If you plan on using metal tubing for any kind of application, you need to think about the quality. Most importantly, it is crucial to make sure tubes won’t have serious defects that could become massive hazards in the future. There is one specific defect to look for if you are using ERW tube; the Freeze Line. We want to have a closer look at this today, including what it is as well as the issues it can cause. Additionally, we’ll look at new equipment to help identify it.
What is it?
ERW and HFW are effective techniques for creating different types of metal tubing. The techniques can offer a number of benefits, including rapid welding speeds. However, there can be situations where the heating of the faces of the material is incomplete. It can end with a cold-welded joint. There can be serious metallurgical issues here.
Generally, the Freeze Line will be above the parent material. You can see it by looking for the lowest point of contour in the weld bead. You can then calculate it by measuring from this spot down to the surface of the tube. It must be a pre-defined height or you have a Freeze Line defect.
The biggest issue with Freeze Line defect occurs when it goes below the surface of the material. Manufacturers remove the weld bead, typically with scarfing after welding or grinding later. However, doing so could mean there is a void of non-welded material within the wall of the tube. That could lead to failure in the future when there is a load on the tubing. The void would lack sufficient strength, and could lead to a crack.
A new way to test for it
One of the most interesting advances in the last few years is the development of machine vision technology. Modern inspection tech can use laser triangulation to measure the contour of a weld on an ERW tube. It can then compare the result to the ideal profile of a tube. This can indicate if there is a Freeze Line and whether it is beyond the pre-defined height. So, it can quickly show if there is a defect.
Laser imaging tech is a really great investment. Crucially, you can utilise it to inspect weld profiles after the weld box. Therefore, it can provide real time feedback on weld features. Operators can then react if there are issues like Freeze Line defects. This can save a huge amount of scrap tubing that would not be saleable. Plus, it means you are not wasting manufacturing time and resources like energy.
The laser imaging tech is a great addition to other non-destructive testing (NDT) equipment. You can utilise it alongside Ultrasonic Testing (UT) and Eddy Current (ECT). It can effectively spot flaws and defects that these other tests would miss.
Do you want to order quality ERW tube?
Union Steel Tubes has been working hard for over two decades to ensure clients can buy high quality tubing. We are an ISO 9001 company and manage every aspect of tube production with care. We also have a skilful and knowledgeable team ready to provide any assistance clients need.
So, if you want ERW tube, speak to us. We produce a wide range of tubes, including different shapes and a variety of sizes. You can then choose different finishes to suit any needs, including galvanisation to improve corrosion resistance.
