Duplex 2205 (UNS S31803 / S32205): Instrumentation Fittings, Valves & Tubing
Duplex 2205, designated UNS S31803 / S32205 and W.Nr. 1.4462, is a 22Cr-3Mo-nitrogen ferritic-austenitic stainless steel. It's split roughly 50/50 between the two phases. Yield strength runs about twice that of 316L, and resistance to chloride pitting and stress-corrosion cracking beats both 316 and 316L by a wide margin. Crestflo supplies this grade as instrumentation tube and compression fittings, instrumentation valves, and instrumentation tubing. Every batch carries heat and lot-number traceability. The fittings are engineered as drop-in replacements for the major suppliers, with delivery running 6-8 weeks and service across the US.
The composition, mechanical, PREN and corrosion figures below reflect standard published data for the alloy, drawn from the applicable ASTM specification. They can be adjusted to requirement.
Scope: Here, Duplex 2205 means 22Cr duplex stainless steel (S31803/S32205), the material used in instrumentation fluid-system components: tube fittings, compression ferrules, valves and tubing. Not structural plate, rebar or decorative sheet. Crestflo supplies this alloy only in instrumentation fitting, valve and tubing forms; mill bar, sheet, plate and pipe aren't part of the offering.
Request a Duplex 2205 Quote · Request a Sample · Reach the Crestflo team directly at sales@crestflousa.com or +1 346 594 9005 (Houston, TX)
Duplex 2205 Also Known As: UNS S31803 / S32205, 1.4462 & SAF 2205
On drawings, datasheets and purchase orders, the same alloy shows up under several different standard designations and mill names. A print might call out "2205 duplex," "duplex stainless steel 2205," "grade 2205" or "22Cr duplex", all of these point to the same ferritic-austenitic stainless grade.
| Designation type | Value |
|---|---|
| Trade / common names | Duplex 2205, 2205 duplex, 2205 stainless steel, SAF 2205, Avesta 2205, NAS 329J3L |
| UNS numbers | UNS S31803 (original 2205), UNS S32205 (modern, nitrogen-enhanced 2205) |
| Werkstoff (W.Nr.) | 1.4462 |
| EN designation | X2CrNiMoN22-5-3 |
| Forging grades (ASTM A182) | F51 (S31803), F60 (S32205) |
| Alloy family | Ferritic-austenitic duplex stainless steel (DSS) |
Modern 2205 usually comes as S32205, which narrows the nitrogen and molybdenum ranges of the original S31803 to lock in corrosion resistance and weldability. A part labeled "2205" today is almost always certified to both UNS numbers at once. UNS S31803/S32205, the US designations, and W.Nr. 1.4462, the European one, all refer to the same 22Cr duplex stainless steel.
Duplex 2205 Chemical Composition (22Cr-3Mo-N, per ASTM)
2205 owes its corrosion resistance to a careful balance: 22% chromium, 3% molybdenum and controlled nitrogen, set within a microstructure that's roughly half ferrite and half austenite. A low carbon ceiling shields the heat-affected zone during welding. Full ranges for both UNS designations appear in the table.
| Element | S31803 (wt %) | S32205 (wt %) |
|---|---|---|
| Chromium (Cr) | 21.0–23.0 | 22.0–23.0 |
| Nickel (Ni) | 4.5–6.5 | 4.5–6.5 |
| Molybdenum (Mo) | 2.5–3.5 | 3.0–3.5 |
| Nitrogen (N) | 0.08–0.20 | 0.14–0.20 |
| Manganese (Mn) | 2.00 max | 2.00 max |
| Silicon (Si) | 1.00 max | 1.00 max |
| Carbon (C) | 0.030 max | 0.030 max |
| Phosphorus (P) | 0.030 max | 0.030 max |
| Sulfur (S) | 0.020 max | 0.020 max |
| Iron (Fe) | Balance | Balance |
Ranges follow the applicable ASTM product-form specification. Crestflo verifies the actual heat chemistry on the EN 10204 material test certificate that comes with every order.
