Threaded Fluid Coupling With Torque-Triggered Sealing Interference
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Solution Overview
Problem
Threaded couplings for fluid conduits often fail to ensure a complete connection, leading to leaks due to inadequate tightening, as operators may hand-tighten connections that pass initial inspections but fail under operational pressures, and existing methods for verifying torque are prone to errors or erasure.
Innovation Solution
A threaded coupling design featuring an interference member that prevents complete sealing unless a predefined load is applied, using mechanisms such as an annular sleeve, pins, biasing members, stops, or pressure-sensitive materials to ensure the connection is only secure when the required torque is met, preventing leaks during initial inspection and operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional torque monitoring and marking methods are used, then the connection can be tightened to the desired torque, but the indication of complete connection may be wrong due to operator errors or erasure by subsequent processes
Solution Approach 1:
The coupling mechanism performs self-verification through the interference member's automatic engagement state. The interference member itself serves as both the torque application mechanism and the verification indicator, eliminating the need for separate marking operations that are prone to human error and erasure.
Solution Approach 2:
The interference member provides immediate feedback on whether the required torque has been applied. When the interference member disengages from the blocking position, it visually or mechanically indicates that sufficient torque has been applied, creating a direct feedback loop between the tightening action and the verification state.
2Ease of operation
If hand-tightening is used to simplify operation, then initial inspection may pass, but the coupling will leak under normal operating pressures and cyclical loading
Solution Approach 1:
The interference member is designed to actively prevent complete sealing engagement until the required torque is applied. It creates a mechanical barrier that blocks the sealing surfaces from making full contact, thereby preemptively preventing the false sense of security that hand-tightening might provide during initial inspection.
Solution Approach 2:
The interference member must be overcome during the tightening process before sealing can occur. This preliminary action requirement ensures that sufficient torque is applied before the coupling can achieve its sealed state, preventing under-tightening from passing inspection.
3Reliability
If an interference member is added to prevent under-tightening, then connection reliability is improved, but device complexity increases
Solution Approach 1:
The interference member serves multiple functions simultaneously: it acts as a torque threshold enforcement mechanism, a verification indicator, and a sealing control element. By combining these functions into a single component, the design adds minimal complexity while achieving multiple reliability objectives.
Solution Approach 2:
The interference member is integrated with the existing coupling structure, merging the verification function with the sealing mechanism. Rather than adding a separate verification device, the interference member is combined with the sealing elements, reducing overall system complexity while maintaining reliability improvements.
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 ensures a leak-free connection under both initial inspection and operational pressures by requiring a specific torque for complete sealing, preventing hand-tightened couplings from leaking and ensuring consistent quality assurance.
Implementation Method 1
The annular sleeve may be frictionally held to the body portion. When the load on the sleeve meets or exceeds the predefined amount, a friction force between the sleeve and the body portion is overcome to allow the sleeve to move relative to the body portion
Implementation Method 2
the interference member includes a biasing member having a predefined spring force which allows the biasing member to move or deflect relative to the body portion by a predetermined amount in response to the load on the biasing member
Data Source
AI summary
A threaded coupling for ensuring a complete connection between fluid conduits includes a body portion of a fluid conduit, an axially forward sealing surface, a thread, and an interference member. The interference member is disposed on the body portion and is engageable with a portion of another fluid conduit to apply a load on the interference member when the fluid conduits are threadably connected together. The interference member is configured to prevent a complete sealing engagement between the fluid conduits when the load on the interference member is less than a predefined amount, and is configured to allow the complete sealing engagement between the fluid conduits when the load on the interference member meets or exceeds the predetermined amount.