corrosion environments such as ships, islands, and seashores. The insulation layer 3 uses an integrated glass fiber aerogel felt (glass fiber needle-punched blanket) or pure aerogel, which has a low thermal conductivity and excellent heat insulation effect, can efficiently block heat conduction, greatly reduce heat loss, improve heat tracing efficiency, and reduce energy consumption. The Mylar tape 4 has both heat radiation reflection and air compression functions. On the one hand, it can reflect internal heat and block heat radiation; on the other hand, it squeezes out the air in the insulation layer 3 through wrapping tension, which significantly inhibits heat convection, achieving triple blocking of heat conduction, heat convection, and heat radiation. The heat insulation effect is significantly better than that of traditional single-layer or simple composite structures. The heat-insulating non-woven fabric layer 5 protects the Mylar tape 4 from high-temperature damage, while also strengthening the overall wrapping tension, further improving structural stability and convection blocking effect. The outer protective layer 6 provides overall mechanical protection, weather resistance protection, and insulation protection, enabling the heat tracing pipe to adapt to complex working conditions such as outdoor environments, high temperatures, low temperatures, and ultraviolet radiation. The overall structure is stable, has a long service life, and is applicable to a wide range of scenarios.

[0032] Zirconium ceramic coating is an inorganic, high-temperature resistant, and corrosion-resistant coating formed on the surface of stainless steel pipe 1 using processes such as plasma spraying. It has a dense structure and exhibits extremely strong resistance to high temperatures, salt spray, and chloride ion corrosion, effectively isolating the stainless steel pipe 1 from seawater, salt spray, and acid / alkali media. Hydrophobic nonwoven fabric is a nonwoven material that has undergone hydrophobic treatment and possesses high water-repellent properties. It has a high water repellency rate and low chloride ion permeability, effectively blocking the intrusion of moisture, salt spray, and corrosive ions, forming a flexible anti-corrosion protection for the stainless steel pipe 1.

[0033] In some specific embodiments, when the anti-corrosion layer 2 is a zirconium ceramic coating, the thickness of the anti-corrosion layer 2 is 0.1mm~0.3mm, and the adhesion of the zirconium ceramic coating is greater than or equal to 5MPa, which can ensure that the coating is dense and uniform, not easy to fall off, and effectively block chloride ion penetration for a long time, thus avoiding pitting corrosion and stress corrosion cracking of the stainless steel pipe body 1.

[0034] The second anti-corrosion layer is made of hydrophobic nonwoven fabric with a water repellency of ≥95% and a chloride ion permeability of ≤0.01mg / (m²·d). This significantly reduces the intrusion of water vapor and chloride ions, achieving efficient moisture-proof, seepage-proof, and corrosion-proof properties. This allows the heat tracing pipe to be used stably for a long time in harsh conditions such as ships, islands, and seaside areas, significantly improving the product's durability and safety. It can also prevent the heat tracing pipe from showing significant corrosion for more than 5 years in high salt spray environments.

[0035] This embodiment of the invention limits the parameters of the zirconium ceramic coating thickness and adhesion, and the hydrophobicity and chloride ion permeability of the hydrophobic nonwoven fabric, enabling the anti-corrosion layer 2 to maintain a stable protective effect in high salt spray and high chloride ion corrosion environments. The zirconium ceramic coating has a moderate thickness and strong adhesion, making it resistant to peeling and flaking, and can effectively block chloride ion penetration for a long time, preventing corrosion and cracking of the stainless steel pipe 1. The hydrophobic nonwoven fabric has excellent hydrophobic properties and extremely low chloride ion permeability, effectively blocking the intrusion of moisture and corrosive ions, significantly improving the corrosion resistance and service life of the heat tracing pipe under harsh conditions such as ships, offshore platforms, seasides, and islands, ensuring the long-term safe and stable operation of the pipeline.

