Cable duct, method for installing a cable duct, and crane for a sulphur mine terminal

Abstract

The application provides a cable tube, a cable tube installation method and a crane of a sulfur mine wharf. The cable tube is applied to the crane of the sulfur mine wharf and is used for penetrating a cable. The cable tube comprises an outer wall and an inner wall connected with the outer wall. The outer wall is formed by extrusion of PVC resin. The inner wall is a foamed layer, and the cable is penetrated in the inner wall. The wall thickness of the cable tube is greater than or equal to a Schedule 40 standard. The cable tube can be applied to a high-acid-mist and high-corrosion environment.

Description

Technical Field

[0001] This invention relates to dock cranes, and more particularly to a cable conduit, a method for installing the cable conduit, and a crane for a sulfur mine dock. Background Technology

[0002] When cranes operate at docks handling highly corrosive materials like sulfur, their cables face multiple forms of corrosion, including high-intensity acidic corrosion from sulfur dust, marine salt spray corrosion, and humid moisture. Furthermore, the cables must move, be dragged, bent, and vibrate with the equipment, placing extremely high demands on the cable conduit's protective performance and structural stability.

[0003] Currently, the cable conduits commonly used on bulk cargo cranes at the dock are mainly made of conventional metal materials such as hot-dip galvanized steel, aluminum alloy, and 304 stainless steel.

[0004] However, due to the characteristics of the port environment, such as high salt spray, high corrosion, strong ultraviolet radiation, and large temperature differences, especially for loading, unloading and stacking / reclaiming equipment at bulk material terminals such as sulfur and lime, the cable pipes made of the above-mentioned metal materials will be severely corroded, resulting in a decrease in structural strength and a shortened service life, making it difficult to meet the needs of the actual use environment. Summary of the Invention

[0005] The purpose of this invention is to provide a cable conduit, a method for installing the cable conduit, and a crane for a sulfur mine wharf, which can meet the requirements of high acid mist and highly corrosive environments.

[0006] One aspect of the present invention provides a cable conduit used in cranes at sulfur mine wharves for laying cables; the cable conduit includes an outer wall and an inner wall connected to the outer wall; the outer wall is extruded from PVC resin; the inner wall is a foamed layer, and the cable is laid inside the inner wall; the wall thickness of the cable conduit is greater than or equal to the Schedule 40 standard.

[0007] In one embodiment, the outer wall has at least two different wall thickness specifications; and / or the inner wall has at least two different wall thickness specifications.

[0008] In one embodiment, the nominal diameter of the inner wall ranges from 1 / 2 inch to 8 inches.

[0009] In one embodiment, the cable conduit is formed in one step by an extrusion process.

[0010] In one embodiment, the cable conduit has a temperature resistance range of -40°C to 90°C; and / or the cable conduit has a flame retardant rating of UL94V-0.

[0011] In one embodiment, adjacent cable conduits are connected by a threaded coupling with a sealing ring, and a sealant is applied between the threads of the cable conduits and the threaded coupling.

[0012] In one embodiment, the sealing rating at the connection between the cable conduit and the threaded coupling is IP65.

[0013] Another aspect of the present invention provides a crane for a sulfur mine terminal, the crane being provided with a cable conduit; the cable conduit being the cable conduit as described in any of the above embodiments.

[0014] Another aspect of the present invention provides a method for installing a cable conduit, for installing the cable conduit described in any of the above embodiments onto a crane; the installation method includes: laying the cable conduit in sections along the path of the crane's electrical component support; fixing the cable conduit to the steel structure of the crane using supports; connecting adjacent cable conduits to form a continuous cable protection channel; threading a cable through the cable conduit; closing the segmented dust covers of the cable conduit; and sealing the joints with mounting sleeves.

[0015] In one embodiment, in the connection of adjacent cable conduits to form a continuous cable protection channel, the indoor cable conduits are connected by flexible hoses, and the outdoor cable conduits are connected by metal stuffing glands; and / or a rubber buffer pad is provided between the bracket and the cable conduit.