Duplex 2205 Mechanical & Physical Properties (Yield, Hardness, Density)
The duplex microstructure gives 2205 roughly double the yield strength of austenitic 316L, while still keeping the ductility needed for forming fittings and valve bodies. Ferrite's presence in the alloy makes it magnetic. The values below are standard published minimums and nominal physical data for the grade; 316L is shown for reference.
Mechanical properties (solution-annealed, room temperature)
| Property | Duplex 2205 | 316 / 316L (reference) |
|---|---|---|
| Yield strength (0.2% offset), min | ≥ 65 ksi (450 MPa) | ~30 ksi (205 MPa) |
| Tensile strength, min | ≥ 90–95 ksi (620–655 MPa) | ~75 ksi (515 MPa) |
| Elongation, min | ≥ 25% | ~40% |
| Hardness, max | ≤ 31 HRC (~290 HB) | ~95 HRB |
Physical properties
| Property | Value |
|---|---|
| Density | 7.80 g/cm³ (0.282 lb/in³) |
| Magnetic response | Ferromagnetic (ferrite-bearing, unlike austenitic 304/316) |
| Max continuous service temperature | ~600 °F (315 °C) |
| Structure | Ferritic-austenitic (~50/50 duplex) |
That 31 HRC ceiling doubles as the sour-service limit for duplex stainless under NACE MR0175 / ISO 15156. Continuous service tops out around 600 °F (315 °C). Push it further, into the 600–1830 °F (315–1000 °C) range, for any length of time, and you risk 475 °C embrittlement along with sigma-phase formation, both of which cut into toughness and corrosion resistance. 2205 isn't built for cryogenic work. For LNG or other deep-cold applications, an austenitic grade like 904L is the better choice. Whatever the numbers end up being for a specific heat, the material test certificate carries the final, certified word.
Duplex 2205 PREN & Corrosion Resistance (Pitting, Chloride SCC, Seawater)
The pitting resistance equivalent number for 2205 comes in around 34, 35, worked out as PREN = %Cr + 3.3 × %Mo + 16 × %N. That's well above austenitic 316L, which sits near 24, and below super duplex 2507, which reaches about 42. Those numbers place 2205 as the workhorse duplex grade for chloride service. Its critical pitting and crevice temperatures run markedly higher than 316L's, and it stands up well against chloride stress-corrosion cracking, the failure mode that most often limits 304 and 316 austenitics in warm chloride environments. Corrosion can still take hold in 2205, as it can in any stainless steel, if surfaces are contaminated, left un-passivated, or pushed past its chloride and temperature limits. Under normal service conditions, though, it resists rust and pitting far better than 304 or 316.
| Media / service | Suitability | Note |
|---|---|---|
| Warm chlorides / brackish water | Excellent | Higher CPT/CCT than 316L |
| Seawater (ambient) | Good | Step to 2507 / 254 SMO for hot seawater |
| Chloride stress-corrosion cracking | Highly resistant | Key advantage over austenitic 304/316 |
| Sour gas (H₂S) | Acceptable (qualified) | Per NACE MR0175 / ISO 15156, controlled hardness |
| Sulfuric & organic acids (dilute) | Good | Better than 316L in many dilute acids |
| Oxidising chlorides, hot seawater | Limited | Upgrade to 2507 / 6Mo |
For a broader look across alloys, check the PREN comparison table; the corrosion-by-media × alloy matrix is worth a look too.
Duplex 2205 for Sour Service (NACE MR0175 / ISO 15156)
Duplex 2205 counts as an accepted duplex stainless steel for sour, H₂S-containing service under NACE MR0175 / ISO 15156-3. That's true only when it's supplied solution-annealed, with controlled chemistry and hardness held within the standard's limit of ≤ 31 HRC. Before specifying it, check the exact service envelope for your application, H₂S partial pressure, chloride level, temperature, against the standard. Crestflo supplies Duplex 2205 fittings and valve material options that comply with NACE MR0175 / ISO 15156. See the NACE MR0175 and ISO 15156 standard pages, plus the sour-service selection guide.
