Positive Material Identification
Positive Material Identification (PMI) is the process of identifying and analyzing the chemical composition of various metal alloys. Being able to verify the correct metallurgical composition of materials is imperative to running a safe and reliable facility. Introducing parts into an environment in which they are not designed to function can lead to equipment failures and/or process safety incidents.
In the past, installation of incorrect metallurgy has caused catastrophic failures in the refining and petrochemical industry. PMI provides a necessary safeguard against human error and deliberate fraud. Some components may have had their composition either intentionally or accidentally misidentified.
Sentinel Integrity provides highly trained technicians to meet our clients’ PMI needs. We offer two methods of conducting PMI: X-ray Fluorescence (XRF) and Optical Emission Spectroscopy (OES).
X-RAY FLUORESCENCE (XRF)
The XRF method works through the use of x-rays. The component being tested is exposed to x-rays, which causes the component to emit secondary x-rays in response. The amount of secondary x-rays are emitted is always consistent, based on the material composition of the component in being tested. By examining the secondary x-rays, it is possible to determine the chemical makeup of a component.
OPTICAL EMISSION SPECTROSCOPY (OES)
The OES method works similarly, however instead of x-rays, it exposes the material to a spark from an electrode. This test is often performed in an atmosphere of argon. The spark causes the material to emit light, which will have a different coloration depending on the composition of the material. By examining the light emitted, the chemical makeup of a component can be identified.
PMI has a number of applications in a variety of industries. It can be used to verify piping and pressure vessel material during fabrication and repairs. It can also be used to verify welding materials. OES Spectrometer are even capable of detecting carbon content in alloy material.
ADVANTAGES OF PMI TESTING
PMI comes with a number of advantages. It is versatile and can be used on any size or shape of component. PMI tests produce consistent results and thus have a high degree of repeatability. The XRF Analyzer used to perform PMI is a portable, lightweight device and is useful for quick analyses of components or materials.
PMI is a valuable tool in any situation where the material composition of a piece of equipment is unknown or in doubt. It is also useful in situations where samples cannot be removed for routine testing. Similarly, PMI is helpful when material documentation has been misplaced or no longer available for material verification.
The formal reports for PMI should consist of a detailed description of the equipment, inspection technique, inspection findings, summary of results, and sketch or photo of the part that was tested.