Jacket Structures

The Jacket Structure is a typical fixed-type offshore platform space truss structure. It is formed by assembling various steel pipe components through welding nodes. The structure is fixed to the seabed foundation by the leg piles and can stably bear various production, living, and drilling equipment modules on the upper part. It is the mainstream foundation form for oil and gas and offshore wind power projects in shallow water and medium-deep water areas. 

Application scenario

- Development of shallow to moderately deep water oil and gas fields: The conventional applicable water depth ranges from 30 to 200 meters, and the maximum applicable water depth for extreme conditions can reach 400 meters, covering most offshore oil and gas resource development scenarios.

- Foundation of fixed production platforms: As the core load-bearing foundation, it provides overall support and fixation for offshore fixed oil and gas production platforms.

- Support structure for living quarters/modules: It bears the upper-level supporting facilities such as the platform living quarters, process treatment modules, and electrical and instrument modules.

- Support structure for drilling platforms: It provides a stable foundation for offshore drilling operation platforms, ensuring the stability and safety of drilling operations.

- Offshore wind power foundation: As a jacket-type wind power foundation, it is widely used in the construction of offshore and moderately deep water offshore wind farms.

- Berthing/anchoring facilities: It can be used to build berthing and anchoring structures for offshore vessels, meeting the needs of vessel berthing and anchoring operations.

Structural composition

- Main Legs: Generally consist of 4 to 8 large-diameter steel pipes, serving as the core vertical load-bearing components of the derrick frame, responsible for bearing the self-weight of the upper structure, equipment loads, and various environmental loads.

- Horizontal Braces: Horizontal steel pipe components that connect each main leg, mainly used to transfer horizontal loads, regularizing the structural load-bearing system and enhancing the overall planar stiffness.

- Diagonal Braces: Adopting classic structures such as X-type and K-type, effectively enhancing the overall lateral stiffness and stability of the derrick frame, and resisting lateral forces generated by waves and ocean currents.

- Joints: Welded connection points where various tubular components intersect, being the most complex and stress-intensive key core part of the derrick frame structure, and a key focus for design and construction quality control.

- Pile Sleeves/Guides: Special guiding sleeve structures, used to guide the precise insertion of pile foundations into the seabed soil, achieving a secure connection and fixation of the derrick frame with the seabed foundation.

- Work Platforms: Supporting platform structures, providing working space for on-site construction, equipment maintenance, and daily operation and maintenance.

- Boat Landing/Bumpers: Special anti-collision docking components, meeting the safety docking requirements for maintenance vessels and operation vessels.

- Anode Supports: Exclusive supporting structure, used for installing sacrificial anode anti-corrosion devices, achieving cathodic anti-corrosion protection for the underwater structure of the derrick frame.

- Conductor Guides: Drilling pipe guiding structure, capable of precisely guiding the positioning of the drilling pipe, ensuring the smooth conduct of offshore drilling operations.

Core structural features

The entire jacket is constructed using circular steel pipe components, featuring a streamlined structure with excellent hydrodynamic performance. This design can effectively reduce the impact loads from waves and ocean currents on the structure. There is a significant stress concentration phenomenon in the structural node area, which is a key control point in the overall structural design, welding construction, and inspection acceptance. During operation, the structure needs to endure complex alternating loads such as ocean winds, ocean currents, and earthquakes for a long time. The structural durability and strength requirements are high. At the same time, the coordinated force and interaction mechanism between the jacket and the seabed pile foundation is the core difficulty and focus of the overall structural design, directly determining the overall stability and service life of the platform. 

With decades of experience in steel supply, Xin Yue Group has a clear advantage in providing high-strength steel supplies. It can offer shipbuilding high-strength structural steels such as AH36/DH36/EH36 (yield strength ≥ 355 MPa) to meet the strict requirements of the ship's material strength and toughness. These steels are suitable for ship hull plates, decks, and bulkhead structures. This includes:

Manufacturing of large-diameter welded steel pipes

- The pipeline systems inside the FPSO hull (ballast pipelines, fire protection pipelines, process pipelines)

- The riser system (Riser System) requires large-diameter, thick-walled steel pipes

- Spiral welded pipes (SSAW) and submerged arc welded pipes (LSAW) can both be applicable

Integrated anti-corrosion treatment

- The FPSO hull is exposed to the marine environment for a long time, and the anti-corrosion requirements are extremely high

- Xinyue can provide anti-corrosion solutions such as 3LPE external anti-corrosion, epoxy paint coating, and hot-sprayed aluminum

- The anti-corrosion of the waterline area and splash zone of the hull is a key technical requirement

Welding quality control

- EN 1090 EXC3 (Execution Level 3, the highest level) certification

- Meeting the strict welding quality requirements of the classification society

- High heat input welding for high-strength steel is possible

Corresponding product standards, material standards:

Marine engineering steel grade:

Welding and Inspection Standards:

Anticorrosion standards: