What is Positive Material Analysis? (PMI)

Material analysis, also called Emission Spectroscopy, is a method for qualitative and semi-quantitative analysis of the chemical composition of steel, primarily for grade identification and sorting.
The analysis is carried out by igniting an electric arc between a vibrating tungsten electrode and the sample surface. The light emitted by this arc is split in a prism system into spectral lines, which are viewed through an eyepiece.

The spectrum consists of iron lines, used as reference lines, and of lines characteristic of the other elements in the sample. A number of characteristic lines can be identified directly from the calibrated scale.

Others must be found by the operator, based on known lines and an overview spectrum.

Samples with a known content of the relevant elements can be very helpful when searching for spectral lines with unknown scale values.

Advantages

Strict regulations for material testing have set a high standard for the instruments used in Positive Material Identification (PMI) within petrochemical, petroleum, energy, and chemical plants. Today’s handheld analyzers are more accurate and powerful than ever, making it possible to detect residual and trace elements in hard-to-reach areas and demanding environments. Many portable analyzers meet ASTM and API requirements as well as the stringent PHMSA “Mega Rule” for pipe material verification, including analysis of low silicon content, carbon, and carbon equivalent.

With various technologies tailored to different PMI testing requirements, these analyzers give you the results you need when you only have one chance to get it right. Portable enough to handle the most challenging and remote locations, yet sensitive enough for demanding applications, such as FAC (Flow-Accelerated Corrosion) analysis.

Choose between XRF (X-ray Fluorescence) for non-destructive testing and OES (Optical Emission Spectroscopy) for measuring carbon equivalence. Our instruments also meet the world’s most stringent requirements for metallurgical alloy chemical testing in PMI, including API 5L testing, API RP578, ASME Section IX B&PV, ISO 17025, and A2LA standards.

PMI Example

Hitachi High Tech PMI presentation video

What is Laser Induced Breakdown Spectroscopy (LIBS)?

As the name suggests, LIBS is a laser-based method in which a high-energy laser pulse is fired at a material to release ionized plasma, which can then be measured and identified from the plasma’s signature.

The main advantage of LIBS is the size of the equipment, which in our new products is handheld and very user-friendly.

The equipment is primarily used for sorting tasks. In addition, the analysis can be used to check the chemical composition of items or components where cutting out a sample is not allowed or is undesirable.

What is Optical Emission Spectroscopy (OES)?

Optical Emission Spectroscopy (OES) is available in portable instruments.
Besides general analysis capabilities, the equipment also offers sorting functions—that is, comparison with programmed standards and the possibility to set a rejection level as well as a visual or audible alarm if the rejection level is exceeded.

What is X-Ray Fluorescence (XRF)?

Portable X-ray fluorescence analyzers can, in addition to analyzing individual elements, classify about 100 standard grades using an internal reference database. Besides steel, the equipment can also analyze certain copper alloys.

The equipment is mainly used for sorting tasks. In addition, the analysis can be used to check the chemical composition of items or components where removing a sample is not allowed or is impractical.

What is Positive Material Analysis? (PMI)