Twelve-layer single-strand rope zero-torque design and verification method

Abstract

A method for designing and verifying zero-torque single-strand ropes with twelve layers is presented. The rope has a structure of 1×573-Ф135mm, a diameter of Ф173mm after double-layer plastic coating, and a 36WS center strand structure. The design method involves determining the center strand structure of the single-strand wire rope core, employing a trial-and-error method based on the regularity of point-contact wire rope construction, and then adjusting the number of wires, lay direction, and lay angle to achieve zero torque and maximize the minimum breaking tensile force. Finally, the axial rotational performance of the wire rope is verified through the plastic coating process. This single-strand rope is used in FPSO positioning and mooring systems, and all design parameters meet relevant standards and usage requirements. This lays a solid foundation for the localization of permanent mooring cables for FPSOs and will have a positive impact on participation in international market competition.

Description

Technical Field

[0001] This invention relates to a zero-torque design and verification method for a twelve-layer single-strand rope, belonging to the field of metal product design technology. Background Technology

[0002] An FPSO (Floating Production Station) is a large-scale, integrated offshore oil production base that combines oil and gas separation, oily wastewater treatment, power generation, heating, crude oil storage and transportation, with personnel living quarters and a production command system. Compared with other types of oil production platforms, FPSOs have advantages such as strong resistance to wind and waves, wide adaptability to water depths, large oil storage / unloading capacity, and portability and reusability. They are widely suitable for the development of deep-sea, shallow-sea, and marginal oil fields far from the coast and have become the mainstream production method for offshore oil and gas field development. Mooring wire ropes are an indispensable and crucial piece of mooring equipment in FPSO mooring systems. Their performance directly affects their service life. Under wind, current, and wave loads, mooring wire ropes inevitably twist, and their failure mode is usually due to torsional shear stress causing wire breakage or rope breakage. How to balance the torque generated by the wire rope, that is, to make the sum of the wire rope torque zero under load, is the key to improving the service life of mooring wire ropes and is also one of the most important key points for global mooring wire rope manufacturers. However, data from wire rope manufacturers in developed countries in Europe and America show that a certain amount of rotation is allowed in the wire rope. The DNV GL classification society specification stipulates a deflection of 0.72° / meter. According to conventional design, it is almost impossible to achieve a zero-torque wire rope.

[0003] With the upgrading of steel wire ropes used in FPSO mooring systems, from the initial unsheathed mooring wire ropes to single-sheathed protected wire ropes, and now to double-sheathed protected wire ropes, my country currently has more than 20 FPSOs. The vast majority of their mooring wire ropes are imported from manufacturers such as Button (UK) and ArcelorMittal (France). The mooring wire ropes used in this Nanhai Fenjin FPSO project were jointly developed by Offshore Oil Engineering Co., Ltd. and Guizhou Steel Rope Co., Ltd., aiming to provide CNOOC Shenzhen Branch with high-quality domestically produced mooring cables. The technical specifications clearly state that the wire rope structure is a single-strand wire rope with a nominal diameter of φ135mm, which becomes φ171mm after double-coating. The rotation angle is no greater than 0.72° / meter, meaning that a certain amount of torque is allowed in the single-strand wire rope. In principle, the lower the torque, the lower the torsional shear stress, the more stable the wire rope structure, and the longer the service life. This project requires a service life of no less than 20 years. In response to the special operating environment and technical requirements of FPSO mooring wire ropes, we conducted a comprehensive technical study on the structural design technology of wire ropes, combined reasonable design parameters, and obtained a zero-torque single-strand wire rope through thorough calculation and verification. This rope is fully applicable to FPSO mooring systems and can effectively avoid torsional shear stress generated when the wire rope is under load. Summary of the Invention

[0004] The present invention aims to design a twelve-layer single-strand steel wire rope with a 1×573 structure and a wire arrangement of (1-7-7+7-14)+20+26+32+37+43+49+55+61+66+72+76. The center strand has a 36WS structure with a wire arrangement of 1-7-7+7-14. Ultimately, through calculation, testing, and installation verification, this mooring single-strand steel wire rope exhibits zero torque and is highly suitable for FPSO mooring systems, thus extending their service life.

