Plastic-Coated Metal Pipe Sheath for Bending Without Coating Damage
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Solution Overview
Problem
Existing metal pipes with glass-fibre reinforced plastic coatings face issues during open-trench pipe-laying due to bending, which affects the mechanical properties of the coating.
Innovation Solution
A metal pipe covered by a thermoplastic sheath and a fibre-reinforced protective sheath with an intermediate layer or weakened sections to allow sliding movement or controlled cracking, preventing bonding and providing compression force relief during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fibre-reinforced protective sheath is applied to protect the plastic coating, then mechanical strength and protection against abrasion are improved, but the coating becomes rigid and susceptible to damage during bending operations
Solution Approach 1:
The fibre-reinforced protective sheath is divided into multiple sections along the pipe length. Some sections have fibre reinforcement while others have reduced or no fibre reinforcement, allowing different mechanical properties in different zones. This segmentation enables the pipe to bend in designated areas without damaging the protective coating, while maintaining strength in sections where bending is not required.
Solution Approach 2:
The protective sheath has non-uniform fibre reinforcement distribution along its length. Sections subjected to bending during installation have reduced fibre content or different fibre orientation, making them more flexible. Sections not subjected to bending maintain full fibre reinforcement for maximum protection. This local variation in quality allows the coating to provide both protection and bending capability where needed.
2Object-affected harmful factors
If a thick fibre-reinforced plastic coating is used to protect against mechanical abrasion, then protection effectiveness is improved, but the pipe becomes more difficult to install in bent configurations
Solution Approach 1:
The protective sheath is segmented into zones with different fibre reinforcement thicknesses. Areas requiring high abrasion protection (such as sections buried in rough terrain or subject to external loads) have thicker fibre reinforcement, while areas needing flexibility for installation have thinner or no fibre reinforcement. This segmentation allows the pipe to be installed in bent configurations while maintaining adequate protection where required.
Solution Approach 2:
The fibre reinforcement thickness and density vary locally along the pipe length based on installation requirements. Sections that will be bent during installation have reduced fibre content to maintain flexibility, while sections that will remain straight receive full fibre reinforcement for maximum abrasion protection. This local quality variation optimizes both installation ease and protection effectiveness.
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 enhances the pipe's ability to bend without damaging the fibre-reinforced protective sheath, maintaining mechanical integrity and protecting the coating from mechanical abrasion.
Implementation Method 1
The intermediate layer is made of a material that prevents chemical bonding between the at least two layers of fibre reinforced plastic and thus allows a sliding movement between the two layers of fibre reinforced plastic during bending
Implementation Method 2
the fibre-reinforced protective sheath is configured to exhibit weakened sections that are configured to crack during bending to thus cause a controlled compression force relief
Data Source
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AI summary
The invention relates to a plastic covered protected metal pipe assembly comprising a metal pipe that is covered by a plastic sheath, in particular with a thermoplastic sheath and a fibre-reinforced protective sheath enclosing the thermoplastic sheath, wherein the fibre-reinforced protective sheath comprises reinforcing fibers embedded in a thermoset plastic material. The plastic covered protected metal pipe comprises at least one longitudinal section wherein the fibre-reinforced protective sheath comprises two layers of fibre reinforced plastic that are separated by an intermediate layer radially disposed between the two layers of fibre reinforced plastic. The intermediate layer is made of a material that prevents chemical bonding between the two layers of fibre reinforced plastic and thus allows a sliding movement between the two layers of fibre reinforced plastic during bending.