Preparation method of service life early warning device of polyurethane lining steel pipe

Abstract

The invention discloses a preparation method of a service life early warning device of a polyurethane lining steel pipe, solves the problem of low sensitivity of a polyurethane-based conductive sensing element, and solves the problem of poor fatigue resistance of the sensing element by utilizing the structure of the sensing element. According to the preparation, embedding and using method of the service life early warning device for the high-sensitivity fatigue-resistant polyurethane lining steel pipe, the metal wire is directly used as a sensing element, a conductive polymer does not need to be prepared, and the cost is reduced; meanwhile, the resistivity of the metal wires is low, so that the problems of weak conductivity and poor sensing sensitivity when a polymer-based conductive material acts on a sensing conductive element are solved; and a low-cost service life alarm method is provided for the polyurethane lining steel pipe. The metal wire spiral structure is adopted as a sensing element, the spiral shape enables the sensor to adapt to the repeated impact effect of the polyurethane inner wall under fluid, the risk of fatigue fracture is greatly reduced, and the monitoring reliability degree is improved.

Description

Technical Field

[0001] The invention belongs to the field of new materials, and in particular relates to a method for preparing a service life warning device for a highly sensitive fatigue-resistant polyurethane lined steel pipe. Background Art

[0002] Polyurethane lined steel pipes are widely used in tailings transportation, coal washing and coal selection transportation, coal slurry transportation, urban water supply and drainage, etc. With the extension of service time, the polyurethane lining layer gradually wears out. At present, the wear degree of the lining layer is difficult to monitor outside the pipe, resulting in untimely replacement and leakage.

[0003] In response to the above problems, CN202311562941 discloses a method for preparing a service life alarm sensor for a polyurethane lined steel pipe, in which a polyurethane-based high-conductivity sensor is made and buried in the lining layer. When the lining layer is worn to a certain height, the conductive part of the sensor is worn and broken, the loop resistance changes, and an alarm signal is triggered. However, during use, due to the high resistance value of the polyurethane-based conductive sensor element, when the content of conductive substances (such as ions, etc.) in the conveying medium is high, the sensing sensitivity is low. Using metal materials as sensing elements also needs to solve the problem of low fatigue resistance. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a service life warning device for a polyurethane lined steel pipe, which solves the problem of low sensitivity of polyurethane-based conductive sensor elements and solves the problem of poor fatigue resistance of the sensor elements by utilizing the sensor element structure.

[0005] The purpose of the present invention is achieved through the following technical solutions: a preparation method of a service life warning device for a polyurethane lined steel pipe: A. Preparation of conductive sensor: a. Preheat the polyurethane resin to 60-70℃, then heat the curing agent to 120-130℃, then add the polyurethane resin and stir at 200-400 rpm for 60-90s. Do not add bubbles during stirring to make a mixed resin; the mass contents of the polyurethane resin and the curing agent are 90-95% and 5-10% respectively; b. First, use a constant temperature box to heat the conductive sensor element mold to 100-120°C, and wind an insulating enameled wire into two spiral wires with opposite spiral directions; c. The spiral wire is buried in the inductor component mold, and mixed resin is added. After being kept at 80-100°C for 60-90 minutes, the conductive sensor is then demoulded to obtain the conductive sensor. B. Conductive sensor embedment: a. Remove rust and oil from the inner wall of the steel pipe, adhere the conductive sensor wires to the pipe wall at the same time, and evenly distribute the conductive sensors in the circumferential direction of the inner wall of the steel pipe; b. All foot lines are led out from the flange; c. After adhesion, keep warm at 100-120℃ for 60-90min; d. Then, the polyurethane lining is processed on the inner wall of the steel pipe by centrifugal method. After heat preservation and cross-linking at 120°C for 12-14 hours and slow curing at room temperature for 80-100 hours, the conductive sensor can be buried; C. Use of conductive sensors: Install a multi-channel disconnection alarm device at the flange to monitor the location of each conductive sensor in real time. When the wire part of the conductive sensor breaks due to wear, it means that the polyurethane lining at a certain point has been worn to the preset thickness of the sensor. At this time, the multi-channel disconnection alarm device will sound an alarm on the corresponding line to provide periodic reminders of the wear of the inner wall.

