Ferralium 255 seamless tube (UNS S32550 / EN 1.4507) is supplied per ASTM A789 (Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service). Solution-annealed at 1100 °C with water quench. Per-heat MTC (EN 10204 type 3.2) documents chemistry, mechanical properties, ferrite content per ASTM E562, hydrostatic test result, and PREN calculation. Same ASTM A789 spec also covers Duplex 2205 tube (UNS S31803/S32205), Ferralium 255 sits in the super-duplex tier (PREN ≥ 40) above standard duplex 2205 (PREN ~35).
| OD range | Wall thickness range | Length | Form |
|---|---|---|---|
| 6 mm – 12 mm | 0.6 – 2.0 mm | up to 6 m | Seamless |
| 12 mm – 25 mm | 0.8 – 3.0 mm | up to 6 m | Seamless / welded |
| 25 mm – 50 mm | 1.5 – 5.0 mm | up to 12 m | Seamless / welded |
| 50 mm – 100 mm | 2.0 – 8.0 mm | up to 12 m | Seamless / welded |
| 100 mm – 200 mm | 3.0 – 15.0 mm | cut to length | Seamless |
ASTM A789 covers both seamless and welded ferritic/austenitic stainless steel tubing. Welded tube manufactured by autogenous laser, plasma, or TIG welding (typically without filler) must meet weld-zone ferrite content 35–65% per NORSOK M-630. Seamless tube preferred for sour-service NACE MR0175 applications and pressure-cycled service. Heat-exchanger U-tube construction typically uses seamless; instrument tubing for hydraulic / pneumatic instrument loops typically welded.
For tubing service exceeding standard-duplex limits (warm seawater > 30 °C, sour-gas above NACE MR0175 thresholds for Duplex 2205, reducing-acid heat exchanger duty), upgrade from Duplex 2205 tube (UNS S31803, PREN ~35) to Ferralium 255 tube (UNS S32550, PREN ≥ 40). Both grades supplied per identical ASTM A789 spec; super-duplex tube has higher chemistry / PREN / CPT margin and is preferred for high-criticality NORSOK M-650 offshore service. See Ferralium 255 vs Duplex 2205 upgrade guide.
Per-heat EN 10204 type 3.2 MTC with chemistry, mechanical properties, ferrite content, PREN calculation, hydrostatic test certificate. NORSOK M-650 QTR available on request per material data sheet MDS D55. NACE MR0175 / ISO 15156-3 sour-service compliance certified per heat. Contact info@torqbolt.com or +91-22-66157017.
