Bi-Directional Seal Element for High External Pressure Sealing
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Solution Overview
Problem
Existing annular seal elements, such as the Straight Bore Metal Seal, are ineffective in sealing against high external pressures encountered in ultra-deep water subsea installations, where external pressure can force the seal to leak due to radial inward movement of the arm sections, and bi-directional seals like BX and RX types are difficult to mechanically energize due to stiff cross-sectional shapes.
Innovation Solution
A bi-directional annular seal element with first and second axially spaced sealing lips that engage internal pressure, and third and fourth axially spaced sealing lips that engage external pressure, utilizing a cylindrical seal body and radially extending sealing flanges with an intervening annular cavity to ensure effective sealing in both directions, reducing the required energization force and allowing for a smaller outer diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional Straight Bore Metal Seal is used to seal against internal pressure, then the seal is effective at preventing internal pressure leakage, but the seal fails to prevent external pressure leakage in ultra-deep water environments
Solution Approach 1:
The seal element is divided into multiple functional segments: a body portion with radially outwardly directed sealing lips for internal pressure sealing, and axially extending arm sections with additional sealing lips for external pressure sealing. This segmentation allows each portion to specialize in sealing against one direction of pressure, achieving reliable bi-directional sealing capability.
2Reliability
If BX or RX type gaskets are used to provide bi-directional sealing, then sealing capability in both directions is achieved, but the seals are difficult to mechanically energize due to stiff cross-sectional shapes
Solution Approach 1:
The seal element employs different cross-sectional geometries in different regions: the body portion has a configuration optimized for internal pressure sealing, while the arm sections have geometries designed for external pressure sealing. This local differentiation allows each region to be easily energized in its specific function without the overall stiffness problem of BX/RX gaskets.
3Stress or pressure
If traditional seal elements are designed for internal pressure sealing, then the sealing lips are positioned to engage internal pressure, but the seal cannot withstand high external pressures that force arm sections radially inward
Solution Approach 1:
The seal element features asymmetric geometry with radially outwardly directed sealing lips on the body portion for internal pressure engagement, and axially extending arm sections with sealing lips oriented for external pressure engagement. This asymmetric design allows the seal to effectively resist both internal and external pressures by directing each sealing lip configuration to counteract the appropriate pressure direction.
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 seal element effectively prevents fluid leakage in both directions across a wide pressure range, reducing the force required for energization and allowing for a more compact and lighter design, addressing the limitations of traditional seals in high-pressure environments.
Implementation Method 1
the seal element is configured to seal the external environment from pressure in the enclosure and to seal the enclosure from pressure in the external environment
Data Source
AI summary
An annular seal element which includes a cylindrical seal body: first and second axially spaced sealing lips which are located on the seal body and are directed generally radially outwardly: first and second spaced-apart sealing flanges which extend radially outwardly from the seal body: and third and fourth sealing lips which are located on the first and second sealing flanges, respectively.