What Causes Pinholes in Welding? Causes & Solutions
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Welding is a technical work that relies on precise calculations, temperature, angle, and welding arc, among other factors. Welders need to prepare their workspace and environment to ensure that the workpiece is not contaminated. Using incorrect methods leads to pinholes in welds. The presence of pinholes in welding does not mean they should be there.
Causes and Solutions to Pinholes in Welding
Pinholes make weld joints weak and compromise the stability of a structure. The causes are:
Sometimes pinholes appear on weld joints over time. This could be a result of the changing seasons that make the surface of the weld wet. Sensitive coatings show pinholes when they are exposed to moisture. The weld joint coating develops pinholes when it is below the dew point.
Outgassing refers to releasing into the atmosphere the dissolved gases that were frozen and trapped by the metal material during welding. Pinholes are evidence of outgassing.
Outgassing is expected because, for every 100 degrees of metal heating, gases frozen or trapped in the weld substrate expand to double their volume. The excess volume forces the gases trapped beneath the metal surface to escape causing pinholes while undergoing the curing process.
This is a lethal agent of pinholes. When the air quality in your workshop is polluted, it affects the workpiece when welding. Contaminants include oil, grease, moisture, and particulates.
4. Coating Thickness
Suppose you apply a thin layer while coating, pinholes will appear. The application technique you settle for can also prevent or encourage the formation of pinholes.
What Happens if the Problem is Beyond Coating?
Only on rare occasions will coating cause pinholes during welding. Should this happen, explore other options before you settle on changing the coating. Re-examine all the steps because you might hurry in changing the coating yet the problem is emanating from another factor within the pool.
How to Check for Pinholes
When dealing with industrial parts, you need to be sure of the welds’ quality leaving your workshop. Pinholes are defects that highlight the integrity of the welding process. Because pinholes can form later after exposure to different climatic changes, finding and eliminating them at the store is a necessity.
The best tool for the job is a holiday detector. Its sole purpose is to detect all forms of pinholes lying within your weld. A holiday detector runs a water charge with 12-90 volts across the weld parts.
What happens when pinholes appear on my weld?
It means that the weld’s quality is compromised and has potential contaminants like trapped gas, oil, or moisture. It weakens the weld joint’s tensile strength.
How can I eliminate pinholes from my welding applications?
Focus on what causes them and prevent it early enough. Even though pinholes appear for various reasons, a controlled work environment coupled with the right welding technique will guarantee quality welds.
Pinholes are a sign of defects emanating from the welding process. While they can be easily eliminated, you should start by preventing their occurrence in the first place. Always apply all the technical principles before you start your welding process.
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Featured Image Credit: terekhov igor, Shutterstock