Subsea Pipeline Bending Restrictor for Ovality Control
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Solution Overview
Problem
Subsea pipelines face challenges in bending beyond elastic limits due to hydrostatic pressures and ovalization, which can lead to deformation, collapse, and hinder fluid flow, while existing solutions either fail to control bending effectively or increase pipeline thickness, complicating installation.
Innovation Solution
A bending restrictor assembly with annular members that translate along the pipeline to allow bending beyond elastic limits, restraining ovality and enhancing strength, using overlying pipe sections with flanges and annular members to secure and translate relative to the pipeline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pipeline wall thickness is increased to resist hydrostatic pressure and prevent ovalization during bending, then the pipeline strength and resistance to collapse improve, but the ease of bending the pipeline beyond elastic limits deteriorates and installation becomes more difficult
Solution Approach 1:
The bending restrictor assembly divides the pipeline into distinct functional zones: a thick-walled section for strength and a thin-walled section for controlled bending. The assembly includes a thick-walled pipe section with end collars, and a thin-walled pipe section with annular members that can translate during bending, allowing each segment to serve its specific purpose
Solution Approach 2:
Different wall thicknesses are applied to different portions of the pipeline based on local requirements. The end sections have thicker walls to resist hydrostatic pressure and provide structural strength, while the middle bending section has thinner walls to allow controlled plastic deformation and bending beyond elastic limits
2Adaptability or versatility
If the pipeline is allowed to bend freely to accommodate sea floor contours, then the pipeline can span uneven terrain, but excessive bending occurs causing permanent deformation, buckling, or uncontrolled cold bending
Solution Approach 1:
The bending restrictor assembly acts as an intermediary device between the pipeline and the sea floor contours. It provides controlled resistance to bending through translatable annular members and keyway-pin mechanisms, allowing the pipeline to adapt to terrain while preventing uncontrolled deformation and maintaining structural integrity
Solution Approach 2:
The assembly controls the bending parameter by allowing translation of annular members along the pipeline axis during bending. The keyway-pin mechanism changes the geometric parameters of the bending restrictor, enabling controlled plastic deformation while maintaining reliability through predetermined bending paths
3Stability of the object's composition
If a weight coating is applied to achieve negative buoyancy, then the pipeline can be submerged and maintain stability against sea current, but plastic deformation causes the concrete coating to crack and break loose
Solution Approach 1:
The pipeline is segmented into thick-walled and thin-walled sections, allowing the thin-walled bending section to deform plastically without damaging the weight coating, while the thick-walled sections provide structural support to prevent coating failure in non-bending areas
4Shape
If the pipeline is bent at subsea location under hydrostatic pressure, then the desired bend configuration can be achieved, but the pipeline starts to ovalize and can collapse, preventing fluid flow and apparatus movement
Solution Approach 1:
The bending restrictor assembly serves as a mediator that prevents ovalization during bending. The annular members with inwardly extending surfaces contact the pipeline outer surface, maintaining circular cross-section geometry while allowing controlled bending to achieve the desired configuration without collapse
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
Enables controlled permanent bending of subsea pipelines, resisting hydrostatic pressures, and reducing ovalization, while maintaining structural integrity and facilitating installation with reduced thickness, thus enhancing pipeline strength and reducing costs.
Implementation Method 1
allow the pipeline section to bend beyond an elastic limit of the pipeline section so as to achieve a permanent bend
Implementation Method 2
restraining ovality and enhancing strength
Implementation Method 3
resisting hydrostatic pressures
Data Source
AI summary
A bending restrictor assembly for permanently bending and restraining ovality of the subsea pipeline has a pipeline section, a first overlying pipe section affixed to the pipeline section, a second overlying pipe section affixed to the pipeline section in spaced relation for the first overlying pipe section, and a plurality of annular members overlying the pipe section and positioned between the first and second overlying pipe sections. The plurality of annular members are translatable along the pipeline section as the pipeline section is bent so as to allow the pipeline section to bend beyond an elastic limit of the pipeline section so as to achieve a permanent bend of the pipeline section.