[0005] To solve the aforementioned zero-torque technical problem, the present invention adopts the following technical solution:

[0006] A zero-torque design method for a twelve-layer single-strand rope includes the following steps:

[0007] 1) Determine the number of steel wires:

[0008] Starting from the center strand, all wires from the second to the twelfth layer of rope have the same diameter. After the twelfth layer of rope is completed, the first and second sheaths are coated respectively. The second layer of rope has 20 wires twisted together. When twisting the third and fourth layers of rope, 6 wires are added to each layer. When twisting the fifth layer of rope, 5 wires are added to the fourth layer. When twisting the sixth, seventh, eighth, and ninth layers of rope, 6 wires are added to each layer. When twisting the tenth layer of rope, 5 wires are added to the ninth layer. When twisting the eleventh layer, 6 wires are added to the previous layer. When twisting the twelfth layer of rope, 4 wires are added to the previous layer. This design breaks the design rule of adjacent layers of point contact strands being composed of 2π.

[0009] 2) Determine the twist direction of each layer of rope:

[0010] The first layer is left-handed, the second layer is right-handed, the third layer is left-handed, the fourth and fifth layers are right-handed, the sixth to tenth layers alternate between left and right-handed, the eleventh layer is left-handed (i.e., the same as the tenth layer), and the twelfth layer is right-handed. This design breaks the design rule of opposite twist directions between adjacent layers of a single-strand wire rope, allowing adjacent layers to have the same twist direction.

[0011] 3) Determine the twist angle of each layer:

[0012] Based on the design of a single-strand wire rope with zero torque, the twist angles of each layer of wire rope should be reasonably matched. The twist angle of the outer layer from the center strand is 18°, the twist angles of the second to fourth layers are all 18°, the twist angle of the fifth layer is 19°, the twist angles of the sixth to ninth layers are 18°, the twist angle of the tenth layer is 19°, the twist angle of the eleventh layer is 18°, and the twist angle of the twelfth layer is 20°. This design breaks the rule that the twist angles of point contact strands are equal.

[0013] 4) Determine the strength and toughness values ​​of each layer of steel wire:

[0014] The design is based on the maximum breaking tensile force of a single-strand wire rope. Once the diameter of the single-strand wire rope is determined, all wires should reach their yield strength simultaneously under stress. The wire strength can be calculated to be 1920MPa. In addition, wires with the same twist angle layer have the same yield strength. For wires with different twist angle layers, the yield strength of the wires is adjusted according to the twist angle.

[0015] 5) Coating with medium-density plastic layer:

[0016] The first and second sheaths are coated separately. During the coating of the second sheath, a plastic marking line layer aligned with the axis of the single strand rope is embedded. After the product is manufactured, 3 to 4 points are selected along the axis of the single strand rope, each 50 to 60 mm apart, and 1 to 2 turns of tape are wrapped around them. Then, the angle between the plastic marking line layer and the circumferentially wrapped tape is measured with an angle ruler to verify the rotational performance of the single strand steel wire rope.

[0017] The single-strand steel wire rope has a structure of 1×573-Ф135mm / Ф171mm, with a total of twelve layers, and each layer is coated with two layers of medium-density polyethylene.

[0018] A method for verifying zero torque in a twelve-layer single-strand rope includes the following steps:

[0019] 1) Determine the rope core structure

[0020] According to technical requirements, the axial stiffness of a single-strand wire rope should meet the usage requirements. Selecting 1×7 or 1×19S as the core structure results in an excessively stiff single-strand wire rope that exceeds the axial stiffness requirement. Selecting 1×55SWS or 1×84WSNS as the core structure does not guarantee the structural stability of the single-strand wire rope and is not within the usage requirements. Through axial stiffness calculation and comparison, the 1×36WS structure is the most suitable for the usage requirements.

[0021] 2) Determine the number of wires in each layer of a single-strand wire rope.

