Stepped Composite Pipe End-Fitting for Compact Steel Transitions
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Solution Overview
Problem
The challenge lies in effectively terminating composite pipes and connecting them reliably to non-composite, especially steel, piping and apparatus at both subsea and surface interfaces, while ensuring a reliable structural and sealing connection, and resisting axial and torsional forces, with a focus on maintaining a small diameter for the pipe termination.
Innovation Solution
A composite pipe termination design featuring a composite pipe with a fused liner, an annular portion with stepped regions, an annular collar with matching stepped portions, and locking means to prevent axial movement, along with sealing elements and metal end-fittings to ensure secure and sealed connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel end-fitting is attached to a composite pipe, then a reliable structural connection is achieved, but the sealing connection becomes challenging due to different structural properties and thermal expansion differences
Solution Approach 1:
The patent introduces a steel annular collar as an intermediary component between the composite pipe and the steel end-fitting. This collar acts as a mediator that bridges the two different materials, allowing the steel end-fitting to be securely attached while maintaining reliable sealing. The collar's steel construction enables it to interface with both the composite pipe through mechanical attachment and the steel end-fitting through threaded connections, thus resolving the incompatibility between different structural properties and thermal expansion characteristics.
Solution Approach 2:
The solution employs a composite structure combining different materials - the steel annular collar attached to the composite pipe, and the steel end-fitting with threaded connections. This composite approach allows each component to be optimized for its specific function: the collar provides a stable base for attachment, while the threaded end-fitting ensures secure connection and sealing, thereby achieving both structural strength and sealing reliability despite material differences.
2Reliability
If the pipe termination diameter is increased to accommodate connection components, then reliable connection to steel piping is achieved, but the diameter becomes significantly larger than the pipe diameter
Solution Approach 1:
The patent resolves the diameter constraint by transitioning from a radial expansion approach to an axial extension approach. Instead of increasing the pipe termination diameter radially, the solution extends the connection components axially - the steel annular collar is attached to the pipe end and extends axially, and the end-fitting threads axially onto the collar. This dimensional change allows reliable connection to steel piping while maintaining a compact radial profile that does not significantly exceed the original pipe diameter.
3Force
If locking means are added to prevent axial movement, then axial force resistance is improved, but the device complexity increases
Solution Approach 1:
The patent merges the locking function with the existing structural components rather than adding separate locking mechanisms. The steel annular collar and end-fitting are designed with integrated threading that inherently provides axial locking capability. The threaded connection itself serves dual purposes: securing the end-fitting to the collar and preventing axial movement. This merging of functions achieves improved axial force resistance without significantly increasing device complexity, as the locking capability is built into the basic structural design.
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 provides a reliable transition from composite to steel pipes, effectively resisting axial and torsional forces, maintaining a small diameter, and enhancing sealing capabilities under harsh conditions.
Implementation Method 1
a liner, wherein the interior pipe surface is fused to the liner
Data Source
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AI summary
A composite pipe termination is provided, comprising: a) a composite pipe having an interior pipe surface, an exterior pipe surface, a pipe end and a liner b) an annular portion of composite material attached to the exterior pipe surface, the annular portion comprising a first stepped region in which the annular portion decreases in radial thickness in the axial direction away from the pipe end by means of at least one step; c) an annular collar enclosing the first stepped region; d) an end-fitting interfacing with the annular portion and locked to the annular collar; the annular collar comprises a stepped portion in which the annular collar increases in radial thickness in the axial direction away from the pipe end by means of the same number of steps as are comprised in the first stepped region, wherein step(s) of the stepped portion mate with step(s) of the first stepped region.