Heat lot → body stamp → MTR
This is Fieldproof proof — not a pipe catalog and not a product for sale. A stranger can use it without paying.
The chain
The pour is the heat. The mill cert (MTR) writes chemistry and mechanicals for that specific heat. The stamp on the piece is the only link. If the heat on the body does not appear on the MTR, treat the piece as unidentified.
EN 10204
Type 3.1 is mill QA — signed independent of production. Type 3.2 adds independent inspection. Type 2.2 is not a heat-specific 3.1 or 3.2.
PMI
PMI (API RP 578 / MSS SP-137) is a second instrument on the metal. It does not replace the MTR.
Cite
NTIA, “Valve Nameplates, MTRs & Material Identification,” 5 Feb 2026. ntia.no/valve-nameplates-mtrs-material-identification
Inspector workflow: nameplate vs PO/datasheet; MTR vs specified grade; physical marks/PMI vs both. Heat number on the valve must appear on the MTR.
Pathnovo: an MTR is for a specific heat. The heat number is on the material and on the cert. pathnovo.com/standards/mtr