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Positive Material Identification (PMI) is a non‑destructive testing (NDT) technique used to verify the chemical composition and alloy grade of metallic materials. PMI helps ensure that the correct materials are used during fabrication, installation, and maintenance, preventing material mix‑ups that could lead to corrosion, equipment failure, or safety incidents.
What is Positive Material Identification (PMI)?
PMI is performed using portable analytical instruments to determine the elemental composition of metals directly on‑site. The technique confirms whether materials comply with applicable codes, specifications, and standards, such as API RP 578. PMI is commonly applied during incoming material inspection, fabrication verification, and in‑service asset integrity programs.

PMI is carried out using two primary methods:

X‑ray Fluorescence (XRF)

X‑ray Fluorescence (XRF)

Arc / Spark Optical Emission Spectroscopy (OES)

Arc / Spark Optical Emission Spectroscopy (OES)

PMI Methods Covered

X‑Ray Fluorescence (XRF)

X‑Ray Fluorescence (XRF)

XRF uses a controlled X‑ray beam to excite atoms in the alloy. The emitted fluorescent radiation is measured to determine elemental composition. XRF is fast, non‑intrusive, and ideal for on‑site screening.

Key Characteristics of XRF:

Detects carbon and light elements

Detects carbon and light elements

Minimal surface preparation required

Minimal surface preparation required

Fully non‑destructive

Fully non‑destructive

Suitable for in‑service and coated components

Suitable for in‑service and coated components

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Limitation: Cannot accurately detect carbon or very light elements

Limitation: Cannot accurately detect carbon or very light elements

ARC / Spark Optical Emission Spectroscopy (OES)
Spark OES (often referred to as ARC PMI) uses a controlled electrical spark to vaporize a small amount of surface material. The emitted light spectrum is analyzed to determine precise elemental composition, including carbon content.

Key Characteristics of Spark OES:

Detects carbon and light elements

Detects carbon and light elements

High accuracy for alloy grade verification

High accuracy for alloy grade verification

Preferred for critical metallurgy applications

Preferred for critical metallurgy applications

Requires light surface cleaning/grinding

Requires light surface cleaning/grinding

Causes minimal surface marking (semi‑destructive)

Causes minimal surface marking (semi‑destructive)

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What PMI detects
PMI verifies and identifies:
Alloy grades (e.g., carbon steel, stainless steel, duplex, nickel alloys)

Alloy grades (e.g., carbon steel, stainless steel, duplex, nickel alloys)

Presence and percentage of key elements (Cr, Ni, Mo, Mn, etc.)

Presence and percentage of key elements (Cr, Ni, Mo, Mn, etc.)

Material mix‑ups and substitution errors

Material mix‑ups and substitution errors

Verification of weld filler and parent material compatibility

Verification of weld filler and parent material compatibility

Key Benefits of PMI (XRF & ARC)

Prevents Material Mix‑Ups

Prevents Material Mix‑Ups

Ensures the correct alloy is used, reducing the risk of corrosion, failure, and safety incidents.

Fast & On‑Site Verification

Fast & On‑Site Verification

Portable equipment delivers results within minutes at site, yard, or workshop.

Compliance with Industry Codes

Compliance with Industry Codes

Supports compliance with standards such as API RP 578 and project specifications.

Accurate Alloy Identification

Accurate Alloy Identification

Combining XRF and Spark OES ensures both rapid screening and carbon‑level verification where required.

Non‑Destructive / Minimal Damage

Non‑Destructive / Minimal Damage

XRF is fully non‑destructive; Spark OES causes only negligible surface impact.

Typical Applications

Industries Using PMI

Industries Using PMI

Oil & Gas

Oil & Gas

Petrochemical & Refinery

Petrochemical & Refinery

Power Generation

Power Generation

Chemical & Pharmaceutical

Chemical & Pharmaceutical

Aerospace & Manufacturing

Aerospace & Manufacturing

Common PMI Inspection Tasks

Incoming material inspection

Incoming material inspection

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Alloy verification of pipes, valves, flanges, and fittings

Alloy verification of pipes, valves, flanges, and fittings

Weld and filler material verification

Weld and filler material verification

In‑service inspection and asset re‑verification

In‑service inspection and asset re‑verification

Failure investigation and root cause analysis

Failure investigation and root cause analysis

How the PMI Process Works

Surface Preparation

Surface Preparation

Cleaning or light grinding where required (especially for Spark OES).

Equipment Selection

Equipment Selection

Choosing XRF or Spark OES based on material and inspection requirement.

Scanning / Analysis

Scanning / Analysis

Portable analyzer measures elemental composition.

Data Interpretation

Data Interpretation

Results are compared against material standards and specifications.

Reporting

Reporting

Digital PMI reports issued for traceability and compliance.

Why Choose Our PMI Services

Certified PMI inspectors with extensive field experience

Certified PMI inspectors with extensive field experience

XRF and Spark OES capability under one service scope

XRF and Spark OES capability under one service scope

Rapid on‑site testing with traceable digital reports

Rapid on‑site testing with traceable digital reports

Compliance with international codes and client specifications

Compliance with international codes and client specifications

Ideal for fabrication, shutdowns, and in‑service inspections

Ideal for fabrication, shutdowns, and in‑service inspections

Contact us at NIsales@setsco.com to discuss your project requirements.
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