PMI

Module from the Inspection and NDE Curriculum curriculum.

Module 7 - PMI and Material Verification (API 578) · Learning Objectives · 1. Identify when PMI is required (alloy vessels, piping, critical service) · 2. Select XRF vs OES vs arc-spark methods · 3. Verify alloy grade vs specification (e.g., T11 vs T22) · 4. Document PMI findings and any discrepancies per API 578 · 5. Track PMI over life cycle: receipt, fabrication, field verify · PMI Technique Comparison

Technique	Principle	Portable	Elements	Limit of Detection	Use
Portable XRF	Energy dispersive	Yes	Na-U	0.01%	Field verification
Portable OES (spark)	Optical emission	Yes	All incl. C	0.001% C	Carbon critical
Laboratory ICP	Plasma emission	No	All	ppm	Full chemistry
Arc spark	Spark emission	Yes	All incl. C	Low	Shop / field
When to PMI (API 578)
100% PMI required: all alloy welds and components (valves, fittings, piping, vessels) in hot hydrogen service, sulfuric acid, HF acid, or covered/critical service. Spot PMI (10%): other alloy piping. Document all results. Replace any component that fails PMI.

Source: Inspection_NDE_Curriculum_v1.xlsx · Sheet: PMI

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