Project Info
- Project Name: Tether Chain Replacement Hydraulic System
- Client Industry: Offshore Platforms and Ocean Engineering
- System operating pressure：30 MPa
- Pump flow：40 L/min
- Motor power：22 kW
- Tank capacity：1,000 L
- Third-Party Testing & Certification: Provided
Project Background
Our client required an integrated hydraulic system for subsea tether chain replacement from a vessel. During operation, the hydraulic cylinders would apply tensile force to a floating platform at a subsea depth of approximately 130 meters.
The project scope included one enclosed 22 kW hydraulic power unit, six large hydraulic cylinders, and three hydraulic hose reel machines. Among the six cylinders, two had a stroke of 5,000 mm and four had a stroke of 2,000 mm. Each hose reel machine was designed to accommodate up to 220 meters of hydraulic hose.
AISOAR commenced the project design on 23 July 2026, with all equipment required to be completed and ready for loading by 22 August 2026.
Customer Project Challenges
The fully submerged marine environment required the cylinders and exposed hydraulic connections to withstand prolonged seawater exposure while maintaining reliable operation. The system also had to hold the cylinders at the designated position for nearly one day and control the main operating cylinders simultaneously within the specified synchronization tolerance.
Manufacturing cylinders with a 300 mm bore, 200 mm rod, and strokes of up to 5,000 mm introduced additional challenges in long-stroke machining, component handling, assembly, and vertical installation. Integrating six cylinders, a hydraulic power unit, control manifold, long hydraulic hoses, and three large hose reel machines further increased the complexity of system coordination.
The entire process—from engineering and procurement to manufacturing, assembly, commissioning, and third-party inspection—had to be completed within only one month. This required multiple project stages to proceed in parallel while maintaining interface compatibility and inspection requirements.
Project Solution — Subsea Hydraulic Cylinder System
Flow Regulation and Distribution for Two-Cylinder Operation
A dedicated hydraulic valve manifold was used to regulate and distribute the flow between the two cylinder circuits. This configuration helps the two cylinders move simultaneously within the required tolerance and provides more controlled operation than a simple parallel circuit.
Corrosion-Resistant Hydraulic Cylinder Design
The hydraulic cylinders were treated with a special protective coating to improve corrosion resistance in the marine environment. Stainless-steel hydraulic tubing was integrated directly onto the cylinder body, reducing the number of separately installed external connections.
Each cylinder was also equipped with a customized stainless-steel counterbalance valve. The valve supports controlled movement and helps maintain the cylinder position during the extended load-holding stage.
Reinforced Hoses and Stainless-Steel Connections
The system uses corrosion-resistant hydraulic hoses reinforced with six layers of steel wire. Stainless-steel fittings connect the hydraulic lines, improving the durability of exposed connections under marine working conditions.
The hoses, fittings, cylinders, and hydraulic power unit were specified as an integrated circuit to ensure interface compatibility throughout the system.
Lifting Lugs for Vertical Handling
The cylinders are installed and operated vertically. Two lifting lugs were welded to each cylinder barrel to support movement, positioning, and assembly during vessel and offshore operations.
Matched Hydraulic Power Unit
The system is powered by a 22 kW hydraulic power unit with a pump flow of 40 L/min and a 1,000 L oil tank. The power unit, control manifold, cylinders, hoses, and fittings were designed as one coordinated solution based on the customer’s operating sequence and subsea application requirements.
Accelerated Engineering and Parallel Production
To meet the one-month delivery schedule, AISOAR established an accelerated project execution plan covering engineering, procurement, manufacturing, assembly, and testing. Design confirmation and material procurement were coordinated from the beginning, while cylinder machining, hydraulic power unit production, hose reel manufacturing, and control-system preparation were advanced in parallel.
Key components and interfaces were reviewed throughout production to reduce delays during final assembly. Once the individual equipment was completed, the hydraulic power unit, cylinders, valve manifold, hoses, fittings, and hose reel machines were integrated and commissioned as one coordinated system. This parallel workflow enabled the project to progress from technical design to completed delivery within the required schedule.
Project Result
AISOAR completed the entire project within the required one-month delivery period. The final scope included one enclosed 22 kW hydraulic power unit, six large hydraulic cylinders with a 300 mm bore and 200 mm rod, and three hydraulic hose reel machines designed for hoses up to 220 meters long. Among the six cylinders, two had a stroke of 5,500 mm and four had a stroke of 2,000 mm.
Despite the short schedule, large workpiece dimensions, long-stroke machining requirements, and system-integration complexity, production, assembly, commissioning, and inspection were completed in time for loading on the afternoon of 24 August 2026.
Before shipment, the completed hydraulic equipment was inspected by an independent third-party organization. An officially stamped inspection report was issued following the inspection, providing documented verification of the delivered equipment.
The successful completion of this project demonstrates AISOAR’s ability not only to develop customized hydraulic solutions, but also to coordinate engineering, manufacturing resources, system integration, and quality inspection for large-scale projects with demanding delivery schedules.
Need a Hydraulic Solution for an Offshore Project?
AISOAR develops customized hydraulic cylinders, hydraulic power units, valve manifolds, and integrated hydraulic systems for marine and offshore applications. Send us your required force, operating depth, cylinder dimensions, installation method, holding time, operating sequence, and environmental requirements for technical evaluation.