[0022] The design is based on the strand composition rules of point-contact steel wire ropes: "The number of steel wires increases outwards by 2π in each layer, with the same wire specifications and lay angle." Technical requirements specify that the axial stiffness EA should be 1750 MN ± 20 MN. The bending stiffness of a single steel wire is expressed as a product (EI), where E is the elastic modulus of the steel wire (200 GPa), and I is the moment of inertia of the steel wire cross-section. For round steel wire, it is defined as: I = πd 4 / 64=0.049 d 4 d is the diameter of the steel wire in mm. The known elastic modulus is E = 1.55 × 10⁻⁶. 5MPa, a single strand of steel wire rope can reach 1.70×10 after repeated loading cycles. 5 MPa; After determining the core structure, the diameter of the remaining steel wires is the same. According to relevant international standards, the diameter of steel wires other than the core should not exceed φ5.00mm. When the steel wire diameter is φ5.00mm, the total number of steel wires should be between 560 and 580 to meet the axial stiffness requirements. When the total number of steel wires is 573, the axial stiffness EA=1720 MN; To ensure tightness and structural stability, there should be no interference between steel wires, the gap between steel wires in the same layer should not exceed 1 / 5 of its diameter, and there should be no protrusions. Using the trial and error method, the final set of twelve layers is the optimal total number of layers.

[0023] 3) Determine the strength of a single strand of wire rope and the lay angle of each layer.

[0024] Based on the design premise of zero torque and maximizing the breaking tensile strength of a single strand wire rope, and drawing on the structural rule of equal strand lay angles in point contact wire ropes, and given the total number of layers in a single strand wire rope, the breaking tensile strength of the single strand wire rope is required to be no less than 19180kN. Through calculation, the wire strength is found to be no less than 1920MPa. Based on the wire diameter and strength, the lay angle of each layer of the wire rope can be calculated and determined.

[0025] 4) Determine the toughness value of the steel wire

[0026] In single-strand steel wire ropes, due to the different lay angles, in order to maximize the breaking tensile strength of the entire wire rope, toughness indicators, namely the yield strength of the steel wire, are specified for steel wires with different lay angles of 18°, 19° and 20°. When under load, the larger the lay angle, the smaller the force, and the smaller the yield strength should be, and vice versa.

[0027] 5) Coated outer layer of medium-density polyethylene

[0028] Medium-density plastic coating is applied, followed by the application of the first and second sheaths. During the application of the second sheath, a plastic marking line is embedded along the axial direction of the single strand rope. After the product is manufactured, 3 to 4 points are selected along the axial direction of the single strand rope, each 50 to 60 mm apart, and 1 to 2 turns of tape are wrapped around the rope. The angle between the plastic marking line and the circumferentially wrapped tape is then measured with an angle gauge to verify the rotational performance of the single strand steel wire rope.

[0029] A second aspect of the present invention provides an application of the method described above in FPSO, floating wind power, and deep-sea aquaculture mooring and positioning systems.

[0030] The beneficial effects of adopting the above technical solution are:

[0031] This invention patent successfully designed a 1×573-Ф135mm galvanized aluminum rare earth alloy double-layer plastic-coated single-strand steel wire rope for FPSOs. After double-layer plastic coating, the diameter reaches Ф171mm, and its torque is verified to be 0. While ensuring the strength of the steel wire rope, its torsional performance far exceeds the relevant standards and design requirements, filling a domestic gap, expanding the company's steel wire rope varieties and application fields, laying a solid foundation for the localization of mooring steel wire ropes for FPSOs in my country, and playing a positive role in demonstrating my country's steel wire rope design technology strength. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the double-layer plastic-coated single-strand steel wire rope structure for FPSO of the present invention.

[0033] In the diagram: 1—Central strand; 2—Second layer rope; 3—Third layer rope; 4—Fourth layer rope; 5—Fifth layer rope; 6—Sixth layer rope; 7—Seventh layer rope; 8—Eighth layer rope; 9—Ninth layer rope; 10—Tenth layer rope; 11—Eleventh layer rope; 12—Twelfth layer rope; 13—First layer sheath; 14—Second layer sheath; 15—Plastic marking line layer; 16—Circumferential wrapping tape.

[0034] Figure 2 This is a partially enlarged schematic diagram of the double-layer plastic-coated single-strand steel wire rope for FPSO of the present invention.

[0035] Figure 3 This is a schematic diagram illustrating the rotational performance test of the double-layer plastic-coated single-strand steel wire rope used in the FPSO of this invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0037] A zero-torque design method for a twelve-layer single-strand rope includes the following steps:

[0038] 1) Determine the number of steel wires:

[0039] Starting from the center strand 1, all wires from the second layer rope 2 to the twelfth layer rope 12 have the same diameter. After completing the twelfth layer rope 12, the first layer sheath 13 and the second layer sheath 14 are coated respectively. The second layer rope 2 has 20 wires twisted together. When twisting the third layer rope 3 and the fourth layer rope 4, each layer increases by 6 wires based on the previous layer. When twisting the fifth layer rope 5, 5 wires are added to the fourth layer rope 4. When twisting the sixth layer rope 6, the seventh layer rope 7, the eighth layer rope 8, and the ninth layer rope 9, 6 wires are added to each layer based on the previous layer. When twisting the tenth layer rope 10, 5 wires are added to the ninth layer rope 9. When twisting the eleventh layer rope 11, 6 wires are added to the previous layer rope. When twisting the twelfth layer rope 12, 4 wires are added to the previous layer rope. This design breaks the design rule that adjacent layers of point contact strands are composed of 2π.

