OES – PMI is a method used to accurately identify metal types and chemical compositions using Optical Emission Spectroscopy. The device generates a high-energy spark on the metal surface, and analyzes the emitted light to determine the exact elements such as Fe, Cr, Ni, and Mo. This method is used when a highly accurate result is required, especially for verifying the percentage of alloy elements to ensure that the component or pipe meets the specified material grade.