Riser Assembly Tether System for Equal Tension Distribution
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Solution Overview
Problem
Current riser assembly tethered configurations face challenges in managing high tension loads, particularly in extreme environments, where tension can exceed the maximum design load of clamps, leading to potential failure and damage to the pipe, especially in deep and ultra-deep water conditions.
Innovation Solution
A riser assembly design where a first and second attachment element are connected via a tether element through a fixed structure, such as a pulley system, ensuring that the tension load at each attachment element remains substantially equal, allowing for higher total tension loads to be accommodated without clamp failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single tether clamp is used to restrain the riser at the lower section, then the riser motion can be reduced, but the tension load on the clamp can exceed the maximum design load, leading to potential clamp failure
Solution Approach 1:
The invention divides the single clamp into multiple clamps (first clamp and second clamp) positioned at different locations along the riser. Each clamp shares a portion of the total tension load, preventing any single clamp from experiencing excessive force that would exceed its design capacity and cause failure.
2Force
If multiple tether elements with respective clamps are used to tether different points along the riser, then the tension load at each clamp is reduced, but the device complexity increases
Solution Approach 1:
The invention introduces a tether element as an intermediary component that connects multiple clamps to a common anchor point on the seabed. This intermediary structure allows the tension load to be distributed across multiple clamps while maintaining a relatively simple overall system architecture, avoiding the need for complex independent tethering systems for each clamp.
3Stability of the object's composition
If the riser is tethered to restrain motion in severe environments, then the riser stability is improved, but the interaction between the pipe and sea bed can damage the outer polymer sheath, allowing corrosion to occur
Solution Approach 1:
By distributing the tethering points across multiple clamps at different locations along the riser, the system reduces the concentration of forces at any single touchdown zone. This segmentation of restraint points minimizes the intensity of interaction between the pipe and sea bed at each location, reducing abrasive damage to the polymer sheath while maintaining overall riser stability through the distributed tethering system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively distributes tension loads across multiple clamps, reducing the risk of clamp failure and enabling the riser assembly to handle tension loads of up to 100 Tonnes or more, while maintaining equal tension at each attachment point, thus enhancing the durability and reliability of the tethered riser system.
Implementation Method 1
a first and second attachment element are connected via a tether element through a fixed structure, such as a pulley system
Implementation Method 2
ensuring that the tension load at each attachment element remains substantially equal
Data Source
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AI summary
A riser assembly and method of installing a riser assembly are disclosed. The riser assembly includes a first attachment element connected to a first portion of flexible pipe and a second attachment element connected to a second portion of flexible pipe. The first attachment element and second attachment element are connected by at least one tether element, via a fixed structure in a configuration such that, in use, in response to movement of the first and second portions of flexible pipe, the tension load at any moment in time, at each attachment element, remains substantially equal.