Resin Pipe Blister Resistance in Flexible Pipes
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Solution Overview
Problem
Flexible pipes used in offshore oil fields face challenges in maintaining barrier performance against gases at high temperatures and pressures, leading to blister issues as the thickness of resin pipes increases to meet these demands.
Innovation Solution
A flexible pipe design featuring a resin pipe with a thickness of greater than 5 mm, utilizing a fluororesin or polyether ether ketone with specific permeability and diffusion coefficients to achieve low permeability and high blister resistance, ensuring excellent performance at temperatures above 100°C and pressures above 70 MPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the resin pipe is increased to improve barrier performance against gases at high temperatures and pressures, then the barrier performance improves, but blisters are more likely to occur due to gas dissolved in the resin
Solution Approach 1:
The patent applies parameter changes by carefully controlling the resin pipe thickness within a specific range (3-8mm) and adjusting the composition ratio of fluororesin components (vinylidene fluoride 10-40%, tetrafluoroethylene 55-80%, third component 2-10 mol%). These parameter optimizations achieve the desired barrier performance while preventing blister formation by balancing gas permeability resistance with internal stress management.
Solution Approach 2:
The patent uses composite materials by creating a terpolymer fluororesin combining three different monomer units (vinylidene fluoride, tetrafluoroethylene, and a third component). This composite resin structure provides both the necessary barrier performance against high-temperature high-pressure gases and reduced tendency for blister formation, as the composite structure optimizes both gas impermeability and internal stress distribution.
2Strength
If the thickness of the resin pipe is increased to meet high-temperature and high-pressure demands, then the structural strength improves, but manufacturing complexity increases due to blister prevention requirements
Solution Approach 1:
The patent simplifies manufacturing by establishing specific parameter ranges for resin pipe thickness (3-8mm) and resin composition (vinylidene fluoride 10-40%, tetrafluoroethylene 55-80%, third component 2-10 mol%). These defined parameters enable consistent production of pipes with both adequate structural strength for high-temperature high-pressure applications and reduced blister formation, avoiding the need for complex additional manufacturing processes.
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 flexible pipe exhibits excellent blister resistance and durability in high-temperature, high-pressure environments, preventing gas leakage and maintaining structural integrity, even at increased thicknesses, thus addressing the issue of blister formation and enhancing durability.
Implementation Method 1
a CO2 permeability coefficient P(CO2) of 20×10-9[cm3(STP)·cm]/[cm2·s·Pa] or less, a CH4 permeability coefficient P(CH4) of 10×10-9[cm3(STP)·cm]/[cm2·s·Pa] or less
Data Source
Figure 1
AI summary
The present invention provides a flexible pipe having excellent blister resistance in a high-temperature and high-pressure environment even though including a thick resin pipe. The flexible pipe includes a resin pipe having a thickness of greater than 5 mm. The resin pipe is formed from a resin having a CO2 permeability coefficient P(CO2) of 20 × 10-9 cm3·cm/cm2·s·cmHg or lower at 150°C, a CH4 permeability coefficient P(CH4) of 10 × 10-9 cm3·cm/cm2·s·cmHg or lower at 150°C, a ratio D(CO2)/S(CO2) between a CO2 diffusion coefficient D(CO2) and a CO2 solubility coefficient S(CO2) of 3 × 10-5 Pa·m2/s or higher at 150°C, and a ratio D(CH4)/S(CH4) between a CH4 diffusion coefficient D(CH4) and a CH4 solubility coefficient S(CH4) of higher than 15 × 10-5 Pa·m2/s at 150°C.