When to Choose Duplex 2205 vs 316L, 304, Super Duplex 2507 & 254 SMO
Duplex 2205 is the step up from 316/304 when chloride pitting, chloride SCC or higher pressure demands outrun what an austenitic can handle. It's also the sensible step down from super duplex 2507 or 254 SMO when their PREN goes beyond what the service actually needs. This comparison puts it side by side with the alloys buyers most often weigh it against.
| Grade | PREN (approx) | Relative cost | Step to it when |
|---|---|---|---|
| 304 / 304L | ~18–20 | Lowest | Mild, non-chloride service |
| 316 / 316L | ~24 | Low | General instrument service; modest chloride |
| Duplex 2205 (this page) | ~34–35 | Moderate | Chloride pitting/SCC + ~2× the yield of 316 |
| 254 SMO | ~43 | High | Warm/aggressive chloride, 6Mo austenitic path |
| Super Duplex 2507 | ~42 | High | Hot seawater, aggressive subsea/sour duty |
If you're deciding between two grades head-to-head, take a look at Duplex vs Super Duplex and 2205 vs 2507 for direct comparisons.
Duplex 2205 ASTM Standards & Product-Form Specs (A789, A790, A479, A182)
Duplex 2205 isn't defined by a single grade name. Its identity comes from UNS numbers spread across a family of ASTM specifications, organized by product form. NORSOK material standards take over for North Sea and subsea duplex work. Together, these specifications spell out what the grade actually is. Crestflo supplies the instrumentation forms, built from certified material that meets them.
| Product form | ASTM spec | UNS / grade |
|---|---|---|
| Seamless & welded tube | ASTM A789 | S31803 / S32205 |
| Seamless & welded pipe | ASTM A790 | S31803 / S32205 |
| Bar & shapes | ASTM A479 | S31803 / S32205 |
| Forgings & fittings | ASTM A182 | F51 (S31803) / F60 (S32205) |
| Offshore duplex qualification | NORSOK M-630 / M-650 | Duplex 2205 |
Values and grades follow the applicable ASTM or NORSOK specification, and each order's accompanied by the relevant material certificates.
Duplex 2205 Product Forms from Crestflo: Tube Fittings, Valves & Tubing
Crestflo carries Duplex 2205 across three instrumentation product forms, and each one gets its own detail page covering sizes, ratings and ordering. This grade goes into compression and ferrule fittings, needle, ball and manifold valves, and instrumentation tubing. It doesn't go into mill bar, sheet or plate.
- Duplex 2205 tube & compression fittings, available in single and double ferrule (twin-ferrule) styles, hardened or non-hardened, in imperial and metric sizes, with end connections running up to 2" (50 mm) OD. You'll also see these called 2205 compression fittings, duplex ferrule fittings, and S32205 fittings. Every compression tube fitting we supply carries performance qualification under ASTM F1387.
- Duplex 2205 instrumentation valves, needle, ball, check, and 2/3/5-way manifold valves, all built in 2205, spanning sizes from 1/16" to 1". The pressure-boundary design follows ASME B16.34, with testing held to API seat-leak practice.
- Duplex 2205 instrumentation tubing, seamless and welded 2205 / S32205 tubing, offered in imperial and metric OD and wall combinations, made to ASTM A789.
Every Crestflo 2205 part carries a heat/lot number and ships with an EN 10204 material test certificate. Sizes, ferrule type and thread standard are set to match what you need. For the full range, visit the tube-fittings hub and the instrumentation valves hub.
Duplex 2205 Applications: Offshore, Subsea, Sour Upstream & Carbon Capture
Chloride resistance, high strength and a moderate price tag: that combination is why 2205 has become the default choice for instrumentation duty in chloride- and pressure-driven settings. Think offshore and subsea production, sour and high-pressure oil and gas upstream work, seawater and brine handling, petrochemical process lines, and the wet-CO₂ and amine streams found in carbon capture (CCS) systems. Anyone selecting alloys for chloride service across the board should consult the offshore chloride selection guide.