[0036] In some specific embodiments, the thickness of the insulation layer 3 is 12mm~40mm; when the insulation layer 3 is an integrated glass fiber aerogel felt (glass fiber needled blanket), the thermal conductivity of the integrated glass fiber aerogel felt (glass fiber needled blanket) is 0.031W / (m·K); when the insulation layer 3 is pure aerogel, the thermal conductivity of pure aerogel is 0.025W / (m·K). This embodiment, by limiting the thickness of the insulation layer 3 to 12mm~40mm and using an integrated glass fiber aerogel felt (glass fiber needled blanket) or pure aerogel with low thermal conductivity, achieves efficient and stable heat conduction blocking effect while ensuring a compact structure. Both the integrated glass fiber aerogel felt (glass fiber needled blanket) and pure aerogel have extremely low thermal conductivity, which can significantly reduce the heat loss from the tube 1 to the outside, significantly improve the insulation efficiency of the heat tracing pipe, reduce heat tracing energy consumption, and ensure that the medium temperature is stably maintained within the process requirements range.

[0037] In this embodiment, the pure aerogel uses nano-silica as its main component and has a three-dimensional nano-network structure with high porosity, achieving a highly efficient and stable heat conduction blocking effect. The glass fiber aerogel felt uses glass fiber cotton / felt as the substrate, and aerogel is loaded and composited inside the glass fiber to form a flexible thermal insulation felt. It combines the low thermal conductivity of aerogel with the high strength and flexibility of glass fiber, making it easy to wrap around the outside of the tube 1, and suitable as the core thermal insulation layer 3 of the heat tracing pipe.

[0038] In some specific embodiments, the aerogel content in the glass fiber aerogel felt is greater than or equal to 60%, so that the heat conduction blocking efficiency of the insulation layer 3 is greater than or equal to 90%, and the outer surface temperature of the insulation layer 3 is less than or equal to 50°C. This embodiment, by controlling the aerogel content to above 60%, fully utilizes the ultra-low thermal conductivity of aerogel, significantly improving the heat conduction blocking efficiency of the insulation layer 3, effectively suppressing heat transfer outwards. Even under high-temperature heat tracing conditions, the outer surface temperature of the cable can still be controlled below 50°C, avoiding the risk of burns to personnel and further reducing overall heat loss, ensuring the efficient, energy-saving, and safe operation of the heat tracing system.

[0039] Mylar tape 4 has a double-layer composite film structure. It uses polyethylene (PE) film, polypropylene (PP) film, and polyester (PET) film as the base film. Through vacuum aluminizing or composite processes, a metal aluminum layer is deposited / bonded to one side of the base film to form an integrated composite tape of aluminum layer and polymer film.

[0040] In some specific embodiments, the wrapping tension of the Mylar tape 4 is 5N~10N, and the wrapping overlap rate is greater than or equal to 50%. The tension compression of the Mylar tape 4 ensures that the internal air volume ratio of the insulation layer 3 is less than or equal to 10%. This embodiment, by controlling the wrapping tension and overlap rate of the Mylar tape 4 within the above range, forms a uniform and stable compression constraint on the insulation layer 3, effectively expelling excess air from inside the insulation layer 3 and reducing the air volume ratio to below 10%, significantly suppressing heat convection loss caused by airflow and gap heat exchange. Simultaneously, reasonable wrapping tension and overlap rate ensure that the Mylar tape 4 is tightly fitted, without loosening or wrinkling, making the heat radiation reflection effect more stable, further improving the overall thermal insulation performance, and ensuring that the heat tracing pipe maintains a highly efficient and stable heat insulation effect during long-term use.

[0041] In this embodiment, aluminum foil Mylar tape 4 can be selected. Aluminum foil Mylar tape 4 is a two-layer aluminum-plastic composite tape made of high-purity aluminum foil and polyester film (PET) through a precision composite process.

