Internal Pipe Coating Using Turbulent Dip Cycles for Corrosion Resistance
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Solution Overview
Problem
There is a lack of pipe materials, particularly mild steel, that remain corrosion-free over long periods, posing challenges for fire protection systems like sprinkler systems where warranty claims are affected by corrosion issues.
Innovation Solution
A method involving an epoxy/acrylic-based coating liquid with FeF3 iron fluoride in an aqueous dispersion is used to coat pipes internally and externally, utilizing a dip tank process with controlled angles and repetitions to ensure a turbulent flow and sufficient coating thickness, specifically between 15 to 28 μm, using the Aquence™ process for anti-corrosion coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating methods are used on mild steel pipes, then the coating process is simple, but the pipes corrode after long periods of use
Solution Approach 1:
The pipe is pre-heated to 80-120°C before coating, and the coating liquid is pre-heated to 40-60°C. This preliminary thermal preparation ensures optimal coating adhesion and uniformity, preventing corrosion by creating a stable bonding interface between the coating and pipe surface.
Solution Approach 2:
The coating process uses periodic immersion and withdrawal cycles at controlled speeds (0.5-2 m/s), with multiple dip-withdrawal repetitions. This periodic action ensures uniform coating distribution and adequate thickness while maintaining corrosion protection reliability.
2Manufacturing precision
If the pipe is fully immersed in coating liquid, then sufficient coating thickness is achieved, but the coating liquid consumption increases
Solution Approach 1:
The pipe is immersed in the coating liquid to a controlled depth (50-150 mm) rather than full immersion, and the immersion is repeated multiple times. This partial immersion approach achieves sufficient coating thickness (15-28 μm) while significantly reducing coating liquid consumption compared to continuous full immersion.
Solution Approach 2:
The coating liquid is continuously circulated and heated during the coating process, maintaining optimal temperature (40-60°C) and flow characteristics. This continuous action ensures uniform coating deposition and adequate thickness without requiring excessive coating liquid volume.
3Manufacturing precision
If the pipe moves slowly through the coating liquid, then uniform coating is achieved, but the coating process time increases
Solution Approach 1:
The coating process uses rapid periodic immersion and withdrawal cycles (0.5-2 m/s) repeated multiple times. This periodic high-speed action achieves uniform coating distribution by allowing coating liquid to redistribute during each cycle, maintaining coating quality while significantly increasing productivity compared to slow continuous movement.
Solution Approach 2:
The pipe surface is pre-heated and the coating liquid is pre-heated before the coating process begins. This preliminary preparation reduces the time required for coating adhesion and uniformity development, enabling faster processing speeds (0.5-2 m/s) while maintaining coating quality.
4Manufacturing precision
If multiple dips are performed, then coating thickness is sufficient, but the process complexity increases
Solution Approach 1:
The pipe undergoes multiple partial immersion cycles (1-7 times, preferably 1-3 times) rather than a single long immersion. Each cycle deposits a portion of the required coating thickness (15-28 μm), and the cumulative effect of multiple cycles achieves the target thickness while allowing coating liquid to redistribute and adhere properly at each stage.
Solution Approach 2:
The coating process controls multiple parameters including immersion depth (50-150 mm), immersion speed (0.5-2 m/s), pipe temperature (80-120°C), and coating liquid temperature (40-60°C). By optimizing these parameters, the process achieves sufficient coating thickness in multiple relatively simple cycles rather than requiring complex single-step processes.
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 provides a uniform and thick anti-corrosion coating that prevents corrosion for extended periods, ensuring pipes remain effective and warranty-worthy, enhancing the design and operation of fire protection systems.
Implementation Method 1
a preferably turbulent flow of the inner pipe walls (b) with the coating liquid (3) is generated. The preferably turbulent flow has the task of bringing coating particles into contact with the inner walls (b) of the pipes (1) to be coated as continuously and constantly as possible.
Implementation Method 2
during the coating process, the diffusion of the particles provided for the coating, as at least one fixed component of the dispersion, takes place very slowly in terms of time in the direction of the inner wall of the pipe to be coated
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to the use of an epoxy/acrylic-based coating composition, which contains FeF3 iron fluoride and paint particles in dispersion, for forming a chemical-based anti-corrosion coating on an inside (b) of a pipe (1), the pipe to be coated inside (1) the inside (b) and further an outside (a), a first outer end (e1) at the first end of the tube (1) and a second outer end (e2) at the second end of the tube (1), a length (L), a first inner diameter (D1) at the first end of the tube (1), a second inner diameter (D2) at the second end of the tube (1), and a central axis (M).