Why Crestflo for Duplex 2205
We Engineer Confidence. For a chloride-service grade like 2205, that's PMI-verified chemistry. It's honest sourcing, real interchange, and specs you can actually pull data from, not something buried in a PDF.
Drop-in interchange for Swagelok®, Parker®, Hoke® and Hy-Lok®: the dimensions line up, and the compression fitting ends carry ASTM F1387 performance qualification. These are interchange or equivalent parts, not the vague "compatible/intermix" claim you'll see elsewhere. Request your Swagelok®/Parker® cross-reference from our engineering team through the cross-reference page.
- Lead time of 6-8 weeks, against 20+ weeks typical for the majors. See the lead-time capability page for the full picture.
- Full traceability. Every part carries a heat/lot number. EN 10204 MTC 3.1 comes as standard, with 3.2 available on request. PMI confirms the material really is S31803/S32205, and our in-house testing and inspection backs all of it up.
- NACE MR0175 / ISO 15156 material options, single and double ferrules (hardened or non-hardened), imperial and metric, across all fittings.
- ISO 9001 / 14001 / 45001 & PED certified. In-house CNC / VMC / EDM machining, small MOQs, and private-label options round out the offer.
- The heritage behind the brand: Crestflo is the instrumentation division of a four-decade-old, Government-of-India-recognized export house with a proven Middle-East delivery track record. Manufacturing is new; the export pedigree isn't. Read more about Crestflo.
Stock & delivery: Standard items ship from stock. Specials are made to order, and delivery runs 6-8 weeks. Origin: Material is of Indian origin, though US and European melt is available on request, each backed by full material traceability (origin & compliance).
Buyers: End users, EPC firms, and panel fabricators can Request a Quote or a Sample. Equipment manufacturers and OEMs should Talk to an engineer / send a print. And if you're looking to sell our products, Become a distributor.
Duplex 2205 FAQs
What is Duplex 2205?
Duplex 2205 is a 22Cr-3Mo-nitrogen ferritic-austenitic stainless steel, split roughly 50/50 between the two phases. Shops know it by UNS S31803 / S32205 and W.Nr. 1.4462, and it turns up in instrumentation fittings, valves, and tubing wherever chloride or sour service is a concern. Yield strength runs about twice that of 316L (316 grades generally). Pitting resistance and resistance to chloride stress-corrosion cracking are far higher as well.
Is Duplex 2205 better than 316 stainless?
Yes, for chloride-heavy, high-pressure, or SCC-prone applications. 2205 offers roughly double the yield strength (≥65 ksi versus a ~30 ksi minimum), plus far better resistance to pitting and chloride-SCC than 316 or 316L. In milder, chloride-free settings, though, 316L does the job at a lower cost. Check the comparison table above for the full breakdown.
What ASTM grade is Duplex 2205 equivalent to?
UNS S31803 / S32205 isn't tied to one ASTM grade name. Instead, it's defined across several product-form specifications: tube falls under ASTM A789, pipe under A790, bar under A479, and forgings and fittings under A182 (grade F51 covers S31803, F60 covers S32205).
What is the difference between 304 and 2205 stainless steel?
304 is a single-phase austenitic grade (18Cr-8Ni), and its strength is modest, with chloride resistance that's limited. 2205, by contrast, is a two-phase duplex (22Cr-3Mo-N). Its yield strength runs about double that of 304, and it holds up far better against pitting and chloride stress-corrosion cracking. There's also a practical distinction worth flagging: because 2205 contains ferrite, it's magnetic. 304 isn't.
Does Duplex 2205 rust?
Under normal service conditions, it outperforms 304 and 316 against rust and pitting. The reason: 22% chromium, 3% molybdenum and nitrogen, giving a PREN of roughly 34, 35. It's not invincible, though. Like any stainless steel, it can corrode if surfaces are contaminated, left unpassivated, or pushed past its chloride and temperature limits.
