Flexible Pipe Cannula with Gas-Permeable Insert
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Solution Overview
Problem
Flexible fluid transport pipes used for hydrocarbons face corrosion issues due to acidic compounds like H2S and CO2, leading to mechanical integrity deterioration, especially at lower pressures where gas accumulation causes local overconsumption of the active sheath, increasing costs and weight.
Innovation Solution
Incorporating a cannula with a chemically active product, either dispersed in a polymer matrix or as a porous ceramic layer, to treat acidic compounds and prevent their accumulation, along with a gas-permeable insert and axial gas evacuation conduit to manage gas migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal cannula is interposed between the pressure sheath and active sheath to crimp the active sheath, then the connection of the flexible pipe is ensured, but a potential zone for accumulation of corrosive gases is generated upstream of the cannula, causing local overconsumption of the active sheath
Solution Approach 1:
A gas-permeable insert is introduced as an intermediary component between the metal cannula and the active sheath. This insert allows corrosive gases to pass through its walls rather than accumulating in the gap, while still maintaining the crimping function. The insert acts as a mediator that eliminates the harmful gas accumulation zone while preserving the connection reliability provided by the cannula structure.
Solution Approach 2:
The gas-permeable insert is made from porous material that allows gas molecules to diffuse through its structure. This porous structure prevents the formation of a gas accumulation zone by enabling continuous gas passage, thereby protecting the active sheath from local overconsumption while maintaining the mechanical connection function.
2Reliability
If the thickness of the active sheath is increased to prevent local overconsumption, then the corrosion risk of armor plies is reduced, but the cost and weight of the pipe increase
Solution Approach 1:
The gas-permeable insert serves as a mediator that eliminates the need for increased active sheath thickness. By providing an alternative gas passage route through the insert, the system prevents gas accumulation without requiring additional active sheath material, thereby maintaining corrosion protection while reducing weight.
Solution Approach 2:
The invention changes the physical parameters of the system by introducing a gas-permeable component with different permeability characteristics. This parameter change allows gas to pass through the insert rather than accumulating, enabling the use of thinner active sheath while maintaining the same level of corrosion protection.
3Object-affected harmful factors
If a gas-permeable insert is applied to the cannula, then gas migration is managed and active sheath overconsumption is prevented, but the device complexity increases
Solution Approach 1:
The gas-permeable insert is nested within the metal cannula structure, with the insert positioned inside the cannula's outer diameter. This nested arrangement allows the gas-permeable function to be integrated within the existing cannula geometry, minimizing the increase in overall device complexity while achieving the gas management function.
Solution Approach 2:
By using a porous insert that can be applied to the existing cannula, the solution adds a relatively simple component rather than redesigning the entire cannula structure. The porous material provides the gas permeability function with minimal structural complexity.
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
This solution significantly reduces the risk of corrosion, lowers the thickness and cost of the active sheath, and maintains the integrity of the armor layers while preventing gas accumulation, resulting in a lighter and more cost-effective pipe.
Implementation Method 1
a chemically active product, capable of reacting with the acid compounds passing through this sheath to neutralize them. Thus, acidic compounds are transformed into other neutral compounds as they pass through the active sheath.
Implementation Method 2
the insert is gas-permeable, the gas being able to pass through this insert from its rear end towards its front end
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
This pipe comprises a first sheath (20) made of polymer material, a second sheath (22) made of polymer material arranged around the first sheath (20), and at least one tensile armour layer. It comprises, at each end of the pipe (16), an end fitting (14). At least one of the end fittings (14) comprises a cannula (58) positioned between the first sheath (20) and the second sheath (22) in contact with at least one of said sheaths (20, 22). The cannula (58) is provided with at least one chemically active product able to react with the acidic compounds originating from the fluid present in the central bore (16) through the first sheath (20).