[0016] This invention, through extensive experimentation and selection comparison, utilizes a composite pipe wall structure combining a PVC resin outer wall and a foamed inner wall, with a Sch40 grade wall thickness as the structural benchmark, to achieve targeted adaptation to the harsh working conditions of sulfur mine dock cranes. The chemical inertness of PVC resin replaces the temporary anti-corrosion mechanism of the coating, eliminating the corrosion damage to the pipe body caused by the highly corrosive sulfur environment, thus extending the service life of the cable conduit. The foamed inner wall provides the pipe wall with elastic buffering function, reducing the risk of cable wear under dynamic dragging and vibration conditions, and protecting the integrity of the cable insulation layer. A wall thickness of Sch40 grade or higher ensures structural rigidity and resistance to external forces, maintaining the long-term structural stability of the cable conduit under high-frequency vibration and external impact loads.

[0017] This invention innovatively applies the cable conduit with the above structure to a crane in a dock environment with high acid mist and high corrosion for the first time. It demonstrates excellent performance under extreme sulfur corrosion environment and can operate stably for a long time in high acid mist and high corrosion environment. Attached Figure Description

[0018] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the installation of indoor cable conduits; Figure 2 This is a schematic diagram of outdoor cable conduit installation. Detailed Implementation

[0019] When cranes operate at docks handling highly corrosive materials like sulfur, their cables face multiple forms of corrosion, including high-intensity acidic corrosion from sulfur dust, marine salt spray corrosion, and humid moisture. Furthermore, the cables must move, be dragged, bent, and vibrate with the equipment, placing extremely high demands on the cable conduit's protective performance and structural stability.

[0020] Currently, most bulk cargo terminals use conventional materials for cable conduits, such as hot-dip galvanized steel, aluminum alloy, and 304 stainless steel. The cable conduits before the improvement had the following defects: 1. Severe corrosion of cable conduits can easily lead to surface cracking and material degradation, resulting in cable protection failure.

[0021] 2. During operation, the crane generates continuous movement and vibration, which can easily cause friction between the cable conduit and the cable. Conventional conduit materials have insufficient buffering performance, vibration resistance, and tensile strength, which accelerates the damage to the cable sheath and makes the joints prone to loosening due to vibration. The poor sealing of the connection can easily lead to the infiltration of sulfur dust, resulting in cable corrosion and wear. The cable cannot withstand the grinding of sulfur dust and the impact of high-frequency vibration.

[0022] 3. The space for laying pipes in the cantilever, slewing, and telescopic chute sections of cranes is limited, and the disassembly and assembly of traditional pipes are inconvenient, affecting maintenance efficiency.

[0023] 4. Galvanized steel pipes are also prone to creating a potential difference with the metal sheath of cables, leading to electrostatic interference faults.

[0024] 5. Conventional metal cable conduit materials are expensive and do not conform to the concept of cost reduction and efficiency improvement.

[0025] Therefore, conventional cable conduits cannot simultaneously adapt to and meet the multiple requirements of sulfur bulk cargo terminals for corrosion resistance, vibration resistance, dust prevention, and wear resistance, resulting in high cable failure rates, high maintenance costs, and impacting crane operation efficiency and safety.

[0026] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the invention and not to limit it. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the invention without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, the invention is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0027] The cable conduit of this invention is applied to cranes at sulfur mine wharves. Sulfur mine wharves refer to wharves where sulfur ore is loaded and unloaded, operating in a highly acidic and corrosive environment. The cable conduit of this invention can also be applied to wharves in other highly acidic and corrosive environments, such as wharves where lime or chemicals are loaded and unloaded.

[0028] Cranes include ship unloaders and ship loaders.

[0029] The term "ship unloader" refers to a specialized machine that uses continuous conveying machinery to lift bulk materials, or has self-retrieving capabilities, or is equipped with material handling and feeding devices, to continuously lift bulk materials out of the ship's hold, unload them onto the boom or frame, and transport them to the main conveyor system on the shore.

[0030] The term "ship loader" refers to a large bulk cargo handling machine used for loading cargo onto ships at a bulk cargo terminal.

[0031] The term "polyvinyl chloride (PVC)" refers to a thermoplastic polymer material prepared by addition polymerization of vinyl chloride monomer. It has excellent chemical inertness and electrical insulation properties and can be processed into pipes with specific cross-sectional shapes through extrusion molding.

[0032] The term "foamed layer" refers to a polymer layer that forms a uniform microporous structure inside by introducing a foaming agent or gas during the molding process. This structure has the functions of elastic cushioning, weight reduction, and reducing internal wall friction.

