For a long time people have looked at the weld in ERW tubes as a weakness. However, thanks to improvements in welding technology and processes, treatments, and quality control, that is no longer the case. From an engineering perspective today, the welds are controllable and verifiable. This is the same as other parts of various components.
If you want to maximise weld quality and ensure the steel tubing is suitable for your applications, there are a number of key things to look at. We want to run through them here so you know what to consider.
Raw materials
The first place to start is understanding the importance of choosing the right products to begin with. This will typically be steel coil or strips. The key thing to look at is the composition of the steel. The specific levels of elements like carbon and sulfur have an impact on weld quality, particularly the chance of embrittlement. So, ideally you want to know the exact composition of the steel.
Another vital thing to think about with the raw materials is the edge quality. ERW heats the edges of the steel strips by applying a high-frequency current, relying on the material’s resistance. However, flaws such as wavy edges, burrs or delamination have a massive impact. In the worst cases they can lead to concentrations of current, ruining the uniformity of the heating. This leads to weld problems in ERW tubes.
Controlling the basics
Ensuring you have good quality steel coil and strips with clean, even edges is the ideal starting point. Beyond that, you need to ensure you control the three basics of ERW welding.
Firstly, like we already touched on, you need to ensure the edges of the steel are heated uniformly. If there is not enough heat, you can have issues like poor penetration or false welds (aka cold welds). While they may look fine visually, they lack strength and can fail dramatically. Excessive heat is a problem too; it can cause overheating and compromises the weld toughness.
Secondly, the extrusion force to push the edges of ERW tubes together must be sufficient to create a strong bond. If the force is excessive, it leads to flaws. On the other hand, if there isn’t enough force, the weld will be weak. You need to find the sweet spot here to create a dense, continuous weld with fewer impurities.
Finally, the welding speed must be sufficient. While working quickly is important to maximise productivity, it can lead to problems. For example, moving too fast shortens the heating time and can lead to weld defects. Dawdling is just as bad though; it can result in excessive heat and non-uniformity.
Post welding
Another thing to keep in mind is the importance of post-welding treatments. They have a big impact on the quality, giving you the opportunity to refine the tubes to meet your specifications.
A key thing to look at is burr removal. Burrs have two big impacts on the tubing. Most critically, they can be a hotspot for corrosion, potentially compromising the service life of the tubes. On top of that, burrs inside a tube will harm flow performance. Therefore, it’s best to remove them.
Last but not least, it’s important to finish with heat treatment of the weld and HAZ. It is fantastic for refining the properties here, getting them as close to the parent material as possible. This can improve toughness and performance.
Order quality ERW tubes
The most important thing to keep in mind is modern ERW tubing is great for various applications, as long as everything is right with the raw materials and processes to create and finish it. The quality keeps improving, especially if you work with reliable manufacturers and stockists.
If you want ERW tubes for projects, you can rely on us. Union Steel Tubes has decades of experience, ISO certification, and an eye for quality. Even better, we provide a fast turnaround wherever possible. Depending on your needs, we may be able to dispatch tubing same day.
So, contact us if you have questions or need further information about products.