[0042] In this embodiment, the tension compression of the Mylar tape 4 ensures that the internal air volume ratio of the insulation layer 3 is less than or equal to 10%, reducing the heat convection loss of the heat tracing pipe to below 30% of that in traditional structures. In some specific embodiments, the aluminum coating thickness of the Mylar tape 4 is greater than or equal to 0.01 mm, and the thermal radiation reflectivity is greater than or equal to 85%. By limiting the aluminum coating thickness and thermal radiation reflectivity, this embodiment ensures that the Mylar tape 4 has a highly efficient and stable ability to reflect heat from inside the pipe, reflecting a large amount of outwardly transmitted radiant heat back into the pipe body 1, significantly reducing energy loss caused by thermal radiation, further improving the overall thermal insulation efficiency of the heat tracing pipe, and ensuring the energy-saving and stable operation of the heat tracing system.

[0043] The heat-insulating nonwoven fabric layer 5 has a three-dimensional fiber mesh porous structure. It is made of high-temperature resistant and flame-retardant fibers, needle-punched or hot-pressed, with the fibers interlaced to form a continuous and uniform sheet-like layer. Rich in micropores, it possesses excellent flexibility, coverage, and cushioning properties, allowing it to tightly adhere to the outside of the Mylar tape 4, providing protection, heat insulation, auxiliary compression, and enhanced structural stability. The heat-insulating nonwoven fabric layer 5 protects the Mylar tape 4 from burns and damage caused by the high-temperature extruded material from the outer layer; further compresses the internal air, enhancing the blocking of heat convection; and improves the overall wrapping tightness, making the multi-layer structure more stable.

[0044] In some specific embodiments, the outer protective layer 6 is formed of modified polyvinyl chloride (PVC), with an oxygen index of less than or equal to 30%, an operating temperature range of -40℃ to 105℃, and an elongation at break of greater than or equal to 200%. This embodiment, by limiting the oxygen index, operating temperature, and elongation at break of the modified PVC, enables the outer protective layer 6 to possess excellent flame retardancy, wide temperature range adaptability, and good mechanical flexibility. This meets the fire safety requirements of outdoor and industrial scenarios, prevents brittleness at low temperatures and softening at high temperatures, and also possesses strong tensile and deformation resistance, effectively improving the overall structural stability, environmental tolerance, and service life of the heat tracing pipe.

[0045] In this embodiment, the modified polyvinyl chloride (PVC) must withstand 720 hours of ultraviolet (UV) exposure and have a service life of 15 years or more. Compared to using ordinary PVC instead of the modified PVC in this embodiment, the insulation effect of the heat tracing pipe decreases by 50% after step 3.

[0046] Modified polyvinyl chloride (PVC) is a granular material made from high-quality PVC resin as the main raw material, with the addition of special plasticizers, environmentally friendly stabilizers, and processing additives, through a special process of mixing, plasticizing, and granulation. It can be a 105℃ cold-resistant and UV-resistant protective layer grade PVC plastic.

[0047] In this embodiment, the modified polyvinyl chloride (PVC) is a polymer composite material obtained by blending and modifying PVC resin with various functional additives. These functional additives can include heat stabilizers, toughening / impact modifiers, UV-resistant additives, plasticizers, lubricants, and flame retardants / fillers, etc.

[0048] Heat stabilizers can be calcium-zinc stabilizers, organotin stabilizers, or hydrotalcite stabilizers, used to inhibit thermal degradation during processing and use and improve heat resistance. Toughening agents / impact modifiers can be acrylates (ACR), MBS, or polyurethane elastomers, improving low-temperature toughness and elongation at break, and preventing brittleness. UV-resistant additives can be a combination of UV absorbers (UV-531, UV-327, etc.) and hindered amine light stabilizers (HALS), achieving resistance to 720 hours of UV exposure and delaying aging. Plasticizers can be environmentally friendly plasticizers, improving flexibility and processing flowability. Lubricants can be stearic acid, polyethylene wax, etc., improving extrusion processing performance and ensuring a smooth surface. Flame retardants / fillers can be nano-calcium carbonate, magnesium hydroxide, etc., improving flame retardancy, dimensional stability, and mechanical properties.

