High Pressure Pipe Joint With Welded Flared Socket
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Solution Overview
Problem
Existing pipe joints with elastomeric seals lack end restraint, leading to potential separation at pipeline bends and heat-induced damage during welding, which causes leakage and corrosion, especially when dealing with plastic or cement mortar linings.
Innovation Solution
A pipe joint design featuring a socket with an outwardly flared end and a spigot with an inverted hump supporting an elastomeric seal, where the coating is removed from the socket and spigot ends to allow for welding without damaging the internal lining, and a protective corrosion-resistant coating is applied to the weld area, ensuring full corrosion protection and restraint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is performed on plastic coated and lined pipes to provide end restraint, then the necessary restraint is achieved, but the heat conducts through the steel causing damage to the internal lining
Solution Approach 1:
The coating is selectively removed from specific welding zones (the forward end of the socket and the protruding hump of the spigot) while preserving the coating in other areas. This segmentation allows welding to occur only where necessary for structural restraint, while protecting the internal lining in areas where heat would cause damage.
Solution Approach 2:
Different regions of the pipe joint have different coating conditions: the welding areas have removed coating to allow heat dissipation and welding access, while the internal lining areas maintain their coating for protection. This local differentiation of properties resolves the contradiction between needing heat for welding and protecting against heat damage.
2Strength
If heat is conducted along the lip of the socket into the elastomeric ring area, then welding provides structural restraint, but the internal coating softens causing the elastomeric ring to expand radially and lose compression
Solution Approach 1:
The coating removal is precisely localized to the welding zones only, creating a thermal barrier by maintaining coating in adjacent areas. This prevents heat conduction along the lip into the elastomeric ring area, preserving the sealing compression while still allowing welding for structural restraint.
Solution Approach 2:
The remaining coating acts as a thermal insulator or intermediary layer between the welding zone and the elastomeric ring area, blocking heat transfer that would otherwise cause the ring to expand and lose compression.
3Strength
If an externally welded lap weld is used to provide full restraint, then end restraint is achieved, but exposed steel sections inside the pipe corrode when exposed to certain water chemistry
Solution Approach 1:
The welding process, which creates exposed steel susceptible to corrosion, is followed by application of a protective corrosion-resistant coating to the weld area. This converts the harmful exposed steel surface into a protected surface, transforming the potential weakness into a strength.
Solution Approach 2:
The surface properties of the weld area are changed by applying a corrosion-resistant coating, transforming the exposed steel surface into a protected surface that resists corrosion from water chemistry while maintaining the structural restraint function.
4Temperature
If the elastomeric ring expands radially due to heat, then the ring material softens, but the compression force between the socket and spigot diminishes enabling water leakage
Solution Approach 1:
The coating serves as a thermal intermediary or insulator between the welding zone and the elastomeric ring seating area, preventing heat from reaching the ring and causing radial expansion that would reduce compression force and enable leakage.
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 corrosion-resistant, pressure-retaining joint capable of withstanding high internal pressures and angular deflections, minimizing bending stresses and fatigue, while maintaining the integrity of the internal coating and preventing leakage and corrosion.
Implementation Method 1
the compression force of the ring between the internal surface of the socket and the external surface of the spigot
Implementation Method 2
an elastomeric seal wherein the inverted hump is spaced from a protruding hump
Implementation Method 3
the heat being conducted through the steel on the spigot causing damage to the internal lining
Data Source
AI summary
A pipe joint between two metallic pipes which have been internally and/or externally coated with a material to prevent corrosion. The pipe joint includes a spigot terminating in an inverted hump supporting an elastomeric seal wherein the inverted hump is spaced from a protruding hump. The pipe joint further includes a socket adapted to fit over the spigot, the socket having an outwardly flared forward end terminating in an annular lip that engages an exterior of the protruding hump wherein the lip is welded to an exterior of the spigot.