RTR Pipe Joint Welding With Resistive Thermoplastic Sealing
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Solution Overview
Problem
The jointing component in RTR pipe systems is often the limiting factor for higher temperature and pressure operating envelopes, with traditional joint designs prone to failures due to improper installation and surface preparation issues, particularly in high-pressure applications.
Innovation Solution
A system and method for coupling RTR pipes using a resistive element with thermoplastic layers and an electrically conducting heating element, which generates heat to melt and seal the thermoplastic material, forming a robust and reliable joint in a single step process without requiring extensive surface preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional adhesive or interference joints are used for RTR pipes, then the jointing process is simpler, but the joint reliability and operating envelope (pressure and temperature) are limited
Solution Approach 1:
The patent uses a composite resistive element comprising thermoplastic material and electrically conductive material (such as carbon fiber or metal particles) to create a joint that combines the sealing properties of thermoplastic with the electrical heating capability of conductive materials. This composite structure enables both high reliability and enhanced operating envelope while maintaining relatively simple installation procedures.
Solution Approach 2:
The patent changes the physical state of the thermoplastic material through controlled heating and cooling cycles. The thermoplastic is heated to melt and fuse the joint components together, then cooled to solidify and create a strong, reliable connection. This parameter change enables the joint to withstand higher pressures and temperatures while maintaining simplicity in the jointing process.
2Reliability
If multiple heating steps and surface preparation are performed to achieve reliable joints, then the joint reliability improves, but the installation time and process complexity increase
Solution Approach 1:
The patent merges the surface preparation function and the heating/fusion function into a single integrated resistive element. The electrically conductive material within the thermoplastic provides direct heating capability at the joint interface, eliminating the need for separate surface preparation steps and multiple heating cycles. This single-step process achieves reliable joints while significantly reducing installation time.
Solution Approach 2:
The resistive element is designed to selfheat when electrical current is applied, generating the necessary heat directly at the joint interface without requiring external heating equipment or complex multi-step heating procedures. This self-service capability simplifies the installation process and reduces installation time while maintaining high joint reliability.
3Stress or pressure
If interference joints with solid contact are used for high-pressure applications, then the pressure handling capability improves, but the sealing reliability deteriorates due to improper installation
Solution Approach 1:
The patent introduces the resistive element as an intermediary between the RTR pipe components at the joint interface. This intermediary provides both the mechanical contact needed for pressure handling and the thermal fusion capability needed for sealing reliability. The thermoplastic material flows to create a uniform seal that is insensitive to installation variations, while the conductive material enables controlled heating to achieve proper fusion.
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
This approach reduces joint failures, enhances the operating envelope up to 1500 psi and temperatures above 200° F, providing a more reliable and efficient coupling method for RTR pipes, eliminating the need for multiple heating steps and surface preparation.
Implementation Method 1
the electrically conducting resistive heating element generates heat sufficient to melt the thermoplastic material
Implementation Method 2
the electrically conducting resistive heating element generates heat sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and/or 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; a coupler having two tapered socket ends adapted to internally receive the respective tapered, spigot ends of the first pipe and the second pipe; and a resistive element. The first pipe, the second pipe, and the coupler are made from a reinforced thermosetting resin (RTR). The resistive element includes a first layer and a second layer of thermoplastic material; and an electrically conducting resistive heating element with positive and negative terminals for connecting electrical power. The electrically conducting resistive heating element is sandwiched by the first layer and the second layer of thermoplastic material. The resistive element is disposed between an interior of the coupler and at least one of: an exterior of the first pipe and an exterior of the second pipe. Upon application of electrical power to the positive and negative terminals of the resistive element, the electrically conducting resistive heating element generates heat sufficient to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and/or the second pipe to the coupler.