What PMI can and cannot confirm

PMI compares measured elemental composition with an approved grade library or acceptance range. It is valuable when multiple carbon, alloy and stainless grades move through the same supply chain.

It cannot prove tensile properties, tenacidad, microstructure, heat treatment or pressure rating. A complete release uses PMI alongside certificates, markings, dimensional inspection and specified NDE.

XRF versus OES

Build a defensible PMI plan

Define whether testing is 100 percent or sample-based, which surfaces may be tested, acceptance ranges, retest rules and how results are recorded. Clean coatings, scale and contamination from the test spot because surface condition can affect readings.

Use certified reference materials and calibration checks required by the project procedure. The report should record instrument serial number, operador, date, item number, heat and results.

PMI controls during fabrication and shipment

Material can be mixed after incoming inspection. For critical work, identification should be maintained through cutting, mecanizado, subcontract heat treatment, NDE and final packing. Final PMI at the marked flange can confirm the released item remains connected to the intended grade.

Colour coding may support segregation, but it should not replace durable marking and documented traceability.