[0033] The term "Schedule 40" (which can be abbreviated as Sch40) is one of the pipe wall thickness grades specified in the American National Standards System. Its specific wall thickness value varies with the nominal diameter and represents the minimum wall thickness specification that meets the structural strength requirements under rated working pressure. It is widely used in the wall thickness classification of electrical conduits.

[0034] The term "threaded joint" refers to a short pipe connector with pipe threads at both ends, used to achieve axial butt joint and sealed connection between two adjacent cable pipe sections.

[0035] The term "installation sleeve" refers to a fastening sleeve fitting that is fitted over the outside of a cable conduit interface. By tightening it, radial pressure is applied, and a sealing ring or sealant is used to achieve mechanical fastening and dustproof sealing at the interface.

[0036] The International Protection Rating (IP) is a quantitative classification system based on the International Electrotechnical Commission (IEC) standards for the ability of equipment to prevent the ingress of solid particles and liquids. In IP65, 6 indicates complete protection against dust ingress, and 5 indicates protection against low-pressure water flow impact.

[0037] The cable conduit of this invention can be applied to cranes at sulfur mine wharves for cable installation. The cable conduit of this invention includes an outer wall and an inner wall connected to the outer wall. The outer wall is extruded from polyvinyl chloride (PVC) resin. PVC resin is a non-polar polymer material; its chemical inertness prevents it from reacting chemically with acidic media such as dilute sulfuric acid, sulfurous acid, and sulfur derivatives, and also prevents electrochemical reactions with marine chloride salt spray corrosion. This eliminates the potential failure hazards associated with the temporary anti-corrosion mechanism of metal pipes relying on coatings, and completely eliminates the risks of electrochemical corrosion and electrostatic interference. The extrusion molding process involves heating PVC resin and appropriate modifying agents to a molten state, then continuously extruding it through a forming die using a screw extruder to form a pipe with specified cross-sectional dimensions and wall thickness. After cooling and shaping, the pipe is cut to specifications. The resulting outer wall pipe has high dimensional accuracy and a smooth surface.

[0038] The inner wall is a foamed layer, through which the cable passes. The microporous structure of the foamed layer gives the inner wall elastic cushioning properties: on the one hand, under dynamic conditions such as crane start-up and shutdown vibrations and amplitude-changing impacts, the inner wall elastically wraps around the cable sheath, reducing the normal pressure and relative friction between the cable and the pipe wall, and inhibiting wear on the cable sheath; on the other hand, the microporous structure can give the pipe wall a certain energy absorption capacity, reducing the transmission of external vibration energy to the cable insulation layer. In addition, the relatively smooth inner wall surface of the foamed layer reduces the resistance to cable installation, facilitating construction.

[0039] The cable conduit of this invention has a wall thickness greater than or equal to the Sch40 standard. The wall thickness refers to the overall wall thickness (or total wall thickness) of the cable conduit, i.e., the total thickness from the outer wall to the inner wall as measured by calipers. The Sch40 wall thickness grade covers a series of standard wall thickness values ​​corresponding to nominal diameters from 1 / 2 inch to 8 inches. This grade serves as the lower limit to ensure that the cable conduit possesses sufficient compressive strength, bending stiffness, and structural integrity under mechanical loads such as vibrations from crane steel structures, impacts from external gravel, and lateral forces from cable dragging. This meets the requirements for rigid PVC cable conduit wall thickness in accordance with the UL651 standard issued by Underwriters Laboratories (UL) and the NEMA TC-2 standard issued by the National Electrical Manufacturers Association (NEMA).

[0040] The cable conduit of this invention employs a composite wall structure combining a PVC resin outer wall and a foamed inner wall, with a Sch40 grade wall thickness as the structural benchmark, achieving targeted adaptation to the harsh working conditions of sulfur mine dock cranes. The chemical inertness of the PVC resin replaces the temporary anti-corrosion mechanism of the coating, eliminating the corrosion damage to the conduit body caused by the highly corrosive sulfur environment, thus extending the service life of the cable conduit. The foamed inner wall provides the conduit with elastic buffering function, reducing the risk of cable wear under dynamic dragging and vibration conditions, and protecting the integrity of the cable insulation layer. The wall thickness of Sch40 grade or higher ensures structural rigidity and resistance to external forces, maintaining the long-term structural stability of the cable conduit under high-frequency vibration and external impact loads.

