Pinned Composite Pipe End Fitting for Shear-Resistant Termination
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Solution Overview
Problem
Existing methods for terminating and connecting composite pipes to metal pipes in subsea hydrocarbon extraction face challenges due to differences in structural properties and thermal expansion, leading to reliability issues and potential fatigue failure, especially when using carbon fiber composite materials.
Innovation Solution
A composite pipe termination system featuring an annular part with a tapered exterior surface and pinning means that extend partially through the pipe wall thickness, providing additional resistance to shear loads without compromising pressure resistance, combined with an annular metal sleeve and locking mechanism for secure fluid communication and load transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an annular part of composite material with tapered exterior surface is attached around the composite pipe end, then structural integrity and resistance to shear loads are improved, but the complexity of the termination structure increases
Solution Approach 1:
The termination structure is segmented into distinct functional components: the composite pipe itself, an annular part of composite material attached to the pipe end, and pinning means that extend through the annular part. This segmentation allows each component to be optimized for its specific function while maintaining overall structural integrity.
Solution Approach 2:
The annular part incorporates a tapered exterior surface that varies in radial thickness, transitioning from a first radial thickness at the pipe end to a second, smaller radial thickness at the distal end. This dimensional variation in the radial direction creates a tapered geometry that enhances load distribution and structural performance without requiring excessive material.
2Reliability
If pinning means extend through the annular part and composite pipe wall, then connection reliability is improved, but pressure resistance may be compromised due to potential leakage paths
Solution Approach 1:
The pinning means act as intermediary elements that transfer loads between the annular part and the composite pipe wall. By extending through both components, the pins create a mechanically interlocked connection that enhances reliability while the composite material surrounding the pins maintains pressure containment.
3Adaptability or versatility
If different materials (composite and metal) are connected at the pipe end, then adaptability to standard steel pipe connections is improved, but structural reliability deteriorates due to thermal expansion differences
Solution Approach 1:
The annular part of composite material serves as an intermediary component between the composite pipe and any metal connection elements. This intermediate layer accommodates differential thermal expansion between composite and metal materials, preventing stress concentration and maintaining connection reliability across material interfaces.
Data Source
AI summary
A composite pipe termination is provided. The composite pipe includes a composite pipe wall thickness and a cut end. An annular part of composite material is attached around the outside of the composite pipe at the cut end. The annular part has a radial thickness which tapers towards the composite pipe in the direction along the composite pipe away from the cut end to provide an exterior surface having a tapered portion. A pinning structure includes one or more pins which extend through the annular part and partially through the composite pipe wall thickness to further attach the annular part to the composite pipe.