A method for preparing a polyurethane-lined steel pipe service life alarm sensor

Abstract

The application discloses a preparation method of a service life alarm sensor of a polyurethane-lined steel pipe, and comprises the following steps: preparing a polyurethane-based high-conductivity sensing element; preparing a polyurethane-based high-conductivity sensor; burying the polyurethane-based high-conductivity sensor; and using the polyurethane-based high-conductivity sensor. The application solves the problem of the lack of a low-cost alarm method for the service life of the polyurethane-lined steel pipe, provides a low-cost service life alarm method for the polyurethane-lined steel pipe, and provides technical support for the effective use of the polyurethane-lined steel pipe.

Description

Technical Field

[0001] This invention belongs to the field of new materials, and in particular, it relates to a method for preparing a service life alarm sensor for polyurethane-lined steel pipes. Background Technology

[0002] Polyurethane-lined steel pipes are manufactured by lining the inner surface of a steel pipe with a certain thickness of polyurethane material. They possess both the strength of metal pipes and excellent wear resistance and corrosion resistance. Polyurethane-lined steel pipes are ideal for fluid transportation and are widely used in tailings transportation, coal washing and preparation transportation, coal slurry transportation, and urban water supply and drainage. The service life of polyurethane-lined steel pipes varies depending on the operating environment. Currently, there is no effective method for low-cost online monitoring of this pipe's service life, i.e., the remaining thickness of the polyurethane lining. Users rely on experience to replace the pipes periodically, often resulting in untimely or premature replacement. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a service life alarm sensor for polyurethane-lined steel pipes, which solves the problem of the lack of low-cost alarm methods for the service life of polyurethane-lined steel pipes, provides a low-cost service life alarm method for polyurethane-lined steel pipes, and provides technical support for the effective use of polyurethane-lined steel pipes.

[0004] The objective of this invention is achieved through the following technical solution: A method for preparing a service life alarm sensor for polyurethane-lined steel pipes, comprising: A) Preheating polyurethane resin to 30-60℃; weighing polyurethane resin, and adding 30-60% by mass of a high-conductivity filler, wherein the high-conductivity filler is one or more of carbon nanotubes, nano-carbon black, graphene, nano-silver wires, and nano-silver spheres; heating to 75-95℃ and then stirring and dispersing thoroughly, followed by vacuum degassing at a vacuum pressure of 0.06-0.12 MPa for 30-90 minutes. n. Continue stirring until no air bubbles are generated in the material. Weigh 12.5% ​​of the curing agent of polyurethane resin, heat to 90-120℃, add polyurethane resin and stir for 30-60 seconds. Do not incorporate air bubbles during stirring to obtain a high conductivity powder-doped polyurethane resin system. Preheat the high conductivity sensor mold to 80-100℃ using a constant temperature oven. Arrange thin wires at the two pins of the high conductivity sensor in the mold. Pour the high conductivity powder-doped polyurethane resin system from this step into the high conductivity sensor mold. After holding at 80-100℃ for 30-60 minutes, demold to obtain the polyurethane-based high conductivity sensor.

[0005] B. Preparation of polyurethane-based high conductivity sensor: First, preheat the polyurethane resin to 30-60℃; weigh the polyurethane resin, heat it to 75-95℃, and then perform vacuum degassing at a vacuum pressure of 0.06-0.12MPa for 30-90 minutes until no bubbles are generated in the material; weigh 12.5% ​​(by mass) of the polyurethane resin curing agent, heat it to 90-120℃, add it to the polyurethane resin, and stir for 30-60 seconds, being careful not to incorporate air bubbles during stirring, to obtain the polyurethane resin system; preheat the polyurethane-based high conductivity sensor mold to 80-100℃ using a constant temperature oven, place one or more polyurethane-based high conductivity sensing elements in the mold, pour the polyurethane resin system from this step into the polyurethane-based high conductivity sensor mold, keep it at 80-100℃ for 30-60 minutes, and then demold to obtain the polyurethane-based high conductivity sensor.

[0006] C. Embedding of polyurethane-based high conductivity sensors: The inner wall of the steel pipe is derusted and degreased. Using the polyurethane resin system prepared in step B, four polyurethane-based high conductivity sensors are adhered to the steel pipe near the flange, with an angle of 90° between them. The wires of the polyurethane-based high conductivity sensors are also adhered to the pipe wall and led out from the flange. After adhesion, the pipe is kept at 80-100℃ for 30-60 minutes. Then, a polyurethane lining is processed on the inner wall of the steel pipe using a centrifugal method. After cross-linking at 110℃ for 8-12 hours and slow curing at room temperature for 3 days, the embedding of polyurethane-based high conductivity sensors is completed.

