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Positive Material Identification (PMI)

Positive Material Identification (PMI) is a non-destructive testing method used to analyze chemical composition of metals and alloys.  PMI aids in quality control and safety compliance.  This NDT testing method is a vital part of production and asset integrity management across industries such as oil and gas, power, petrochemical, nuclear and fabrication.

Positive Material Identification can identify possible manufacturing product failures.  Pre-service and in-service inspections of welds and critical components can prevent equipment breakdowns and costly downtime.

Positive Material Identification is performed using either of the two techniques below:

  • X-Ray Fluorescence (XRF) analyzer: This is the most common method as the portability hand-held equipment allows the PMI inspection to be done on-site. The handheld analyzer determines the element composition of the material. However, it cannot detect carbon and some lighter elements.
  • Optical Emission Spectroscopy (OES): This method covers the analysis of chemical elements including carbon, lighter elements, and carbon steel. The older OES equipment is portable but can be bulking and fragile.  Newer technology advancements are allowing the OES systems to become more portable and durable similar to the XRF handheld systems.

Positive Material Identification application includes:

  • Ensuring products and chemical composition of metal and alloys
  • Finding potentially mixed-up alloys
  • Ensuring material follows the code standard and specification (both customer and industry)
  • Confirming welded components have used the correct filler material

Positive Material Identification advantages:

  • Quick and accurate analysis
  • Highly portable hand-held digital technology
  • The instrument must be able to maintain surface contact with the material

Positive Material Identification limitations:

  • The depth of penetration of the x-ray for most elements is less than 0.001”. So the technician must determine if the area being examined is a chemical representation of the entire piece.
  • The surface of the item must be accessible and surface preparation may be needed
  • Analyzers are limited to identifying only those alloys that are listed in the manufacturer’s library
  • Carbon, sulfur and phosphorous cannot be identified with XRF method
Positive Material Identification

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XCEL NDT Inspection Services

With offices geographically located throughout the central United States, XCEL NDT is ready to service your NDT needs.

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