[0006] A further improvement of the present invention is that the diameter of the metal wire in the enameled wire is 0.05-0.5 mm, and the material is one of iron, steel, copper, silver, nickel, aluminum, and tungsten.

[0007] A further improvement of the present invention is that the pitch of the spiral wire is 0.5-1.5mm, the diameter is 2-5mm, the height is the warning height actually required, the two spiral wires are left-handed and right-handed respectively, the upper ends are connected to each other, and two leg wires are led out from the lower end to form a loop.

[0008] A further improvement of the present invention is that in step B, the number of the conductive sensors is X, X is 4, 8 or 16, the conductive sensors are evenly distributed in the circumferential direction, and the interval angle is 360 / X°; in the length direction, every 4 conductive sensors form a group, and each group is distributed at an interval of 100-200 mm.

[0009] Compared with the prior art, the present invention has the following advantages: 1. The present invention provides a method for preparing, embedding and using a service life warning device for a highly sensitive and fatigue-resistant polyurethane lined steel pipe. Metal wire is directly used as a sensing element, and there is no need to prepare a conductive polymer, thereby reducing costs. At the same time, the metal wire has a low resistivity, which solves the problem of weak conductivity and poor sensing sensitivity when polymer-based conductive materials act as sensing conductive elements. A low-cost life alarm method is provided for polyurethane lined steel pipes.

[0010] 2. The present invention adopts a metal wire spiral structure as a sensing element. The spiral shape enables the sensor to adapt to the repeated impact of the fluid on the inner wall of the polyurethane, greatly reducing the risk of fatigue fracture and improving the reliability of monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structure of a spiral line. DETAILED DESCRIPTION

[0012] In order to make the purpose, 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 part of the embodiments of the present invention, rather than all of the embodiments. The elements and features described in one embodiment of the present invention may be combined with the elements and features shown in one or more other embodiments. It should be noted that for the purpose of clarity, the representation and description of components and processes that are not related to the present invention and are known to those of ordinary skill in the art are omitted in the description. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0013] A preparation method for a service life warning device for a polyurethane lined steel pipe: A. Preparation of conductive sensor: preheat the polyurethane resin to 60-70℃, heat the curing agent to 120-130℃, add the polyurethane resin and stir at 200-400 rpm for 60-90s. Do not wrap bubbles during stirring to make a mixed resin; the mass content of polyurethane resin and curing agent are 90-95% and 5-10% respectively; first use a constant temperature box to heat the conductive sensor element mold to 100-120℃, wind an insulating enameled wire into two spiral wires with opposite spiral directions; bury the spiral wire in the inductor element mold, add the mixed resin, keep it at 80-100℃ for 60-90min and then demold it to make a conductive sensor;. The diameter of the metal wire in the enameled wire is 0.05-0.5mm, and the material is one of iron, steel, copper, silver, nickel, aluminum, and tungsten; the pitch of the spiral wire is 0.5-1.5mm, the diameter is 2-5mm, and the height is the warning height required by actual needs. The two spiral wires are left-handed and right-handed respectively, the upper ends are connected to each other, and two leg wires are led out from the lower end to form a loop, such as Figure 1 shown.

[0014] B. Embedding of conductive sensors: Remove rust and oil from the inner wall of the steel pipe, and adhere the conductive sensor wires to the pipe wall at the same time, with a quantity of X (4, 8, 16). The sensors are evenly distributed in the circumferential direction, with an interval angle of 360 / X°; in the length direction, each group of 4 sensors is distributed with an interval of 100-200mm, and all leg wires are led out from the flange; after adhesion, keep warm at 100-120℃ for 60-90min; then use the centrifugal method to process the polyurethane lining on the inner wall of the steel pipe, and after heat preservation and cross-linking at 120℃ for 12-14h, and slow curing at room temperature for 80-100 hours, the conductive sensor can be buried.

[0015] C. Use of conductive sensors: Install a multi-channel disconnection alarm device at the flange to monitor the location of each sensor in real time. When the wire part of the conductive sensor breaks due to wear, it means that the polyurethane lining at a certain point has been worn to the preset thickness of the sensor. At this time, the multi-channel disconnection alarm device will sound an alarm on the corresponding line to provide periodic reminders of the wear of the inner wall.

