PMI is a reliable NDT method that can be used in a controlled laboratory environment or on-site.



Introduction



Positive material identification is a procedure involving the determination of the metal alloys present in the material. It is one of many nondestructive methods used to determine the metallic composition of a material.

PMI is a reliable method because it can be used in a controlled laboratory environment or on-site. Recognition of metallic elements in materials is important for a variety of industrial, engineering and chemical applications. As more than eighty metals are known in chemistry, proper identification is required!



There is a wide range of applications in which the evaluation of a material is crucial. Manufacturing industries view the analysis of the composition of materials as an essential process. Equally important in the technical aspects of production, its importance in key processes cannot be compromised.



Many industrial activities cannot continue without testing suitable materials. PMI is not something that can be delayed or left out. Material assessment is vital and therefore part of standard procedures.

Benefits of Positive Material Identification

Positive material identification determines the composition of the alloy and the class of material, whether accompanied by a certificate or not. The goal is to know if the qualification indicated on the label is true. The process is commonly used for high-quality metals, such as precious alloys and stainless steel. It is an excellent test method without changing the physical or chemical material.

PMI is one of the most effective means of recognizing materials and one of the most reliable methods of recognizing metals in place. It is used in various applications involving the recognition of metallic elements – particularly for nondestructive analysis. Non-ferrous metal testing may require this procedure and it is part of quality control, production, and engineering.

PMI is one of the most effective means of recognizing materials and one of the most reliable methods of recognizing metals in place. It is used in various applications involving the recognition of metallic elements – particularly for nondestructive analysis. Non-ferrous metal testing may require this procedure and it is part of quality control, production, and engineering.

Types of Positive Material Identification

There are usually two ways to test the material positively, namely X-ray fluorescence and arc emission spectroscopy.



X-ray Fluorescence: In this process, an electron beam displaces electrons from their atomic orbit. The displacement of an electron from an atom causes energy to be released. The energy which is emitted by an excited atom is unique. As a result, this method can effectively identify the elements present in a material. All of this is registered and recorded by the XRF instrument. X-ray fluorescence not only detects which elements are present but can also determine the quantity of each element.

Arc Emission Spectroscopy: In this process, electrical energy generated by an electrode is applied to a metal sample. This causes atoms in the metal to become excited and vaporize. The excited atoms and ions in the vapor emit radiation that is visible optically. The unique wavelengths of the radiation are recorded by a piece of equipment called a spectrometer. An element produces a consistent, unique emission spectrum like a fingerprint. So, by capturing this emission spectrum, the presence of an element can be determined.

In this process, electrical energy generated by an electrode is applied to a metal sample. This causes atoms in the metal to become excited and vaporize. The excited atoms and ions in the vapor emit radiation that is visible optically. The unique wavelengths of the radiation are recorded by a piece of equipment called a spectrometer. An element produces a consistent, unique emission spectrum like a fingerprint. So, by capturing this emission spectrum, the presence of an element can be determined.

Conclusion

Materials are rarely pure; they are generally alloyed or mixed with other elements to make them more durable and tough. Frequently, engineers must be aware of the exact element composition of a material, because element levels affect properties of the material. For example, the durability of a material will be determined by the proportions of the elements it contains. The presence of impurities can limit the usefulness of the material. A bad PMI report can even render a material useless for a project. Engineers cannot find any other way to determine if a material will be suitable for a particular use other than methodical testing, and PMI is just one of those standard tests used to check the suitability of material.

Citations

Positive Material Identification - PMI Testing. (n.d.). Retrieved January 21, 2020, from https://www.element.com/materials-testing-services/positive-material-identification-pmi-testing



Rheinland, T. Ü. V. (n.d.). Positive Material Identification (PMI) Testing Services. Retrieved January 21, 2020, from https://www.tuv.com/indonesia/en/positive-material-identification-(pmi)-testing-services.html



What Is PMI? How to Do It? (n.d.). Retrieved January 21, 2020, from https://alloytester.com/what-is-pmi-testing

What is Positive Material Identification (PMI) and Why is it Important? (n.d.). Retrieved January 21, 2020, from https://hha.hitachi-hightech.com/en/blogs-events/blogs/2018/06/28/what-is-positive-material-identification-(pmi)-and-why-is-it-so-important/