Galvanisation is one of the most popular ways to finish steel products, including ERW tubes, sheets, and more. It improves the corrosion resistance, boosting the service life, and enhances the aesthetics. However, incomplete galvanisation can lead to serious issues. We want to have a closer look here to explore what it is, how it happens, and some ways to avoid it.
Flaws
As you may be able to guess, incomplete galvanisation means there isn’t a consistent coating of zinc. There could be different flaws here, including thin sections, bare patches, black spots, and pinholes.
The major problem with incomplete galvanisation is it compromises the corrosion resistance. The whole idea is to create a consistent coating of zinc to preserve the steel. However, if the coating is thin or there are bare spots or patches, it will be vulnerable. Ultimately, it can massively reduce the service life of the steel, including ERW tubes, especially if it is a challenging environment with a higher risk of corrosion.
How to prevent it?
A number of different factors lead to incomplete galvanisation. It is vital to be aware of them and then take steps to minimise the chance of problems. It will pay off, providing higher quality galvanised products.
Interestingly, many of the issues relate back to a common cause; poor preparation. If there are contaminants on the surface of the steel or there are flaws in the treatment, it can prevent zinc from adhering. In the worst cases, there will be bare patches, spots, and pinholes. The solution is to be very careful with prep, ensuring full removal of grease, rust, and residues. If the steel is pickled to remove impurities, make sure the picking is sufficient; you may need to extend the time.
It is also important to take a close look at the fluxing. If there are issues like incorrect flux ratio or low concentration, it can lead to “missed plating”. It can be a serious problem for ERW tubes and other products. The solution is to get the flux settings correct, ensuring the concentration is sufficient.
Incomplete galvanisation can also occur if you make the coating excessively thick. As you increase the thickness, you raise the likelihood of delamination. So, make sure you carefully calculate how thick you need the zinc to be.
In many cases the galvanisation process is done by dipping into a bath of zinc. However, issues can occur here. For example, there may be too much aluminium in the bath, the feed time could be too slow, and the immersion time may not be enough to allow proper adhesion. The solution is to ensure everything is in order with the bath and loading/unloading.
Speak to us if you want to order galvanised ERW tubes
High quality steel tubing can last a very long time, especially when it has the right finishes. Galvanisation, plating, and other protective coatings can protect it from moisture, humidity, and all manner of corrosive elements. As a result, it means the tube is suitable for a wider array of applications.
If you want to order ERW tubes, you can rely on us. Union Steel Tubes has been supplying them for years, offering a wide selection and options to suit a growing list of end users. We work hard to provide consistent standards, especially product quality and customer service. Not surprisingly, this ensures we have many happy returning customers.
Get in touch today and let us know what you need.
