Dual-Layer Heat Shrinkable Casing for Tubular Pipe Connections
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Solution Overview
Problem
Existing casing members for connecting tubular sections, especially preinsulated pipes, face challenges with non-concentricity and inadequate bonding quality due to deformation or irregular shapes, and are limited by the thickness of heat shrink layers, which affects the reliability and quality of connections, particularly for larger diameter pipes.
Innovation Solution
A casing member with a heat-shrinkable crosslinked plastics material layer and an electrically heatable member that applies hoop stress to a second, less crosslinked plastics layer, facilitating a fusion bond between the casing and the tubular section, using external heat sources and electrically heatable elements to ensure a high-quality bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat shrink layers are made thin to permit heat penetration and shrinking, then heat shrinkage function is improved, but the casing member cannot be used for large diameter pipes where thicker casing is desired
Solution Approach 1:
The casing member is divided into two distinct layers: an outer heat shrink layer and an inner structural layer. This segmentation allows each layer to perform its specific function optimally - the outer layer provides heat shrinkage for bonding while the inner layer provides the necessary thickness and structural support for large diameter pipes.
Solution Approach 2:
The inner structural layer acts as an intermediary between the outer heat shrink layer and the pipe surface. It provides thermal mass and structural support while the outer layer provides the heat shrinkage function, mediating between the need for thickness and the need for heat penetration.
2Ease of manufacture
If electric heating elements are used to form a bond between plastic casing and jacket, then bonding process is simplified, but connection quality is inadequate when tubular sections are deformed or non-concentric
Solution Approach 1:
The invention changes the bonding mechanism from simple heating to a combination of mechanical compression and heating. The heat shrink layer, when heated, shrinks and applies compressive force to bond the casing to the jacket, providing reliable connection even for deformed or non-concentric tubular sections.
Solution Approach 2:
The casing member uses composite construction with different materials having different properties - the outer heat shrink layer and inner structural layer work together to provide both bonding capability and structural support, improving reliability for various pipe conditions.
3Quantity of substance
If the heat flux from built in heating element is relatively small, then heat shrink layers can be made thin, but the article becomes less useful for large diameter preinsulated pipes requiring thicker casing
Solution Approach 1:
The dual-layer construction allows the heat shrink layer to remain thin for effective heat penetration while the inner structural layer provides the additional thickness needed for large diameter pipes, making the article adaptable to various pipe sizes.
Solution Approach 2:
The inner structural layer serves multiple functions: it provides structural support for large diameter pipes, acts as a thermal mass, and supports the outer heat shrink layer. This multi-functionality makes the casing member versatile for different pipe sizes and applications.
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 robust and high-quality fusion bond, capable of handling larger diameters and irregular shapes, ensuring a continuously homogeneous weld and improved connection reliability by applying hoop stress and using electrically heatable elements for efficient bonding.
Implementation Method 1
an electrically heatable member spaced inwardly from said first layer and for heating the second layer to cause it to fusion bond with a plastics material jacket of a tubular section
Implementation Method 2
at least said first layer being heat shrinkable in the direction of the circumference of the adjacent tubular section
Implementation Method 3
heating the second layer to cause it to fusion bond with a plastics material jacket of a tubular section
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A casing member for forming a connection between two tubular sections, said casing member having a first, cross-linked, heat shrinkable plastic layer, and a second, inner, non-crosslinked (or less cross-linked) layer. The casing member also has an electrically heatable member spaced inwardly from the first layer, for fusion bonding the second layer to the tubular sections.