Flexible Pipe Pressure Vault Venting Against Corrosive Gas Buildup
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Solution Overview
Problem
Flexible fluid transport pipes used in the oil and gas industry face corrosion and stress corrosion cracking due to the presence of corrosive gases, leading to reduced service life and potential mechanical integrity issues, particularly at the pressure vault level.
Innovation Solution
The flexible pipe design incorporates additional passages and notches in the pressure vault to allow gas diffusion, preventing gas accumulation and reducing corrosive environments, while maintaining structural integrity through specific radial clearances and materials like stainless steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pressure vault is stapled to limit creep of the pressure sheath under internal pressure, then the mechanical strength and creep resistance are improved, but corrosive gas accumulates in the annular space leading to increased corrosion and stress corrosion cracking
Solution Approach 1:
The pressure vault is segmented with radial passages that divide the annular space into multiple compartments, allowing corrosive gas to escape from different locations while maintaining the structural integrity and creep resistance provided by the stapled construction
Solution Approach 2:
Radial passages are created in the pressure vault to extract and remove corrosive gas from the annular space between the pressure sheath and outer sheath, preventing gas accumulation that would otherwise lead to stress corrosion cracking while preserving the stapled pressure vault structure
2Object-affected harmful factors
If radial passages are added to the pressure vault to allow gas diffusion, then corrosion and stress corrosion cracking are reduced, but the structural integrity and creep resistance may be compromised
Solution Approach 1:
Radial passages are localized in specific regions of the pressure vault where they provide gas escape paths without compromising the overall structural integrity, with passages strategically positioned to allow corrosion prevention while maintaining strength in critical load-bearing areas
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 design significantly reduces the partial pressure of corrosive gases within the pressure vault, minimizing corrosion and stress corrosion cracking, thereby extending the service life and maintaining mechanical integrity of the pipe.
Implementation Method 1
The flexible conduit (10) comprises a pressure vault (27) which is interposed between the pressure sheath (20) and the layer of tensile armor (24, 25)... at least one additional passage (68) for the circulation of gases is provided in the pressure vault (27)... allowing the passage of gases from the inside of the conduit (10) to the annular space between the pressure sheath (20) and the outer sheath (30)
Data Source
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AI summary
The invention relates to a flexible fluid transport pipe, comprising: - a polymer tubular sheath delimiting a central-axis fluid circulation passage; - a pressure vault, disposed around and outside the tubular sheath, the pressure vault comprising a short-pitch winding of at least one stapled shaped wire (40), the shaped wire (40) comprising a plurality of stapled turns (42), each turn (42) having, in section in a median axial plane, a profile defining at least one stud (50, 56) and, for the or each stud (50, 56), a groove (52, 58) adjacent to the stud (50, 56), the stud (50, 56) being suitable for being stapled into a groove (58, 52) of an adjacent turn of a shaped wire (40) of the pressure vault; - at least one reinforcement layer disposed on the outside of the pressure vault, and at least one additional passage (68) for gas circulation through the pressure vault from the inside of the pressure vault to the outside of the pressure vault is defined in the or each stud (50, 56) and/or in the bottom (60, 54) of the or each groove (58, 52), the additional passage (68) allowing gas circulation between the inside of the pressure vault and the outside of the pressure vault in addition to at least one clearance (J1, J2) between the stud (50, 56) of one turn (42) and the bottom (60, 54) of the groove (58, 52) of the adjacent turn, or in the absence of clearance between the stud (50, 56) of one turn (42) and the bottom (60, 54) of the groove (58, 52) of the adjacent turn.