Composite Pipe End-Fitting With Interlocking Collet Seal
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Solution Overview
Problem
The challenge lies in effectively terminating composite pipes, particularly those made of fibre-reinforced thermoplastic polymer, to non-composite steel piping and apparatus, ensuring a reliable structural and sealing connection while withstanding harsh conditions and axial and torsional forces, and maintaining a small diameter.
Innovation Solution
A composite pipe termination design featuring a composite pipe with an annular portion having circumferentially extending ridges, a collet with grooves, an annular collar, and locking means, which together prevent axial movement and provide a secure connection to an end-fitting, utilizing thermoplastic polymer and reinforcing fibers like carbon or glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel end-fitting is attached to a composite pipe, then a structural connection is achieved, but the different structural properties and thermal expansion differences create challenges for reliable structural and sealing connection
Solution Approach 1:
The patent introduces a composite transition piece as an intermediary component between the steel end-fitting and the composite pipe. This transition piece has a first end with external threading for engagement with the steel fitting and a second end that is substantially composite in construction for integration with the composite pipe. This intermediary structure bridges the structural and thermal expansion property differences between steel and composite materials, enabling both reliable structural connection and sealing without direct steel-to-composite attachment challenges
Solution Approach 2:
The transition piece utilizes composite materials construction at its second end to match the composite pipe's material properties. This allows the transition piece to exhibit similar thermal expansion characteristics and structural behavior as the composite pipe, while the first end provides steel-compatible threading. The use of composite materials in the transition piece resolves the contradiction by providing a material bridge that maintains both structural integrity and sealing reliability across the steel-composite interface
2Ease of operation
If the pipe termination diameter is increased to accommodate connection features, then connection capability is improved, but the diameter becomes significantly larger than the pipe diameter
Solution Approach 1:
The patent employs threading features that extend axially along the first end of the transition piece rather than requiring radial expansion. The external threading allows for secure engagement with steel end-fittings while maintaining a compact radial profile. This dimensional approach to connection design enables robust connectability without significantly increasing the termination diameter beyond the pipe diameter
Solution Approach 2:
The transition piece features localized threading and connection elements concentrated at the first end, while the second end maintains a compact profile matching the pipe diameter. The connection capability is achieved through localized structural features (threading, sealing surfaces) rather than uniform diameter expansion. This local quality approach allows the termination to provide excellent connection capability at the interface while keeping the overall termination diameter minimal and close to the pipe diameter
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 design ensures a reliable, sealed connection that withstands harsh conditions and axial forces, maintaining a small diameter, thus addressing the challenges of connecting composite pipes to steel piping.
Implementation Method 1
the external surface comprises circumferentially extending ridges; a collet having an interior collet surface, wherein the collet encloses at least a part of the annular portion and wherein the interior collet surface comprises circumferentially extending grooves, and wherein circumferentially extending ridges on the external surface of the annular portion mesh with circumferentially extending grooves on the interior collet surface to provide axial movement blocking means which prevent or limit axial movement of the collet relative to the annular portion
Implementation Method 2
a liner, wherein the interior pipe surface is fused to the liner; These pipes may be manufactured by winding tapes of composite material onto a pipe liner and fusing them thereto
Data Source
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) a composite annular portion attached to the exterior pipe surface, the external surface of the annular portion comprising circumferentially extending ridges; c) a collet having an interior collet surface, wherein the collet encloses at least a part of the annular portion and wherein the interior collet surface comprises circumferentially extending grooves, and wherein circumferentially extending ridges on the external surface of the annular portion mesh with circumferentially extending grooves on the interior collet surface to provide axial movement blocking means; d) an annular collar which encloses and mates with the collet to prevent the collet from moving axially relative to the annular collar; e) an end-fitting locked to the annular collar.