Plastic Pipe Transition End Installation Using Stiffener Sleeve
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Solution Overview
Problem
Existing methods for transitioning plastic pipes to metal components are complex, impractical for field installations, and often result in reduced holding strength due to compression and cold flow issues, particularly when using internal stiffeners inserted from the opposite end of the plastic pipe.
Innovation Solution
A field completion tool and method that installs a metal transition end on the open end of a plastic pipe using a stationary and mobile section with a clamping ring, tie rods, and a segmented grip to securely place a stiffener sleeve within the plastic pipe, eliminating the need for butt welding and accommodating thermal stress through a relief groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an internal stiffener sleeve is inserted within the plastic pipe to secure a surrounding metal transition end, then the transition end can be secured to the plastic pipe, but the technique requires butt welding of the pipe section and presents field installation complications
Solution Approach 1:
The patent inverts the installation approach by inserting the stiffener sleeve from the exterior of the pipe end rather than from the interior. The installer forces the stiffener sleeve downwardly into the mouth of the metal pipe and plastic pipe throat from the outside, eliminating the need for butt welding and complex field operations while maintaining secure attachment
Solution Approach 2:
The stiffener sleeve is installed beforehand into the pipe end before the transition fitting is attached. This preliminary insertion of the stiffener from the exterior prepares the pipe end for subsequent transition fitting installation, simplifying the overall field installation process
2Ease of manufacture
If a compression fitting is used to attach the metal transition end to the plastic pipe, then the transition can be made, but the plastic tends to cold flow resulting in reduced holding strength over time
Solution Approach 1:
The patent applies local quality by providing a relief groove in the plastic pipe end at the specific location where the transition fitting attaches. This localized feature allows controlled deformation and stress relief precisely where needed, preventing cold flow in the critical holding area while maintaining installation simplicity
Solution Approach 2:
The relief groove is provided in advance in the plastic pipe end to cushion and accommodate potential cold flow before it occurs. This preemptive measure prevents the plastic from deforming in a way that would reduce holding strength, addressing the cold flow issue before it compromises the connection
Data Source
AI summary
An apparatus and method are shown for installing a metal transition end on an open end of a length of plastic pipe having an outer diameter and an inner diameter by placing a stiffener sleeve within the inner diameter of the plastic pipe at a point which is circumscribed by the metal transition end. An actuating sleeve, carried on the draw rod, allows the stiffener sleeve to be installed in a desired location within the open plastic pipe end by using the draw rod to first position the stiffener sleeve in the desired location. The metal transition end is provided with an internal relief groove which accepts any excess plastic material forced past the stiffener sleeve during the installation process.