Subsea Riser Tubular Sections for Current-Induced Vibration Damping
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Solution Overview
Problem
Subsea tubular systems, such as risers and flowlines, face significant challenges in managing vibrations induced by subsea currents, which can lead to reduced system lifespan and potential failure due to the difficulty in predicting and modeling these dynamic conditions.
Innovation Solution
The integration of vibration damping tubular sections made of a second material, such as titanium or nickel alloys, interposed between conventional tubular sections to form part of the flow path, altering the dynamic properties of the system and reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy steel alloys are used along the entire length of the riser, then the system can resist considerable stresses from subsea currents, but the system becomes excessively heavy and may still fail during periods of significant vibration
Solution Approach 1:
The riser system incorporates sections of different materials at different locations. Heavy steel alloy sections are used where structural strength is critical, while sections made of materials with vibration-damping properties (such as titanium or nickel alloys) are strategically placed in areas prone to vibration. This localized differentiation allows the system to resist stresses without requiring heavy materials throughout the entire length, thereby reducing overall weight while maintaining strength where needed.
Solution Approach 2:
The riser system is constructed as a composite structure combining multiple materials with different properties. By integrating sections of heavy steel alloy with sections of vibration-damping materials (titanium, nickel alloys, or other suitable materials), the system achieves both the strength required to resist considerable stresses and the vibration-damping characteristics needed to reduce dynamic loads during current-induced oscillations, effectively resolving the contradiction between strength and weight.
2Reliability
If the riser is designed to withstand maximum possible stresses, then reliability is improved, but the system complexity and cost increase due to overbuilding
Solution Approach 1:
Rather than uniformly overbuilding the entire riser system to withstand maximum stresses, the design applies different material properties to different sections based on their specific functional requirements and vibration exposure. This localized approach ensures reliability in critical areas while avoiding the unnecessary complexity and cost of over-engineering sections that are less susceptible to vibration or stress.
Solution Approach 2:
The composite construction using heavy steel alloy sections combined with vibration-damping material sections creates a system that achieves high reliability through material diversity rather than uniform over-engineering. This approach simplifies the overall design by allowing each section to be optimized for its specific role, reducing the complexity associated with designing a uniformly heavy-duty system while maintaining the reliability needed to prevent failure during periods of significant vibration.
3Ease of manufacture
If conventional uniform material sections are used throughout the riser, then manufacturing is simplified, but the system cannot effectively damp vibrations caused by resonant frequencies
Solution Approach 1:
The riser system incorporates sections of different materials at different locations. Heavy steel alloy sections are used where structural strength is critical, while sections made of materials with vibration-damping properties (such as titanium or nickel alloys) are strategically placed in areas prone to vibration. This localized differentiation allows the system to resist stresses without requiring heavy materials throughout the entire length, thereby reducing overall weight while maintaining strength where needed.
Solution Approach 2:
The riser system is constructed as a composite structure combining multiple materials with different properties. By integrating sections of heavy steel alloy with sections of vibration-damping materials (titanium, nickel alloys, or other suitable materials), the system achieves both the strength required to resist considerable stresses and the vibration-damping characteristics needed to reduce dynamic loads during current-induced oscillations, effectively resolving the contradiction between strength and weight.
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 approach effectively reduces loading and stresses caused by vibrations and movement, allowing for the use of lighter and less costly materials in the conventional sections, thereby extending the system's lifespan and reducing the risk of failure.
Implementation Method 1
The second material has mechanical properties that damp vibration of the tubular system when subjected to underwater currents
Data Source
AI summary
A subsea tubular system comprises extended sections of a first material and interposed sections of a second, different material that aids in damping vibration resulting from subsea dynamic conditions such as current. The vibration damping sections may make up a portion of the overall system significantly less than the sections of the first material. The number, length, and positions of the vibration damping sections may be selected based on factors such as the diameter, overall length, profile, and so forth. The system may be used as a riser or other conduit for the production of minerals such as oil and gas.