[0007] D. Use of polyurethane-based high conductivity sensors: A resistance measuring device is installed at the flange to monitor the sensor resistance in real time. When a polyurethane-based high conductivity sensing element wears and breaks, it indicates that the polyurethane liner has worn down to the preset thickness of the polyurethane-based high conductivity sensing element. At this time, the measured resistance value will have a large difference compared with the original resistance value, and an alarm will be triggered.

[0008] A further improvement of the present invention is that: the polyurethane-based high conductivity sensing element is shaped like an inverted U, an inverted V, or a semi-circle; the cross-section of the polyurethane-based high conductivity sensing element is circular with a diameter of 1.0-2.0 mm; the height of the polyurethane-based high conductivity sensing element is designed according to the warning requirements; and the ratio of the width to the height of the polyurethane-based high conductivity sensing element is 1.0-1.5:1.

[0009] A further improvement of the present invention is that the wires used in the polyurethane-based high conductivity sensing element are copper enameled wires with a diameter of 0.1-0.3 mm.

[0010] A further improvement of the present invention is that the high conductivity dopant used in the high conductivity powder-doped polyurethane resin system is a mixture of carbon nanotubes and nano-carbon black, with a mass ratio of 3:0.5-2; the length of the carbon nanotubes is 20-50 μm and the diameter is 20-50 nm; the diameter of the nano-carbon black is 50-200 nm.

[0011] A further improvement of the present invention is that the thickness of the polyurethane-based high conductivity sensor is 8-20 mm, and its width and height are 1.5-2.5 times the width and height of the largest polyurethane-based high conductivity sensing element in the sensor.

[0012] A further improvement of the present invention is that: the polyurethane-based high conductivity sensing element in the sensor can be a single element that triggers an alarm once when the inner lining of the polyurethane-lined steel pipe wears to a preset height; or it can be multiple elements that trigger multiple alarms when the inner lining of the polyurethane-lined steel pipe wears to different preset heights.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] This invention provides a method for preparing a lifespan alarm sensor for polyurethane-lined steel pipes, providing a low-cost lifespan alarm method for polyurethane-lined steel pipes.

[0015] This invention uses a polyurethane-based high conductivity sensing element, whose material is similar to the sensing element packaging material and polyurethane liner, thereby reducing the stress concentration effect between the sensing element, sensor and polyurethane liner.

[0016] Polyurethane-based high conductivity sensing elements and sensors are not subjected to thermal cross-linking at 110℃ and slow curing at room temperature during molding. When polyurethane-based high conductivity sensors are embedded, a good cross-linking interface can be formed between the sensing element, the sensor, and the polyurethane liner, which enhances the interface strength.

[0017] High aspect ratio carbon nanotubes can achieve long-range charge transport through oriented distribution in polyurethane resin systems. Spherical carbon black particles tend to accumulate near carbon nanotubes, reducing the contact resistance between carbon nanotubes. The two form a synergistic conductive network, thereby effectively reducing the percolation threshold of conductive composite materials and achieving high conductivity with a low doping ratio. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Elements and features described in one embodiment of the present invention can be combined with elements and features shown in one or more other embodiments. It should be noted that, for clarity, representations and descriptions of components and processes unrelated to the present invention and known to those skilled in the art are omitted in the description. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] A method for fabricating a service life alarm sensor for polyurethane-lined steel pipes:

[0020] A. Preparation of polyurethane-based high-conductivity sensing elements: First, preheat the polyurethane resin to 30-60℃; weigh the polyurethane resin, and add 30-60% by weight of a high-conductivity filler, which can be one or more of carbon nanotubes, carbon black nanoparticles, graphene, silver nanowires, and silver nanospheres; heat to 75-95℃ and stir thoroughly to disperse, then perform vacuum degassing at a vacuum pressure of 0.06-0.12MPa for 30-90 minutes until no bubbles are generated in the material; weigh 12.5% ​​by weight of a curing agent for the polyurethane resin, heat to 90-120℃, add to the polyurethane resin and stir for 30-60 seconds, being careful not to incorporate air bubbles during stirring, to obtain a high-conductivity powder-doped polyurethane resin system; preheat the high-conductivity sensing element mold to 80-100℃ using a constant temperature oven, and arrange thin wires at the two pins of the high-conductivity sensing element in the mold, thus incorporating the high-conductivity... A polyurethane-based high-conductivity sensing element is prepared by pouring a polyurethane powder-doped resin system into a mold, holding it at 80-100℃ for 30-60 minutes, and then demolding. The polyurethane-based high-conductivity sensing element can be in the shape of an inverted U, inverted V, or semi-circle. Its cross-section is circular with a diameter of 1.0-2.0 mm. The height is designed according to the warning requirements. The width-to-height ratio is 1.0-1.5:1. The wires used are copper enameled wires with a diameter of 0.1-0.3 mm. The high-conductivity dopant used in the polyurethane powder-doped resin system is a mixture of carbon nanotubes and nano-carbon black, with a mass ratio of 3:0.5-2. The carbon nanotubes have a length of 20-50 μm and a diameter of 20-50 nm. The nano-carbon black has a diameter of 50-200 nm.

