Segmented Pipe Joint Gasket for Axial Thrust Resistance
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Solution Overview
Problem
Current pipe joint gaskets, particularly those for molecularly oriented polyvinylchloride pipes, fail to effectively prevent separation under pressurization and over-pressurization due to insufficient resistance to axial thrust forces, leading to potential pipe damage and leakage, as traditional metal segments are not configured to handle the dynamic nature of plastic pipes.
Innovation Solution
A gasket with rigid metal segments featuring progressively increasing lengths between vertices, configured to engage both the bell and spigot ends, which rotate to direct thrust forces axially and radially, maintaining engagement and preventing separation by increasing the effective length of the segments as the pipes flex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional metal segments are used in pipe gaskets, then the gasket can provide basic sealing function, but the segments cannot effectively prevent pipe separation under pressurization and over-pressurization due to insufficient resistance to axial thrust forces
Solution Approach 1:
The gasket is divided into multiple rigid metal segments spaced around its inner perimeter. Each segment acts as an independent thrust-resistant element that can engage with the spigot and bell surfaces to counteract axial separation forces. This segmentation allows the gasket to distribute and handle thrust forces more effectively than a continuous band structure.
Solution Approach 2:
The gasket combines rubber material for sealing with rigid metal segments for thrust resistance. This composite structure integrates the complementary properties of both materials: the rubber provides water-tight sealing while the metal segments provide the necessary mechanical strength to resist axial thrust forces during pressurization and over-pressurization events.
2Reliability
If toothed metal segments are used to prevent pipe withdrawal, then axial separation is prevented, but excessive axial thrust force causes the segments to exert destructive radial loads upon the inner surface of the bell end and outer surface of the spigot
Solution Approach 1:
The metal segments feature acutely pointed configurations that concentrate the engagement force at specific localized points on the spigot and bell surfaces. This localized engagement allows the segments to effectively prevent withdrawal while minimizing the distribution of destructive radial loads across the entire pipe surface. The pointed geometry creates controlled insertion points rather than distributed surface loading.
Solution Approach 2:
The segments are designed with specific geometric parameters including acute angles and pointed configurations that optimize the force distribution. By carefully controlling the segment shape parameters, the gasket achieves effective engagement to prevent withdrawal while reducing the magnitude of harmful radial loads exerted on the pipe surfaces during thrust events.
3Force
If metal segments exert increased pressure on bell and spigot to counteract thrust forces, then separation is prevented, but the distance between spigot outer wall and bell inner wall increases due to pipe flexibility
Solution Approach 1:
The gasket design accommodates the dynamic nature of plastic pipe joints by allowing the metal segments to maintain effective engagement despite changes in the distance between spigot and bell walls. The segments are positioned and configured to adapt to the flexing and movement that occurs during pressurization, ensuring continuous thrust resistance while accounting for the dynamic geometry of the joint.
Data Source
AI summary
A method for inhibiting separation of joined pipes including providing within a pipe bell a gasket including rigid segments, each segment having bell teeth configured for engaging the bell and a spigot tooth configured for engaging a pipe spigot seated in the bell. Upon pressurization and over-pressurization of the joint, resulting axial forces exerted on the joint, which can cause pipes to separate, are countered by wedging the segments between the bell and the spigot and rotating each segment so that the thrust forces are directed radially. To prevent radially-directed thrust forces from damaging the joint through over-rotation of the segments, the bell teeth and the spigot tooth are adapted and arranged to maintain the thrust forces load path carried by each segment within a desired angular range relative to the spigot by transferring the load path between adjacent bell teeth whereby the effective length of each segment is increased.