Flux Induced Pitting: Causes, Risks, and How to Prevent It
Flux Induced Pitting happens when excess flux inside a pipe stops the protective copper oxide layer from forming, decreasing the useful life of your pipework.
Last Updated: Sep 2, 2024
What Is Flux Induced Pitting?
Flux-induced pitting is a form of corrosion that occurs when excess flux enters the inside of a pipe during installation. This prevents the formation of the protective layer on the copper surface, leading to pitting and, eventually, leaks.
How Does Flux Cause Leaks?
Copper relies on a protective layer of copper oxide and copper carbonates that forms naturally when it reacts with water. This layer shields the pipe from corrosion. However, if the layer fails to develop, the pipe becomes vulnerable to water quality issues and corrosion.
Flux is used during soldering to create an oxide-free surface, ensuring a secure joint between the pipe and fitting. However, if residual flux remains inside the pipe or fitting after installation, it inhibits the formation of the protective oxide layer during operation.
Without this oxide layer, pitting corrosion can occur. This pitting also exacerbates erosion corrosion as turbulence around the pitted areas accelerates the damage, eventually causing pinhole leaks. Flux-induced leaks typically appear between one to five years after the system is commissioned.
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How Can You Avoid Flux Induced Pitting?
Flux-induced pitting is primarily caused by the excessive application of flux during the jointing process. To prevent this, apply flux sparingly and only to the areas where the pipe and fitting overlap.
Here are some tips to avoid flux-induced pitting:
Use the Right Amount of Flux: Apply flux only where necessary, ensuring it doesn’t enter the inside of the pipe.
Choose the Right Flux Type: Some fluxes are more aggressive than others, and water-soluble fluxes are available that are easier to remove during flushing.
Flush the System: Before commissioning, flush the system with hot water to remove any residual flux inside the pipes.
Follow Installation Guidelines: Refer to our instructions for connecting Flowflex End Feed and Flowflex Solder Ring fittings, our Capillary Fittings Range, for detailed guidance on proper jointing techniques.
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