In offshore oil and gas transfer operations, the Catenary Anchor Leg Mooring (CALM) system is a critical piece of equipment for nearshore crude oil loading and unloading. The system relies on the coordinated operation of three core units—the buoy mooring mechanism, surface floating hoses, and underwater transfer hoses—to ensure the stable transfer of fluids between tankers and onshore storage tanks. Zebung Plastic Technology has long specialized in the R&D and manufacturing of marine flexible hoses, creating specialized oil transfer hoses tailored to CALM operating conditions. Through differentiated structural designs and high safety standards, the company establishes a robust safety barrier for offshore energy transport.
● Hose Solutions for the Three Core Units
1. Surface Floating Hoses: Diverse Hose Types for Tanker Connection
Surface floating hoses serve as the vital link between the tanker and the buoy transfer unit. The complete hose assembly includes rail hoses, tail hoses, reducer hoses, main hoses, and single-end reinforced semi-floating hoses; configurations—whether single-line or multi-line—can be flexibly adjusted based on tanker tonnage and flow rate requirements. The products feature two structural systems: single-carcass and double-carcass. The double-carcass hose utilizes an innovative “pipe-in-pipe” nested structure, featuring an additional protective secondary carcass on the outside and an integrated real-time leak monitoring module. In the event of damage or leakage in the primary carcass, the system issues an immediate warning; the outer carcass maintains the seal, effectively preventing marine oil pollution accidents at the source. All floating hoses comply with international industry standards and support project-specific customization to adapt to the wind, wave, and current conditions of different marine environments.
2. Buoy and Mooring Support System
The core buoy of the CALM system features a low-profile cylindrical design, topped with a 360° rotating turntable and a centrally mounted Fluid Transfer Unit (PDU) that enables unobstructed rotation via heavy-duty bearings. The buoy is anchored to the seabed via multiple radial catenary anchor chains; the tension from these chains stabilizes the buoy’s position and limits drift. The buoy allows the tanker to rotate freely in response to wind, waves, and currents, significantly reducing stress on mooring lines and minimizing equipment wear. Zebung hoses integrate seamlessly with the buoy’s turntable interface, ensuring a secure, leak-proof transfer process under dynamic operating conditions.
3. Subsea Hoses: Highly Durable Double-Carcass Structure Reduces O&M Costs
Subsea hoses are buried deep in the seabed; replacement is difficult and costly, necessitating strict standards for strength and service life. Consequently, the industry generally favors subsea hoses with a double-carcass structure. Current mainstream installation configurations include the free S-shape, small-angle S-shape, and “Chinese lantern” layouts. The lantern configuration reduces the total pipeline length and prevents collisions or abrasion between lines, while S-shaped layouts are typically used in conjunction with surface floating hoses, making them suitable for dynamic floating operations in shallow water. Drawing on extensive practical experience in offshore projects, Zebung customizes installation plans based on water depth, currents, and seabed topography to extend pipeline service life and significantly cut future maintenance and replacement costs.
● Complete Oil and Gas Transfer Workflow
Upon arrival at the operational site, the tanker is secured to the buoy’s rotating turntable via mooring lines, and floating hoses establish a transfer channel between the vessel and the buoy’s PDU (Pipeline Distribution Unit). Oil and gas flow through the subsea hoses at the base of the buoy into the seabed manifold network, eventually reaching onshore storage tanks. The buoy’s full-rotation capability counteracts lateral loads caused by wind, waves, and currents, preventing pipeline tension, twisting, or damage, and ensuring continuous, all-weather transfer operations.
● Industry Outlook
With its modular architecture and design optimized for dynamic adaptability, the CALM (Catenary Anchor Leg Mooring) system stands as the most technologically mature and widely implemented offshore oil and gas transfer solution in the single-point mooring sector. Zebung Plastic Technology remains deeply committed to the technological evolution of flexible marine pipelines, pursuing a strategy that integrates standardized production with customized R&D. The company consistently delivers highly reliable, long-lasting flexible hoses for offshore oil and gas transport, leveraging technological innovation to drive the safe, efficient, and green development of the global offshore oil and gas industry.
Post time: Sep-28-2026