Services - NDT

Positive Material Identification (PMI)

Positive Material Identification or (PMI) is a means to acquire detailed element information through the analysis of materials to identify the complete composition, or material grade, using various Non-Destructive methods and not limited to the following:

The most common techniques of PMI used at MHT are X-Ray Fluorescence (XRF) and Optical Emission Spectroscopy (OES).

XRF works by the scope producing primary X-rays which reacts with the material to emit secondary X-rays from the component. The secondary X-rays produced are dependent upon the makeup of that material. Thus by evaluating the secondary X-ray data it is possible to determine the chemical makeup of the unknown material.

OES works by exposing the material to an electrical spark and an electrode, often in an atmosphere of Argon. OES produces an arc between the material which produces color and varying intensities based on the elements it is emitted from. It offers a wider range of PMI than XRF, and can determine different levels of carbon in a material.

PMI is a well-established technique which is recognized and documented within industrial standards, such as:

ASME B31.3 Process Piping

ASME Section II Part C Materials

DIN EN 10204 Metallic products - Types of inspection documents

ASTM E 1476 Standard Guide for Metals Identification, Grade Verification, and Sorting

ASTM E 572 Standard Test Method for Analysis of Stainless and Alloy Steels by Wavelength Dispersive X-Ray Fluorescence Spectrometry

ASTM E 322 Standard Test Method for Analysis of Low-Alloy Steels and Cast Irons by Wavelength Dispersive X-Ray Fluorescence Spectrometry

API RP-571 Corrosion and Materials

RP-578 Material Verification for New and Existing Alloy Piping

RP-939-C Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures in Oil Refineries

How Does It Benefit The Client: