Method for preparing deep-sea high-water-pressure-resistant composite watertight cable and seawater-resistant test method

Abstract

The invention relates to the field of watertight cables, in particular to a deep-sea high-water-pressure-resistant composite watertight cable preparation and seawater-resistant test method, which comprises the following steps: selecting a tinned copper or silver-plated copper conductor for bunch stranding, and controlling the stranding pitch and direction; the twisting body watertight treatment is filled with a silicone-based sealant by utilizing rotating centrifugal force; the extrusion insulation adopts a specific process and material; wrapping is added when the cable is twisted, and the performance is enhanced by adopting a double-layer wrapping structure; the stranded cable is subjected to watertight treatment, filled with a water-blocking rope and wrapped with a water-blocking tape; a proper material is selected for extruding the sheath and the quality of the sheath is controlled; and the end head is vulcanized and sealed through assembly treatment. The seawater-resistant test method comprises sample selection, environment simulation and seawater soaking test, and the seawater-resistant performance of the cable is evaluated through long-time soaking and multi-dimensional test. The water tightness and anti-interference performance of the cable are effectively improved, the service life is prolonged, the seawater resistance of the cable can be comprehensively evaluated, and reliable guarantee is provided for deep sea application.

Description

Technical Field

[0001] The present invention relates to the technical field of watertight cables, and particularly to a method for preparing a deep-sea high-water-pressure-resistant composite watertight cable and a seawater resistance test method therefor. Background Art

[0002] In the related technical field of deep-sea high-water-pressure-resistant composite watertight cables, the prior art has deficiencies in multiple key aspects. In the stranding process of the cable, the prior art often uses simple and single wrapping materials and a single-layer wrapping structure, which makes the cable perform poorly in preventing friction between the sub-shields, anti-interference, and watertight performance. The sub-shields are easily damaged, signal transmission is easily interfered, and moisture is also easily penetrated, thus shortening the service life of the product. For the treatment of the cable end, the prior art mostly uses simple bandaging or ordinary sealing methods. When filling the rubber material, it is impossible to ensure its uniform distribution in the mold cavity of the complex-shaped end, resulting in an insecure and loose sealing structure, making it difficult to resist the intrusion of seawater from the end, seriously affecting the watertight integrity and service life of the cable underwater. In the aspect of the seawater resistance performance test of the cable, the existing test methods have a short soaking time and a single test dimension. Only short-term soaking is carried out and the appearance change is concerned, lacking long-term monitoring of multiple dimensions such as electrical performance. It is impossible to truly simulate the long-term use of the cable in seawater, difficult to comprehensively evaluate its seawater resistance performance, and easy to ignore the influence of seawater penetration on the internal electrical performance of the cable, leaving potential safety hazards in actual use.

[0003] Therefore, it is very necessary to propose a method for preparing a deep-sea high-water-pressure-resistant composite watertight cable and a seawater resistance test method to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a deep-sea high-water-pressure-resistant composite watertight cable and a seawater resistance test method to solve the problems of poor anti-interference and watertight performance and difficulty in comprehensively evaluating its seawater resistance performance.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A method for preparing a deep-sea high-water-pressure-resistant composite watertight cable and a seawater resistance test method, comprising the following steps: Stranding: Select a tinned copper conductor or a silver-plated copper conductor, and perform stranding in accordance with the regular stranding form, controlling the stranding pitch and the stranding direction during the stranding process; Watertight treatment of the stranding body: Fill a special waterproof sealant in the conductor gaps. Before filling the sealant, fix the stranded conductor on a rotatable device, and uniformly fill the sealant through the centrifugal force generated by rotation; Extrusion of insulation: Extrude the insulation by using the extrusion tube method or the semi-extrusion method, and control the insulation concentricity and the unilateral nominal thickness by using a high-precision mold and advanced extrusion equipment; Stranding and cabling: The insulated conductors are stranded and cabled, and wrapping is added outside both the partial shield and the overall shield during the stranding process. Cable watertight treatment: Water blocking ropes are filled in the gaps of the cable core, and a layer of water blocking tape is wrapped outside the cable core. Extruding the sheath: The sheath is extruded using the extrusion tube type or semi-extrusion type process, and the concentricity of the sheath and the thinnest thickness of the sheath are controlled. Component treatment: The cable ends are vulcanized and sealed. Through special vulcanization equipment and molds, the ends and the cable form an integral sealed structure. During the vulcanization process, the vulcanization temperature, time, and pressure parameters are controlled.