[0041] Considering the varying requirements for mechanical strength and cushioning performance of cable conduits in different crane installation environments, in some embodiments, the outer wall has at least two different wall thickness specifications. Similarly, the inner wall also has at least two different wall thickness specifications. For example, regarding the outer wall thickness: in areas with high vibration intensity, such as the slewing mechanism and trolley track areas, a larger wall thickness is selected to provide higher bending stiffness and impact resistance; in less vibrating internal areas such as machine rooms and electrical rooms, a smaller wall thickness can be used to reduce the overall structural weight and lower the load-bearing capacity requirements of the supports. Similarly, regarding the inner wall thickness: in power cable sections with larger cable outer diameters, a thicker foamed inner wall is selected to provide stronger elastic cushioning and radial support capabilities.

[0042] In this embodiment, by providing at least two different outer wall thickness specifications and at least two different inner wall thickness specifications, the cable conduit can be configured in a targeted manner for different working conditions of the crane, avoiding resource waste and insufficient protection caused by over-design or under-design of a single specification of pipe, so that the structural strength, buffer performance and lightweight target are comprehensively optimized at the whole machine level.

[0043] In some embodiments, according to Schedule 40 standards, the nominal diameter of the inner wall ranges from 1 / 2 inch to 8 inches. In the electrical systems of sulfur mine terminal cranes, cable types encompass various specifications, including power cables, control signal cables, and sensor cables, requiring different cable diameters. In imperial units, a 1 / 2-inch (approximately 12.7 mm) nominal diameter is suitable for sensor cables and fine-gauge control signal harnesses; a 2-inch (approximately 50.8 mm) nominal diameter is suitable for medium-gauge control cable harnesses; and nominal diameters from 4 inches (approximately 101.6 mm) to 8 inches (approximately 203.2 mm) are suitable for scenarios where multiple power cables are bundled together to meet the power supply needs of high-power equipment such as crane drive motors and frequency converters. It should be ensured that the effective inner diameter of the cable conduit is not less than 1.5 times the total outer diameter of the cables being run through it, to guarantee smooth cable routing and necessary heat dissipation space.

[0044] In this embodiment, by setting the nominal diameter of the inner wall to a wide range of 1 / 2 inch to 8 inches, the present invention can cover the typical cable specifications of crane electrical systems, realize the flexible adaptation of product series configuration and engineering selection, and meet the differentiated piping requirements of different line sections in the same sulfur mine terminal crane project.

[0045] In some embodiments, the cable conduit is formed in one step by an extrusion process. In this way, when the cable conduit is subjected to external bending loads, radial pressure, or axial tension, no relative slippage or delamination occurs between the two wall layers, ensuring the structural stability and long-term functional consistency of the composite pipe wall under dynamic conditions such as crane vibration and cable dragging.

[0046] Due to the significant temperature variations in the operating environment of the sulfur mine dock crane, in some embodiments, the cable conduit has a temperature resistance range of -40℃ to 90℃ and a flame retardant rating of UL94V-0.

[0047] Optionally, a cold-resistant toughening modifier can be added to the PVC resin formulation of the cable conduit to ensure that the conduit does not experience low-temperature brittleness at -40°C and maintains sufficient impact strength. Heat stabilizers and heat-resistant additives can be added to ensure that the conduit does not undergo thermal deformation or softening at 90°C, maintaining stable mechanical properties and meeting the heat distortion temperature requirements of ASTM D648 (American Society for Testing and Materials) and the relevant provisions for the thermal properties of rigid PVC conduits in ASTM D1784.

[0048] UL 94V-0 is the highest self-extinguishing rating in the flammability performance standards for plastic materials published by Underwriters Laboratories (UL). It requires the sample to self-extinguish within 10 seconds of removing the ignition source, with no molten droplets igniting the underlying padding during combustion. In crane electrical systems, cables are centrally routed. If an insulation fault causes a cable fire, and the cable conduit lacks flame-retardant properties, the flame will spread rapidly along the axial direction of the conduit, threatening the electrical safety of the entire machine. Setting the flame-retardant rating of the cable conduit to UL 94V-0 effectively blocks the axial propagation path of the flame along the conduit, controlling the fire risk to a localized area, protecting the safety of the crane's entire electrical system, and meeting the flame-retardant specifications for crane electrical equipment required by ports and classification societies.