[0040] 2) Determine the twist direction of each layer of rope:

[0041] The first layer is left-handed (1), the second layer is right-handed (2), the third layer is left-handed (3), the fourth layer is right-handed (4), and the fifth layer is right-handed (5). The sixth layer is left-handed, the tenth layer is right-handed, and the eleventh layer is left-handed (11), which is the same as the tenth layer (10). The twelfth layer is right-handed (12). This design breaks the design rule that adjacent layers of a single-strand wire rope have opposite twist directions, allowing adjacent layers to have the same twist direction.

[0042] 3) Determine the twist angle of each layer:

[0043] Based on the design of a single-strand wire rope with zero torque, the lay angles of each layer of wire rope should be reasonably matched. The lay angle of the outer layer of the center strand 1 is 18°, the lay angles of the second layer rope 2 to the fourth layer rope 4 are all 18°, the lay angle of the fifth layer rope 5 is 19°, the lay angles of the sixth to ninth layers rope 9 are 18°, the lay angle of the tenth layer rope 10 is 19°, the lay angle of the eleventh layer rope 11 is 18°, and the lay angle of the twelfth layer rope 12 is 20°. This design breaks the rule that the lay angles of point contact strands are equal.

[0044] 4) Determine the strength and toughness values ​​of each layer of steel wire:

[0045] The design is based on the maximum breaking tensile force of a single-strand wire rope. Once the diameter of the single-strand wire rope is determined, all wires should reach their yield strength simultaneously under stress. The wire strength can be calculated to be 1920MPa. In addition, wires with the same twist angle layer have the same yield strength. For wires with different twist angle layers, the yield strength of the wires is adjusted according to the twist angle.

[0046] 5) Coating with medium-density plastic layer:

[0047] The first sheath 13 and the second sheath 14 are coated separately. At the same time, during the coating of the second sheath 14, a plastic marking line layer 15 is embedded along the axial direction of the single strand rope. After the product is manufactured, 3 to 4 points are selected along the axial direction of the single strand rope, each point is 50 to 60 mm apart, and tape is wrapped around the rope circumferentially 1 to 2 times. Then, the angle between the plastic marking line layer 15 and the circumferentially wrapped tape 16 is measured with an angle ruler to verify the rotation performance of the single strand steel wire rope.

[0048] The single-strand steel wire rope has a structure of 1×573-Ф135mm / Ф171mm, with a total of twelve layers, and each layer is coated with two layers of medium-density polyethylene.

[0049] A method for verifying zero torque in a twelve-layer single-strand rope includes the following steps:

[0050] 1) Determine the rope core structure

[0051] According to technical requirements, the axial stiffness of a single-strand wire rope should meet the usage requirements. Selecting 1×7 or 1×19S as the core structure results in an excessively stiff single-strand wire rope that exceeds the axial stiffness requirement. Selecting 1×55SWS or 1×84WSNS as the core structure does not guarantee the structural stability of the single-strand wire rope and is not within the usage requirements. Through axial stiffness calculation and comparison, the 1×36WS structure is the most suitable for the usage requirements.

[0052] 2) Determine the number of wires in each layer of a single-strand wire rope.

