Induction Heating Pipe Coating for Field Joint Corrosion
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Solution Overview
Problem
Field-welded joints in pipelines are prone to corrosion due to inadequate protection, as existing coating methods are either difficult to use in field conditions or fail to provide sufficient corrosion resistance, especially when compared to factory-applied coatings.
Innovation Solution
A method and apparatus for applying a polymer coating using a movable die and induction heating to enhance adhesion, allowing for efficient application of a melt polymer film on the pipe surface, which can be used in field conditions and reduces energy consumption by eliminating the need for a separate heating stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating methods (shrink-sleeve, spray guns, machine taping) are used for field-welded joints, then corrosion protection can be achieved, but the methods are difficult to use in field conditions or fail to provide adequate protection
Solution Approach 1:
The patent replaces complex mechanical coating systems (spray guns, taping machines) with a simplified system consisting of a heating element and polymer material application. This substitution maintains corrosion protection while dramatically improving ease of operation in field conditions by eliminating the need for complex equipment setup and operation.
Solution Approach 2:
The patent changes the physical state of the polymer material from solid to melt form, and controls the temperature parameter of the substrate surface to enable bonding. By heating the surface to specific temperature ranges and applying polymer in melt form, the system achieves reliable corrosion protection through a simple phase change process that is easy to implement in field conditions.
2Reliability
If a separate heating stage is used before polymer application, then adhesion is improved, but energy consumption increases
Solution Approach 1:
The patent merges the heating function and polymer application function into a single integrated process. The heating element is positioned to heat the surface simultaneously with or immediately before polymer material application, eliminating the need for a separate heating stage. This combination maintains adequate adhesion while reducing total energy consumption and process time.
Solution Approach 2:
The patent performs heating as a preliminary action immediately before polymer application, but integrates it into the same operational sequence rather than using a separate stage. The surface is heated to the required temperature just before the polymer material is applied, ensuring adequate adhesion while minimizing energy consumption by avoiding prolonged heating.
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 method and apparatus provide a reliable, efficient, and energy-efficient way to coat field joints and other pipe surfaces, achieving results comparable to factory coatings while being operational in all weather conditions and allowing for easy repair, with reduced energy consumption and improved adhesion.
Implementation Method 1
a limited area of the surface is heated by induction heating before or simultaneously to the application of the polymer film or sheet
Implementation Method 2
applying at least one polymer material in the form of a melt film or sheet on the surface of the pipe or pipe section from a moving die or nozzle
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c
AI summary
Method and apparatus for coating a pipe (2) or a pipe section with a layer of at least one polymer. The method comprises providing a pipe (2) or a pipe section having an outer surface defining the periphery of the pipe or pipe section; applying on the outer surface of the pipe or pipe section a layer of at least one polymer material in melt stage using a nozzle (3), which is mounted on a carriage (1,15a,15b) capable of travelling along the periphery of the pipe (2) or pipe section; and moving the carriage along at least a part of the periphery during the application of the polymer material to form a layer on the surface of the pipe (2) or pipe section. The outer surface of the pipe or pipe section is being locally heated by induction heating before the application of the polymer material onto said surface. The present invention is particularly useful for coating field joints in pipelines.