Residual Gas Analysis
Test method for the quantitative determination of dissolved gases such as hydrogen, nitrogen, and oxygen in metals using carrier gas hot extraction. It serves for quality control of weldable materials.
Residual gas analysis means: you melt or heat a sample from the workpiece and see which gases are inside. Mainly it's about hydrogen, nitrogen, and oxygen. Hydrogen is the classic – if it's too high, you get cracks in the material after welding. Nitrogen and oxygen also ruin the structure if they are in excess. You put the sample into a measuring device that heats it up and captures the gases that come out. Then you compare the values with what is allowed for your material. If you're above, you have to work cleaner before welding or prepare the material differently.