RTR Pipe Joints Using Induction-Welded Thermoplastic Tie Layers
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Solution Overview
Problem
High-pressure reinforced thermosetting resin (RTR) pipe joints are prone to failures due to improper installation, leading to leaks and reduced confidence in the material's performance, especially at higher temperatures and pressures, as conventional jointing techniques rely heavily on skilled labor and are susceptible to misalignment and degradation over time.
Innovation Solution
A system and method combining integral threading with thermoplastic welding using tie layers coated with thermoplastic materials and susceptor inclusions, where induction heating melts and solidifies the thermoplastic to create a permanent seal and strengthen the joint, allowing for de-skilled installation and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesive or interference joints are used for RTR pipes, then the jointing process is simpler, but the joint reliability deteriorates due to improper installation, misalignment, and degradation over time
Solution Approach 1:
The patent replaces conventional mechanical jointing methods (adhesive bonding, threaded connections, key-lock joints) with induction welding. This substitution eliminates the need for skilled manual assembly while creating a permanent, reliable weld joint that is not subject to degradation over time, thereby improving joint reliability without significantly increasing installation complexity
Solution Approach 2:
The patent changes the physical state of the thermoplastic tie layer through induction heating, melting it to create a permanent bond between pipes. This parameter change (from solid to molten and back to solid) creates a reliable joint that tolerates installation defects, resolving the contradiction between joint reliability and installation complexity
2Stress or pressure
If threaded or key-lock joints are used for high-pressure RTR pipes, then the pressure handling capability is improved, but the joint becomes prone to failures due to improper installation and misalignment
Solution Approach 1:
The patent replaces mechanical threaded or key-lock jointing methods with induction welding. This substitution eliminates the failure modes associated with improper thread assembly, misalignment, and mechanical wear, while maintaining the ability to handle high pressures through the permanent weld joint
Solution Approach 2:
The thermoplastic tie layer is pre-applied to the pipe ends before joining. This preliminary action ensures that the bonding material is in place before the induction welding process, allowing the joint to tolerate installation defects and ensuring reliable high-pressure performance without requiring precise alignment during assembly
3Ease of operation
If adhesive joints are used for lower pressure RTR pipes, then the installation process is simpler, but the joints are susceptible to degradation over time and improper surface preparation
Solution Approach 1:
The patent replaces adhesive bonding with induction welding of thermoplastic material. This substitution eliminates the degradation issues associated with adhesives over time while maintaining installation simplicity, as the induction welding process is automated and does not require skilled surface preparation or assembly techniques
Solution Approach 2:
The patent uses thermoplastic material that can be melted and solidified through induction heating. This parameter change creates a permanent, durable joint that is not subject to the degradation seen in adhesive joints, while the automated induction process maintains installation simplicity
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 significantly reduces joint failures by providing a permanent, reliable seal and increased strength, tolerating installation defects, and enabling automated and efficient coupling of RTR pipes, suitable for high-pressure applications up to 1500 psi and temperatures above 200° F, with potential for on-site repair and integrity monitoring.
Implementation Method 1
wherein, upon application of induction heating to the coupler, the heat between the first pipe, the second pipe, and the coupler is sufficient to melt the thermoplastic material
Implementation Method 2
the heat between the first pipe, the second pipe, and the coupler is sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and the second pipe to the coupler
Data Source
AI summary
A system for coupling pipes includes a first pipe having a tapered, spigot end; a second pipe having a tapered, spigot end; wherein the first pipe and the second pipe are made from a reinforced thermosetting resin (RTR), and a coupler having two tapered socket ends adapted to internally receive the respective tapered, spigot ends of the first pipe and the second pipe, wherein a thermoplastic material is disposed between an exterior of the first pipe and an interior of the coupler. A thermoplastic material is disposed between an exterior of the second pipe and the interior of the coupler. Upon application of induction heating to the coupler, the heat between the first pipe, the second pipe, and the coupler is sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and the second pipe to the coupler. A system for coupling pipes includes a first pipe having a tapered, spigot end; and a second pipe having a tapered, socket end adapted to internally receive the tapered, spigot end of the first pipe. The first pipe and the second pipe are made from a reinforced thermosetting resin (RTR). A thermoplastic material is disposed between an exterior of the first pipe and an interior of the second pipe. Upon application of induction heating to the coupler, the heat between the first pipe and the second pipe is sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe to the second pipe. A method includes disposing a thermoplastic material between an exterior of a first pipe and an interior of a coupler; disposing a thermoplastic material between an exterior of a second and an interior of the coupler; inserting the first pipe and the second pipe into the coupler; and applying induction heating to the coupler sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and the second pipe to the coupler. A method of coupling pipes includes disposing a thermoplastic material between an exterior of a first pipe and an interior of a second pipe; inserting the first pipe into the second pipe; and applying induction heating to the coupler sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe to the second pipe.