Modular VIV Suppression Strake Assembly for Roller Load Flexibility
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Solution Overview
Problem
Existing VIV suppression strakes for subsea pipelines face challenges in balancing the flexibility required for strake fins to withstand increased roller loads while maintaining the stiffness needed for the strake fin support shells to prevent deformation, particularly due to the contradictory material compatibility and assembly issues with adhesives and fasteners in corrosive environments.
Innovation Solution
A kit of parts comprising separate, modular strake fins and support shells made from different materials, where the strake fin is engineered for flexibility and the support shell for stiffness, with an aperture and anchor design allowing secure attachment without adhesives or fasteners, enabling easy assembly and resistance to external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the strake fin is made flexible to withstand roller loads, then the strake fin can bend and rebound while passing rollers, but the strake fin support shell requires increased stiffness to prevent deformation
Solution Approach 1:
The VIV suppression strake is divided into two separate components: a flexible strake fin and a stiff support shell. This segmentation allows each component to be optimized independently for its specific functional requirements without compromising the other.
Solution Approach 2:
Different parts of the assembly have different mechanical properties tailored to their specific functions. The strake fin is made flexible locally to accommodate roller passage, while the support shell is made stiff locally to maintain structural integrity and prevent wave pattern formation.
2Reliability
If adhesives or fasteners are used to attach the strake fin to the support shell, then the assembly is secure, but material compatibility issues arise in corrosive subsea environments
Solution Approach 1:
The attachment mechanism is extracted from chemical adhesives or metallic fasteners and replaced with a mechanical interlocking system using protrusions and recesses. This eliminates the need for materials that are susceptible to corrosion and compatibility issues in subsea environments.
Solution Approach 2:
The strake fin assembly is designed to be self-attaching through its own geometric features (protrusions and recesses) without requiring external adhesives, fasteners, or additional attachment materials. The structure attaches itself to the support shell through form-fit mechanical engagement.
3Strength
If the strake fin is made stiff to maintain structural integrity, then the support shell can be simpler, but the strake fin cannot bend while passing rollers
Solution Approach 1:
The system is segmented into a flexible strake fin and a stiff support shell, allowing the fin to bend during roller passage while the shell maintains structural integrity. After passing the roller, the fin rebounds to its original position, maintaining its structural function.
Solution Approach 2:
The strake fin is designed with dynamic flexibility to accommodate the transient loading conditions during roller passage. The fin can dynamically bend and rebound in response to roller contact, then return to its rigid operational state for VIV suppression.
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 simplifies assembly, enhances durability by avoiding material compatibility issues, and effectively suppresses vortex-induced vibrations by allowing flexible strake fins to bend and rebound while maintaining the stiffness of the support shells, thus improving the overall performance under increased loads.
Implementation Method 1
the fins are required to bend while passing the roller and rebound after passing the roller. In view thereof the fins are preferably engineered to be flexible.
Implementation Method 2
the strake fin support shell is preferably engineered to be stiff in order to prevent deformation of the strake fin support shell while passing a roller.
Implementation Method 3
the fin is provided at the fin base with an anchor, which anchor is configured for engaging the fin support shell on the pipe side of the aperture.
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The present invention relates to Vortex Induced Vibration (VIV) suppression strakes, in particular VIV suppression strakes that are arranged on subsea pipelines. The present invention provides a VIV suppression strake assembly (9, 11), comprising a strake fin support shell (23, 25) that is configured to be arranged against the outer surface of a section of pipe and at least one strake fin (15) having a fin tip (35) and a fin base (37). The strake fin support shell (23, 25) comprises an aperture (29) that is configured for inserting the fin (15) therein, and the fin (15) is provided at the fin base with an anchor (39), which anchor is configured for engaging the fin support shell (23, 25) on the pipe side of the aperture. Further, the aperture is a slot. Furthermore, the slot is dimensioned to allow the fin (15) to be inserted in the slot from the pipe side of the slot with the fin tip (35) leading until the fin base (37) engages the shell.