[0053] The design is based on the strand composition rules of point-contact steel wire ropes: "The number of steel wires increases outwards by 2π in each layer, with the same wire specifications and lay angle." Technical requirements specify that the axial stiffness EA should be 1750 MN ± 20 MN. The bending stiffness of a single steel wire is expressed as a product (EI), where E is the elastic modulus of the steel wire (200 GPa), and I is the moment of inertia of the steel wire cross-section. For round steel wire, it is defined as: I = πd 4 / 64=0.049 d 4 d is the diameter of the steel wire in mm. The known elastic modulus is E = 1.55 × 10⁻⁶. 5 MPa, a single strand of steel wire rope can reach 1.70×10 after repeated loading cycles. 5MPa; After determining the core structure, the diameter of the remaining steel wires is the same. According to relevant international standards, the diameter of steel wires other than the core should not exceed φ5.00mm. When the steel wire diameter is φ5.00mm, the total number of steel wires should be between 560 and 580 to meet the axial stiffness requirements. When the total number of steel wires is 573, the axial stiffness EA=1720 MN; To ensure tightness and structural stability, there should be no interference between steel wires, the gap between steel wires in the same layer should not exceed 1 / 5 of its diameter, and there should be no protrusions. Using the trial and error method, the final set of twelve layers is the optimal total number of layers.

[0054] 3) Determine the strength of a single strand of wire rope and the lay angle of each layer.

[0055] Based on the design premise of zero torque and maximizing the breaking tensile strength of a single strand wire rope, and drawing on the structural rule of equal strand lay angles in point contact wire ropes, and given the total number of layers in a single strand wire rope, the breaking tensile strength of the single strand wire rope is required to be no less than 19180kN. Through calculation, the wire strength is found to be no less than 1920MPa. Based on the wire diameter and strength, the lay angle of each layer of the wire rope can be calculated and determined.

[0056] 4) Determine the toughness value of the steel wire

[0057] In single-strand steel wire ropes, due to the different lay angles, in order to maximize the breaking tensile strength of the entire wire rope, toughness indicators, namely the yield strength of the steel wire, are specified for steel wires with different lay angles of 18°, 19° and 20°. When under load, the larger the lay angle, the smaller the force, and the smaller the yield strength should be, and vice versa.

[0058] 5) Coated outer layer of medium-density polyethylene

[0059] Medium-density plastic layers are coated, and the first sheath 13 and the second sheath 14 are coated respectively. At the same time, during the coating of the second sheath 14, a plastic marking line layer 15 is embedded along the axial direction of the single strand rope. After the product is manufactured, 3 to 4 points are selected along the axial direction of the single strand rope, each point is 50 to 60 mm apart, and tape is wrapped around them circumferentially 1 to 2 times. Then, the angle between the plastic marking line layer 15 and the circumferentially wrapped tape 16 is measured with an angle ruler to verify the rotation performance of the single strand steel wire rope.

[0060] A second aspect of the present invention provides an application of the method described above in FPSO, floating wind power, and deep-sea aquaculture mooring and positioning systems.

[0061] This invention provides a design and manufacturing process for a 1×573-Ф135mm / Ф171mm galvanized aluminum rare earth alloy double-layer plastic-coated single-strand steel wire rope. The breakthrough begins with an analysis of the wire rope's structural design concept: "Single-strand steel wire rope is a type of point-contact steel wire rope. In point-contact steel wire rope strands, the wire diameters are the same except for the center wire. They are layered and twisted, with each layer of wires twisted concentrically. Therefore, the difference between the outer circumference of the strand and the circumference of the adjacent inner layer is 2π times the wire diameter, approximately 6.28 times. In actual production, the number of wires can only be an integer. Therefore, the difference in the number of wires between two adjacent layers in a round-strand point-contact steel wire rope strand is always 6, and the twist direction of each layer is the same." Based on the structural rules of point-contact steel wire ropes, without affecting the forming and minimum breaking strength of the single-strand steel wire rope, the torque value of the single-strand steel wire rope can be reduced to 0 by adjusting the overall parameters of the twist angle, twist pitch, and twist direction of each layer, and by appropriately reducing the number of wires in a certain layer. Secondly, by adjusting the steel grade of the wires with different lay angles through heat treatment, coating, and drawing, all the load-bearing wires in the wire rope simultaneously reach the yield strength σs when under load, thus ensuring the overall tensile strength of the single-strand wire rope. Thirdly, the torsion angle of the single-strand wire rope is visually verified during the sheath manufacturing process. During plastic coating, an axial mark is used to verify the torsion angle of the single-strand wire rope. An angle gauge is used to measure the angle at multiple points along at least one meter of the single-strand rope length on a horizontal plane, comparing it with the circumferential mark of the single-strand rope. If the single-strand wire rope deflects, it will produce a certain torsion angle.

