Segmented Flexible Seal for Threaded Joint Leak Prevention
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Solution Overview
Problem
Conventional threaded joints in gas processing installations, particularly those with high hydrogen sulfide content, suffer from gas leakage due to inefficient sealing, leading to safety risks and frequent seal replacement, which increases downtime.
Innovation Solution
A threaded joint design featuring a flange with a counter bore, a nut with a groove, and a flexible seal with complementary threads, allowing for rotational movement and application of torque to ensure a tight seal, reducing the likelihood of shredding and enhancing leak prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seal with rubber flaps is used in a threaded joint, then the seal can cover the stem and prevent leakage, but the rubber flaps become shredded after a few movements of the stem, substantially lowering the sealing capability
Solution Approach 1:
The seal is divided into multiple independent rubber flaps (typically three flaps spaced 120 degrees apart) instead of a continuous rubber ring. This segmentation allows each flap to move independently during stem rotation, preventing the shredding that occurs when a continuous rubber structure is subjected to repetitive deformation. The segmented design maintains sealing capability while significantly extending service life.
Solution Approach 2:
The seal design accommodates the dynamic movement of the stem by allowing the rubber flaps to flex and move during rotation. The flaps are designed to deform elastically during stem movement and return to their original position, adapting to the dynamic operational conditions rather than resisting them rigidly. This dynamic response prevents material fatigue and shredding.
2Reliability
If high torque is applied to the nut to ensure a tight seal, then the sealing efficiency improves, but the rubber portion of the seal becomes shredded and requires frequent replacement
Solution Approach 1:
By segmenting the rubber seal into multiple flaps, the structural stress from high torque is distributed across separate elements rather than concentrating in a continuous ring. Each flap can deform independently under torque, preventing the cumulative stress that leads to shredding in conventional continuous rubber seals. This maintains sealing efficiency while preserving structural integrity.
Solution Approach 2:
The seal utilizes flexible rubber flaps that can elastically deform under high torque conditions. The flexibility of the rubber material allows it to conform to the threaded surfaces under compression while distributing the mechanical stress. This flexible design maintains the tight seal required for high-pressure hydrogen sulfide environments without the rigid structure that would lead to shredding.
3Object-affected harmful factors
If the seal is replaced frequently to maintain sealing capability, then the safety against hydrogen sulfide leakage is maintained, but the downtime of the gas processing installation increases
Solution Approach 1:
The segmented flap design with typical three flaps spaced 120 degrees apart creates multiple independent sealing surfaces that work in parallel. This redundancy ensures that if one flap experiences wear or damage, the other flaps continue to provide sealing capability, significantly extending the service life of the seal and reducing the frequency of replacements required for safety.
Solution Approach 2:
The dynamic design allows the seal to adapt to operational conditions including stem rotation and pressure variations. The rubber flaps flex and move during operation, maintaining sealing contact without experiencing the repetitive stress concentrations that lead to premature failure. This extends the interval between seal replacements, reducing installation downtime while maintaining continuous safety against hydrogen sulfide leakage.
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 design effectively prevents fluid leaks and extends the life cycle of seals by allowing high torque application without shredding, ensuring safer operation in high-pressure environments with hydrogen sulfide presence.
Implementation Method 1
a flexible seal having threads on an inner surface, the threads of the flexible seal having shapes complementary to the threads on the outer surface of the stem. The flexible seal is configured to move by rotation relative to the stem
Implementation Method 2
the torque that can be applied to the nut 140 is relatively low... in absence of a tight fit ensured when a substantial torque can be applied to the nut 140, the efficiency of the sealing is too low
Data Source
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AI summary
A threaded joint (200) includes a flange (230), a nut (240) and a flexible seal (250). The flange (230), the nut (240) and the flexible seal (250) have threads on respective inner surfaces, the threads having shapes complementary to threads on an outer surface of a stem (220). The flange (230) is configured to allow the stem (220) to move by rotation through the flange. The nut (240) and the flexible seal (250) are configured to move by rotation relative to the stem. The flange (230) has a counter bore (280) and the nut (240) has a groove (270). The flexible seal (250) has a first portion (290) configured to fill the counter bore (280) in the flange (230), and a second portion (300) configured to fill the groove (270) of the nut (240).