[0049] In this embodiment, by setting the temperature resistance range to -40℃ to 90℃ and the flame retardant rating to meet the UL94V-0 level requirements, the cable conduit can operate stably in the entire climate range of the sulfur mine terminal from severe winter to hot summer. At the same time, it meets the mandatory requirements of electrical fire protection specifications for flame retardant performance, reduces the risk of fire spread caused by cable insulation failure, and improves the overall safety of crane operation.

[0050] In some embodiments, adjacent cable conduits are connected by a threaded coupling with a sealing ring, wherein a sealant is applied between the threads of the cable conduit and the threaded coupling.

[0051] Specifically, a threaded coupling is a short pipe connector with threads at both ends. Its ends are screwed onto the end threads of two adjacent cable pipe sections to achieve axial connection. A sealing ring is installed in an annular groove on the inner wall of the threaded coupling. When the cable pipe threads are screwed into the coupling, the sealing ring is compressed, forming an elastic seal between the pipe thread end face and the inner wall of the coupling, blocking the path of sulfur dust and moisture seeping in along the thread gap.

[0052] An additional, uniform sealant is applied to the threaded surfaces of the cable conduit and the threaded coupling; after curing, the sealant fills the tiny gaps between the thread teeth, forming a sealing barrier together with the sealing ring.

[0053] In the operating environment of cranes at sulfur mine docks, sulfur dust particles are extremely fine, and the gaps between the teeth of ordinary threaded connections cannot effectively prevent its penetration. Through a double-sealing combination of sealing rings and sealant, the sealing continuity of the connection is consistent with the pipe body, effectively preventing acid mist, water vapor, and sulfur dust from entering through the pipe connection interface. Compared with traditional cable conduit butt welding connections, threaded couplings are detachable structures. During maintenance at high altitudes such as crane booms, the pipe section can be quickly disassembled and reinstalled by unscrewing the threaded coupling, eliminating the need for welding and avoiding thermal damage to the PVC pipe body caused by welding, while maintaining the consistency of overall corrosion resistance.

[0054] In this embodiment, the present invention adopts a composite sealing connection scheme of threaded joint with sealing ring and pipe thread sealant, which effectively blocks sulfur dust and water vapor at the connection point, while retaining the convenience of maintenance brought by threaded disassembly, taking into account the sealing reliability and maintenance efficiency, and reducing the risk of cable corrosion and insulation degradation caused by connection interface sealing failure.

[0055] In some embodiments, the sealing rating at the connection between the cable conduit and the threaded coupling is IP65. Achieving an IP65 sealing rating requires comprehensive design and verification of the cable conduit and its connection interface. Regarding interface sealing, the IP65 dustproof requirement can be achieved using a sealing structure of a threaded coupling with a sealing ring and thread sealant. The cable conduit is a continuous, integral structure, eliminating potential leakage points such as weld seams in the metal pipe or micropores caused by thread corrosion, ensuring the continuous sealing of the conduit itself. This allows the entire cable conduit system to meet the IP65 dustproof and waterproof test requirements under rated test conditions.

[0056] In this embodiment, the cable conduit system can effectively isolate the cables inside the conduit from external sulfur dust and moisture during loading and unloading operations at the sulfur mine terminal, ensuring that the cable insulation layer is in a clean and dry protective environment for a long time. This significantly reduces the risk of cable insulation degradation, corrosion aging, and short circuit faults caused by dust accumulation or moisture intrusion, and improves the overall reliability of the crane's electrical system.

[0057] The following is a comparison between the cable conduit of the present invention and the traditional hot-dip galvanized cable conduit for port machinery before the improvement: Table 1. Comparison of the cable conduit of the present invention and the traditional hot-dip galvanized cable conduit for port machinery before the improvement.

