Thin-Wall Pipe Compression Junction Using Elastic Seating Cones
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Solution Overview
Problem
Existing compression fittings for thin-wall metallic pipes face issues such as reduced supporting action due to thermal expansion, increased complexity and cost from additional components, and reduced fluid flow passage, especially at high temperatures and in applications like cryogenic systems and palladium alloy pipes, where differential expansions cause fitting failure.
Innovation Solution
A device using compression forces to flare the pipe with two inserts that undergo elastic yield, rather than plastic deformation, ensuring a secure seal without additional components, and is adaptable to various materials and temperatures through specific flaring angles and equipment design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If supporting lock nuts or inserts are used for thin-wall pipes, then the fitting can be applied to thin-wall metallic pipes, but the supporting action is reduced due to differential thermal expansions at high temperatures
Solution Approach 1:
The invention changes the fundamental mechanism from plastic deformation (supporting lock nuts) to elastic deformation (seating cones). The seating cones are designed with specific geometric parameters (cone angle, length, radius) that allow them to elastically yield and conform to the flared pipe end, creating a reliable seal that can accommodate thermal expansion without losing supporting action.
Solution Approach 2:
The invention uses two seating cones that replicate the flared geometry of the pipe end. The first seating cone copies the external flare shape, while the second seating cone copies the internal flare shape. This geometric copying allows the cones to elastically conform to the pipe, providing reliable support and sealing that is not compromised by differential thermal expansion.
2Adaptability or versatility
If supporting lock nuts or inserts are used, then thin-wall pipes can be connected, but additional components increase complexity and cost
Solution Approach 1:
The invention merges the functions of supporting and sealing into a single integrated component - the seating cones. Unlike prior art that required separate supporting lock nuts and sealing elements, the seating cones simultaneously provide mechanical support and create the seal through their elastic yielding against the flared pipe end. This eliminates unnecessary intermediate components and simplifies the overall assembly.
Solution Approach 2:
The invention extracts and eliminates the intermediate supporting lock nuts or inserts from the connection assembly. By directly using the flared pipe end geometry and matching seating cones, the design removes the need for additional supporting components, reducing both part count and assembly complexity while maintaining the ability to connect thin-wall pipes.
3Adaptability or versatility
If inserts are used inside pipes, then thin-wall pipes can be fitted, but the inner section available for fluid flow is reduced
Solution Approach 1:
Instead of inserting components inside the pipe that reduce flow area, the invention inverts the approach by using external flaring of the pipe end and matching seating cones that contact the external flare. The first seating cone engages the external flare, and the second seating cone engages the internal flare, creating a seal without blocking the fluid passage. This inversion eliminates the flow restriction problem while maintaining thin-wall pipe compatibility.
4Ease of manufacture
If double ferrule fittings are used, then compression fittings can be made, but they require plastic deformation and are limited to raw metal and thick-wall pipes
Solution Approach 1:
The invention changes the deformation parameter from plastic (double ferrule) to elastic (seating cones). The seating cones are designed with material properties and geometric parameters that enable elastic yielding rather than plastic deformation. This parameter change allows the same compression fitting mechanism to be applied to thin-wall and mild metal pipes that would be damaged by plastic deformation, while still achieving reliable sealing and support.
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, cost-effective, and efficient sealing connection that withstands high temperatures and differential expansions, maintaining fluid flow and reducing the risk of pipe breakage, as demonstrated by experimental tests and finite element analysis.
Implementation Method 1
two seating cones which undergo elastic yield, rather than plastic deformation
Implementation Method 2
The friction which is generated by the compression forces which are applied by the lock nuts is sufficient to hold the fitting
Data Source
Figure 1~3
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AI summary
The invention relates to a device for making fittings of the compression fitting type on thin-wall metallic pipes. The device consists of two special inserts (IS, TS) which act on the flared end of a thin-wall pipe (T) exploiting the compression forces applied by means of appropriate lock nuts (GSI, GSS). The device adapted to make the flaring of the pipe (T) is also described.