[0006] Preferably, before extruding the insulation using the extrusion tube type or semi-extrusion type process, the insulation material is fully dried to remove moisture. The extruded insulation material is selected from at least one of fluoroplastics or insulating rubbers that are resistant to high and low temperatures.

[0007] Preferably, in the step of extruding the sheath using the extrusion tube type or semi-extrusion type process, polyether type polyurethane or chloroprene rubber is selected as the raw material. The appearance of the extruded sheath is inspected to ensure that the sheath is smooth and flat, without obvious visible damage, pits, or bulges. If defects are found, the extrusion process parameters are adjusted in a timely manner or the mold is repaired.

[0008] Preferably, the wrapping material during the stranding process is at least one of polyester tape, water blocking tape, or non-woven fabric wrapping.

[0009] Preferably, in the stranding and cabling step, the wrapping layers outside the partial shield and the overall shield both adopt a double-layer structure. The inner layer is polyester tape, and the outer layer is a mixed winding tape of water blocking tape and non-woven fabric wrapping.

[0010] Preferably, during the vulcanization treatment, the pre-treated rubber material is placed into the cavity of the mold. For cable ends with complex shapes, a step-by-step filling method is adopted to ensure that the rubber material is evenly distributed in the cavity. After vulcanization is completed, wait for the mold to cool, and then perform the demolding operation. The watertightness of the cable ends is detected by immersing the cable ends in water under a certain pressure.

[0011] Preferably, the waterproof sealant is a silicone-based sealant. Before filling, the surface of the stranded conductor is cleaned by wiping with anhydrous ethanol to remove the oil stains and impurities on the surface.

[0012] Preferably, a seawater resistance test method for a deep-sea high-water-pressure composite watertight cable includes the following steps: Sample selection: Randomly select 3 - 5 watertight cables of different specifications from the production batch, including different water pressure resistance levels. The cable length is not less than 1 meter, and ensure that the appearance has no obvious defects and the markings are complete. Environmental simulation: Use seawater salt, deionized water and acid-base regulators to configure a simulated seawater solution with a salinity controlled at 3.2% - 3.7% and a pH value maintained at 7.5 - 8.6; Use a pressure test device to provide a water pressure of 0 - 120 MPa; Seawater immersion test: Completely immerse each cable sample in a container of simulated seawater and apply the corresponding water pressure according to the water pressure resistance level of the cable; Set the immersion time to 90 days, observe the color and odor changes of the seawater solution once a week, as well as the corrosion signs on the cable surface and record them.

[0013] Preferably, before the test, use a caliper to measure the outer diameter of the cable, the thickness of the insulation layer, and the thickness of the sheath size to allocate different water pressures to be applied, and check the end seal to ensure uniform vulcanization.

[0014] Preferably, on the 30th, 60th, and 90th days of immersion, take the cable out of the seawater, dry it with a dry cloth, and then use an insulation resistance tester to measure the insulation resistance. For fluoroplastic insulated cables, it should be ≥ 1000 MΩ・Km, and for rubber insulated cables, it should be ≥ 100 MΩ・Km. If it is lower than the standard, it is determined that the seawater has penetrated and affected the insulation performance; Use a high-precision multimeter to measure the DC resistance of the cable conductor. At each time point on the 30th, 60th, and 90th days of immersion, measure 3 times at different positions and take the average value. Compare it with the requirements of GJB774A - 2020. If the resistance increases significantly, it is determined that the conductor is corroded.

[0015] Technical effects and advantages of the present invention: 1. In the present invention, by using polyester tape, water blocking tape or non-woven fabric for winding in the stranding and cabling step, and adopting a double-layer structure for the winding layer outside the sub-screening and total screening, the effects of preventing friction between sub-screenings, improving the mechanical properties and anti-interference ability of the cable, enhancing the watertight performance are achieved, and the service life of the product is extended.

[0016] 2. In the present invention, in the component processing step, for the cable end with complex shape, rubber material is filled step by step, and vulcanization and watertightness detection are carried out, achieving the effects of making the sealed structure firm and tight after vulcanization, improving the end seal performance, preventing moisture from invading the cable interior from the end, and ensuring the underwater watertight integrity of the cable.

