Composite Pipe Coating for Trenchless Mechanical Protection
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Solution Overview
Problem
Existing buried steel pipes with thin polypropylene, polyethylene, or polyurethane coatings suffer from low mechanical strength and poor adhesion, leading to mechanical damage during trenchless pipe-laying processes, which compromises corrosion protection.
Innovation Solution
A metal pipe with a thermoplastic casing surface and a glass-fibre-reinforced thermo-setting coating, applied using a wet-on-wet method with cross-wound glass fibres and a resin matrix, providing enhanced mechanical strength and directional protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin thermoplastic coating (polypropylene, polyethylene, or polyurethane) is applied to buried steel pipes, then corrosion protection is ensured, but mechanical strength and adhesion are insufficient, leading to mechanical damage during pipe-laying
Solution Approach 1:
The patent applies a multi-layer composite coating system consisting of a thermoplastic base layer (polypropylene, polyethylene, or polyurethane) for corrosion protection, overlaid with a fibre-reinforced thermo-setting coating (glass fibres in vinyl ester, polyester, or epoxy resin). This composite structure combines the corrosion-resistant properties of thermoplastics with the high mechanical strength and adhesion of fibre-reinforced thermosetting materials, resolving the contradiction between corrosion protection and mechanical strength
2Strength
If a fibre cement casing is added to protect the thermoplastic coating from mechanical abrasion, then mechanical protection is improved, but adhesion remains poor due to low adhesive power of the thermoplastic coating
Solution Approach 1:
The patent introduces an intermediary fibre-reinforced thermo-setting coating layer between the thermoplastic base coating and the outer protective layer. This intermediate layer has high adhesive power that bonds effectively to the thermoplastic surface, while also providing the mechanical strength and abrasion resistance needed. The fibre reinforcement (glass fibres in vinyl ester, polyester, or epoxy resin) acts as a mediator that bridges the adhesion gap, allowing subsequent layers to adhere properly without direct contact with the low-adhesion thermoplastic surface
3Adaptability or versatility
If cross-wound glass fibre layers are applied in the outermost layer, then directional protection is improved allowing advancement in any direction, but manufacturing complexity increases
Solution Approach 1:
The patent applies glass fibres in the outermost layer in multiple winding directions (cross-wound pattern including axial, diagonal, and circumferential directions) to provide reinforcement in all orientations. This multi-dimensional fibre arrangement ensures the coating can withstand mechanical stresses from pipe advancement in any direction, transforming the protection from single-direction to omnidirectional. The increased manufacturing complexity is justified by the significant gain in adaptability and versatility for trenchless pipe-laying operations
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 significantly improves mechanical strength and adhesion, reducing damage during pipe-laying and maintaining effective corrosion protection, allowing pipes to be advanced in any direction with reduced risk of damage.
Implementation Method 1
at least one layer of the thermo-setting coating is formed by cross-wound textile glass rovings or glass fibre mats or glass-fibre fabric or a combination of these glasses. Cross-wound means that the glass fibres are applied to the pipe by winding, whereby one (glass) layer is applied in a first winding direction and a second (glass) layer is applied in the opposite direction to this winding direction
Implementation Method 2
The thermo-setting coating consists of multiple layers of glass-fibre-reinforced plastic (GfK), whereby the layers are made of glass-fibre-reinforced plastic, glass fibres in the form of rovings, UD fabrics, UD scrims, glass fibre mats or glass-fibre fabrics or a combination of these, and the layers are applied to the thermoplastic casing surface using a vinyl ester, polyester, or epoxy resin
Implementation Method 3
the layers are applied to the thermoplastic casing surface using a vinyl ester, polyester, or epoxy resin in a wet-on-wet method
Data Source
AI summary
The invention relates to a pipe having a thermoplastic casing surface and a glass-fibre-reinforced thermo-setting coating surrounding the thermoplastic casing surface. The thermo-setting coating is formed from multiple layers of glass-fibre matting or glass-fibre fabric, or a combination of the two, wherein the layers are applied to the thermoplastic casing surface in a wet-on-wet method using a vinylester, polyester or epoxy resin. According to the invention, an outer layer of the thermo-setting coating is formed from cross-wound glass-fibre fleece or glass-fibre fabric.