Offshore Jacket Installation Using Pre-Installed Pile Guides
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Solution Overview
Problem
Current methods for installing offshore support structures, such as those for wind turbines, are limited by the need for grouting operations and are sensitive to weather conditions, restricting installation periods and rates, and often require expensive and time-consuming vessel operations.
Innovation Solution
A pre-installation subframe with pile guide holes and angled installation points allows for pile and jacket leg engagement, enabling installation in varied weather conditions and eliminating the need for a standard pile guide template, using a Dynamically Positioned vessel, and incorporating quick-locking mechanisms for faster installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If grouting operations are performed at the same time as or soon after jacket structure emplacement, then strong permanent joints are created, but installation periods are restricted and weather sensitivity increases
Solution Approach 1:
The installation process is divided into distinct phases: first installing the jacket structure without grouting, then performing grouting operations separately later. This segmentation allows the jacket to be installed in a wider range of weather conditions while maintaining the requirement for strong joints through subsequent grouting.
Solution Approach 2:
The jacket structure is installed in advance without immediate grouting, allowing the structure to be emplaced in suitable weather conditions first, and then grouted at a later convenient time. This preliminary installation action separates the structural placement from the joint strengthening operation.
2Manufacturing precision
If standard pile guide templates are used for pile installation, then precise pile positioning is achieved, but installation time increases and vessel requirements increase
Solution Approach 1:
Installation points with conical guides are pre-attached to the jacket structure legs before offshore installation. These pre-positioned guides eliminate the need for separate pile guide templates, maintaining positioning precision while reducing installation time and vessel requirements.
Solution Approach 2:
The pile guiding function is merged with the jacket structure itself by incorporating conical guides into the installation points on the legs. This integration eliminates the need for separate guide templates and reduces the number of installation steps.
3Reliability
If jacket structures are installed in series with grouting operations, then structural integrity is ensured, but installation costs increase due to vessel time requirements
Solution Approach 1:
The installation process is segmented into jacket installation phase and grouting phase, allowing these operations to be performed at different times with different vessel configurations. This reduces the complexity and cost of vessel operations while maintaining structural integrity through subsequent grouting.
Solution Approach 2:
The jacket structure is installed preliminarily without immediate grouting, allowing for simpler vessel operations during installation. Grouting is then performed later when structural integrity can be ensured with potentially different or reduced vessel requirements.
4Manufacturing precision
If conical guides are provided at installation points, then jacket leg alignment is improved, but manufacturing complexity increases
Solution Approach 1:
The conical guide is segmented as a separate component that can be manufactured independently and then attached to the jacket structure legs. This allows the guide to be produced using simple forming processes and then bolted or welded to the leg, maintaining ease of manufacture while providing alignment precision.
Data Source
Figure 1~1b
Figure 2
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AI summary
Improved embodiments, apparatus and method relating to the manufacture and installation of offshore steel support structures,known as jackets, for Wind Turbine Generators, including transition pieces thereof.