[0017] 3. In the present invention, in the stranding body watertight treatment step, the stranded conductor is fixed on a rotatable device to fill silicone-based sealant using centrifugal force, and the surface of the conductor is cleaned, achieving the effects of making the sealant fully fill the conductor gaps and enhancing the bonding effect, effectively preventing moisture from entering the conductor interior, improving the watertight performance of the cable, preventing problems such as conductor corrosion and short circuit, and extending the service life of the cable in the underwater environment.

[0018] 4. By soaking the cable for a long time in the seawater immersion test step of the seawater resistance test method, observing and recording regularly, and conducting electrical performance tests, the effects of simulating the long-term use of the cable in seawater, promptly detecting performance change problems, evaluating the seawater resistance performance of the cable from multiple dimensions, and providing rich data support for judging the reliability and service life of the cable are achieved. Brief Description of the Drawings

[0019] Figure 1 It is a flowchart of a preparation method for a deep-sea high-water-pressure-resistant composite watertight cable of the present invention.

[0020] Figure 2 It is a flowchart of a seawater resistance test method for a deep-sea high-water-pressure-resistant composite watertight cable of the present invention. Detailed Embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] The present invention provides a preparation method for a deep-sea high-water-pressure-resistant composite watertight cable as shown in Figure 1 the following, including the following steps; Stranding S11: Select a tinned copper conductor or a silver-plated copper conductor, and conduct stranding in accordance with the regular stranding form, controlling the stranding pitch and stranding direction during the stranding process; Modern stranding machines are usually equipped with precise pitch control systems. Operators input the corresponding parameters on the control panel of the equipment according to the pitch value determined by the design. During the stranding process, equipment such as a laser measuring instrument is used to monitor the stranding pitch in real time. The laser measuring instrument can accurately measure the stranding pitch of the conductor and feed the data back to the control system. If there is a deviation between the actual pitch and the set value, the control system will automatically adjust the motor speed or traction speed to restore the pitch to the set range; control the stranding through the stranding machine, and after the stranding is completed, check the stranding direction of the cable to ensure it is consistent with the design requirements.

[0023] Waterproof treatment of the stranded body S12: Fill a special waterproof sealant in the gaps of the conductor. Before filling the sealant, fix the stranded conductor on a rotatable device and evenly fill the sealant through the centrifugal force of rotation; The waterproof sealant is a silicone-based sealant. Before filling, clean the surface of the stranded conductor, wipe it with anhydrous ethanol to remove the oil stains and impurities on the surface.

[0024] Extruded Insulation S13: The insulation is extruded using the tube extrusion or semi-extrusion process. The concentricity of the insulation and the nominal thickness on one side are controlled by using high-precision molds and advanced extrusion equipment. Before extruding the insulation using the tube extrusion or semi-extrusion process, the insulation material is fully dried to remove moisture. At least one of fluoroplastics or insulating rubbers resistant to high and low temperatures is selected as the extruded insulation material.

[0025] Stranding and Cabling S14: The insulated conductors are stranded and cabled. During the stranding process, wrapping is added outside both the partial shield and the overall shield. At least one of polyester tapes, water blocking tapes, or non-woven fabrics is used as the wrapping material during the stranding process. In the stranding and cabling step, the wrapping layers outside both the partial shield and the overall shield adopt a double-layer structure. The inner layer is a polyester tape, and the outer layer is a mixed winding tape of a water blocking tape and a non-woven fabric wrapping.

[0026] Cable Core Watertight Treatment S15: A water blocking rope is filled in the gaps of the cable core, and a water blocking tape is wrapped around the cable core. Extruded Sheath S16: The sheath is extruded using the tube extrusion or semi-extrusion process, and the concentricity of the sheath and the thinnest thickness of the sheath are controlled. In the step of extruding the sheath using the tube extrusion or semi-extrusion process, polyether-type polyurethane or chloroprene rubber is selected as the raw material. The appearance of the extruded sheath is inspected to ensure that the sheath is smooth and flat, without obvious visible damage, pits, or bulging defects. If defects are found, the extrusion process parameters are adjusted in a timely manner or the mold is repaired.

