Cement-Lined Socket Pipe Ends Without Mortar Tearing

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Solution Overview

Problem

Existing cast iron pipes with cement mortar coatings are not economical to manufacture due to the risk of mortar tearing during removal of cement cutters, requiring retouching and lacking effective corrosion protection, especially at the ends.

Innovation Solution

The pipe design incorporates annular barriers made of synthetic or thermoplastic materials to prevent mortar flow during coating, with additional anti-corrosion layers and coatings to ensure controlled thickness and durability, reducing the need for post-manufacturing touch-ups and enhancing corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rubber cement cutters are used to prevent axial flow of mortar, then the mortar can be contained during pouring, but the mortar may tear when the cutters are removed requiring retouching

Engineering Contradiction:
Improvemortar containmentVSAvoidmanufacturing economy
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses disposable paper or cardboard collars instead of reusable rubber cutters. These inexpensive, single-use barriers prevent mortar tearing upon removal since they are designed to be discarded after serving their containment function during the cementing process.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The paper or cardboard collar acts as an intermediary barrier between the mortar and the pipe end. This intermediate layer prevents direct contact between the mortar and the rubber cutter, eliminating the tearing issue while maintaining effective mortar containment during the cementing process.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If cement cutters are removed after mortar hardening, then the formwork function is completed, but mortar damage occurs requiring subsequent touch-up work

Engineering Contradiction:
Improvemanufacturing speedVSAvoidretouching requirement
Core Design Contradiction:
ProductivityVSEase of repair

Solution Approach 1:

The disposable paper or cardboard collars are removed easily after serving their purpose, and any minor mortar imperfections can be addressed without requiring extensive retouching operations, thus maintaining productivity while reducing repair needs.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The paper or cardboard collar is extracted from the system after serving its containment function. Unlike permanent rubber cutters that remain in the system and cause tearing, these disposable barriers are completely removed, taking potential damage sources with them and leaving the mortar coating intact.

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If traditional cement cutters are used, then mortar flow is controlled, but corrosion protection at pipe ends is insufficient

Engineering Contradiction:
Improvemortar thickness controlVSAvoidcorrosion resistance
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs composite protection systems combining cement mortar lining with additional corrosion-resistant materials such as polyethylene or epoxy coatings at the pipe ends. This multi-layer composite approach maintains precise mortar thickness control while providing enhanced corrosion protection that traditional single-material cutters cannot offer.

Inventive Principle:
Principle #40Composite materials

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 results in a more economical and easier-to-manufacture pipe with controlled cement mortar thickness and improved corrosion protection, minimizing post-manufacturing touch-ups and ensuring effective corrosion resistance, particularly at the ends.

Implementation Method 1

applying the cement mortar in a non-solid state to the inner surface of the barrel, solidifying the cement mortar to obtain the cement mortar coating

Methodology Applied
Scientific EffectSolidification: Freezing

Data Source

PatentEP4400754B1Pipe, tubular connection and corresponding manufacturing method
Publication Date: 2025.09.10 SAINT-GOBAIN PAM CANALISATION
  • EP4400754B1 patent drawingFigure 1
  • EP4400754B1 patent drawingFigure 2
  • EP4400754B1 patent drawingFigure 3

AI summary

This pipe comprises a base body (16) forming a shaft (22), the shaft having an inner shaft surface (24), an outer shaft surface (26), a first axial end (28), and a second axial end (30). The pipe includes a cement mortar coating (80) disposed on the inner shaft surface, and a socket end (12), the socket end being defined by a socket portion (40) of the base body which includes an inner socket surface (42). The pipe includes a socket coating (60) extending over the inner socket surface. The plain end is defined by the second axial end of the shaft. The socket portion (40) has an outer socket surface (44) and a front socket surface (46). The interlocking part is located on the side of the first axial end (28) of the shaft and is connected to this axial end.The interlocking coating (60) extends over the front interlocking surface (46) and over the outer interlocking surface (44).