Checking for weld discontinuities

Radiographic Inspection

Welding is still the most common way of joining metals. There are several different methods, each with pros and cons. Whatever method it is though, it is vital that the weld is high quality. It must have as few discontinuities as possible. If it has too many, the product will be defective because it will fail to meet the necessary standards. The best way to check this is with radiographic inspection, a form of non-destructive testing (NDT).

Common discontinuities

There are a number of things to look for when you test a weld. The most common issues are:


One of the worst things that can happen during welding is gas getting into the weld pool. It can occur because of atmospheric contamination or impurities. What happens is the gas creates permanent bubbles that can mean the weld is weaker than it should be.


It is surprisingly easy for inclusions like slag, oxides, and non-metal elements to get into the weld. Unfortunately their presence can compromise the structural integrity. To reduce the risk, you need to clean the metal properly before welding.

Incomplete fusion

In some cases there will not be complete fusion between the metals. This can be because of a problem with the filler material or choosing the wrong welding process entirely.

Insufficient joint penetration

When welding, it is important to ensure that there is sufficient joint penetration to allow fusion between the metals. If there isn’t it creates a discontinuity and means the weld will be weaker.


If a weld deposit is larger than the specified joint, it can flow over the edge. When this happens it creates an overlap. In turn this prevents metal fusion and also causes a weaker weld.

Talk to us about radiographic inspection

Format NDT Ltd works hard to help clients inspect welds and ensure they meet the right standards. Our goal is to give them a very accurate idea of what kind of discontinuities there are. We can even locate them.

To maximise accuracy, we ensure our technicians have the right certifications, up to date training, and the best equipment. Most importantly, they are able to interpret the results correctly every time.

So, if you need radiographic inspection to ensure your welding is safe and a high standard, contact us. We work with clients in many industries and always give them the best service.