[0058] This invention provides a crane for a sulfur mine terminal, the crane being equipped with cable conduits as described in any of the above embodiments. The crane for the sulfur mine terminal includes, but is not limited to, ship loaders and ship unloaders. Electrical component supports are installed on the crane's steel structure, and the cable conduits are laid along these supports and fixed to the crane's steel structure, forming a continuous cable protection channel covering all areas of the crane's mechanisms. For each area, including the crane's trolley traveling mechanism, trolley moving mechanism, cantilever beam, slewing mechanism, and machine room / electrical room, cable conduits with corresponding nominal diameters and wall thicknesses are selected based on the actual environmental corrosion level and cable specifications. In areas with high concentrations of acid mist and hydrogen sulfide (H2S) accumulation (such as under hoppers or in belt conveyor areas), high-strength cable conduits with a wall thickness of Sch40 or higher are selected, ensuring that the effective inner diameter is not less than 1.5 times the outer diameter of the cable being laid, to guarantee smooth cable threading and heat dissipation space. In the slewing mechanism areas with severe vibration, a flexible buffer mechanism is used for transition to adapt to the dynamic requirements of towing.

[0059] In a typical application at a sulfur mine terminal, the cable conduits provided by this invention were installed in all indoor and outdoor areas of the six ship loaders and two ship unloaders, covering major structural areas such as the trolley traveling mechanism, front and rear cantilever beams, engine room, electrical room, and unloading system. After six months of continuous operation, the cable conduits showed no corrosion, cracking, or leakage; the cable insulation performance remained stable; and the cable sheath showed no wear under vibration and impact conditions. Compared with traditional metal steel pipes, the cable failure rate was reduced by approximately 82%, effectively solving the historical problem of frequent cable conduit replacements and meeting the requirements of long-term terminal operation.

[0060] This invention provides a method for installing a cable conduit, used to install the cable conduit described in any embodiment to a crane. The installation method includes the following steps: In step S100, the cable conduit is laid in sections along the path of the crane's electrical component support, and the cable conduit is fixed to the steel structure of the crane by the support.

[0061] The crane's electrical component supports are pre-arranged on the steel structures of various mechanisms, including the trolley traveling mechanism, front and rear cantilever beams, machine room, electrical room, and unloading system, according to the electrical wiring plan. Before installation, cable conduits are selected and segmented based on the corrosion level and vibration intensity of each area. The selected cable conduits are laid segment by segment along the path of the electrical component supports for each mechanism, and the cable conduits are secured to the supports using pipe clamps or U-bolts. The fixing interval is determined based on the pipe diameter and unit weight of the pipe material to prevent the cable conduits from sagging due to their own weight or from axial displacement and lateral deflection due to vibration.

[0062] A rubber buffer pad can be installed between the support and the cable conduit. When the crane vibrates during its movements such as traveling, luffing, and slewing, the rubber buffer pad absorbs and dissipates the vibration energy through its elastic deformation, blocking the direct rigid transmission of vibration from the steel structure to the cable conduit. The rubber layer also forms electrical insulation, preventing wear on the pipe surface caused by long-term fretting friction between the metal support and the PVC pipe wall, thus extending the service life of the cable conduit and the cable sheath inside.

[0063] In step S200, adjacent cable conduits are connected to form a continuous cable protection channel. Specifically, the indoor cable conduits 10 are connected using flexible hoses 20, such as... Figure 1 As shown, Figure 1 Electrical junction box 40 and fire alarm box 50 are also shown; outdoor cable conduit 10 is connected using metal stuffing glands, such as... Figure 2 As shown, Figure 2 The unloader beam 60 and unloader column 70 are also shown. The cables exiting the beam 60 and column 70 enter the cable conduit 10 through bare wires in a 316L stainless steel bend 30.

[0064] Adjacent cable sections are connected by a threaded coupling with a sealing ring as described in Example 6. Before screwing, a sealant is evenly applied to the threaded surface of the cable end; after screwing, the sealing ring is axially compressed to form an elastic seal, and the sealant, after curing, fills the tiny gaps between the thread teeth, so that each section is connected to form a sealed and continuous cable protection channel.

[0065] Vibration is relatively low in indoor areas of cranes (such as the machine room and electrical room), and the layout of electrical components is flexible, with slight angular deviations or misalignments in conduit routing. Flexible conduits (i.e., flexible conduits with a certain degree of bending deformation capacity) are used to connect adjacent cable conduits, allowing for smooth connection even with slight angular deviations. The elastic deformation capacity of the conduits themselves further absorbs residual indoor vibrations. The length of the flexible conduit should be controlled within 900mm. If the actual installation length exceeds this limit, a fixed support must be added in the middle to prevent the conduit from bending due to its own weight or accumulated vibration, which could lead to loose connections and seal failure.