[0021] B. Preparation of Polyurethane-Based High Conductivity Sensor: First, preheat the polyurethane resin to 30-60℃; weigh the polyurethane resin, heat it to 75-95℃, and then perform vacuum degassing at a vacuum pressure of 0.06-0.12MPa for 30-90 minutes until no bubbles are generated in the material; weigh 12.5% ​​(by weight) of the polyurethane resin curing agent, heat it to 90-120℃, add it to the polyurethane resin, and stir for 30-60 seconds, being careful not to incorporate air bubbles during stirring, to obtain the polyurethane resin system; preheat the polyurethane-based high conductivity sensor mold to 80-100℃ using a constant temperature oven, and place one or more polyurethane-based high conductivity sensing elements into the mold, thus completing the process described in step [missing information]. The polyurethane resin system is poured into a mold for a polyurethane-based high conductivity sensor, kept at 80-100℃ for 30-60 minutes, and then demolded to obtain the polyurethane-based high conductivity sensor. The thickness of the polyurethane-based high conductivity sensor is 8-20mm, and its width and height are 1.5-2.5 times the width and height of the largest polyurethane-based high conductivity sensing element in the sensor. The sensor can have one polyurethane-based high conductivity sensing element, which will trigger an alarm when the inner lining of the polyurethane-lined steel pipe wears to a preset height; or it can have multiple elements, which will trigger multiple alarms when the inner lining of the polyurethane-lined steel pipe wears to different preset heights. The latter can more accurately grasp the wear status of the inner lining of the polyurethane-lined steel pipe.

[0022] C. Embedding of polyurethane-based high conductivity sensors: The inner wall of the steel pipe is derusted and degreased. Using the polyurethane resin system prepared in step B, four polyurethane-based high conductivity sensors are adhered to the steel pipe near the flange, with an angle of 90° between them. The wires of the polyurethane-based high conductivity sensors are also adhered to the pipe wall and led out from the flange. After adhesion, the pipe is kept at 80-100℃ for 30-60 minutes. Then, a polyurethane lining is processed on the inner wall of the steel pipe using a centrifugal method. After cross-linking at 110℃ for 8-12 hours and slow curing at room temperature for 3 days, the embedding of polyurethane-based high conductivity sensors is completed.

[0023] D. Use of polyurethane-based high conductivity sensors: A resistance measuring device is installed at the flange to monitor the sensor resistance in real time. When a polyurethane-based high conductivity sensing element wears and breaks, it indicates that the polyurethane liner has worn down to the preset thickness of the polyurethane-based high conductivity sensing element. At this time, the measured resistance value will have a large difference compared with the original resistance value, and an alarm will be triggered.

[0024] This invention provides a method for fabricating a lifespan alarm sensor for polyurethane-lined steel pipes, offering a low-cost lifespan alarm method for polyurethane-lined steel pipes. The invention employs a polyurethane-based high-conductivity sensing element, the material of which is similar to the sensing element encapsulation material and the polyurethane liner, reducing stress concentration effects between the sensing element, sensor, and polyurethane liner. During molding, the polyurethane-based high-conductivity sensing element and sensor do not undergo 110°C thermal cross-linking and slow curing at room temperature. This allows for the formation of a good cross-linking interface between the sensing element, sensor, and polyurethane liner during the embedding of the polyurethane-based high-conductivity sensor, enhancing interface strength. High aspect ratio carbon nanotubes in the polyurethane resin system can achieve long-range charge transport through oriented distribution. Spherical carbon black particles tend to accumulate near the carbon nanotubes, reducing the contact resistance between carbon nanotubes. These two elements form a synergistic conductive network, effectively reducing the percolation threshold of the conductive composite material and achieving high conductivity with a relatively low doping ratio.

[0025] Finally, it should be noted that although the present invention and its advantages have been described in detail above, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the invention is not limited to the specific embodiments of the processes, apparatus, means, methods, and steps described in the specification. Those skilled in the art will readily understand from the disclosure of this invention that existing and future processes, apparatus, means, methods, or steps that perform substantially the same function or obtain substantially the same results as the corresponding embodiments described herein can be used according to the present invention. Therefore, the appended claims are intended to include such processes, apparatus, means, methods, or steps within their scope.

