Multi-layer Polymeric Conduit for Trenchless Installation
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Solution Overview
Problem
Conventional polyolefin conduits fail to withstand large abrasion forces and point loads, and engineering polymers used as alternatives often suffer from dimensional uniformity issues and sensitivity to temperature, shear, and moisture, making them unsuitable for trenchless installation methods like HDD, which require materials with high abrasion resistance, low-temperature toughness, and insulative properties.
Innovation Solution
A multi-layer polymeric conduit is developed through coextrusion, where a high-melt-viscosity layer, such as polyamide or HDPE, is combined with a lower-melt-viscosity layer like TPU, with specific thickness ratios to enhance mechanical stability and processability, allowing for improved dimensional integrity and resistance to deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If engineering polymers are used to replace polyolefins for enhanced mechanical performance, then abrasion resistance and strength are improved, but dimensional uniformity deteriorates due to hypersensitivity to temperature, shear, and moisture
Solution Approach 1:
The patent applies parameter changes by carefully controlling the extrusion process parameters (temperature, pressure, shear rate) to minimize the impact of environmental variables on the engineering polymer layers. By optimizing these parameters, the patent achieves dimensional uniformity while maintaining the enhanced abrasion resistance and mechanical strength provided by the engineering polymers.
Solution Approach 2:
The patent uses composite materials by combining engineering polymers with polyolefin layers in a multi-layer conduit structure. This composite approach allows the engineering polymers to provide enhanced mechanical performance and abrasion resistance, while the polyolefin layers contribute to dimensional stability and processability, thereby achieving both improved strength and manufacturing precision.
2Strength
If stainless steel tubes are used to resist large abrasion forces and point loads, then strength and durability are improved, but ease of installation deteriorates due to rigidity and requirement for additional straightening tools
Solution Approach 1:
The patent applies flexible shells and thin films by using a multi-layer polymeric conduit structure that combines the strength needed to resist abrasion forces and point loads with the flexibility required for easy installation. The conduit can be easily pulled through soil and can be bent around corners without requiring additional straightening tools, while still providing the necessary mechanical protection.
3Strength
If metallic ducts are used for trenchless installation, then strength and load-bearing capacity are improved, but adaptability deteriorates due to interference with telecommunication applications such as optical fiber sensing
Solution Approach 1:
The patent applies the extraction principle by removing the metallic component from the conduit structure and replacing it with polymeric materials. This extraction of the metal eliminates the interference with telecommunication applications such as optical fiber sensing, while the multi-layer polymeric structure maintains the necessary strength and load-bearing capacity for trenchless installation.
4Ease of manufacture
If polyolefins are used for conduit manufacturing due to versatility and ease of processability, then ease of manufacture is improved, but mechanical capacity deteriorates in environmentally challenging circumstances beyond material capacity
Solution Approach 1:
The patent uses composite materials by combining polyolefin layers with engineering polymer layers in a multi-layer conduit structure. The polyolefin layers provide ease of processability and versatility, while the engineering polymer layers enhance mechanical capacity and reliability in environmentally challenging circumstances, such as resistance to abrasion, chemical exposure, and extreme temperatures.
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different layers of the conduit. The polyolefin layers are optimized for processability and chemical resistance, while the engineering polymer layers are optimized for mechanical strength and abrasion resistance. This local differentiation of material properties allows each layer to perform its specific function optimally.
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 multi-layer conduit demonstrates enhanced mechanical properties, including increased crush load, improved abrasion resistance, and better handling of deformation, outperforming standard HDPE conduits in trenchless installation scenarios.
Implementation Method 1
A first melt viscosity of the first concentric layer is higher than a second melt viscosity of the second concentric layer
Implementation Method 2
The first concentric layer and the second concentric layer are coextruded
Implementation Method 3
The multi-layer conduit demonstrates enhanced mechanical properties, including increased crush load, improved abrasion resistance
Data Source
AI summary
A conduit including a first concentric layer and a second concentric layer that are coextruded, the first concentric layer having a higher melt viscosity than the second concentric layer, and the first concentric layer being of a thickness of at least 3% of a combined thickness of the first and second concentric layers, is provided. Conduits further including third and fourth concentric layers and conduits further including at least one microduct within a lumen defined by the first concentric layer are further provided.