Stepped Annular Gasket Structure to Eliminate Flange Dead Space
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Solution Overview
Problem
Conventional pipe joints with annular seal projections on flange surfaces create dead spaces that trap high-purity gases, affecting concentration management in semiconductor manufacturing processes.
Innovation Solution
An annular gasket with radially inner and outer surfaces orthogonal to the axial direction, plastically deforming to eliminate dead spaces and ensure maximum sealability, detected by a helium leak test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If annular seal projections are formed on flange surfaces to improve adhesion, then adhesion between seal projections and gasket is improved, but dead spaces are formed between the gasket and seal surfaces on the gas contact side
Solution Approach 1:
The gasket is segmented into multiple radial sections (first, second, third radial sections) with different structural characteristics. The first radial section has a flat surface for sealing, while the second and third radial sections have inclined surfaces that slope toward the gas contact side, creating a stepped configuration that eliminates dead spaces while maintaining adhesion.
Solution Approach 2:
The invention transitions from a conventional two-dimensional flat gasket surface to a three-dimensional stepped structure with inclined surfaces. This dimensional change allows the gasket to conform to the seal projections while eliminating radial dead spaces, as the inclined surfaces create a gradient that prevents gas trapping.
2Reliability
If the gasket is crushed by seal projections to improve sealing, then adhesion is improved, but dead spaces cause gas to stay trapped affecting concentration management
Solution Approach 1:
Different radial sections of the gasket are given different local qualities: the first radial section has a flat surface optimized for sealing contact, while the second and third radial sections have inclined surfaces optimized for eliminating dead spaces. This local differentiation allows the gasket to simultaneously achieve reliable sealing and prevent gas trapping.
3Reliability
If radially inner surface is plastically deformed to eliminate dead space, then sealability is maximized, but deformation may occur in the wrong direction without proper constraints
Solution Approach 1:
The gasket is pre-formed with a stepped structure including flat and inclined surfaces before assembly. This preliminary configuration ensures that when the flange is tightened, the radially inner surface deforms plastically in the correct direction (radially outward) to eliminate dead spaces, rather than deforming unpredictably.
Solution Approach 2:
The gasket features an asymmetric stepped structure with inclined surfaces that slope toward the gas contact side. This asymmetric geometry guides the plastic deformation in a specific direction during tightening, ensuring the radially inner surface deforms outward to eliminate dead spaces while maintaining structural stability.
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
Eliminates dead spaces between the gasket and flange portions, enhancing sealability and allowing reliable detection of leaks through a helium leak test, while maintaining mechanical strength and safety.
Implementation Method 1
the radially inner surface comes into contact with the seal surface to be plastically deformed
Data Source
AI summary
The present invention eliminates a dead space between a gasket and flanges and the present invention is an annular gasket 30 attached between planar seal surfaces 12x of opposing flange portions 12, in which steps 30d are formed between radially inner surfaces 30b continuous with an inner peripheral surface 30a and radially outer surfaces 30c, each radially inner surface 30b is located axially outward the corresponding radially outer surface 30c, the radially inner surface 30b and the radially outer surface 30c each have a planar shape orthogonal to an axial direction, and each radially outer surface 30c comes into contact with the corresponding seal surface 12x after each radially inner surface 30b comes into contact with the corresponding seal surface 12x.