Positive Material Identification (PMI)
PMI stands for Positive Material Identification. It is a non-destructive testing (NDT) method used to determine the composition of materials, particularly in metal alloys. The goal of PMI is to verify that the material used in a component or structure matches the specified or required composition. This is crucial in industries where the use of specific materials with certain alloy compositions is critical for the performance and integrity of the product.
PMI is a fast and Non-Destructive method of verifying the chemical composition of metals and alloys. PMI is portable and can be carried out in-house or on clients’ sites.
key aspects of Positive Material Identification (PMI)
• Methodology: PMI methods involve the use of various techniques to analyse the elemental composition of a material. Common methods include X-ray fluorescence (XRF), optical emission spectrometry (OES), and laser-induced breakdown spectroscopy (LIB
Applications
PMI is commonly used in industries such as petrochemical, aerospace, construction, and manufacturing, where the correct alloy composition is crucial for safety, quality, and compliance with industry standards.
Quality Control and Assurance:
PMI is an essential tool for quality control and assurance. It helps ensure that the materials used in construction, fabrication, or manufacturing meet the specified requirements and standards.
On-Site and Laboratory Testing:
PMI can be performed on-site using portable handheld devices or in a laboratory setting with more sophisticated equipment. On-site testing is often preferred for its convenience, especially in situations where components are large or immobile.
Verification of Welds:
PMI is frequently used to verify the composition of welds, ensuring that the welding material matches the base material and that the weld meets the required specifications.
X-ray Fluorescence (XRF):
XRF is a widely used PMI technique. It involves irradiating a sample with X-rays, which cause the atoms in the material to emit characteristic X-ray fluorescence. By measuring the energy and intensity of these emitted X-rays, the elemental composition of the
Optical Emission Spectrometry (OES):
OES involves applying electrical energy to the material, causing it to emit light. The emitted light is then analysed to determine the elemental composition. OES is particularly effective for analysing metals and alloys.
Laser-Induced Breakdown Spectroscopy (LIBS):
LIBS uses a laser to ablate a small amount of material from the surface of the sample. The resulting plasma emits light, and the analysis of this light provides information about the elemental composition of the material.