Claims

1. A method for preparing a service life alarm sensor for polyurethane-lined steel pipes, characterized in that: Includes the following steps: A. Preparation of polyurethane-based high-conductivity sensing elements: First, preheat the polyurethane resin to 30-60℃; weigh the polyurethane resin, and add 30-60% by weight of a high-conductivity filler, which can be one or more of carbon nanotubes, carbon black nanoparticles, graphene, silver nanowires, and silver nanospheres; heat to 75-95℃ and stir thoroughly to disperse, then perform vacuum degassing at a vacuum pressure of 0.06-0.12 MPa for 30-90 minutes until no bubbles are generated in the material; weigh out 12.5% ​​by weight of... The curing agent of polyurethane resin is heated to 90-120℃, and after adding polyurethane resin, it is stirred for 30s-60s. During stirring, air bubbles should not be incorporated to obtain a high conductivity powder-doped polyurethane resin system. The high conductivity sensing element mold is preheated to 80-100℃ using a constant temperature oven. Fine wires are arranged at the two pins of the high conductivity sensing element in the mold. The high conductivity powder-doped polyurethane resin system from this step is poured into the high conductivity sensing element mold. After holding at 80-100℃ for 30-60 minutes, it is demolded to obtain a polyurethane-based high conductivity sensing element. B. Preparation of polyurethane-based high conductivity sensor: First, preheat the polyurethane resin to 30-60℃; weigh the polyurethane resin, heat it to 75-95℃, and then perform vacuum degassing at a vacuum pressure of 0.06-0.12MPa for 30-90 minutes until no bubbles are generated in the material; weigh 12.5% ​​(by mass) of the polyurethane resin curing agent, heat it to 90-120℃, add it to the polyurethane resin, and stir for 30-60 seconds, being careful not to incorporate air bubbles during stirring, to obtain the polyurethane resin system; preheat the polyurethane-based high conductivity sensor mold to 80-100℃ using a constant temperature oven, place one or more polyurethane-based high conductivity sensing elements in the mold, pour the polyurethane resin system from this step into the polyurethane-based high conductivity sensor mold, keep it at 80-100℃ for 30-60 minutes, and then demold to obtain the polyurethane-based high conductivity sensor. C. Embedding of polyurethane-based high conductivity sensors: The inner wall of the steel pipe is derusted and degreased. Using the polyurethane resin system prepared in step B, four polyurethane-based high conductivity sensors are adhered to the steel pipe near the flange, with an angle of 90° between them. The wires of the polyurethane-based high conductivity sensors are also adhered to the pipe wall and led out from the flange. After adhesion, the pipe is kept at 80-100℃ for 30-60 minutes. Then, a polyurethane lining is processed on the inner wall of the steel pipe using a centrifugal method. After cross-linking at 110℃ for 8-12 hours and slow curing at room temperature for 3 days, the embedding of polyurethane-based high conductivity sensors is completed. D. Use of polyurethane-based high conductivity sensors: A resistance measuring device is installed at the flange to monitor the sensor resistance in real time. When a polyurethane-based high conductivity sensing element wears and breaks, it indicates that the polyurethane liner has worn down to the preset thickness of the polyurethane-based high conductivity sensing element. At this time, the measured resistance value will have a large difference compared with the original resistance value, and an alarm will be triggered.

2. The method for preparing a service life alarm sensor for a polyurethane-lined steel pipe according to claim 1, characterized in that: The polyurethane-based high conductivity sensing element is shaped like an inverted U, an inverted V, or a semi-circle; the cross-section of the polyurethane-based high conductivity sensing element is circular with a diameter of 1.0-2.0 mm; the height of the polyurethane-based high conductivity sensing element is designed according to the warning requirements; the width-to-height ratio of the polyurethane-based high conductivity sensing element is 1.0-1.5:

1.

3. The method for preparing a service life alarm sensor for a polyurethane-lined steel pipe according to claim 1, characterized in that: The conductors used in the polyurethane-based high conductivity sensing element are copper enameled wires with a diameter of 0.1-0.3 mm.

4. The method for preparing a service life alarm sensor for a polyurethane-lined steel pipe according to claim 1, characterized in that: The highly conductive powder-doped polyurethane resin system uses a mixture of carbon nanotubes and carbon black nanoparticles in a mass ratio of 3:0.5-2. The carbon nanotubes have a length of 20-50 μm and a diameter of 20-50 nm, while the carbon black nanoparticles have a diameter of 50-200 nm.

5. The method for preparing a service life alarm sensor for a polyurethane-lined steel pipe according to claim 1, characterized in that: The polyurethane-based high conductivity sensor has a thickness of 8-20 mm, and its width and height are 1.5-2.5 times the width and height of the largest polyurethane-based high conductivity sensing element in the sensor.

6. The method for preparing a service life alarm sensor for a polyurethane-lined steel pipe according to claim 1, characterized in that: The sensor may contain a single polyurethane-based high-conductivity sensing element that triggers an alarm when the lining of the polyurethane-lined steel pipe wears to a preset height; or it may contain multiple elements that trigger multiple alarms when the lining of the polyurethane-lined steel pipe wears to different preset heights.