Multi-Clamp Pipe Support for Deepwater Pipe-Lay Fatigue Control
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Solution Overview
Problem
Deep water pipelines experience high axial and bending stresses during pipe-lay from rolling and pitching vessels, leading to fatigue damage, which limits the duration the pipe can be held in a clamp and increases project costs due to the need for larger, more stable vessels.
Innovation Solution
A dual clamp system is employed, where a lower clamp handles axial loads and an upper clamp manages bending moments, with actuators allowing relative movement between the clamps to distribute stress effectively, and variable stiffness spring layers in the clamps to mitigate bending stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single rigid pipe clamp is used to hold the pipeline during pipe-lay, then the pipe can be securely supported, but high bending stresses are generated in the pipe due to vessel roll and pitch motions
Solution Approach 1:
The single rigid clamp is divided into multiple separate clamps (typically three clamps arranged in a triangular pattern). Each clamp independently supports the pipe, distributing the support function across multiple locations. This segmentation reduces the bending moment at any single location and allows the pipe to rotate slightly as a rigid body without generating high stresses in any one clamp or pipe section.
Solution Approach 2:
The multiple clamps work together to provide both support and stress distribution functions. Each clamp not only supports the pipe weight but also contributes to reducing bending stresses by providing distributed support points that allow the pipe to accommodate vessel motions more gracefully.
2Reliability
If the pipe is held rigidly in a pipe clamp, then support stability is achieved, but fatigue damage occurs due to cyclic bending stresses from vessel motions
Solution Approach 1:
By using multiple clamps instead of a single rigid clamp, the system provides stable support while distributing the cyclic loading across multiple locations. This reduces the stress concentration and fatigue damage at any single point, allowing the pipe to be held in the clamp for longer durations without exceeding fatigue limits.
3Reliability
If larger, more stable vessels are used to reduce pipe fatigue damage, then pipe integrity is maintained, but project costs increase due to higher day rates
Solution Approach 1:
The multiple clamp configuration allows smaller, less stable vessels to perform deep water pipe-lay operations by distributing the support and reducing cyclic stresses on the pipe. This eliminates the requirement for large, expensive stabilised vessels while maintaining pipe integrity and reducing project costs.
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 reduces fatigue damage to the pipe by minimizing tensile bending stresses, allowing smaller, less costly vessels to be used for deep water pipe-lay operations while maintaining the integrity of the pipeline.
Implementation Method 1
variable stiffness spring layers in the clamps to mitigate bending stresses
Data Source
AI summary
The present invention relates to an apparatus for and a method of holding high top tension pipeline (101) during pipe-lay from a rolling and pitching vessel (730). In one implementation, a clamp system (711, 712) for supporting a pipe on a vessel includes a first clamp for coupling to the pipe and a second clamp for coupling to the pipe. The second clamp is disposed above the first clamp. At least one of the first clamp or the second clamp is movable relative to the other of the first clamp or the second clamp.