Super Duplex 2507 Buttweld Pipe Fittings
ASTM A815 WP2507 / EN 1.4410 (X2CrNiMoN25-7-4) — 25Cr-7Ni-4Mo-0.28N super duplex stainless steel for the most aggressive seawater, chloride and sour-gas environments. PRE ≥40. Minimum yield strength 550 MPa. Subsea manifolds, seawater injection, desalination brine, offshore platforms. EN 10204 3.1/3.2. PED 2014/68/EU.
½″–48″
Size Range
PRE ≥40
Highest Duplex
730 MPa
Min UTS (EN)
EN 10204
3.1 Std / 3.2 On Req.
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Super Duplex 2507 Grade Equivalents
| ASTM | EN W.Nr. | EN Name | UNS | ASME P-No. |
|---|---|---|---|---|
| A815 WP2507 (fittings) | 1.4410 | X2CrNiMoN25-7-4 | S32750 | 10H |
| A182 F53 (flanges) | 1.4410 | X2CrNiMoN25-7-4 | S32750 | 10H |
| A790 S32750 (pipe) | 1.4410 | X2CrNiMoN25-7-4 | S32750 | 10H |
| Also known as | — | Ferralium 255 (similar) | S32550 (related) | — |
Chemical Composition — Super Duplex 2507 / EN 1.4410
| Standard | C | Cr | Ni | Mo | N | Mn |
|---|---|---|---|---|---|---|
| ASTM A815 WP2507 | ≤0.030 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 | ≤1.2 |
| EN 1.4410 (X2CrNiMoN25-7-4) | ≤0.030 | 24.0–26.0 | 6.0–8.0 | 3.5–4.5 | 0.24–0.32 | ≤1.0 |
Higher Cr, Mo and N than duplex 2205. PRE = %Cr + 3.3×%Mo + 16×%N. For 2507: 25 + 3.3×4 + 16×0.28 = 25 + 13.2 + 4.5 = 42.7 — well above the ≥40 minimum.
Mechanical Properties — Super Duplex 2507 / EN 1.4410
| Standard | Min. UTS (MPa) | Min. YS (MPa) | Elongation (%) | Max Hardness | HT Condition |
|---|---|---|---|---|---|
| ASTM A815 WP2507 | 770 | 550 | ≥15% | 32 HRC | Solution annealed 1040–1120°C |
| EN 1.4410 | 730–930 | ≥550 | ≥15% | 310 HBW | Solution annealed |
Heat Treatment & Microstructure
⚠ Solution Anneal Only — No PWHT. Supplied solution annealed at 1040–1120°C, water quench. Intermetallic (sigma, chi) phases form rapidly above 300°C — never apply post-weld heat treatment. Cool inter-pass below 100°C strictly.
Filler Metal
ER2594 (GTAW/TIG) or E2594-16 (SMAW). The 2594 filler is over-alloyed (25Cr-9Ni-4Mo-0.25N) to compensate for nitrogen loss in the weld pool and ensure the correct ferrite/austenite balance.
Preheat
Not required for super duplex 2507.
Inter-pass Temperature
Maximum 100°C — strictly enforced. This is tighter than duplex 2205 (150°C). Monitor with contact thermometer between passes.
Heat Input
0.5–1.5 kJ/mm. 2507 is significantly more sensitive to heat input than 2205. Welder qualification to WPS specifically for super duplex is essential.
Ferrite Number Target
FN 30–70. Verify with Ferritescope measurement on production welds.
ASME P-Number
P-No. 10H. Separate WPS qualification required — cannot be combined with standard duplex (P-No. 10H Group 1).
Duplex Stainless Steel Comparison
| Grade | PRE | Min YS (MPa) | Max Service Temp | Cost vs 316L |
|---|---|---|---|---|
| 316L (1.4404) | ~24 | 170 | 870°C | Baseline |
| Duplex 2205 (1.4462) | ≥35 | 450 | 315°C | +30–40% |
| Super Duplex 2507 (1.4410) | ≥40 | 550 | 300°C | +60–80% |
| 904L (1.4539) | ~33 | 220 | 400°C | +50–60% |
Applications
Subsea Manifolds & Risers
Deep-sea flowlines, subsea production manifolds and riser piping where seawater ingress and high chloride concentrations demand PRE ≥40.
Seawater Injection Systems
High-pressure seawater injection headers and distribution piping for enhanced oil recovery — the primary application for super duplex globally.
Desalination Brine Stage
Multi-stage flash (MSF) and RO brine recirculation where concentrated chlorides exceed the corrosion threshold of duplex 2205 and 904L.
Sour Gas (H2S) Service
Gas injection and production piping with H2S partial pressure — 2507 meets NACE MR0175 / ISO 15156 requirements for sour service in the hardness range.
Offshore Platform Process Piping
Topsides process piping, heat exchanger headers and manifolds exposed to produced water and seawater on FPSO vessels and fixed platforms.
Chemical Industry (HCl, H2SO4)
Moderate-temperature acid service — dilute hydrochloric and sulphuric acid process pipework where chloride SCC risk eliminates austenitic options.
Super Duplex 2507 Fitting Types
Elbows
45° / 90° / 180° LR & SR
ASME B16.9 · EN 10253-2
Equal Tees
ASME B16.9 · EN 10253-2
Reducing Tees
ASME B16.9 · EN 10253-2
Concentric Reducers
ASME B16.9 · EN 10253-2
Eccentric Reducers
ASME B16.9 · EN 10253-2
Pipe Caps
ASME B16.9 · EN 10253-2
Stub Ends / Lap Joint
ASME B16.9 · MSS SP-43
Crosses & Laterals
ASME B16.9 custom sizes
Custom & Special Fittings
To drawing / PED · EN 10253-2 Type B
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