Weldable Half-Shell Fitting for Double Pipe Systems

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Solution Overview

Problem

Existing double pipe systems require complex and costly connection processes, involving multiple simultaneous connections that are difficult to inspect and repair, leading to inefficiencies and potential leaks.

Innovation Solution

A fitting design featuring two plastic half-shells with integrated heating wires and snap connection elements, allowing for easy assembly and inspection of connections between primary and secondary pipelines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If simultaneous or cascade welding is used to join inner and outer pipes to fittings, then connection strength is improved, but the complexity of the connection process and difficulty of inspection increase

Engineering Contradiction:
Improveconnection strengthVSAvoidconnection process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The fitting is divided into two separate half-shells that can be assembled around the pipe after welding. This segmentation allows the welding process to be simplified to single-pipe connections rather than simultaneous multi-pipe connections, while still achieving the required connection strength through the half-shell assembly structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inner pipe is welded to the fitting first, and the fitting is inspected before the outer pipe is installed. This preliminary action allows inspection of critical welds before the secondary containment is added, simplifying the overall process while ensuring connection integrity.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If adhesive bonding is used to join pipes to fittings, then ease of operation is improved, but connection strength and reliability deteriorate

Engineering Contradiction:
Improveease of connectionVSAvoidconnection strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The connection process is segmented into two independent steps: first welding the inner pipe to the fitting, then separately installing the outer pipe. This eliminates the need for complex simultaneous adhesive bonding of multiple surfaces while maintaining strong mechanical connections through welding.

Inventive Principle:
Principle #1Segmentation

3Reliability

If multiple simultaneous connections are required for installation, then complete sealing is improved, but installation time and complexity increase

Engineering Contradiction:
Improvesealing reliabilityVSAvoidinstallation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The sealing system is segmented into an inner sealed connection (inner pipe to fitting) and an outer containment shell. The inner connection can be completed and inspected first, then the outer shell is installed to provide additional containment, allowing sequential rather than simultaneous operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inner pipe connection and sealing are completed as a preliminary action before installing the outer containment shell. This allows the critical sealing function to be established first, then reinforced by the outer shell without requiring simultaneous operation.

Inventive Principle:
Principle #10Preliminary action

4Manufacturing precision

If the fitting is designed as a complete closed structure, then manufacturing precision is improved, but ease of inspection and repair deteriorates

Engineering Contradiction:
Improvefitting integrityVSAvoidconnection inspection ease
Core Design Contradiction:
Manufacturing precisionVSEase of repair

Solution Approach 1:

The fitting is segmented into two half-shells that can be separated from each other. This allows the fitting to maintain its precise manufactured form when assembled, while enabling easy disassembly for inspection and repair by separating the half-shells to access internal connections.

Inventive Principle:
Principle #1Segmentation

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 fitting enables efficient and cost-effective installation of secondary pipelines by simplifying the connection process, allowing for pre-installation checks of primary pipeline welds, and facilitating easier identification and repair of any leaks.

Implementation Method 1

Each half-shell has an integrated heating wire, the heating wire being arranged in the areas of the connection spigots and having several meandering turns

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4296554B1Fitting with weldable half-shells
Publication Date: 2025.05.14 GEORG FISCHER ROHRLEITUNGSSYSTEME AG
  • EP4296554B1 patent drawingFigure 1~2
  • EP4296554B1 patent drawingFigure 3~4
  • EP4296554B1 patent drawingFigure 5

AI summary

Fitting for connecting a secondary plastic pipeline of a double pipe system comprising two plastic half-shells, each half-shell having an integrated heating wire, the heating wire being arranged in the areas of the connection spigots and having several meandering turns, the heating wire being arranged in a groove provided for this purpose in the half-shell and connecting elements connecting the two half-shells, characterized in that the fitting has spacer elements arranged on the inner circumference of the half-shells for the concentric arrangement of the fitting relative to a primary pipeline.