Flexible Pipe Polymer Layer with Selective Crosslinking
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Solution Overview
Problem
Flexible pipes used in deep and ultra-deep water environments face challenges due to extreme conditions such as high pressures and temperatures, leading to localized strain and microcrazing in polymer layers, which can result in pipe failure and loss of pressure containment.
Innovation Solution
A flexible pipe design with a tubular layer where the polymer is crosslinked to a greater degree at the outer region than at the inner region, increasing the elastic modulus at the outer surface relative to the inner surface, reducing the risk of microcrazing and localized strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the polymer layer is subjected to high internal pressure in deep water environments, then the pipe can transport production fluids at greater depths, but the polymer layer experiences localized strain and microcrazing that leads to failure
Solution Approach 1:
The patent applies selective crosslinking to create different polymer properties at different locations within the tubular layer. The outer region (adjacent to armour layer) has a higher degree of crosslinking than the inner region, creating a gradient structure that provides localized strain resistance where needed while maintaining overall pipe flexibility and reliability in deep water environments
Solution Approach 2:
The patent changes the crosslinking degree parameter of the polymer to create regions with different mechanical properties. By controlling the crosslinking degree to decrease from the outer surface toward the inner surface, the polymer structure is optimized to resist localized strain at the outer region while maintaining adequate flexibility throughout the layer
2Strength
If the polymer is highly crosslinked throughout the entire tubular layer, then the elastic modulus increases and resistance to microcrazing improves, but the pipe loses flexibility and becomes prone to bending stresses
Solution Approach 1:
The patent creates a non-uniform crosslinking distribution where only the outer region of the tubular layer is highly crosslinked, while the inner region maintains lower crosslinking. This localized approach provides the necessary strength and microcrazing resistance at the outer region without compromising the overall flexibility of the pipe, thus resolving the contradiction between strength and flexibility
Solution Approach 2:
Instead of uniformly crosslinking the entire polymer layer, the patent applies crosslinking partially to only the outer region adjacent to the armour layer. This partial action provides sufficient strength where needed while preserving flexibility in the inner region, avoiding the adverse effects of complete uniform crosslinking
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 selective crosslinking of the polymer layer reduces the risk of microcrazing and enhances the pipe's resistance to high pressures and temperatures, improving the durability and performance of the flexible pipe.
Implementation Method 1
the polymer is crosslinked to a greater degree at an outer region of the tubular layer than at an inner region of the tubular layer
Data Source
Figure 1~2
Figure 3
AI summary
A flexible pipe comprising a tubular layer comprising a polymer that is crosslinked to a greater degree at an outer region of the tubular layer than at an inner region of the tubular layer, wherein the outer region is defined by the outer surface of the tubular layer to a depth of 5% of the total thickness of the tubular layer and the inner region is defined by the inner surface of the tubular layer to a depth of 5% of the total thickness of the tubular layer.