Shape Memory Pipe Lining for Low-Elongation Compression Fit
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Solution Overview
Problem
Existing pipeline restoration methods, such as 'swage-lining', face issues like excessive axial elongation, mechanical failure, and post-installation creep, leading to incomplete lining and potential leaks, due to the inherent properties of polymeric materials used.
Innovation Solution
The use of shape memory polymer (SMP) pipes with a pipe tensioning mechanism and deformation tool mechanism to minimize axial elongation and achieve uniform deformation, allowing for a compression-fit bi-layer composite pipe structure that maintains pressure rating and leak integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a polymeric liner is pulled through a deformation die to reduce its diameter for swage-lining, then the liner can be inserted into the host pipe, but excessive axial elongation occurs leading to mechanical failure and post-installation creep
Solution Approach 1:
The patent applies temperature as a parameter change to modify the polymer material properties. By heating the SMP liner to its transition temperature, the material becomes more ductile and deformable, allowing diameter reduction with minimal axial elongation. The temperature parameter transformation enables the liner to undergo radial compression without excessive axial stretching, resolving the contradiction between shape change and length preservation.
Solution Approach 2:
The patent utilizes the phase transition of shape memory polymer from a rigid state to a soft, deformable state through temperature-induced transition. During installation, the SMP liner is heated to transition to a compliant phase that allows easy deformation and insertion. After cooling and removing constraints, it transitions back to the rigid phase, recovering its original shape and providing the compression fit against the host pipe without excessive axial elongation.
2Shape
If the liner is grossly stretched through a single abrupt die, then diameter reduction is achieved, but extreme point friction and over-strain occur causing mechanical failure
Solution Approach 1:
The patent segments the deformation process into multiple stages using a multi-section die with progressively reducing diameters. Instead of forcing the liner through a single abrupt die, the deformation is distributed across multiple sections, each causing a smaller, more manageable reduction. This segmentation reduces extreme point friction and prevents over-strain at any single location, thereby preventing mechanical failure while achieving the required diameter reduction.
Solution Approach 2:
The patent introduces dynamic control of the deformation process by using a deformable die or controlled expansion mechanism that adapts to the liner's properties. The die can dynamically adjust its geometry or the rate of deformation to match the material's capacity, preventing sudden stress concentrations that would cause mechanical failure while still achieving the necessary diameter reduction for insertion.
3Length of moving object
If the liner is pulled through the host pipe with large forces, then insertion is achieved, but the liner retains memory of original shape causing incomplete lining and potential leaks
Solution Approach 1:
The patent uses temperature as a controlling parameter to suppress the liner's shape memory effect during insertion. By maintaining the SMP liner at its transition temperature during the pulling process, the material remains in a compliant state that allows complete insertion without premature recovery. After insertion, cooling the liner triggers the shape recovery, ensuring the liner conforms precisely to the host pipe's internal geometry, thereby achieving both complete insertion and manufacturing precision.
Solution Approach 2:
The patent applies preliminary heating of the SMP liner before insertion to prepare it for deformation and insertion. This preliminary action of heating puts the material in a state where it can be easily deformed and inserted without retaining excessive memory of its original shape. The pre-heating ensures that when the liner is pulled through the host pipe, it remains compliant and can be fully seated, and subsequent cooling ensures complete shape recovery for a precise fit.
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 approach results in a more uniform and durable composite pipeline with reduced axial creep, improved pressure capacity, and enhanced leak integrity, overcoming the limitations of traditional methods by minimizing axial elongation and ensuring consistent diameter recovery.
Implementation Method 1
allowing the shape memory polymer to recover memory, return to its near original outer diameter, and be fully seated within, and become united with, the host pipe
Implementation Method 2
deformation tool mechanism to minimize axial elongation and achieve uniform deformation, allowing for a compression-fit bi-layer composite pipe structure
Data Source
AI summary
A method and apparatus for lining a host pipe with a shape memory polymer liner in which the liner is fed through a manufacturing assembly including a pipe tensioner, followed by a deformation tool, prior to entering the host pipe, the liner being pulled through the host pipe from a leading end, the component parts of the manufacturing assembly acting to temporarily reduce the liner outside diameter during the pulling operation, while allowing the liner to revert to at least the internal diameter of the host pipe upon removal of the pulling load. The liner being used is a shape memory polymer which exhibits the ability to return from a deformed shape to an original shape induced by an external stimulus.