Welding Cross-Linked Polyethylene Shrink Sleeves
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Solution Overview
Problem
Existing methods for connecting jacketed medium pipes with cross-linked polyethylene shrink sleeves face challenges such as high costs, precise work requirements, and potential sealing issues due to the perceived non-weldability of cross-linked polyethylene, leading to suboptimal weld seams and complex manufacturing processes.
Innovation Solution
The method involves welding sealing plugs into cross-linked polyethylene shrink sleeves at elevated temperatures (270-273°C) with extended preheating times, allowing for effective sealing without the need for special manufacturing precautions or covering holes, using a plug welder to ensure a strong and reliable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross-linked polyethylene shrink sleeves are used for connecting jacketed medium pipes, then improved material properties and thermal insulation are achieved, but the openings cannot be sealed by welding due to non-weldability of cross-linked polyethylene
Solution Approach 1:
The patent changes the temperature parameter for welding cross-linked polyethylene from conventional temperatures to elevated temperatures of 270-273°C. This parameter change enables the welding of sealing plugs into cross-linked polyethylene shrink sleeves, overcoming the previously believed non-weldability and achieving both improved sealing quality and simplified manufacturing process
Solution Approach 2:
The patent applies preliminary heating to the shrink sleeve and sealing plugs before welding. This preliminary action prepares the materials for welding by raising their temperature to the required 270-273°C range, enabling successful welding of sealing plugs into the cross-linked polyethylene material
2Reliability
If percussion plugs are hammered into openings of cross-linked polyethylene shrink sleeves, then sealing is achieved, but the process is expensive and requires very precise work
Solution Approach 1:
The patent replaces the mechanical percussion (hammering) method with a thermal welding process. Instead of mechanically forcing plugs into openings, the invention uses heat to fuse sealing plugs into the shrink sleeve material, eliminating the need for precise manual positioning and reducing labor complexity
3Reliability
If openings are covered with blanks during manufacture of shrink sleeves, then cross-linking protection is achieved, but the manufacturing process becomes complex
Solution Approach 1:
The patent extracts the protection concept from the manufacturing stage to the application stage. Instead of incorporating protective blanks during shrink sleeve manufacture, the invention applies a protective coating to the exterior surface of the already-manufactured shrink sleeve, eliminating complex manufacturing steps while achieving the same protection function
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 high-quality pipe connections with improved sealing, reduced complexity, and cost-effectiveness by enabling welding of cross-linked polyethylene sleeves, overcoming previous limitations in sealing and manufacturing processes.
Implementation Method 1
a shrink sleeve made of crosslinked polyethylene... which has been shrunk on to the two jacketed medium pipes
Implementation Method 2
the openings being closed by welding in sealing plugs... at a joining temperature of at least 270°C
Implementation Method 3
the annular space under the shrink sleeve, i.e. the annular space between the carrier pipe and the shrink sleeve, is filled with foam
Data Source
AI summary
A method for connecting sheathed medium pipes (1) is described. In this method, after welding the medium pipes (1), a pushed-on shrink-fit sleeve (2) of crosslinked polyethylene is shrunk onto the connected joint. To fill the annular space located under the shrunk-on shrink-fit sleeve (2) with foam, holes (3, 4) are drilled into the lateral surface of the shrink-fit sleeve (2) and, after filling with foam, are closed with the aid of welded-in closure plugs. The method succeeds in welding sleeves of crosslinked polyethylene.