[0066] The outdoor areas of the crane (such as the main beam columns, the outer side of the cantilever beam, and the unloading system) are directly exposed to sulfur dust, marine salt spray, and rainfall, and the cables are subject to a certain drag tension as the mechanism moves. Adjacent cable conduits are connected using metal cable glands (metal cable sealing joints). The metal cable glands use internal packing to compress the cable sheath, forming a mechanical seal to prevent outdoor corrosive media from entering along the pipe joint. Simultaneously, the clamping mechanism of the metal cable glands applies an axial holding force to the cable, preventing it from slipping out of the joint under dragging conditions, thus ensuring the continuity of the cable conduit system's joint seal under dynamic outdoor conditions.

[0067] In step S300, a cable is threaded through the cable conduit, the segmented dust covers of the cable conduit are closed, and the joints are sealed by mounting sleeves.

[0068] After the cable conduits are installed and connected into a continuous channel, the cable is threaded through one end of the channel. The smooth inner wall of the foamed inner layer reduces threading resistance, allowing the cable to be smoothly guided to the target connection point. After threading, the dust covers of each section are closed to seal non-threading sections or temporary openings, preventing sulfur dust and moisture from entering the pipeline during construction breaks. Installation sleeves are fitted onto the joints of each pipe section and tightened. The installation sleeves apply additional tightening force to the joints through radial compression. Combined with sealant and sealing rings, this further enhances the mechanical stability and dustproof sealing reliability at the joints.

[0069] Based on field tests and applications at sulfur mine wharves, this invention provides a new type of PVC cable pipe that is resistant to sulfur corrosion, vibration and shock, and salt spray aging, is easy to install and disassemble, and is also competitively priced, thus ensuring the stable operation of crane cables.

[0070] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A cable conduit, characterized in that, The cable conduit is used on the cranes at the sulfur mine wharf for laying cables. The cable conduit includes an outer wall and an inner wall connected to the outer wall; The outer wall is extruded from PVC resin; The inner wall is a foamed layer, and the cable passes through the inner wall. The wall thickness of the cable conduit is greater than or equal to the Schedule 40 standard.

2. The cable conduit as described in claim 1, characterized in that, The outer wall has at least two different wall thickness specifications; and / or The inner wall has at least two different wall thickness specifications.

3. The cable conduit as described in claim 1, characterized in that, The nominal diameter of the inner wall ranges from 1 / 2 inch to 8 inches.

4. The cable conduit as described in claim 1, characterized in that, The cable conduit is formed in one step through an extrusion process.

5. The cable conduit as described in claim 1, characterized in that, The cable conduit has a temperature resistance range of -40℃ to 90℃; and / or The cable conduit has a flame retardant rating of UL94V-0.

6. The cable conduit as described in any one of claims 1-5, characterized in that, Adjacent cable conduits are connected by a threaded coupling with a sealing ring, and a sealant is applied between the threads of the cable conduit and the threaded coupling.

7. The cable conduit as described in claim 6, characterized in that, The sealing rating at the connection between the cable conduit and the threaded coupling is IP65.

8. A crane for a sulfur mine wharf, characterized in that, The crane is equipped with a cable conduit; The cable conduit is the cable conduit as described in any one of claims 1-7.

9. A method for installing a cable conduit, characterized in that, Used for installing the cable conduit according to any one of claims 1-7 to a crane; The installation method includes: The cable conduit is laid in sections along the path of the crane's electrical component support, and the cable conduit is fixed to the crane's steel structure by the support. Connect adjacent cable conduits to form a continuous cable protection channel; A cable is run through the cable conduit, and the section dust covers of the cable conduit are closed. The joints are secured and sealed with mounting sleeves.

10. The installation method as described in claim 9, characterized in that, In the connection of adjacent cable conduits to form a continuous cable protection channel, the indoor cable conduits are joined using flexible hoses, while the outdoor cable conduits are joined using metal stuffing glands; and / or A rubber buffer pad is provided between the bracket and the cable pipe.

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