Flexible Pipe Barrier Layer for High-Temperature Oil and Gas
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Solution Overview
Problem
Conventional flexible pipes face issues with material degradation and permeation at high temperatures, leading to reduced mechanical properties and flexibility, especially when handling crude oil or natural gas above 130°C, due to the limitations of existing materials like polyethylene and PVDF.
Innovation Solution
A flexible pipe with a multi-layer structure featuring a spirally wound plastic tape made of suitable molding compounds, such as PEEK or polyphenylene sulfide, which is welded under tension to provide a barrier against creep and permeation, and additional layers like fluoropolymers or polyamides for enhanced stability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional materials like polyethylene or PVDF are used for the inner lining, then the pipe can be manufactured and assembled, but the material degrades and loses mechanical properties at temperatures above 130°C
Solution Approach 1:
The patent changes the material parameter by selecting PEEK (polyether ether ketone) with a melting point of 343°C and polyphenylene sulfide with a melting point of 285°C, both significantly higher than the 130°C limit of conventional materials. This parameter change enables the inner lining to maintain mechanical properties at elevated temperatures while providing sufficient barrier performance against hydrocarbon permeation.
2Temperature
If the inner lining is made from high-temperature resistant materials, then temperature resistance improves, but the flexibility and ability to wind the pipe is reduced
Solution Approach 1:
The patent employs a composite structure where the inner lining combines PEEK or polyphenylene sulfide (providing high-temperature resistance) with a polyamide outer layer (providing flexibility and toughness). This composite material approach allows the pipe to achieve both temperature resistance above 130°C and sufficient flexibility for winding and handling operations.
3Ease of manufacture
If polyethylene is used as the inner lining material, then the pipe can be easily manufactured, but the material swells and creeps when exposed to crude oil or natural gas
Solution Approach 1:
The patent replaces the problematic polyethylene material with PEEK or polyphenylene sulfide, which do not exhibit swelling or creeping when exposed to hydrocarbons. These alternative materials provide long-term dimensional stability and resistance to chemical degradation, eliminating the need for frequent replacement due to material failure.
4Strength
If the pipe structure is made rigid to maintain structural integrity, then strength improves, but the flexibility and pliability required for transport is lost
Solution Approach 1:
The patent segments the pipe structure into distinct functional layers: an inner lining layer (PEEK or polyphenylene sulfide) for high-temperature resistance and chemical stability, and separate reinforcement layers (carcass and armor) for structural strength. This segmentation allows each layer to optimize its specific function while maintaining overall flexibility through the unbonded construction that permits relative movement between layers.
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 resistance to high temperatures, maintains mechanical stability, and prevents material degradation, allowing for flexible operation above 130°C without the need for cooling processes, while ensuring sufficient flexibility for winding and handling.
Implementation Method 1
a barrier layer formed from a plastic tape which has been wound spirally... providing a barrier against creep and permeation
Implementation Method 2
providing a barrier against creep and permeation
Implementation Method 3
overlapping areas are simultaneously or then welded together
Implementation Method 4
offers a high resistance to the diffusion of gases from a conveyed fluid
Data Source
AI summary
The invention relates to a flexible tube of multilayer construction having unbonded layers, wherein at least one layer is formed in that a tape made of a plastic molding compound is spirally wound about a further inner layer, wherein the upper and lower layers of the tape are simultaneously or subsequently welded to each other at overlapping regions. The tube is particularly suitable for offshore application in oil and gas extraction