[0027] Component Treatment S17: The cable ends are vulcanized and sealed. Through special vulcanization equipment and molds, the ends and the cable form an integral sealed structure. The vulcanization temperature, time, and pressure parameters are controlled during the vulcanization process. During vulcanization treatment, the pre-treated rubber material is placed into the cavity of the mold. For cable ends with complex shapes, a step-by-step loading and filling method is adopted to ensure that the rubber material is evenly distributed in the cavity. After vulcanization is completed, wait for the mold to cool, and then perform the demolding operation. The watertightness of the cable ends is detected by immersing the cable ends in water under a certain pressure.

[0028] In the method for preparing a watertight cable proposed by the present invention, by fixing the stranded conductors on a rotatable device and using the centrifugal force of rotation to evenly fill the silicone-based sealant, this method can enable the silicone-based sealant to fully fill the gaps between the conductors, avoid the occurrence of voids, effectively prevent moisture from entering the interior of the conductors, thereby improving the watertight performance of the cable, preventing problems such as conductor corrosion and short circuits caused by moisture intrusion, and extending the service life of the cable in an underwater environment. The wrapping material is at least one of polyester tape, water-blocking tape or non-woven fabric wrapping. The wrapping layer outside the partial shield and the overall shield adopts a double-layer structure. The inner layer is polyester tape, and the outer layer is a mixed winding tape of water-blocking tape and non-woven fabric wrapping, which can effectively prevent the friction between the partial shields from reducing the service life of the product and is conducive to meeting the bending radius requirement. Water-blocking ropes are filled in the gaps of the cable core, and a layer of water-blocking tape is wrapped around the cable core to form a double watertight protection. When the water-blocking ropes encounter moisture, they will expand to fill the gaps and prevent further penetration of moisture. The water-blocking tape can form a barrier outside the cable core to effectively block the entry of moisture into the cable core, greatly improving the overall watertight performance of the cable and ensuring the normal operation of the cable under the high water pressure environment in the deep sea. For the cable ends with complex shapes, a filling method of step-by-step feeding is adopted to ensure that the rubber material is evenly distributed in the mold cavity. The uniform distribution of rubber can make the vulcanized sealing structure more firm and tight, improve the sealing performance of the end, effectively prevent moisture from invading the cable interior from the end, and ensure the watertight integrity of the cable underwater.

[0029] Please refer to Figure 2 , the present invention provides a seawater resistance test method for a deep-sea high-water-pressure resistant composite watertight cable, including the following steps: Sample selection S21: Randomly select 3 - 5 watertight cables with different specifications from the production batch, including different water pressure resistance levels, and the cable length is not less than 1 meter, ensuring that there are no obvious defects on the appearance and the markings are complete. Such a sampling method can cover various product situations in the production batch. Cables with different specifications and water pressure resistance levels can test the seawater resistance performance under different conditions, making the test results more universal and representative, effectively reflecting the quality level of the entire production batch of products, and avoiding the influence of individual special samples on the judgment of the overall performance of the products.

[0030] Environment simulation S22: Configure a simulated seawater solution using seawater salt, deionized water and acid-base regulators, control the salinity at 3.2% - 3.7%, and maintain the pH value at 7.5 - 8.6; use a pressure test device to provide a water pressure of 0 - 120 MPa. Seawater immersion test S23: Immerse each cable sample completely in a container of simulated seawater, apply the corresponding water pressure according to the water pressure resistance level of the cable; set the immersion time to 90 days, observe the changes in the color and smell of the seawater solution once a week, as well as the corrosion signs on the cable surface and record them.

[0031] Before the test, use a caliper to measure the outer diameter of the cable, the thickness of the insulation layer, and the thickness of the sheath to allocate different water pressures to be applied, and check the sealing at the end to ensure uniform vulcanization.

[0032] On the 30th, 60th, and 90th days of immersion, take the cable out of the seawater, dry it with a dry cloth, and then measure the insulation resistance with an insulation resistance tester. For fluoroplastic insulated cables, it should be ≥1000 MΩ・Km, and for rubber insulated cables, it should be ≥100 MΩ・Km. If it is lower than the standard, it is determined that the seawater has penetrated and affected the insulation performance; use a high-precision multimeter to measure the DC resistance of the cable conductor. At each time point on the 30th, 60th, and 90th days of immersion, measure 3 times at different positions and take the average value, and compare it with the requirements of GJB774A-2020. If the resistance increases significantly, it is determined that the conductor is corroded.