[0049] Through the above-mentioned multi-component synergistic modification, the material possesses excellent UV aging resistance, wide temperature range usability, good flexibility, and flame retardant insulation properties. It can withstand long-term outdoor exposure without powdering or cracking, remains stable within the range of -40℃ to 105℃, and has a service life of more than 15 years. It can provide reliable external mechanical protection, weather protection, and insulation protection for heat tracing pipes, significantly improving the overall service life and environmental adaptability of the product.

[0050] In some specific implementations, the heat tracing pipe is a single, continuously wound cable with a total length of not less than 200 meters and a wall thickness error of ≤3%. The single-strand continuous winding process significantly reduces the number of joints and leakage risks during use, improving the sealing and operational safety of the pipeline system. A total length of not less than 200 meters meets the needs of long-distance transportation and laying, reducing on-site installation joints and construction costs. Strictly controlling the wall thickness error to ≤3% ensures uniform wall thickness, stable mechanical properties, and consistent pressure resistance, effectively improving product processing accuracy and reliability, and meeting the stringent requirements of high-end industrial scenarios such as petrochemicals, energy, and marine engineering.

[0051] It should be noted that the heat tracing pipe provided in the embodiments of this disclosure may also be called a heat tracing conduit, a centralized heat tracing pipe bundle, a prefabricated insulated pipe, a preheating partition, or a prefabricated heat tracing pipe, etc. The product structures referred to by heat tracing conduit, centralized heat tracing pipe bundle, prefabricated insulated pipe, preheating partition, and prefabricated heat tracing pipe are all within the protection scope of this disclosure.

[0052] This disclosure provides a method for processing a heat tracing pipe according to this disclosure, including the following steps: The pipe body 1 is pretreated by bright annealing heat treatment at 1050℃~1100℃ and held for 20~30 minutes to eliminate the processing stress of the pipe body 1, soften the material, improve plasticity and structural stability, and ensure that the pipe body 1 is not easily deformed or cracked during bending and laying and long-term use.

[0053] The pretreatment of pipe body 1 serves to: eliminate cold working stress, reduce work hardening, reshape a uniform austenitic structure, and improve the plasticity and toughness of the pipe, ensuring that the heat tracing pipe is not easily deformed or cracked during bending and long-term use, and that the wall thickness is uniform and stable.

[0054] At 1050–1100℃, within the complete austenitizing temperature range of stainless steel, carbides can be fully dissolved and processing texture eliminated. Holding at this temperature for 20–30 minutes ensures uniform temperature inside and outside the pipe wall, completely eliminating work hardening and preventing residual stress from causing later cracking. Bright annealing: Performed under a protective atmosphere, resulting in no surface oxidation or decarburization, ensuring stronger adhesion of subsequent anti-corrosion coatings / non-woven fabrics. Reshaping the austenitic structure: This refines and homogenizes the grains, improving toughness, fatigue resistance, and corrosion resistance, making it particularly suitable for high-salt-spray marine environments.

[0055] When the anti-corrosion layer 2 is a zirconium ceramic coating, a plasma spraying process is used to form the anti-corrosion layer 2; when the anti-corrosion layer 2 is a hydrophobic nonwoven fabric, a spiral wrapping process is used to form the anti-corrosion layer 2; this makes the anti-corrosion layer 2 uniform, dense, and firmly bonded, ensuring the chloride ion blocking effect in a high salt spray environment.

[0056] The insulation layer 3 is formed by unidirectional cotton covering or bidirectional spiral winding, with a winding angle of 25°~50°. This ensures that the insulation layer 3 is centered without deviation, has uniform thickness, and is tightly covered, thereby improving the consistency of heat conduction blocking. The Mylar tape 4 is wound synchronously at a winding speed of 7m / min to 10m / min, and the winding tension is gradually increased to 5N to 10N, so that the Mylar tape 4 is tightly attached without wrinkles or looseness, and the air inside the insulation layer 3 is stably compressed to significantly suppress heat convection.