What is the PREN of Duplex 2205?
Roughly 34 to 35, worked out as PREN = %Cr + 3.3 × %Mo + 16 × %N. That number lands between austenitic 316L, part of the broader 316 stainless family, at around 24, and super duplex 2507, up near 42. It's the reason 2205 serves as the workhorse duplex grade for chloride environments.
Is Duplex 2205 suitable for sour (H₂S) service?
Yes, it can be qualified to NACE MR0175 / ISO 15156 in the solution-annealed condition, provided chemistry stays controlled and hardness holds within the limit (≤ 31 HRC). Confirm the exact service envelope on the RFQ. Crestflo supplies NACE-compliant 2205 fittings and valve material options.
Is Duplex 2205 magnetic?
Yes, that's correct. Roughly half its structure is ferrite, and that's what makes it ferromagnetic. Compare that to the austenitic 304 and 316 grades: in the annealed condition, they're essentially non-magnetic.
What is the maximum service temperature for Duplex 2205?
Continuous service tops out around 600 °F (315 °C). Hold the alloy anywhere in the 600–1830 °F (315–1000 °C) band too long, and you risk 475 °C embrittlement along with sigma-phase formation, both of which chip away at toughness and corrosion resistance. That's why 2205 has no place in hot service or cryogenic duty.
When should I step up from 2205 to Super Duplex 2507 or 254 SMO?
Push into 2507 or 254 SMO territory when chloride levels and temperature push past what 2205's PREN can handle. Hot seawater is a good example, or aggressive subsea and sour service that calls for a PREN around 40 or higher. Check the Super Duplex 2507 and 254 SMO pages, along with the 2205-vs-2507 guide, for more detail.
Can I get instrumentation fittings, valves and tubing in Duplex 2205?
Crestflo carries compression and tube fittings, ferrules, valves, manifolds and tubing in Duplex 2205. Compression fittings meet ASTM F1387. Valves are built to ASME B16.34, tested under API test practice. Each part ships with a heat number and an EN 10204 3.1 certificate; 3.2 is available on request.
Can Crestflo Duplex 2205 fittings replace Swagelok or Parker parts?
Yes. Crestflo 2205 fittings are dimensional interchange equivalents for the major brands, and the compression fitting ends carry ASTM F1387 performance qualification. Swagelok® and Parker® remain trademarks of their respective owners. Crestflo parts are interchange or equivalent, not "compatible/intermix." Ask for a cross-reference on any brand you need it for.
What is the price and lead time for Duplex 2205 parts?
Pricing runs on quotation only; there's no online cart to check out through. Standard items are kept in stock and ship right away. Specials are made to order, and those typically take six to eight weeks to deliver. The standard product comes from India. If you need US or European melt, we can supply it on request, and every batch carries full traceability. To get a configured part number and price, send an RFQ specifying size, form, material and rating.
Related Alloys & Resources
- Super Duplex 2507: a step up in PREN, built for hot seawater and demanding subsea work.
- 254 SMO, 6-molybdenum super-austenitic alternative for warm-chloride duty.
- 904L, austenitic alternative with better cryogenic toughness.
- 316 / 316L stainless and 304 / 304L form the baseline grades you'd consider before stepping up to duplex.
- For decision guides, look at Duplex vs Super Duplex, 2205 vs 2507, and the PREN comparison table.
- Browse the full range from the materials hub.
Request a Duplex 2205 Quote
Send us your form type, fittings, valves or tubing, along with size, end connections and line conditions. The Crestflo Engineering Team will get back to you with a configured part number, ratings and price.
Request a Quote · Request a Sample · Browse the materials hub sales@crestflousa.com · +1 346 594 9005 · Houston, TX
Datasheets and CAD files are available to customers upon request. The Crestflo Engineering Team reviewed this material. Swagelok®, Parker®, Hoke® and Hy-Lok® remain trademarks of their respective owners; Crestflo parts are interchange/equivalent.