Prestressing Cable Sheath Repair Using Electrofusion Welding

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Solution Overview

Problem

Existing methods for repairing prestressing cable sheaths are inadequate for ensuring rapid, reliable, and safe repair, especially in difficult-to-access areas, which can lead to mechanical integrity and corrosion issues.

Innovation Solution

A process involving the positioning of heating resistances around the degraded sheath area, followed by the assembly and welding of polymer cylindrical sleeves to form a sealed sleeve for injecting a filling material, thereby repairing the sheath.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional repair methods are used for prestressing cable sheaths, then the repair process becomes complex and time-consuming, but the mechanical integrity and corrosion protection are compromised

Engineering Contradiction:

Improvemechanical integrityVSAvoidrepair process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The repair system is divided into modular components: a cylindrical sleeve that segments the repair zone, heating resistors that segment the thermal treatment areas, and injection ports that segment the material delivery points. This segmentation enables controlled, localized repair while maintaining overall structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The heating resistors are positioned inside the cylindrical sleeve, creating a nested configuration where the resistors are contained within the sleeve structure. This nesting allows the heating elements to be protected and precisely positioned during the repair process while maintaining a compact overall structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Productivity

If rapid repair intervention is implemented to prevent corrosion, then the repair speed increases, but the quality and watertightness of the repair may be compromised

Engineering Contradiction:

Improverepair speedVSAvoidwatertightness quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The cylindrical sleeve is pre-positioned and secured to the sheath before the actual repair materials are injected. The heating resistors are pre-installed within the sleeve, and the system is prepared in advance, allowing rapid initiation of the repair process while ensuring proper sealing and watertightness from the outset.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Traditional mechanical sealing methods are replaced with a integrated sleeve system that combines mechanical fitting with thermal processing. The heating resistors provide controlled thermal expansion and bonding, substituting complex mechanical sealing arrangements with a more reliable thermal-mechanical hybrid approach that ensures watertightness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If electrofusion welding is used to join heating resistors with polymer sleeves, then the bonding strength increases, but the energy consumption and process complexity increase

Engineering Contradiction:

Improvebonding strengthVSAvoidenergy consumption

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The electrofusion welding process applies energy locally at the interface between the heating resistors and the polymer sleeve, rather than heating the entire structure. This localized energy application achieves strong bonding at the critical joint areas while minimizing overall energy consumption and avoiding unnecessary heating of non-critical components.

Inventive Principle:

Principle #3Local quality

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 allows for quick and reliable repair of prestressing cable sheaths, ensuring mechanical integrity and preventing corrosion, while being adaptable to various cable dimensions and materials.

Implementation Method 1

electrofusion welding of the end heating resistors with the two sleeve portions by applying an electric current to the terminals of the end heating resistors

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

electrofusion welding of the end heating resistors with the two sleeve portions

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

extrusion welding of the first sleeve portion with the second sleeve portion

Methodology Applied

Scientific EffectExtrusion welding: Extrusion

Data Source

PatentEP4306740B1Method and device for repairing pre-stressed wire sheath

Publication Date: 2025.04.16 SCUOCH CLAUDE

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AI summary

The invention relates to a method for repairing a damaged area (Z) of a prestressing cable sheath (2), comprising the following steps: positioning two end heating elements (3) around the sheath (2), positioning two polymer sleeve sections above said elements (3), electrofusion welding of the elements (3) to the sleeve sections (1A, 1B) by applying an electric current, and extrusion welding of the first sleeve section (1A) to the second sleeve section (1B) to form a cylindrical sleeve around the damaged area (Z), thus allowing the subsequent injection of a filler material into the cylindrical sleeve formed, thereby repairing the prestressing cable sheath (2). The invention also relates to a prestressing cable sheath repair assembly adapted for implementing said method.