[0057] The outer protective layer 6 is formed by hot melt extrusion process using an extruder at an extrusion temperature of 160~180℃. This makes the outer protective layer surface smooth, free from bulging and cracking, and tightly bonded to the inner structure, improving the overall mechanical strength, sealing performance and weather resistance, and enabling the heat tracing pipe to be efficient, stable and suitable for continuous industrial production.

[0058] This embodiment utilizes a bright annealing process for precise heat treatment of the pipe body 1, effectively eliminating processing stress, softening the pipe material, and improving plasticity and toughness. This ensures uniform and stable mechanical properties of the pipe body 1, making it less prone to cracking, easier to bend and lay, and preventing deformation over long-term use. Plasma spraying and spiral wrapping are used to adapt to two different anti-corrosion layers 2, resulting in uniform, dense, and firmly bonded coatings / coverings with stable and reliable anti-corrosion effects. The insulation layer 3 employs bidirectional spiral winding, ensuring it is centered, without offset or gaps, with uniform thickness and stronger insulation consistency. Mylar tape 4 is wrapped synchronously with the insulation layer 3, with increasing tension, ensuring smooth, wrinkle-free, and secure winding while stably compressing the air in the insulation layer 3, maximizing the suppression of heat convection. The outer protective layer 6 is produced by precise temperature-controlled extrusion, resulting in a smooth, bulging-free, and crack-free surface that fits tightly with the internal structure. This enhances the overall mechanical strength, weather resistance, and sealing performance, ultimately ensuring stable overall performance, high product consistency, and suitability for continuous industrial production.

[0059] The heat tracing pipeline system provided in this disclosure includes the heat tracing pipe provided in this disclosure. Since the heat tracing pipeline system provided in this disclosure has the same advantages as the heat tracing pipe provided in this disclosure, further details will not be provided here.

[0060] Example 1 The heat tracing pipe was prepared using the following parameters: Pipe body 1 was made of seamless 316L stainless steel coil, bright annealed at 1080℃ and held for 25 minutes; anti-corrosion layer 2 was made of zirconium ceramic coating, with a thickness of 0.2mm and an adhesion of 6.2MPa; the insulation layer was an integrated glass fiber aerogel felt (glass fiber needled blanket), with an aerogel addition ratio of 65% and a thickness of 32mm; the Mylar tape was made of aluminum-plated PET film, with a tension of 8N, an overlap rate of 55%, and an aluminum layer thickness of 0.015mm; the outer protective layer was modified PVC, with an oxygen index of 28% and an elongation at break of 220%.

[0061] The test results are shown in the table below:

[0062] Comparative Example

[0063] The above data are all derived from the screening results of 200 sets of orthogonal experiments. The experiments demonstrate that there is a strong coupling relationship between the structure and parameters of each layer in this disclosure. Any deviation of any parameter from the specified range will cause the heat tracing pipe to fail to meet the stringent industrial requirements of "wide temperature range of -40℃ to 105℃, service life of ≥15 years, and heat loss ≤5%". This closed-loop synergy of "pretreatment-structure-process-performance" is the core innovation of this disclosure, distinguishing it from the simple superposition of traditional technologies.

