In-Place Thermoset Pipe Coating for Low-Lead Water Service Lines
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Solution Overview
Problem
Current methods for reducing lead and copper leaching from drinking water pipes, such as chemical additions and internally placed resin coatings, are inefficient and often require long cure times, leading to non-compliance with regulatory standards, especially in small diameter pipes, and deplete scarce phosphate resources.
Innovation Solution
A method for applying a phenol-free and plasticizer-free amine adducted thermoset resin coating to the interior and exterior of drinking water pipes and fittings in a single operation, using a two-component system that can be cured with air or water, reducing leaching of metals like lead and copper to below 10 µg/L within 1 to 2 hours, without the need for disassembling the pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thin set linings (100-400 microns) are applied to small diameter pipes to maintain flow, then coating thickness is reduced, but pinholing and lead particulate contamination occur making compliance difficult
Solution Approach 1:
The patent changes the chemical parameters of the coating system by using a two-component epoxy-amine system with specific molecular weight ratios and incorporating lead stabilizing agents. This chemical parameter change allows the coating to achieve both thin profile (100-400 microns) and high reliability (lead leaching <10 μg/L) by controlling the curing chemistry and adding corrosion inhibitors directly to the coating formulation.
Solution Approach 2:
The patent creates a composite coating system combining epoxy resin with amine hardener and lead stabilizing agents. This composite material approach integrates multiple functions into a single coating layer: adhesion, barrier properties, and corrosion inhibition, enabling thin set linings to achieve compliance without pinholing or contamination.
2Reliability
If conventional resin based coatings are used, then lead leaching is reduced, but long cure times are required and potential leachates from coating occur
Solution Approach 1:
The patent changes the curing kinetics parameters by using a two-component epoxy-amine system that cures rapidly at ambient temperatures. The specific selection of amine hardener and curing conditions (temperature, humidity) controls the reaction rate, reducing cure time from days to hours while maintaining low lead leaching through proper formulation with lead stabilizing agents.
Solution Approach 2:
The patent accelerates the curing process by incorporating catalysts and controlling environmental conditions (temperature, humidity) to speed up the epoxy-amine reaction. This accelerated curing reduces the time required to achieve full cure while the lead stabilizing agents ensure compliance with lead standards throughout the curing process.
3Reliability
If phosphate-based materials are added to water supply, then lead leaching is reduced, but phosphate resources are depleted
Solution Approach 1:
The patent extracts the lead corrosion inhibition function from the water supply (phosphate dosing) and transfers it to the pipe coating system. By incorporating lead stabilizing agents directly into the coating formulation, the solution eliminates the need for continuous phosphate addition to water, conserving phosphate resources while maintaining lead leaching control.
Solution Approach 2:
The patent introduces a coating system as an intermediary between the lead pipe and water supply. This coating acts as a barrier and includes lead stabilizing agents that prevent lead dissolution, replacing the need for phosphate-based water treatment and eliminating ongoing phosphate consumption.
4Ease of operation
If compression fittings and in-line connectors are used, then installation is simplified, but pipe ends and exterior portions remain exposed to water
Solution Approach 1:
The patent makes the coating system universal by designing it to coat not only the pipe interior but also exterior surfaces and pipe ends through fittings. This multi-functional coating application eliminates exposed metal surfaces while maintaining installation simplicity, addressing both ease of operation and prevention of water exposure to metal.
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 effectively reduces lead and copper leaching to compliant levels, extends pipe system lifespan, conserves phosphate resources, and allows for rapid restoration of water services, meeting regulatory standards for drinking water quality.
Implementation Method 1
A method for applying a phenol-free and plasticizer-free amine adducted thermoset resin coating to the interior and exterior of drinking water pipes and fittings in a single operation, using a two-component system that can be cured with air or water
Data Source
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AI summary
Methods, processes, compositions and systems for preventing leaching effects from drinking water service pipes (such as lead, steel and copper) having an inner diameter of at least approximately 12mm and the pipe coatings. 2-step thermoset resin coating is applied to pipe interiors and inner surfaces of fittings/valves, and exterior ends of the pipes that fit within the fittings/valves "in place" without dismantling the pipes from fittings where the curing agent can be phenol free and plasticizer free adduct. The coating can reduce heavy metals, such as lead, from leaching from installed pipes and fittings to less than approximately 10 μg/L (10 ppb). When cured, specific leachates, Bisphenol A and Epichlorohydrin from the coatings will be (less than) < 1 μg/L (1ppb) with overall TOC levels measured at (less than) < 2.5mg/L (2.5ppm). Pipes can be returned to service from at least approximately 1 to approximately 2 hours.