API RP 578

Covers — establishing and running a material verification program (MVP) using positive material identification (PMI): risk-based sampling/coverage, PMI techniques (XRF/OES), acceptance and reconciliation of results, and documentation, for new construction and existing assets.

Does NOT cover (exclusions) — the following are governed elsewhere:

• The base material specification/grade → the ASTM material spec.
• The inspection program and intervals → API 570; damage mechanisms → API RP 571.
• Welding understanding → API RP 577.

RP 578 confirms the material is what the spec calls for; it does not define the material or the inspection program.

RP 578 sets program requirements for material verification:

• Program & Coverage — a written MVP with risk-based extent of PMI (100% for high-consequence alloys down to sampling).
• PMI Methods — techniques (XRF, OES) and their capabilities/limitations, including light-element detection.
• Acceptance & Reconciliation — comparing measured chemistry to the specified grade and resolving discrepancies.
• Documentation — records tying verified material to the component and location.

API RP 578 defines how to run a material verification program using positive material identification (PMI). Its purpose is to catch alloy mix-ups — a wrong-material component that looks identical but fails in service. It sets risk-based PMI coverage (up to 100% for high-consequence alloy systems), the PMI techniques and their limits, and the acceptance/documentation of results.

It works alongside the inspection code (API 570), damage-mechanism knowledge (RP 571), and welding understanding (RP 577). It confirms the material is what the specification calls for; it does not define the material or set the inspection program itself.

Engineering Note: Extend PMI to weld filler metal and small components, not just pipe and fittings — an alloy line "verified" on the base metal but welded with the wrong filler can still fail at the weld in the intended service.