Duplex Stainless Steel
Duplex 2205 Buttweld Pipe Fittings
Ferritic-austenitic stainless steel (UNS S32205 / S31803, EN 1.4462) — elbows, tees, reducers and caps to ASME B16.9 / ASTM A815, 1/2" to 24" NB. Double the strength of 316L with PREN ~35 chloride resistance. EN 10204 3.1 / 3.2 traceable.
Where Duplex 2205 Is Used
- ✓ Seawater, cooling water and desalination piping
- ✓ Oil and gas piping, including sour service to NACE MR0175
- ✓ Hot chloride process lines where 316L suffers stress-corrosion cracking
Duplex 2205 Compared With Related Grades
| Grade | PREN | Key difference |
|---|---|---|
| A403 WP316L | about 24 | Lower strength; prone to chloride stress-corrosion cracking |
| A815 S31803 / S32205 | about 35 | About twice the yield strength of 316L; resists chloride stress-corrosion cracking |
| A815 S32750 | about 42 | For seawater and the most aggressive chlorides |
How to Specify Duplex 2205 Fittings on a Purchase Order
A complete order line avoids clarification rounds. Example:
Equal tee, 4" SCH 40S, ASTM A815 WPS32205, ASME B16.9, EN 10204 3.1
- ✓ Ask for ferrite content and a test for harmful intermetallic phases (ASTM A923) if your specification requires it
- ✓ Add NACE MR0175 / ISO 15156 hardness for sour service
- ✓ Add 3.2 witnessed inspection if required
Grade Overview
Duplex 2205 (UNS S32205 / S31803, EN 1.4462) is the workhorse duplex stainless steel, with a roughly 50/50 ferrite-austenite microstructure. That dual-phase structure gives it about twice the yield strength of standard 316L austenitic stainless, together with markedly better resistance to chloride pitting, crevice corrosion and — critically — chloride stress-corrosion cracking, the failure mode that limits 304/316 in warm chloride service.
Buttweld fittings in 2205 are covered by ASTM A815 (WP-S32205) to ASME B16.9 dimensions. After hot forming, fittings are solution annealed and water quenched to restore phase balance. Supplied with EN 10204 3.1 or 3.2 certification and PREN reporting on request.
Chemical Composition — S32205 / 1.4462
| Element | Requirement | Note |
|---|---|---|
| Chromium (Cr) | 22.0 – 23.0% | Pitting & oxidation resistance |
| Nickel (Ni) | 4.5 – 6.5% | Austenite stabiliser |
| Molybdenum (Mo) | 3.0 – 3.5% | Pitting resistance |
| Nitrogen (N) | 0.14 – 0.20% | Strength, austenite & pitting |
| Carbon (C) | ≤ 0.030% | Low-carbon, sensitization control |
| Manganese (Mn) | ≤ 2.00% | — |
PREN = %Cr + 3.3 × %Mo + 16 × %N ≈ 35, giving strong resistance to chloride pitting.
Mechanical Properties — Duplex 2205
| Property | Requirement |
|---|---|
| Tensile Strength (min) | 620 MPa (90 ksi) |
| Yield Strength (min) | 450 MPa (65 ksi) |
| Elongation (min) | ≥ 25% |
| Hardness (max) | ≤ 31 HRC / 290 HBW |
| Heat Treatment | Solution annealed ~1040°C + water quench |
Equivalent Grades
| Product Form | Specification |
|---|---|
| Buttweld fittings | ASTM A815 WP-S32205 / S31803 |
| EN designation | EN 1.4462 (X2CrNiMoN22-5-3) |
| Seamless pipe | ASTM A790 / A928 UNS S32205 |
| Forgings / flanges | ASTM A182 F51 / F60 |
EN 10253 equivalent: see DUPLEX 2205 pipe fittings on arshyapipefittings.com, and the European grade EN 1.4462 (X2CrNiMoN22-5-3).
