Category Archives: Main Reason Of Welding Defect In Pinhole

Main Reason Of Welding Defect In Pinhole

The main reason of the appearance of the welding defect called the pinhole in your weld is you not paying attention to the little details. Pinholes – although they aren’t really an occurrence that can be called as rare – they are preventable or should I say, they can be minimized.  Pinholes are common to welders. They appear out of the blue every now and then, which is really annoying to deal with. There are ways to rid of them, or as I said minimize. That may be the right term, so let us get on with it.


Have you ever seen a pinhole?

Do you see that little hole? That’s what you call a pinhole. It looks annoying right? It does not look nice at all. Plus it makes your weld look broken and not well done. I’m sure that you wouldn’t want your customers to think that your welding product isn’t of good quality. You are going to have problems with your customers if you can’t hide or minimize the pinholes. Lucky for you, there are ways that you can do so. A pinhole is somehow considered to be part of the porosity family, but not really. It’s like the adopted child of the porosity family so to speak. There are many reasons for the appearance of pinholes, but for porosity, it all comes back to an atmospheric interference with the weld puddle, or you being lazy by not cleaning the weld metal before you began welding.  In a way, the causes of pinholes are the same. The pinhole appears if there is a moment or a few seconds of incomplete gas coverage, and also if the metal you are about to weld is dirty with rust, oil, grease, paint, and other substances.


Wiping your weld metal or your wire clean is not that hard of a task. You can do that easily before you begin welding. Please don’t be lazy because not only are the presence of the substances I mentioned above able to raise the percentage of pinholes forming, but once they have been exposed to heat, they emit poisonous fumes which can be harmful to your health if you inhale it and also to the environment. You can prevent both by just taking time to wipe the metal clean. Studies show that pinholes often appear in MIG Welding compared to other welding processes, and also if your welding position is down-hand. As I said, there are ways to prevent pinholes from appearing.


There is an expert who said that pinholes are considered as “gas” porosities since they just occur in or just below the surface, which is normally cause by gas bubbles becoming trapped under the solidified skin of the casting. If the casting is think, then somehow pinholes are lessen since the gas bubbles will have enough time to pop and escape, and it is also the same for thin walled castings since it is thin so the gas bubbles have no time to even form.



What can you say about pinholes? There are also other ways to prevent them. Here they are:


  • As I said above pinholes and porosity can be caused by a slight disturbance in the atmosphere, or in pinholes to be specific, a disturbance in the flow of the shielding gas. The shielding gas works by protecting the metal from the atmospheric air, so you don’t want to disrupt it.

    Check the tube for kinks.
    Check the welding room for any ventilation. Don’t get me wrong, ventilation is good but you just have to make sure that it doesn’t disrupt the flow of the shielding gas.
    Check the status or amount of your shielding gas. If it is about to run out, this can cause pinholes.

  • Clean the metal you are about to weld.
  • Wipe the moisture that has formed in your metal to be weld.



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