Subsea Pipeline Clamp Assembly Using Weld Shrinkage Compression
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Solution Overview
Problem
Conventional pipeline clamps for subsea applications face challenges such as high cost, complexity, and stress generation due to bulkiness and the need for bolted connections, which can fail over time, especially in deep underwater environments, and require costly forged pieces and complex welding processes.
Innovation Solution
A method involving clamp parts with a part-circular cross-section cradle and shells that are welded with a gap to allow shrinkage, compressing the pipeline without direct welding or bolted connections, using weld shrinkage to exert a strong mechanical clamping force radially inward.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction clamps are made lengthy to maximise contact area, then grip on pipeline is improved, but bulk and cost increase
Solution Approach 1:
The clamp utilizes the phase transition of weld metal from molten state to solid state, exploiting thermal contraction during cooling to generate clamping force. This eliminates the need for lengthy friction-based clamps by using a different physical mechanism (thermal contraction rather than friction) to achieve secure attachment.
Solution Approach 2:
The invention replaces the mechanical friction-based clamping system with a thermal-welding-based system. Instead of relying on friction between clamp surfaces and pipeline, the system uses weld deposition and subsequent thermal contraction to create a secure mechanical bond, substituting one physical principle for another more efficient one.
2Ease of manufacture
If bolted clamps are used to secure pipeline, then ease of assembly is improved, but reliability deteriorates due to creep and inconsistent clamping force
Solution Approach 1:
The invention replaces the bolted mechanical connection system with a direct weld-based system. Instead of using bolts and nuts that are prone to creep and loosening, the clamp is directly welded to the pipeline, creating a permanent, reliable connection that eliminates clamping force inconsistency over time.
Solution Approach 2:
The clamp structure and pipeline are merged through direct welding, eliminating the separate fastening components (bolts, nuts, washers) that characterize bolted connections. This integration creates a unified structural element that maintains consistent mechanical properties throughout the service life.
3Stability of the object's composition
If clamps are made rigid to provide stable support, then stability is improved, but stress in pipeline increases due to restricted bending freedom
Solution Approach 1:
The clamp transitions from a static rigid structure to a dynamic system that adapts to pipeline movement. The weld-based connection allows the clamp to move with the pipeline during thermal expansion and contraction, maintaining stability while accommodating dimensional changes without generating excessive stress.
4Strength
If direct welding to pipeline is performed to secure clamp, then strength is improved, but complexity and cost increase due to forged pieces and specialized welding
Solution Approach 1:
The welding process is segmented into two distinct stages: first welding the clamp to the support structure, then welding the pipeline to the clamp. This segmentation allows each welding operation to be optimized independently and simplifies the overall process by breaking down the complex multi-step procedure into manageable, sequential tasks.
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 method provides a secure, cost-effective, and simple solution for fixing pipelines to structures or items to pipelines, ensuring consistent clamping force without enlarging the clamp or requiring direct welding to the pipeline, reducing stress and complexity.
Implementation Method 1
cooling and shrinking the or each weld to draw together, and to compress the pipeline between, the clamp parts
Data Source
Figure 1
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AI summary
A method of fixing a clamp around a pipe comprises supporting the pipe between curved clamp parts, namely a cradle and shells, that are assembled in mutual opposition about the pipe while fabricating the clamp. By placing the pipe into the cradle and then bringing the shells into contact with the pipe, those opposed clamp parts are simultaneously in contact with the pipe. Initially, a gap is maintained at an interface between the clamp parts. A full penetration weld is then formed in the gap. As the weld cools and shrinks, the clamp parts are drawn together, to a mutual spacing narrower than the original gap, to compress the pipe between them. The clamp is suitable for attaching the pipe to a structure such as the frame of a subsea pipeline accessory, for example a valve in fluid communication with the pipe.