Trenchless Pipe Unit with Protective Sheathing

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Solution Overview

Problem

Existing methods for trenchless laying of multiple pipes in the ground often result in non-standard compliant pressure pipes, with issues such as reduced cross-section for media transport, lack of shear force resistance, and complex production processes, which limits their applicability for pressure pipes like gas, water, or wastewater transport.

Innovation Solution

A tube unit comprising a standard-compliant pressure pipe with a core made of hard plastic and an outer protective layer, encapsulating a smaller pipe or cable, ensuring shear strength and protection during laying without altering the core pipe's properties, allowing simultaneous trenchless laying of multiple pipes without relative movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple pipes are bundled with clamping devices and pulled in simultaneously, then trenchless laying of multiple pipes is achieved, but the parallelism of the pipes is not guaranteed and the device complexity increases

Engineering Contradiction:
Improvesimultaneous laying of multiple pipesVSAvoidclamping device complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Multiple pipes are merged into a single pipe unit during manufacturing, with pipes arranged concentrically or side-by-side within a common outer protective layer. This integration eliminates the need for complex clamping devices during installation, as the pipes remain fixed relative to each other throughout the trenchless laying process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The pipes are pre-positioned and fixed in their final configuration during the pipe manufacturing process. The outer protective layer is applied in advance to secure the pipes in place, ensuring correct parallelism and spacing before installation. This preliminary arrangement eliminates the need for complex alignment equipment during actual laying operations.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If pipes are laid using directional horizontal drilling technique, then trenchless parallel laying is achieved, but relatively large borehole diameters are required and the method is limited to certain soil types

Engineering Contradiction:
Improvetrenchless parallel laying capabilityVSAvoidsoil type limitation
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The pipe unit is designed as a segmented structure with an outer protective layer and inner pipes that can be manufactured separately and then assembled. This segmentation allows the pipes to be pulled through existing boreholes of standard size without requiring enlarged diameters, and the modular design enables adaptation to different soil conditions through appropriate material selection.

Inventive Principle:
Principle #1Segmentation

3Temperature

If foam is used to fill cavities between pipes for thermal insulation, then thermal insulation is improved, but the free cross-section for media transport is reduced

Engineering Contradiction:
Improvethermal insulation performanceVSAvoidfree cross-section for media transport
Core Design Contradiction:
TemperatureVSArea of moving object

Solution Approach 1:

Thermal insulation is applied locally only where required, such as on the outer surface of pipes carrying hot media, rather than filling the entire cavity between pipes. This selective insulation approach maintains the free cross-section for media transport while providing adequate thermal protection where needed.

Inventive Principle:
Principle #3Local quality

4Ease of manufacture

If inner pipe is made displaceable in axial direction, then ease of assembly is improved, but shear force resistance between inner and outer pipe is lost

Engineering Contradiction:
Improveassembly easeVSAvoidshear force resistance
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The inner pipes are nested within the outer protective layer in a fixed concentric arrangement. The outer layer acts as a rigid envelope that maintains the position of inner pipes while allowing for controlled assembly. The nesting structure provides inherent shear force resistance through the interaction between the outer protective layer and inner pipes, eliminating the need for additional displacement mechanisms.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 enables the use of standard-compliant pressure pipes for trenchless laying with enhanced shear strength and protection, maintaining the core pipe's integrity and properties, facilitating efficient and cost-effective installation of multiple pipes or cables without the need for additional fixing means.

Implementation Method 1

the cladding layer covers the second smaller tube at its outer circumference and this is held by the cladding layer in the shear force-resistant bond between the cladding layer and the tube core

Methodology Applied
Scientific EffectShear force resistance: Shear Stress

Data Source

PatentEP2025986B1Pipe unit containing at least two pipes
Publication Date: 2011.07.27 EGEPLAST WERNER STRUMANN
  • EP2025986B1 patent drawingFigure 1
  • EP2025986B1 patent drawingFigure 2

AI summary

The method involves providing a larger pipe with an outer protective layer (11) and a sheathing layer. The larger pipe is laid together with a smaller pipe (12), a line or a cable. The smaller pipe is enclosed by the protective layer or the sheathing layer such that the pipes, the line or the cable form a pipe unit (14), where the smaller pipe is an empty duct for the cable or the line. An inner core barrel (13) of the larger pipe is extruded from plastic while producing the pipe unit, where the smaller pipe and/or the line or the cable is positioned at the inner core barrel.