Reverse Hub Flange Design for Stress Reduction
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Solution Overview
Problem
Conventional high-pressure pipe connections are large, heavy, and costly due to the need for a large bolt circle and thick flanges to withstand stress, which increases weight and manufacturing costs.
Innovation Solution
The design incorporates a reverse spline hub between the flange outer portions and weld necks, reducing stress and allowing for a smaller bolt circle and thinner flanges, along with a staggered bolt configuration to minimize material usage and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional high-pressure pipe connections use large bolt circles and thick flanges to withstand stress, then structural strength is improved, but weight and manufacturing cost increase
Solution Approach 1:
The patent applies the inversion principle by using a reverse hub configuration where the hub diameter decreases in the direction of the pipe axis (from the flange face toward the weld neck), which is opposite to conventional hub designs. This reverse geometry redistributes stresses more efficiently, allowing the flange to maintain required strength while using less material, thereby reducing weight without compromising structural integrity under high pressure and bolt loads.
Solution Approach 2:
The patent changes the geometric parameters of the hub by implementing a reverse taper profile with specific angle ranges (15-45 degrees) and controlled transitions. By modifying the hub's dimensional parameters and stress distribution characteristics, the design achieves optimal strength-to-weight ratio, allowing thinner flanges and smaller bolt circles while maintaining the ability to withstand high-pressure connections.
2Strength
If conventional high-pressure pipe connections use large bolt circles and thick flanges to withstand stress, then structural strength is improved, but manufacturing cost increases
Solution Approach 1:
The reverse hub configuration inverts the conventional design approach, creating a geometry that is more efficient for manufacturing. The reverse taper profile allows for optimized material removal during machining and reduces the overall material inventory required, leading to lower raw material costs and reduced manufacturing complexity despite maintaining high structural strength requirements.
Solution Approach 2:
By changing the hub geometric parameters to a reverse taper with controlled angles and transitions, the patent optimizes the balance between strength requirements and manufacturing economy. The specific parameter ranges enable more efficient machining operations and reduce material waste, thereby lowering manufacturing costs while meeting strength specifications.
3Stress or pressure
If the reverse hub taper follows a spline curve, then stress minimization between inner portion and outer flange portion is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies curvature principles by using a spline curve to define the reverse hub taper profile. This curved geometry smoothly transitions between the hub and flange portions, eliminating sharp corners and stress concentration points. The continuous curvature distribution optimizes stress flow patterns, minimizing peak stresses while maintaining manufacturability through standard machining processes capable of producing spline profiles.
Data Source
AI summary
A pipe connection in which at least one of the flanges has a reverse hub between the outer portion of the flange and the inner portion of the flange that extends outward to form to the weld neck. The reverse hub tapers down toward the sealing face of the flange, rather than away from the face of the flange. This taper may follow a spline curve which is empirically determined to reduce stresses that are caused by rotation of the outer portion of the flange around the gasket. The reverse hub eliminates material that would be required for a positive hub and thereby reduces the weight of the flange. By reducing the stresses resulting from rotation of the outer portion of the flange around the gasket, the thickness of the flange may also be reduced, further reducing the weight of the flange.