German Marine Bending Restrictor Case
A renowned German ship research institute, with long-term expertise in marine engineering equipment R&D, undertook a deepwater floating wind power project in the North Sea and required customized special bending protection equipment. In this project, offshore floating cables, as the core carrier for energy transmission, are continuously subjected to dynamic bending stresses caused by wave impacts, ocean current drag, and floating body attitude adjustments. Traditional metal bending limiters have drawbacks such as heavy weight, insufficient corrosion resistance, and low bending protection accuracy, failing to adapt to the complex deep-sea operating conditions. A customized solution featuring lightweight, high rigidity, and marine environment resistance was urgently needed.
Core Customization Requirements
Functional Positioning: Design a J-type middle tube sealing bending limiter for offshore floating cables to accurately limit the cable bending angle, avoiding insulation damage or conductor breakage due to excessive bending. Simultaneously, ensure the sealing performance of the J-type structure to prevent seawater from invading internal components.
Structural Requirements: Adopt a modular design for easy offshore installation and later maintenance/replacement. The connection between modules must adapt to the dynamic displacement characteristics of the floating platform to ensure continuous fitting protection.
Material Standards: The main material must have high rigidity and low creep properties, while meeting the requirements of salt spray corrosion resistance, low-temperature resistance (-20℃~50℃), and UV aging resistance in marine environments. Rigid polyurethane composite material was ultimately selected.
Solutions and Implementation
Optimized Material Ratio: Collaborated with material laboratories to adjust the formula of the rigid polyurethane composite material. Added glass fiber reinforcement phase to improve rigidity, and incorporated antioxidants and anti-corrosion additives to enhance weather resistance. Through multiple mechanical tests, the material's bending strength reached 85MPa, meeting the design requirement of ±2° bending limit accuracy.
Modular Structural Design: Adopted a combined structure of "J-type sealed cavity + segmented limiting module". The J-type middle tube sealing device is equipped with a lip seal ring to achieve IP68-level sealing. The limiting modules are spliced through tenon-and-mortise structures, and each module has a built-in arc-shaped guide groove to guide the cable to bend along a preset trajectory, avoiding local stress concentration.
Operating Condition Simulation and Verification: Built a deep-sea environment simulation chamber in the laboratory to simulate cyclic wave impacts, temperature cycles, and salt spray corrosion conditions. Conducted 100,000 dynamic bending fatigue tests on the bending limiter. The test results showed no attenuation in sealing performance, stable bending angle control accuracy, and no material cracking or aging.
Project Achievements
After the commissioning of this batch of customized polyurethane bending limiters, the bending failure rate of offshore floating cables dropped from 8.2% with the traditional scheme to 0.3%. The equipment maintenance cycle was extended to 24 months, and the weight was reduced by 40% compared with the metal scheme, significantly lowering offshore hoisting and installation costs. Meanwhile, the corrosion resistance of the rigid polyurethane composite material ensures an expected service life of 15 years for the equipment, far exceeding the project's 10-year design life requirement. It provides core equipment support for the stable operation of the North Sea deepwater floating wind power project and offers a reusable customized reference scheme for similar deep-sea cable protection projects.
If you are facing similar challenges in subsea cable protection or need customized marine engineering equipment solutions, feel free to contact us—we will tailor high-performance, reliable technical solutions based on your specific project requirements.
