Riser Assembly Rigid Buoyancy Support Deep Water
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Solution Overview
Problem
Flexible pipes used in deep and ultra-deep water environments face failure due to high tension loads from internal pressure and weight, and existing buoyancy aids can exacerbate compression loads, leading to riser failure, especially when operating beyond 6,500 feet in water depth.
Innovation Solution
A riser assembly with integrated or secured rigid buoyancy modules at junctions between flexible pipe segments, using a rigid buoyancy support to decouple topside dynamic loads and provide buoyancy, allowing for secure attachment of buoyancy elements via clamping, welding, or mechanical fastening, utilizing materials like syntactic foam or steel tanks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If buoyancy aids are added to alleviate high tension loads, then the pipe can withstand tension better, but compression loads increase leading to potential failure
Solution Approach 1:
The riser is divided into multiple pipe segments with rigid buoyancy supports positioned at the junctions between segments. This segmentation allows the buoyancy force to be applied at discrete locations rather than continuously, providing tension relief while minimizing compression on any single pipe section.
Solution Approach 2:
Rigid buoyancy supports act as intermediary structures between the flexible pipe segments. These supports provide a stable platform for attaching buoyancy aids while protecting the flexible pipe body from direct compression loads and mechanical damage.
2Ease of manufacture
If clamps are used to secure buoyancy modules, then buoyancy can be attached to the riser, but compression loads are induced on the pipe body
Solution Approach 1:
The rigid buoyancy support serves as an intermediary structure that receives the clamping force from buoyancy module attachments. By positioning this rigid support at the junction between pipe segments, the compression load is transferred to the rigid structure rather than being applied directly to the flexible pipe body, which is better suited to handle such localized compressive forces.
3Ease of operation
If free-hanging riser configuration is used, then installation is simpler, but high tension loads from pipe weight cause failure in deep water
Solution Approach 1:
Rigid buoyancy supports providing buoyant elements are positioned at strategic junctions along the riser to provide upward buoyant forces that counterbalance the downward weight of the pipe and its contents. This reduces the net tension load on the flexible pipe, enabling operation in deep water where weight-induced tension would otherwise cause failure.
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
The solution enables the flexible pipe to withstand combined high internal pressure and tension loads, maintaining structural integrity and reliability by distributing buoyancy effectively, reducing compression loads and preventing buoyancy module movement, thus enabling operation in water depths up to 10,000 feet.
Implementation Method 1
a rigid buoyancy support for providing at least one buoyancy element at said support
Data Source
AI summary
A riser assembly and method for providing buoyancy to a riser assembly are disclosed. The riser assembly which is of the type for transporting fluids from a sub-sea flowline to a floating structure comprises a first segment of flexible pipe, a further segment of flexible pipe and a rigid buoyancy support for providing at least one buoyancy element at the support.