Why Use Nitrogen to Weld Plastic

You may be wondering, "Why use nitrogen to weld plastic? Why not just use hot air?" The reason is that welding with nitrogen makes a stronger weld.

When you weld plastic with hot air, the melted plastic gets oxidized or burned in the process. When you weld with air, the plastic will literally burn. You can see smoke and sometimes even ash or sparks will form in the weld zone.

How do you make a fire? You need a source of fuel, you need heat, and you need oxygen. If you snuff out the oxygen, the fire goes out. That’s the idea behind using nitrogen for welding. Welding with hot nitrogen gas flushes the air out of the weld zone. The plastic melts cleanly with no contamination, no smoke, no fire, no oxidation. The melted plastics can then fuse together with no contamination for maximum strength.

This video demonstrates the difference between hot air welding and nitrogen welding. You can see the plastic smoking and burning when it is welded with hot air, which doesn't happen when using nitrogen.

Always wear proper safety gear while working!

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Click here: https://www.youtube.com/watch?v=Br096FaPnnI

Video Notes:

English Closed Captions have been provided for this video. Click on the CC button to turn them on or off.
The length of this video is in no way representative of the actual time required to perform a complete repair and therefore should not be used for estimating purposes.

English Transcript:

You may be wondering, "Why use nitrogen to weld plastic? Why not just use hot air?" The reason is that nitrogen makes a stronger weld.

Air is about 80 percent nitrogen and 20 percent oxygen. The oxygen in the air is what causes the problem. When you weld plastic with hot air, the melted plastic gets oxidized or burned in the process. When you weld with air, the plastic will literally burn. You can see smoke and sometimes even ash or sparks will form in the weld zone.

How do you make a fire? You need a source of fuel, you need heat, and you need oxygen. If you snuff out the oxygen, the fire goes out. That's the idea behind using nitrogen for welding. Welding with hot nitrogen gas flushes the air out of the weld zone. The plastic melts cleanly with no contamination, no smoke, no fire, no oxidation. The melted plastics can then fuse together with no contamination for maximum strength.

Here you can see the effect of the nitrogen. You can see the plastic residue on the welder tip smoking as the air oxidizes it. When you blow nitrogen on the tip, the smoke disappears. The nitrogen flushes the air out of the area and keeps the tip from smoking.

You can also use other inert gases for welding. You might find it more convenient to use argon/CO2 blend since you already use it for your MIG welder. That's fine. Nitrogen is just usually a little cheaper. Do not use oxygen or hydrogen. The Hindenburg used hydrogen, and we all know how that worked out.