Fitting Types Available in Duplex 2205
- Elbows — 45° / 90° / 180°, LR & SR (B16.9 / B16.28)
- Tees — equal & reducing (B16.9)
- Reducers — concentric & eccentric
- Caps — buttweld end closures
- Stub Ends — Type A & B for lap joints
- Laterals & Crosses — branch connections
Related grades: Super Duplex 2507 · 316L · 304L · Stub ends · IBR grades list
Testing & Inspection — Duplex 2205
- Chemical analysis of each heat, including nitrogen — essential for strength, phase balance and pitting resistance (PREN ≈ 35).
- Ferrite content measurement to confirm the austenite–ferrite balance after solution annealing.
- ASTM A923 testing for harmful intermetallic phases (sigma) available on request.
- Tensile and hardness tests (620 MPa min. tensile, 450 MPa min. yield, ≤290 HBW); Charpy impact tests on request.
- PMI, dimensional and visual inspection to ASME B16.9 / ASTM A815; NDE as specified.
Dimensions & Size Range — ASME B16.9
Duplex 2205 fittings are made to ASME B16.9 dimensions under ASTM A815, from 1/2" to 24" NB, in schedules SCH 10 to SCH 80 / XXS. Wall thickness matches the connecting pipe schedule. Centre-to-end dimensions for the most-ordered sizes:
| NPS | Outside diameter (mm) | 90° LR elbow “A” (mm) | 45° LR elbow “B” (mm) | Equal tee “C” (mm) |
|---|---|---|---|---|
| 1/2" | 21.3 | 38 | 16 | 25 |
| 1" | 33.4 | 38 | 22 | 38 |
| 2" | 60.3 | 76 | 35 | 64 |
| 3" | 88.9 | 114 | 51 | 86 |
| 4" | 114.3 | 152 | 64 | 105 |
| 6" | 168.3 | 229 | 95 | 143 |
| 8" | 219.1 | 305 | 127 | 178 |
| 10" | 273.1 | 381 | 159 | 216 |
| 12" | 323.9 | 457 | 190 | 254 |
| 16" | 406.4 | 610 | 254 | 305 |
| 20" | 508.0 | 762 | 318 | 381 |
| 24" | 610.0 | 914 | 381 | 432 |
Long-radius elbows have a centre-line radius of 1.5 × NPS; short-radius (ASME B16.28) 1.0 × NPS. Full tables to NPS 48, reducing tees, reducers and caps are available with every quotation. For EN 10253 dimensions see arshyapipefittings.com.
Export Documentation & Packing
We ship Duplex 2205 fittings to projects outside India with the documents EPC contractors and inspection agencies expect:
- Mill test certificate — EN 10204 3.1 as standard; 3.2 with third-party witness
- Third-party inspection — Bureau Veritas, TÜV, Lloyd’s Register, SGS, DNV or the client’s own inspector
- Traceability — every fitting marked with grade, size, schedule and heat number, matching the certificate
- Packing — seaworthy wooden cases or pallets, bevel ends protected with end caps
- Shipping documents — commercial invoice, packing list and certificate of origin; FOB, CFR or CIF terms
Send your BOQ through the RFQ form (Excel or PDF attachments accepted) or on WhatsApp — quotations are usually issued within 24 hours.
Duplex 2205 Fittings — Frequently Asked Questions
What is the difference between UNS S31803 and S32205?
S32205 is a tighter version of S31803 with higher minimum chromium, molybdenum and nitrogen, giving more consistent corrosion resistance. Most material today meets both and is dual-certified S31803/S32205.
Is Duplex 2205 suitable for sour service?
Yes, within the limits of NACE MR0175 / ISO 15156 and with hardness controlled. See duplex in sour service (NACE MR0175).
Why test for sigma phase?
Incorrect heat treatment or welding can form brittle sigma phase, which sharply reduces toughness and corrosion resistance. ASTM A923 testing confirms its absence. More: sigma phase in duplex fittings.