Manufacturer Qualification Test Records for super duplex stainless steel in North Sea offshore service
NORSOK M-650 is the Norwegian Continental Shelf industry standard for Qualification Test Records (QTR), governing how a manufacturer of stainless and nickel-alloy components demonstrates that the production process consistently produces material meeting the relevant material data sheet (MDS). For Ferralium 255 (UNS S32550) the controlling MDS is NORSOK M-630 MDS D55, which sets the chemistry envelope, mechanical property minima, ferrite-content range (35 to 55% base metal, 35 to 65% weld zone), Critical Pitting Temperature acceptance (≥ 35 °C per ASTM G48 method A), and microstructural acceptance (no sigma, chi, or Cr2N detectable at 500× per ASTM E407 etch). The QTR is product-form-specific: a separate qualification is required for bar, plate, pipe, fittings, forgings, and welded fabrications, with each form qualified across the full thickness range proposed for supply.
| Section | Content |
|---|---|
| Manufacturer identification | Plant location, quality system certification, ISO 9001 / API Q1 record |
| Material specification | UNS S32550, EN 1.4507, MDS D55 reference, customer-specified supplementary requirements |
| Manufacturing route | Melt practice (AOD, VOD, ESR), forging or rolling reduction ratio, heat-treat schedule |
| Chemistry | Per-heat analysis, all elements to two decimal places, calculated PREN |
| Mechanical properties | Tensile, yield, elongation, RA at room temperature; Charpy V-notch energy at -46 °C |
| Hardness | HRC traverse, three locations per piece, all readings ≤ 32 HRC |
| Ferrite content | ASTM E562 point count, transverse and longitudinal sections, 35 to 55% range |
| Microstructure | 500× metallographic, no sigma / chi / Cr2N permitted, ASTM E407 etch reagent |
| Critical Pitting Temperature | ASTM G48 method A, ≥ 35 °C acceptance |
| NDE record | UT, MT, PT per the form-specific ASTM standard, results documented |
| Welding (where applicable) | WPS / PQR per ASME IX with NORSOK M-630 supplementary, ferrite weld-metal point count |
The QTR is a one-time manufacturer qualification, valid for the qualified production route as long as no essential variable changes. The per-heat MTC (EN 10204 type 3.2) accompanies each consignment and demonstrates that the specific heat satisfies the chemistry, mechanical, and ferrite-content acceptance criteria. The customer typically requests both: the QTR before placing the first order (proves the manufacturer can produce qualifying material), and the MTC with each shipment (proves the actual heat shipped meets the requirements). For projects on the Norwegian Continental Shelf or where the customer specification cites NORSOK M-630 / M-650, the QTR is mandatory; for non-NORSOK projects requiring sour-service qualification, ASTM A479 plus the NACE MR0175 conformance statement is the typical alternative route.