[0033] In the embodiment of the present invention, in the storage area of the watertight cable finished products of the production batch, use a random number generator to determine the specific cable positions for sampling. According to different specifications, such as the number of cores, wire diameter, and water pressure resistance levels of 10 MPa, 30 MPa, and 70 MPa, select 3-5 cables, measure the outer diameter, insulation layer thickness, and sheath thickness of each cable with a caliper, and record the data. Use a magnifying glass or a high-definition camera to check the appearance of the cable to ensure that there are no defects such as scratches, dents, bubbles, and bulges. At the same time, check the markings to ensure that the information such as the cable model, specification, production date, and water pressure resistance level is clear and complete. Number the selected cables, and record the appearance, size measurement data, and numbers in detail in the test log for easy correspondence and traceability of subsequent test data; Prepare a corrosion-resistant container large enough to store the simulated seawater solution. Use tools such as a measuring cylinder and an electronic scale to weigh seawater salt and deionized water according to the ratio, and use acid-base regulators, dilute hydrochloric acid and sodium hydroxide solution, and accurately measure through a pH meter to control the salinity of the simulated seawater solution at 3.2% - 3.7% and maintain the pH value at 7.5 - 8.6. Connect the pressure test device to the immersion container and check the tightness of the device and the pressure control system. According to the water pressure resistance levels of different cables, set the water pressure output by the pressure test device to ensure that a stable water pressure of 0 - 120 MPa can be provided during the test; Check the appearance of the cable again, especially the end sealing part, to confirm that the vulcanization is uniform and there are no defects. According to the previously measured cable size data and combined with its water pressure resistance level, determine the water pressure value to be applied to each cable during immersion and record it in the test log; carefully place the cable into the container of simulated seawater to ensure complete immersion, connect the pressure test device, and slowly increase the pressure according to the set water pressure value. After reaching the predetermined water pressure, keep it stable; observe the changes in the color and smell of the seawater solution at a fixed time every week to check for any turbidity, strange smell, etc. At the same time, use a high-definition camera to take pictures of the cable surface to check for signs of corrosion, such as the disappearance of metallic luster, the appearance of rust spots, the discoloration or deformation of the sheath, etc., and record the observation results in detail in the test log; On the 30th, 60th, and 90th days of immersion, take out the cable from the seawater and gently dry the surface moisture with a dry cloth. Connect the electrodes of the insulation resistance tester to the cable conductor and sheath according to the correct method, and start the tester to measure the insulation resistance. If the insulation resistance of the fluoroplastic insulated cable is ≥1000 MΩ・Km and the insulation resistance of the rubber insulated cable is ≥100 MΩ・Km, it is recorded as qualified; if it is lower than the standard value, record in the test log that it is determined that seawater has penetrated and affected the insulation performance, and mark the cable; use a high-precision multimeter to measure the DC resistance at different positions of the cable, such as both ends and the middle part of the cable, measure 3 times at each position, and take the average value. Compare the measurement results with the requirements of GJB774A-2020. If the resistance increases significantly, it is determined that the conductor has corroded, and record the relevant situation and data in the test log.

[0034] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a deep - sea high - water - pressure - resistant composite watertight cable, characterized in that, It includes the following steps: Stranding: Select tinned copper conductor or silver-plated copper conductor and conduct stranding in accordance with the regular stranding form, controlling the stranding pitch and direction during the stranding process; Waterproof treatment for the stranded body: Fill the gaps between conductors with special waterproof sealant. Before filling the sealant, fix the stranded conductor on a rotatable device and evenly fill the sealant through the centrifugal force generated by rotation; Extruding insulation: Extrude the insulation using the extrusion tube type or semi-extrusion type process, and control the insulation concentricity and unilateral nominal thickness by using high-precision molds and advanced extrusion equipment; Stranding into cable: Stranded the insulated conductors into a cable, and add wrapping outside the sectional shield and overall shield during the stranding process; Waterproof treatment for the stranded cable: Fill water blocking ropes in the gaps of the cable core and wrap a layer of water blocking tape outside the cable core; Extruding sheath: Extrude the sheath using the extrusion tube type or semi-extrusion type process, and control the sheath concentricity and the thinnest thickness of the sheath; Component treatment: Conduct vulcanization sealing treatment on the cable ends. Through special vulcanization equipment and molds, form an integral sealed structure between the ends and the cable, and control the vulcanization temperature, time and pressure parameters during the vulcanization process.

