Metal Sealed Stem Locking Mechanism for Subsea Valves
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Solution Overview
Problem
Dynamic metal seals and elastomeric or polymeric seals in valves are temperamental and prone to leakage over time, especially in high-pressure and static environments, posing environmental and safety risks.
Innovation Solution
A metal-sealed, cap-type device with a stem hub and rotatable stem, where a metal seal is pressed between the upper stem and the stem hub to create a long-term pressure containment and prevent inadvertent rotation, using an operating mechanism to move the upper stem between locked and unlocked positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic metal seals are used for stem sealing, then sealing reliability is improved, but the device becomes temperamental and requires fine surface finishes and contaminant free environments
Solution Approach 1:
Instead of using a dynamic rotating metal seal that requires precise surface finishes, the patent inverts the approach by using a static metal seal that is pressed against the stem. The seal remains stationary while the stem rotates within it, eliminating the complexity of dynamic metal-to-metal contact and fine surface finish requirements while maintaining sealing reliability
Solution Approach 2:
The patent segments the sealing function from the rotation function. The metal seal is separated into a distinct component that can be independently positioned and pressed against the stem, allowing the sealing surface to be simplified while the rotational movement occurs separately within the sealed environment
2Ease of operation
If elastomeric or polymeric seals are used, then ease of operation is improved, but the seals deteriorate over time due to product exposure or loss of elastomeric properties
Solution Approach 1:
The patent changes the material parameter of the seal from elastomeric or polymeric material to metal material. This fundamental material parameter change eliminates the deterioration issues associated with elastomeric properties loss while maintaining the ease of installation through the pressing mechanism
Solution Approach 2:
The patent employs a composite sealing approach where a metal seal combines the durability of metal with a pressing mechanism that distributes load, creating a seal system that resists product exposure deterioration while maintaining operational ease
3Ease of operation
If the stem is unlocked for rotation, then valve operation is enabled, but inadvertent rotation may occur causing safety hazards
Solution Approach 1:
The patent implements a dynamic locking system where the locking mechanism can be easily engaged or disengaged based on operational needs. The stem can be locked in place during static periods to prevent inadvertent rotation, and unlocked when valve operation is required, providing adaptive safety control
4Object-affected harmful factors
If a locking mechanism is added to prevent inadvertent rotation, then safety is improved, but device complexity increases
Solution Approach 1:
The patent merges the locking function with the existing seal assembly. The same component structure that provides sealing also provides locking capability through the pressing mechanism, eliminating the need for a separate locking device and reducing overall system 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
The solution provides a reliable, long-term pressure containment and prevents inadvertent rotation, reducing leakage and ensuring safety in high-pressure systems, particularly in subsea applications.
Implementation Method 1
The metal seal may seal the first end portion of the rotatable stem inside the upper stem and the stem hub when the upper stem is in the locked position
Implementation Method 2
A portion of the upper stem may press the metal seal between the upper stem and the stem hub when the upper stem is moved to a locked position. The upper stem may be inhibited from rotating or moving when in the locked position
Data Source
AI summary
A device includes a stem hub attached to a fitting body. A rotatable stem is located at least partially within the stem hub. Rotation of the rotatable stem operates a blocking element located in the fitting body. In an embodiment, an upper stem is coupled to a first end portion of the rotatable stem so that rotation of the upper stem rotates the rotatable stem. A metal seal is located on the stem hub. A portion of the upper stem presses the metal seal between the upper stem and the stem hub when the upper stem is moved towards the stem hub. An operating mechanism moves the upper stem towards the stem hub and away from the stem hub. The upper stem is moved by the operating mechanism in a direction normal to the rotational axis of the rotatable stem and the upper stem.