[0062] This invention addresses the characteristics of single-strand steel wire ropes: large specifications, multiple layers, high breaking strength, and resistance to rotation. It breaks away from the design conventions of point-contact steel wire ropes by calculating and adjusting the lay angle and lay distance parameters of each layer, rationally changing the lay direction, and employing methods with varying yield strengths of the steel wires. This approach ensures both the overall breaking strength of the single-strand steel wire rope and achieves a sum of zero torque within each strand. The single-strand steel wire rope is then twisted according to the design, and the result is verified to have a zero sum of torque during the sheath manufacturing process.

Claims

1. A method for manufacturing a twelve-layer single-strand rope with zero torque, characterized in that: It includes the following steps: 1) Determine the number of steel wires: Select a 1×36WS structure as the center strand (1). Starting from the center strand (1), all wires from the second layer rope (2) to the twelfth layer rope (12) have the same diameter, which is 5.00mm. After completing the twelfth layer rope (12), coat the first layer sheath (13) and the second layer sheath (14) respectively. The second layer rope (2) is twisted with 20 wires. When twisting the third layer rope (3) and the fourth layer rope (4), each layer increases by 6 wires based on the previous layer. Twisting the fifth layer rope (5) is done on the 1st layer rope. Five steel wires are added to the four-layer rope (4); when twisting the sixth layer rope (6), the seventh layer rope (7), the eighth layer rope (8), and the ninth layer rope (9), six steel wires are added to each layer based on the previous layer; the tenth layer rope (10) is made by adding five steel wires to the ninth layer rope (9), the eleventh layer rope (11) is made by adding six steel wires to the previous layer rope, and the twelfth layer rope (12) is made by adding four steel wires to the previous layer rope, breaking the design rule that adjacent layers of point contact strands are composed of 2π. 2) Determine the twist direction of each layer of rope: The first strand (1) is left-handed, the second layer (2) is right-handed, the third layer (3) is left-handed, the fourth layer (4) and the fifth layer (5) are both right-handed, the sixth layer (6) to the tenth layer (10) alternate between left-handed and right-handed twists, the eleventh layer (11) is left-handed, that is, the same as the twist direction of the tenth layer (10), and the twelfth layer (12) is right-handed; this breaks the design rule of opposite twist directions between adjacent layers of a single-strand wire rope, that is, it allows adjacent layers to have the same twist direction; 3) Determine the twist angle of each layer: Based on the design of a single-strand wire rope with a torque of 0, the twist angles of each layer of wire rope should be reasonably matched. The outer twist angle of the center strand (1) is 18°, the twist angles of the second layer rope (2) to the fourth layer rope (4) are all 18°, the twist angle of the fifth layer rope (5) is 19°, the twist angles of the sixth to ninth layers rope (9) are 18°, the twist angle of the tenth layer rope (10) is 19°, the twist angle of the eleventh layer rope (11) is 18°, and the twist angle of the twelfth layer rope (12) is 20°, breaking the rule that the twist angles of the point contact strands are equal; 4) Determine the strength and toughness values ​​of each layer of steel wire: The design is based on the maximum breaking tensile force of a single-strand wire rope. Once the diameter of the single-strand wire rope is determined, all wires should reach their yield strength simultaneously under stress. The wire strength can be calculated to be 1920MPa. In addition, wires with the same twist angle layer have the same yield strength. For wires with different twist angle layers, the yield strength of the wires is adjusted according to the twist angle. 5) Coating with medium-density polyethylene layer: The first sheath (13) and the second sheath (14) are coated respectively. At the same time, during the coating of the second sheath (14), a plastic marking line layer (15) aligned with the axis of the single strand rope is embedded. After the product is manufactured, 3 to 4 points are selected along the axis of the single strand rope, each point is 50 to 60 mm apart, and the tape is wrapped around the circumference 1 to 2 times. Then, the angle between the plastic marking line layer (15) and the circumferentially wrapped tape (16) is measured with an angle ruler to verify the rotation performance of the single strand steel wire rope. Both the first sheath (13) and the second sheath (14) are medium-density polyethylene; The single-strand steel wire rope structure is 1×573-Ф135mm / Ф171mm, with a total of twelve layers; Ф135mm is the diameter before coating, and Ф171mm is the diameter after coating.

2. The application of the twelve-layer single-strand rope manufactured according to the method described in claim 1 in FPSO, floating wind power, and deep-sea aquaculture mooring and positioning systems.

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