Split Heating Coil Sleeve for Pressure-Tight Pipe Repair

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Solution Overview

Problem

Existing electrofusion couplings for connecting plastic pipes fail to provide a homogeneous welded joint when a trailing medium is present, leading to leaks and requiring complex, non-axial insertion methods, which are often not feasible during repairs.

Innovation Solution

A split heating coil sleeve composed of two separate halves with spaced-apart seals and heating coil zones, allowing for axial assembly and ensuring a homogeneous welded joint despite the presence of a trailing medium, using a mechanical connection such as screws or clamps to secure the halves together.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealing insert is used to prevent trailing medium escape, then pressure tightness is improved, but the complexity of assembly increases and axial insertion becomes impossible

Engineering Contradiction:
Improvepressure tightnessVSAvoidassembly ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The heating coil sleeve is divided into two separable halves that can be independently positioned on the pipe ends. This segmentation allows the sleeves to be assembled axially without requiring complex sealing inserts, as each half can be independently positioned and then joined together to form the complete sealing connection.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the pipe ends are moved toward each other for sealing insert insertion, then sealing is achieved, but adaptability to repair scenarios is reduced

Engineering Contradiction:
Improvesealing effectivenessVSAvoidadaptability to repair scenarios
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of moving pipe ends toward each other to insert a sealing insert, the invention inverts the approach by moving the heating coil sleeves onto the pipe ends in the axial direction. The sleeves are then joined together, reversing the traditional sequence and making the process adaptable to repair scenarios where pipe ends cannot be moved relative to each other.

Inventive Principle:
Principle #13The other way round (Inversion)

3Ease of operation

If compression seals are used for repairs, then ease of operation is improved, but pressure tightness and service life deteriorate

Engineering Contradiction:
Improveease of assemblyVSAvoidpressure tightness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention changes the fundamental parameters of the connection method by using a heating coil sleeve that melts and fuses the pipe ends together, transitioning from mechanical compression sealing to thermal welding. This parameter change achieves both ease of operation (axial assembly) and high reliability (homogeneous welded joint resistant to pressure).

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If machining is performed to remove contaminants, then connection quality is improved, but time consumption increases

Engineering Contradiction:
Improveconnection qualityVSAvoidtime consumption
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The heating coil sleeve performs preliminary heating and melting action on the pipe ends, which automatically removes contaminants and oxides through the melting process. This preliminary thermal action eliminates the need for separate machining steps, achieving high connection quality while reducing overall time consumption.

Inventive Principle:
Principle #10Preliminary action

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

Enables pressure-tight connections up to 40 bar by preventing medium contamination and facilitating easy assembly, adhering to DVS 2207-1 guidelines, even in challenging repair scenarios.

Implementation Method 1

a coiled electrical conductor is arranged in the inner wall of the sleeve. Current can be passed through the conductor via connections, causing it to heat up due to the electrical resistance

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The seals are axially spaced from each other. This allows the first sleeve half to be pushed over the connection area of two pipes so that one seal surrounds the first pipe end and another seal surrounds the second pipe end

Methodology Applied
Scientific EffectSealing:

Data Source

PatentEP4235008B1Heating coil sleeve for connecting and method for connecting two pipe sections with discharging medium
Publication Date: 2025.08.27 FRANK & CO GMBH
  • EP4235008B1 patent drawingFigure 1
  • EP4235008B1 patent drawingFigure 2
  • EP4235008B1 patent drawingFigure 3

AI summary

The disclosure relates to a heating coil coupling for joining plastic pipes, comprising a first coupling half that is slidable on a pipe. The first coupling half includes at least two spaced-apart seals and a second coupling half. The second coupling half is connectable to the first coupling half. At least the first and/or second coupling half comprises a heating coil zone.