Explore this topic

Overview of Positive Material Identification (PMI)

Positive Material Identification (PMI) is a term that refers to the analysis and identification of materials through various nondestructive methods. PMI is able to determine the alloy composition of materials, and is a well-established technique that can either be performed in the field using handheld devices or in a laboratory.

PMI is an effective tool in situations where, for whatever reason, the material certificate for a component has been misplaced, destroyed, or is otherwise missing. It can be used in any situation where there is uncertainty about the material composition of a component.

There are several nondestructive examination (NDE) methods that can be used for PMI. Two of the more popular are X-Ray Fluorescence (XRF) and Optical Emission Spectroscopy (OES).

XRF works by exposing the material to be tested to an X-ray, causing the material to emit its own secondary X-rays in response. The levels of X-rays emitted by any particular material are always consistent based on the composition of that material. Thus by analyzing the secondary X-rays it is possible to determine the chemical composition of any unknown material. However, it should be noted that XRF cannot distinguish between material grades in certain elements such as carbon and silicon, among others.

OES works by exposing the material to an electrical spark and an electrode, often in an atmosphere of Argon. This spark works in a similar way to the X-rays in that it forces the material to emit light, which will differ in color and intensity based on the material that it is emitted from. It tends to offer a more complete view than XRF, and is the only method that can distinguish between levels of carbon in a material. While OES is considered a nondestructive method, it requires grinding the material for surface preparation and the process does cause slight burning on the surface as well.


Is this definition incomplete? You can help by contributing to it.

Share this Topic

Related Topics

Cathodic Protection Coatings Condition Monitoring Locations (CMLs) Corrosion Control Documents (CCDs) Damage Mechanisms Flue Gas Dew Point Corrosion Green Rot Pitting Corrosion
Articles about Positive Material Identification (PMI)
  • September/October 2018 Inspectioneering Journal

    The best approach for better inspection confidence and long term asset integrity is to conduct baseline inspections upon receipt of an asset. Baseline inspection can save millions by providing accurate baseline information for later comparisons and preventing safety incidents caused by critical oversights during the construction phase.

  • July/August 2016 Inspectioneering Journal
    By Brian Wilson at Thermo Fisher Scientific

    The instrumentation available to detect inadvertent material substitutions through positive material identification (PMI) has never been more available, portable or powerful than it is today. For one industrial services company, Tacten Industrial, Inc., embracing the latest technological advances in PMI while using rope access to conduct inspections has helped to transform their business. It has found the ideal formula for retroactive PMI that allows its team and its clients to rest assured that they’ve conducted their testing right – the first time.

  • March/April 2016 Inspectioneering Journal
    By Mark Lessard at Thermo Fisher Scientific

    In numerous industries that require elemental and material testing, including the oil and gas, power generation, and petrochemical industries, positive material identification (PMI) is at the forefront of any operation. In fact, an increasing number of facilities are adopting a 100% PMI program to ensure that every metal component is made up of exactly the desired chemical composition.

  • March/April 2015 Inspectioneering Journal
    By Paolo Torrado at Engineering and Inspection Services, LLC.

    An issue that arises frequently in the oil and gas industry is poor or missing documentation of pressure vessels. It is common in the industry to repurpose old equipment, bring equipment back into operation after a long period of time out of service, or rerate equipment due to debottlenecking of process units.

  • Blog
    January 6, 2014 By Nick Schmoyer at Inspectioneering

    In 2013 Inspectioneering published content covering a wide array of topics, from risk-based inspection, to advanced nondestructive testing methods, to pipeline integrity management systems. Last year, we published more content than any year prior; we expect the same trend to continue into 2014.

  • Partner Content

    The Vanta handheld XRF is Olympus’ first full spectrum PMI analyzer that is IP65 rated and drop tested. The analyzer provides accurate, repeatable material chemistry and alloy grade matching in as little as 1–2 seconds. Operation is simple with an intuitive touch screen and swipe interface. Optional Wi-Fi, with the Olympus Scientific Cloud, provides seamless connectivity for efficient data and fleet management.

  • November/December 2013 Inspectioneering Journal
    By Mike Urzendowski at Valero Energy

    A recent High Temperature Hydrogen Attack (HTHA) failure atarefineryinthestateofWashingtonwasa“wakeupcall” to our industry. On April 2, 2010, the shell of a feed-effluent heat exchanger in the Naphtha Hydrotreating (NHT) unit at the Tesoro Anacortes WA refinery ruptured, ultimately resulting in seven fatalities.

  • January/February 2011 Inspectioneering Journal
    By John Reynolds at Intertek

    In the first article in this series entitled How to Put It All Together - Guide to Organizing a Successful PEI Program, (1) I provided an overview of the necessary Management Systems (MS) for a successful program to achieve excellence in pressure equipment integrity (PEI). This is the sixth article in that series.

  • November/December 2004 Inspectioneering Journal
    By John Reynolds at Intertek

    Unfortunately there is a recurring theme of pressure equipment integrity incidents in the hydrocarbon process industry which has been identified by the API and that is leaks and fires caused by the inadvertent substitution of materials of construction in piping systems - the so called positive materials identification (PMI) incidents.

  • July/August 2004 Inspectioneering Journal
    By John Reynolds at Intertek

    High temperature sulfidation is probably the most common high temperature corrosion nemesis in the refining industry, since there are very few “sweet” refineries still in operation. Sulfidation corrosion typically is of concern in sour oil services starting at temperatures in the 500F (260C) range.

  • May/June 2000 Inspectioneering Journal
    By John Reynolds at Intertek

    This is the first of a series of articles that outlines the 101 essential elements that need to be in place, and functioning well, to preserve and protect the reliability and integrity of pressure equipment (vessels, exchangers, furnaces, boilers, piping, tanks, relief systems) in the refining and petrochemical industry.

  • September/October 1995 Inspectioneering Journal
    By John Reynolds at Intertek

    In August of 1993, the hydrocarbon process industry once again experienced a catastrophic loss when a major coker unit fire occurred in Louisiana. The cause of that incident was not unlike many others that have occurred over the years throughout the industry: inadvertent substitution of construction materials.

    Videos related to Positive Material Identification (PMI)
      White Papers related to Positive Material Identification (PMI)
        Downloads & Resources related to Positive Material Identification (PMI)
          Events related to Positive Material Identification (PMI)
            News related to Positive Material Identification (PMI)

              Inspectioneering Journal

              Explore over 20 years of articles written by our team of subject matter experts.

              Company Directory

              Find relevant products, services, and technologies.

              Job Postings

              Discover job opportunities that match your skillset.

              Case Studies

              Learn from the experience of others in the industry.

              Event Calendar

              Find upcoming conferences, training sessions, online events, and more.

              Industry News

              Stay up-to-date with the latest inspection and asset integrity management news.


              Read short articles and insights authored by industry experts.


              Commonly used asset integrity management and inspection acronyms.

              Asset Intelligence Reports

              Download brief primers on various asset integrity management topics.


              Watch educational and informative videos directly related to your profession.

              Expert Interviews

              Inspectioneering's archive of interviews with industry subject matter experts.