What is it and when is it used?
PMI (Positive Materials Identification) is the identification or analysis of metal alloys through nondestructive methods. Usually conducted in the field, PMI has various uses, such as:
- Receiving MRO (maintenance, repair, and operations) materials
- Welding on unknown metals
- Verifying mix-ups in installed parts
Selection of a PMI technique depends on the need and the speed, coupled with the consequences of part failure.
Need is related to the level of accuracy required to distinguish an unknown metal. Complete chemical composition may be required for one purpose and separation of two metals for another. Speed depends on how quickly determination is required and what methods are available.
Types of Test Methods
PMI may be grouped into four methods.