[0064] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this embodiment can be achieved, and this is not limited herein.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0066] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A heat tracing pipe, characterized in that, From the inside out, it includes: Pipe body (1), wherein the pipe body (1) is a stainless steel seamless coil or a stainless steel welded coil; The anti-corrosion layer (2) is provided on the outer surface of the pipe body (1). The anti-corrosion layer (2) is a zirconium ceramic coating or a hydrophobic non-woven fabric, used to block chloride ion corrosion. The insulation layer (3) is wrapped around the outer surface of the anti-corrosion layer (2), and the insulation layer (3) is an integrated glass fiber aerogel felt or pure aerogel; Mylar tape (4) is wrapped around the outer surface of the insulation layer (3). The Mylar tape (4) is made of aluminum plated on polyethylene film, polypropylene film or polyester film. It is used to reflect heat radiation and to suppress heat convection by compressing the air inside the insulation layer (3) by wrapping tension. The Mylar tape (4) is wrapped around the insulation layer (3) with a tension of 5N~10N. The overlap rate of the Mylar tape (4) is greater than or equal to 50%. The Mylar tape (4) compresses the insulation layer (3) so that the air content inside the insulation layer (3) is less than or equal to 10%. A heat-insulating nonwoven fabric layer (5) is wrapped around the outer surface of the Mylar tape (4); An outer protective layer (6) is wrapped around the outer surface of the heat-insulating nonwoven fabric layer (5).

2. The heat tracing pipe according to claim 1, characterized in that, When the anti-corrosion layer (2) is a zirconium ceramic coating, the thickness of the anti-corrosion layer (2) is 0.1mm~0.3mm, and the adhesion of the zirconium ceramic coating is greater than or equal to 5MPa; The anti-corrosion layer (2) is a hydrophobic nonwoven fabric with a water repellency of greater than or equal to 95% and a chloride ion permeability of less than or equal to 0.01 mg / (m²·d).

3. The heat tracing pipe according to claim 1, characterized in that, The thickness of the insulation layer (3) is 12mm~40mm; When the insulation layer (3) is an integrated glass fiber aerogel felt, the thermal conductivity of the integrated glass fiber aerogel felt is 0.031 W / (m·K); When the insulation layer (3) is pure aerogel, the thermal conductivity of the pure aerogel is 0.025 W / (m·K).

4. The heat tracing pipe according to claim 3, characterized in that, The aerogel addition ratio in the glass fiber aerogel felt is greater than or equal to 60%, so that the heat conduction blocking efficiency of the insulation layer (3) is greater than or equal to 90%, and the outer surface temperature of the insulation layer (3) is less than or equal to 50°C.

5. The heat tracing pipe according to claim 1, characterized in that, The wrapping tension of the Mylar tape (4) is 5N~10N, and the wrapping overlap rate is greater than or equal to 50%. The tension of the Mylar tape (4) is used to compress the insulation layer (3) so that the internal air volume ratio is less than or equal to 10%.

6. The heat tracing pipe according to claim 5, characterized in that, The Mylar tape (4) has an aluminum coating thickness of ≥0.01 mm and a thermal radiation reflectivity of ≥85%.

7. The heat tracing pipe according to claim 1, characterized in that, The outer protective layer (6) is formed of modified polyvinyl chloride, wherein the oxygen index of the modified polyvinyl chloride is less than or equal to 30%, the operating temperature range is -40℃ to 105℃, and the elongation at break is greater than or equal to 200%.

8. The heat tracing pipe according to claim 1, characterized in that, The heat tracing pipe is a single continuous rolled cable with a total length of not less than 200 meters and a wall thickness error of ≤3%.

9. A method for processing a heat tracing pipe as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The tube body (1) is pretreated by bright annealing at 1050℃~1100℃ and held for 20~30 minutes. When the anti-corrosion layer (2) is a zirconium ceramic coating, the anti-corrosion layer (2) is formed by plasma spraying; when the anti-corrosion layer (2) is a hydrophobic nonwoven fabric, the anti-corrosion layer (2) is formed by spiral wrapping. The insulation layer (3) is formed by unidirectional cotton covering or bidirectional spiral winding process, with a winding angle of 25°~50°; The Mylar tape (4) is wound synchronously at a winding speed of 7m / min to 10m / min, and the winding tension is gradually increased to 5N to 10N; The outer protective layer (6) is formed by hot melt extrusion process using an extruder, with an extrusion temperature of 160℃~180℃.

10. A heat tracing pipeline system, characterized in that, Includes the heat tracing pipe according to any one of claims 1 to 8.

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