Composite Pipe Liner Structure for Gas Permeation Control
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Solution Overview
Problem
Existing polymer-lined pipelines in hydrocarbon service face challenges with gas permeation, which can lead to corrosive species reaching the host pipe and causing liner collapse, as current solutions either mitigate the risk of collapse or do not address permeation effectively.
Innovation Solution
A liner comprising a porous inner polymer pipe surrounded by a metallic barrier layer, with an optional outer non-porous polymer pipe, designed to allow gas to pass freely between the internal bore and the barrier layer, preventing gas accumulation and permeation through the liner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional polymer pipe liner is used, then the pipeline can be produced at lower cost compared to CRA pipelines, but gas permeation occurs through the polymer material causing liner collapse risk
Solution Approach 1:
The patent applies composite materials by combining a polymer liner with a corrosion-resistant alloy (CRA) barrier layer. The polymer provides cost advantages and flexibility, while the CRA layer prevents gas permeation and liner collapse. This composite structure resolves the contradiction by integrating materials with complementary properties to simultaneously achieve low cost and high reliability.
Solution Approach 2:
The patent applies local quality by selectively applying a CRA barrier layer only where gas permeation occurs (at the polymer-host pipe interface), rather than using CRA throughout the entire pipeline. This localized approach maintains cost effectiveness while preventing liner collapse at the critical interface where permeation happens.
2Object-affected harmful factors
If a polymer liner is used to line the host pipe, then corrosion prevention is achieved, but gas accumulates in the annular space between the liner and host pipe causing liner collapse
Solution Approach 1:
The patent uses a composite structure with a polymer liner providing corrosion protection and a CRA barrier layer preventing gas accumulation. The CRA layer acts as a gas impermeable barrier that maintains the annular space free of accumulated gas, thereby preserving liner structural integrity while maintaining corrosion protection benefits.
Solution Approach 2:
The CRA barrier layer serves as an intermediary between the polymer liner and the host pipe. It prevents gas from accumulating in the annular space by providing a gas-impermeable pathway, thus mediating between the polymer's corrosion protection function and the structural integrity requirement.
3Ease of manufacture
If the liner is made from polymer material, then cost advantage over CRA pipelines is achieved, but corrosive species can permeate through the polymer and contact the host pipe
Solution Approach 1:
The patent creates a composite liner system where the polymer provides cost effectiveness and the CRA barrier layer prevents corrosive species permeation. The CRA layer acts as a selective barrier that blocks corrosive gases while allowing the polymer to maintain its cost advantages and installation benefits.
Solution Approach 2:
The CRA barrier layer is applied locally at the interface where corrosive species would contact the host pipe, providing targeted protection against permeation only where needed, rather than requiring expensive CRA construction throughout the entire pipeline.
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 effectively prevents corrosive species from reaching the host pipe and reduces the risk of liner collapse by allowing gas to pass through the liner, thereby enhancing pipeline integrity and reducing the need for costly corrosion-resistant alloys.
Implementation Method 1
The inner polymer pipe is porous and gas can pass freely through it
Implementation Method 2
the external diameter of a liner made from a memory retaining plastics material is reduced by up to 15% by pulling the liner through a die at ambient temperature. After pulling through the pipework the liner is allowed to expand within the pipework by relaxation of pulling tension followed by memory induced expansion at ambient temperature and pressure.
Data Source
AI summary
An improved pipe liner and associated methods, including a method of manufacturing the improved pipe liner and a method of lining a host pipe with such a pipe liner. The invention solves the problem of gas permeation through a polymer liner in hydrocarbon service which can result in corrosion of the host pipe and can also cause liner collapse. Corrosion occurs due to contact between corrosive species and the host pipe itself. Gases (307) can also accumulate in an annulus between or within the liner (305) and the host pipe (303) and expand during operational de-pressurisation of the pipeline, causing collapse of the liner. The improved pipe liner comprises a barrier layer (311), which prevents permeation through the liner, surrounding an inner polymer pipe (305A) and optionally covered by an outer polymer pipe (305B). The inner polymer pipe is porous which permits free movement of gas between the internal bore (302) of a lined pipe and the barrier layer, so as to prevent accumulation of gases anywhere in the lined pipe, while ensuring that gases do not permeate to, and damage, the host pipe. The liner can be inserted using Swagelining, roll-down, or any other suitable close-fit lining techniques, without compromising the effectiveness of the barrier layer.