2. The preparation method of a deep-sea high-water-pressure-resistant composite watertight cable according to claim 1, characterized in that: Before extruding the insulation using the extrusion tube type or semi-extrusion type process, fully dry the insulation material to remove moisture. The extruded insulation material is selected from at least one of fluoroplastics or insulating rubbers that are resistant to high and low temperatures.

3. The preparation method of a deep-sea high-hydrostatic-pressure-resistant composite watertight cable according to claim 1, characterized in that: In the step of extruding the sheath using the extrusion tube type or semi-extrusion type process, select polyether-type polyurethane or chloroprene rubber as the raw material, conduct an appearance inspection on the extruded sheath to ensure that the sheath is smooth and flat, without obvious visible damages, pits, bulging defects. If defects are found, adjust the extrusion process parameters or repair the mold in a timely manner.

4. The preparation method of a deep-sea high-water-pressure-resistant composite watertight cable according to claim 1, wherein: The wrapping materials during the stranding process are at least one of polyester tape, water blocking tape or non-woven fabric wrapping.

5. The preparation method of a deep-sea high-water-pressure-resistant composite watertight cable according to claim 4, characterized in that: In the step of stranding into cable, the wrapping layers outside the sectional shield and overall shield both adopt a double-layer structure. The inner layer is polyester tape, and the outer layer is a mixed winding tape of water blocking tape and non-woven fabric wrapping.

6. A method for preparing a deep-sea high-water-pressure-resistant composite watertight cable according to claim 1, characterized in that: During the vulcanization treatment, put the pre-treated rubber material into the cavity of the mold. For the cable ends with complex shapes, adopt a step-by-step loading filling method to ensure that the rubber material is evenly distributed in the cavity. After vulcanization is completed, wait for the mold to cool, and then conduct demolding operation. Detect the water tightness of the cable ends by immersing the cable ends in water under a certain pressure.

7. A method for preparing a deep-sea high-water-pressure-resistant composite watertight cable according to claim 1, characterized in that: The waterproof sealant is silicone-based sealant. Before filling, clean the surface of the stranded conductor, wipe it with anhydrous ethanol to remove the oil stains and impurities on the surface.

8. A seawater resistance test method for a deep-sea high-water-pressure-resistant composite watertight cable, characterized in that, It includes the following steps: Sample selection: Randomly select 3 - 5 water-tight cables with different specifications from the production batch, including different water pressure resistance levels, and the cable length is not less than 1 meter, ensuring that there are no obvious defects on the appearance and the markings are complete; Environmental simulation: Configure a simulated seawater solution using seawater salt, deionized water and acid-base regulators, control the salinity at 3.2% - 3.7%, and maintain the pH value at 7.5 - 8.6; Use a pressure test device to provide a water pressure of 0 - 120 MPa; Seawater immersion test: Completely immerse each cable sample in a container with simulated seawater, apply the corresponding water pressure according to the water pressure resistance level of the cable; Set the immersion time to 90 days, observe the color and smell changes of the seawater solution and the corrosion signs on the cable surface once a week and record them.

9. A seawater resistance test method for a deep-sea high-water pressure-resistant composite watertight cable according to claim 8, characterized in that: Before the test, use a caliper to measure the outer diameter of the cable, the thickness of the insulation layer, and the thickness of the sheath size to allocate different water pressures, and check the end seal to ensure uniform vulcanization.

10. A seawater resistance test method for a deep-sea high-hydrostatic-pressure composite watertight cable according to claim 8, characterized in that: On the 30th, 60th, and 90th days of immersion, take the cable out of the seawater, dry it with a dry cloth, and then use an insulation resistance tester to measure the insulation resistance. For fluoroplastic insulated cables, it should be ≥1000 MΩ・Km, and for rubber insulated cables, it should be ≥100 MΩ・Km. If it is lower than the standard, it is determined that the seawater has penetrated and affected the insulation performance; use a high-precision multimeter to measure the DC resistance of the cable conductor. At each time point on the 30th, 60th, and 90th days of immersion, measure 3 times at different positions and take the average value. Compare it with the requirements of GJB774A-2020. If the resistance increases significantly, it is determined that the conductor is corroded.

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