Helical Edge Repair Coupling for Pipe Welding
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Solution Overview
Problem
Prior repair couplings face difficulties due to O-rings pushing through lubricant after storage, causing dry interference and making axial movement challenging, and also struggle with gripping the interior tube during the welding process due to its smooth surface.
Innovation Solution
A repair coupling design featuring a hollow body with a helical body edge and a tubular insert with a helical insert edge, allowing for slidable movement and easy rotation by engaging locking lugs, which facilitates assembly and welding by providing a thrust mechanism for the tubular insert.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If O-rings are used to seal the interior tube to the body, then sealing is achieved, but after storage the O-rings push through the lubricant causing dry interference that makes axial movement difficult
Solution Approach 1:
The repair coupling is divided into two main segments: a body and an interior tube that can move independently within it. This segmentation allows the tube to slide axially for installation and removal while the body remains stationary, resolving the contradiction between maintaining a seal and enabling movement.
Solution Approach 2:
A lubricant is introduced as an intermediary substance between the O-rings and the interior surface of the body. This lubricant layer prevents direct contact and friction, allowing the interior tube to slide axially even after storage when the O-rings have pushed through the lubricant. The lubricant acts as a mediator that maintains ease of operation despite seal degradation.
2Manufacturing precision
If the interior tube has a smooth distal end for proper adhesive distribution, then welding quality is improved, but gripping the tube to effect rotation during welding becomes difficult
Solution Approach 1:
The interior tube is designed with different surface qualities at different locations: the distal end maintains a smooth surface for proper adhesive distribution and welding quality, while the proximal end or intermediate sections incorporate external ribs or protrusions that provide gripping surfaces. This local differentiation resolves the contradiction between smooth surfaces for welding and textured surfaces for gripping.
Solution Approach 2:
The solution moves the gripping function to a different dimension or location along the tube's length. Instead of trying to grip the smooth distal end, the design provides gripping features at the proximal end or intermediate sections, allowing rotation to be applied at one location while the smooth distal end maintains its welding function.
3Strength
If the body surrounds much of the interior tube, then structural support is provided, but accessing and rotating the interior tube during welding becomes difficult
Solution Approach 1:
The repair coupling is segmented into an outer body and an inner tube, with the body providing structural support while the tube remains accessible for welding operations. The telescoping design allows the tube to be manipulated independently within the body's confines.
Solution Approach 2:
The design allows manipulation of the interior tube along the axial dimension (sliding in and out) and rotational dimension (turning within the pipe section), even while the body provides radial containment and structural support. This multi-dimensional freedom of movement resolves the contradiction between structural support and operational accessibility.
Data Source
AI summary
A repair coupling for joining a first pipe with a second pipe includes (a) a hollow body having a first open end, a second open end, and a passageway the interior surface of the body defining a peripheral, helical body edge terminating in a body edge locking lug, and (b) a hollow tubular insert slidably disposed within the body, the tubular insert having a first open end and a second open end, the tubular insert defining a passageway he exterior surface of the tubular insert defining a peripheral, helical insert edge terminating in an insert edge locking lug. The tubular insert is slidable between (i) a first insert position wherein the helical insert edge is in contract with the helical body edge and (ii) a second insert position wherein the helical insert edge is spaced apart from the helical body edge.