[0016] The invention solves the problem of low sensitivity of polyurethane-based conductive sensor elements, and simultaneously solves the problem of poor fatigue resistance of the sensor elements by utilizing the sensor element structure.

[0017] The present invention provides a method for preparing, embedding and using a service life warning device for a highly sensitive, fatigue-resistant polyurethane lined steel pipe. Metal wire is directly used as a sensing element, and there is no need to prepare a conductive polymer, thereby reducing costs. At the same time, the metal wire has a low resistivity, which solves the problem of weak conductivity and poor sensing sensitivity when polymer-based conductive materials act as sensing conductive elements. A low-cost service life alarm method is provided for polyurethane lined steel pipes.

[0018] The present invention adopts a metal wire spiral structure as a sensing element, and its spiral shape enables the sensor to adapt to the repeated impact of the fluid on the inner wall of the polyurethane, greatly reducing the risk of fatigue fracture and improving the reliability of monitoring.

[0019] 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 transformations can be made without exceeding the spirit and scope of the present invention as defined by the appended claims. Moreover, the scope of the present invention is not limited to the specific embodiments of the processes, devices, means, methods and steps described in the specification. It will be easily understood by those of ordinary skill in the art from the disclosure of the present invention that existing and future processes, devices, means, methods or steps that perform substantially the same functions as the corresponding embodiments described herein 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, devices, means, methods or steps within their scope.

Claims

1. A method for preparing a service life warning device for a polyurethane lined steel pipe, characterized in that: The steps include: A. Preparation of conductive sensor: a. Preheat the polyurethane resin to 60-70℃, then heat the curing agent to 120-130℃, then add the polyurethane resin and stir at 200-400 rpm for 60-90s. Do not add bubbles during stirring to make a mixed resin; the mass contents of the polyurethane resin and the curing agent are 90-95% and 5-10% respectively; b. First, use a constant temperature box to heat the conductive sensor element mold to 100-120°C, and wind an insulating enameled wire into two spiral wires with opposite spiral directions; c. The spiral wire is buried in the inductor component mold, and mixed resin is added. After being kept at 80-100°C for 60-90 minutes, the conductive sensor is demoulded to obtain the conductive sensor. B. Conductive sensor embedment: a. Remove rust and oil from the inner wall of the steel pipe, adhere the conductive sensor wires to the pipe wall at the same time, and evenly distribute the conductive sensors in the circumferential direction of the inner wall of the steel pipe; b. All foot lines are led out from the flange; c. After adhesion, keep warm at 100-120℃ for 60-90min; d. Then, the polyurethane lining is processed on the inner wall of the steel pipe by centrifugal method. After heat preservation and cross-linking at 120°C for 12-14 hours and slow curing at room temperature for 80-100 hours, the conductive sensor can be buried; C. Use of conductive sensors: Install a multi-channel disconnection alarm device at the flange to monitor the location of each conductive sensor in real time. When the wire part of the conductive sensor breaks due to wear, it means that the polyurethane lining at a certain point has been worn to the preset thickness of the sensor. At this time, the multi-channel disconnection alarm device will sound an alarm on the corresponding line to provide periodic reminders of the wear of the inner wall.

2. The method for preparing a service life warning device for a polyurethane lined steel pipe according to claim 1, characterized in that: The diameter of the metal wire in the enameled wire is 0.05-0.5 mm, and the material is one of iron, steel, copper, silver, nickel, aluminum, and tungsten.

3. The method for preparing a service life warning device for a polyurethane lined steel pipe according to claim 1, characterized in that: The pitch of the spiral wire is 0.5-1.5mm, the diameter is 2-5mm, and the height is the warning height actually required. The two spiral wires are left-handed and right-handed respectively, the upper ends are connected to each other, and two leg wires are led out from the lower end to form a loop.

4. The method for preparing a service life warning device for a polyurethane lined steel pipe according to claim 1, characterized in that: In step B, the number of the conductive sensors is X, where X is 4, 8 or 16. The conductive sensors are evenly distributed in the circumferential direction with an interval angle of 360 / X°; in the length direction, every 4 conductive sensors form a group, and each group is distributed with an interval of 100-200 mm.

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