How To Perform Inspection Of Welding Defects For Quality Welding

As a welder, you have to deal with welding defects. This is part of the great journey to become an expert welder. You see the problem, now it’s time to inspect it. There is no single form of inspection.

By this time, you already know, there could be various types of welding defects. Welding defects don’t have to be limited to porosity, undercut, cracks, and so on. Sometimes, it depends on the welding quality.

And be 100% sure that even if you have the best quality welding machine, these problems may still occur.

Welding quality itself is a relative term. What may seem a good welding quality to you, may not be as good to others. You have to employ different nondestructive examination to inspect them.

Inspection of Welding Defects

inspection of welding defects

I am not gonna talk about why you should inspect the welding defects, but you will be a fool if you don’t. You do not want to release the weak or defective weld in the field. This will not be just a performance issue; it can be a serious safety hazard too.

If you inspect them first, you can take corrective measures. Only then a satisfactory performance can be expected from your hard work. Here is how you can complete the inspection:

NDE Method To Detect Welding Defects

More commonly known as Nondestructive examination. This method employs the examination of the surface of the weld and the overall surrounding of the base material.

You can inspect the finished weld in 5 different methods like visual inspection (VT), Radiographic Inspection (X-ray), magnetic particle, liquid penetration, ultra-sonic. I will talk briefly on each of them.

  • VT – Visual Inspection

Totally cost-free way to inspect the welding defects. The visual inspection should be performed not only during the welding but also before and after the welding as well. You don’t need any fancy equipment to perform such inspection.

All you need is a pretty good eye-sight and some small tools like a magnifying glass, ample light, and weld size gauge. Along with perpendicularity, you have to check the alignment and straightness for which you need a straight edge and square.

The visual inspection will help you tremendously to prevent under and over the welding. Check for defective materials, quality/size/types of the materials. Clean all the grease, oil, paint, etc.

During the welding, check for inadequate penetration, gas/slag inclusions, etc. Do not forget to wear your welding helmet while doing this check during the welding process. When welding is done, check for surface flaws, porosity, cracks, etc.

  • Radiography (X-ray) Inspection

Most important, versatile, generally accepted methods of the non-destructive method. Applying this inspection method can reveal the internal soundness of the weld.

  • MT – Magnetic Particle Inspection

Tiny discontinuities and surface defects are sometimes hard to detect. That’s where Magnetic Particle Inspection plays a great role. No matter what the sizes of the surface cracks (both tiny & big), this type of inspection will perfectly identify them.

Besides, for incomplete infusion or undercut in the weld or the problematic repaired edges of the weld – this is a great way to inspect them. However, this inspection method cannot be thinking of as a replacement for the radiographic inspection.

  • LT – Liquid Penetrant Inspection

Sometimes you can’t see the pinholes and tiny surface cracks with your naked eyes. Only liquid penetration inspection can help greatly.

There are some welding areas like welding with nonferrous materials and austenitic steels where magnetic particle inspection won’t be much helpful to locate leaks. This is where liquid penetrant inspection is great.

Remember, this is just an extended version of the visual inspection mentioned above. As the liquids, only fluorescent and visible dye are used. Whatever liquids to be used, make sure to clean and dry the inspected areas first. If the surface is not clean and dry, liquids can’t get close to the cracks or pinholes.

  • UT – Ultrasonic Inspection

To detect welding discontinuities, this method is good. A high-frequency sound beam is directed through the weld and the base plate. Whenever the beam sound strikes and interruption, part of the sound bound back and displayed in the instrument’s monitor.

Whatever inspection method you use to detect welding defects, always keep in mind the following 5 P’s so that each time your welding quality is within the standard:

  • Process Selection – a wrong process for a particular job can’t achieve the expected welding quality. Don’t forget, always employ the right process.
  • Preparation – after the welding process is right, make sure it is compatible with the joint configuration.
  • Procedures – it’s more like always stick to the plan. Make a detailed procedure and follow it always.
  • Pre-test – mock-up test should be performed to check whether the above process and procedure promise desired welding quality.
  • Personnel – Only qualified people ought to do the job.

No matter what sort of welding inspection method you follow to find the defects, don’t forget wearing your protective safety equipment. It does not matter whether it is just a bird’s eye-view inspection or a thorough inspection, you can’t afford to forget wearing your safety gear like the welding jacket, glasses, and other equipment.

As you have noticed from the above discussion that some inspection method involves potentially dangerous ultrasonic method, some method involves using electricity and examining other welding tools, it is wise to take safety measures.


Welding defects inspection plays a great role to make your next welding job above standard. Employing the right inspection method will give you the right reasons behind every welding defects.

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