Monopile Upending With Variable-Length Rigging and Fixed Pivot
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Solution Overview
Problem
Existing methods for upending bulky elongate structures like monopiles are limited by the height restrictions of installation vessels, load capacity, and the complexity of controlling buoyancy, leading to inefficiencies and risks in installation processes, especially for extra-extra-large monopiles.
Innovation Solution
A lifting arrangement using rigging elements connected to the structure at spaced connection axes, with a variable-length element and a frame-supported winch, allowing controlled upending by pivoting around a fixed pivot axis, reducing the weight burden on the winch and enabling a single lift operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a monopile is longer than the height available between the crane hook and the water surface, then transporting and installing the monopile by conventional method is not possible, but the invention enables upending of extra-extra-large monopiles by providing a pivot axis and controlled pivoting motion
Solution Approach 1:
The invention transitions from vertical lifting to a pivoting motion around a horizontally extending pivot axis. By changing the dimension of motion from vertical to rotational, the system can accommodate monopiles longer than the vessel height, as the monopile pivots horizontally rather than being lifted vertically the entire length.
Solution Approach 2:
The lifting operation is segmented into two distinct phases: first lifting one end of the monopile to create a pivot point, then rotating the monopile around this pivot axis. This segmentation allows the monopile to be positioned and stabilized incrementally rather than requiring single-step vertical placement.
2Reliability
If upending is performed by suspending between two cranes or winches, then the structure can be controlled, but the device complexity and risk increase due to synchronizing multiple heavy-lifting devices
Solution Approach 1:
The invention extracts one end of the monopile as a fixed pivot point that remains stationary during rotation. By taking this end out of the active lifting system and using it as a stable reference point, the complexity of coordinating multiple moving lifting devices is reduced, as only one end requires active winch control.
Solution Approach 2:
The pivot axis acts as an intermediary element that mediates between the stationary vessel and the moving monopile. This fixed reference point simplifies the control system by providing a stable rotation center, eliminating the need for complex synchronization between multiple moving cranes or winches.
3Ease of operation
If ballasting is used to upend the monopile in water, then upending can be achieved, but the manufacturing complexity and time increase due to installing and removing plugs
Solution Approach 1:
The invention replaces the ballasting mechanism (which requires hydraulic or mechanical plugs to control water intake) with a pure mechanical lifting system using a winch and pivot axis. This substitution eliminates the need for complex ballasting infrastructure, reducing manufacturing complexity and installation time.
Solution Approach 2:
The monopile is lifted and positioned in a controlled manner before being placed in the water. By performing the upending action preliminarily in air or at the water surface using the pivot axis mechanism, the system avoids the need for complex in-water ballasting operations and plug installation/removal.
4Force
If the winch capacity is increased to handle the full weight of the monopile, then the monopile can be lifted directly, but the cost and complexity increase significantly
Solution Approach 1:
The invention merges the functions of lifting and rotating into a single pivot-based mechanism. The winch only needs to provide enough force to lift one end of the monopile and control the rotation, rather than lifting the entire weight. This combining of functions reduces the required winch capacity while maintaining operational effectiveness.
Solution Approach 2:
The fixed pivot point acts as a counterweight or fulcrum that supports the majority of the monopile's weight during rotation. This mechanical advantage allows the winch to control the monopile's movement with minimal force, as the pivot point bears the static load while the winch only needs to overcome friction and control the rotational motion.
Data Source
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AI summary
A crane for upending an elongate structure such as a monopile supports elongate rigging elements that are connected to the structure at respective connection axes spaced longitudinally along the structure. At least one of those elements, of fixed length, extends to a first connection axis and at least one other of those elements, of variable length, extends to a second connection axis. A frame suspended from the crane supports a winch that pays out the variable-length element of the rigging to lengthen that element. This lowers the second connection axis relative to the first connection axis, which serves as a pivot axis about which the structure is upended.