Duplex 2205 Tube Fittings (UNS S31803 / S32205 / W.Nr. 1.4462, 22Cr Duplex Stainless)
Duplex 2205 tube fittings are mechanical-grip compression fittings machined from UNS S31803 / S32205 duplex stainless steel, a nominal 22Cr-5Ni-3Mo-N grade with a roughly 50/50 ferrite-plus-austenite microstructure and a Pitting Resistance Equivalent Number around 35. One or two ferrules swage onto the tube's outside diameter for a leak-tight, gas-tight seal and a firm mechanical grip. That is exactly the reason 2205 has become the default duplex for instrument lines in chloride and sour service: it resists chloride pitting and stress-corrosion cracking far better than 316, carries about twice the yield strength of 316L, and does it at a lower cost than super duplex or a nickel alloy. Crestflo carries these fittings from 1/8-inch through 2-inch (50 mm) tube OD, in both single and double (twin) ferrule versions, imperial and metric. They are qualified to ASTM F1387 and offered to NACE MR0175 / ISO 15156 for sour service. Standard items ship from ready stock; specials are built to order, with delivery running 6-8 weeks. Request a quote to price out your configuration.
SAF™ 2205 is a trademark of Alleima (formerly Sandvik). Crestflo supplies UNS S31803 / S32205 to standard chemistry and is not affiliated with or endorsed by any mill or trade-name owner referenced here.
What Duplex 2205 Compression Tube Fittings Are
A Duplex 2205 compression tube fitting is built for fluid-system instrumentation work: a body, a nut, and one or two ferrules that bite onto the tube's outer diameter as the nut is pulled up. The joint comes apart and goes back together without losing integrity. No flaring, no welding, no elastomer seal sitting in the leak path. The seal is metal-to-metal, so the service window comes from the alloy itself, not from an O-ring giving out first.
Scope matters here. These are instrumentation compression tube fittings in S31803 / S32205 duplex stainless, not mill plate, not structural bar, not rebar, and not electrical wire ferrules. They land on small-bore instrument tubing for transmitters, analyzers, sample lines, chemical-injection systems, and process taps across offshore topside, chemical plant, seawater, and sour-gas service, the chloride- and pressure-driven duty where 316 pits, cracks, or simply runs out of strength.
Also Known As: UNS S31803, S32205, 1.4462, F51/F60 & SAF 2205
Buyers and specifiers write this grade several ways, but they all point to the same 22Cr duplex stainless. On drawings and in material call-outs it shows up as Duplex 2205, 2205 duplex, 2205 stainless steel, grade 2205, and 22Cr duplex. Its formal designations are UNS S31803 (the original 2205) and UNS S32205 (the modern, nitrogen-enhanced version), plus EN / Werkstoff 1.4462 (EN steel name X2CrNiMoN22-5-3). In forged and fitting form it maps to ASTM A182 Grade F51 (S31803) and F60 (S32205). SAF™ 2205 is Alleima's trade name for the same grade, referenced here for identification only.
| Designation type | Value |
|---|---|
| Common names | Duplex 2205, 2205 duplex, 2205 stainless steel, grade 2205, 22Cr duplex |
| UNS numbers | S31803 (original 2205), S32205 (nitrogen-enhanced 2205) |
| EN / Werkstoff (W.Nr.) | 1.4462 |
| EN steel name | X2CrNiMoN22-5-3 |
| ASTM forged / fitting grade | A182 F51 (S31803), F60 (S32205) |
| Trade name (attributed) | SAF™ 2205 (Alleima) |
Modern 2205 usually ships as S32205, which tightens the nitrogen and molybdenum ranges of the original S31803 to lock in corrosion resistance and weldability. A fitting labeled "2205" today is almost always certified to both UNS numbers at once. Asking for "2205 ferrule fittings," "S32205 tube fittings," or "duplex stainless instrumentation fittings" gets you exactly what's described on this page, the terms are interchangeable.
Why Choose Duplex 2205 for Instrumentation Tube Fittings
Duplex 2205 is a nitrogen-bearing duplex stainless, nominally 22% chromium, 5% nickel, 3% molybdenum, with controlled nitrogen, and its roughly 50/50 ferrite-austenite structure is what makes it the workhorse pick for a fitting in chloride service. Two properties drive the choice. First, corrosion: with a PREN near 35, 2205 resists chloride pitting and crevice corrosion well beyond 316L (≈24), and its duplex structure gives it strong resistance to chloride stress-corrosion cracking, the failure mode that most often limits austenitic 304 and 316 in warm chloride environments. Second, strength: the grade's minimum yield is roughly double that of annealed 316/316L, so a fitting body and ferrule hold their rated pressure with less wall, which lets a 2205 fitting carry more pressure than a 316 fitting of the same geometry.
Be precise about where 2205 sits, though. It is the leaner, lower-alloy duplex, a step up from 316, not a replacement for super duplex. Its PREN of about 35 trails Super Duplex 2507's >42, so for the most aggressive duty, hot seawater, demanding subsea, and the harshest sour service, 2507 is the step up, not 2205. Where ambient chloride, moderate sour service, and a strength advantage over 316 are what the line needs, 2205 is the cost-effective answer and 2507 is over-specified.
One limit to respect: continuous service is generally capped at about 600 °F (315 °C). Above that range, prolonged exposure risks sigma-phase formation and 475 °C embrittlement, both of which cut into toughness and corrosion resistance, so 2205 is not a high-temperature alloy, and its ferrite content rules it out of cryogenic duty too. Keep it in the chloride, moderate-sour, and high-strength window where it earns its keep.
For the full metallurgical picture, composition, mechanical and physical properties, phase behavior, and corrosion-by-media data, see the Duplex 2205 grade page. The reference composition is summarized below for convenience when writing specs. Values follow the applicable ASTM/EN specification and can be customized to requirement; actual per-heat chemistry is reported on the material test certificate that ships with each order.
| Element | Min % | Max % |
|---|---|---|
| Chromium (Cr) | 22.0 | 23.0 |
| Nickel (Ni) | 4.5 | 6.5 |
| Molybdenum (Mo) | 3.0 | 3.5 |
| Nitrogen (N) | 0.14 | 0.20 |
| Carbon (C) | — | 0.030 |
| Manganese (Mn) | — | 2.00 |
| Silicon (Si) | — | 1.00 |
| Phosphorus (P) | — | 0.030 |
| Sulfur (S) | — | 0.020 |
| Iron (Fe) | Balance | |
The chemistry above is the modern S32205 range; the original S31803 allows slightly wider nitrogen and molybdenum windows. Chromium, molybdenum, and nitrogen together drive the pitting resistance, while balanced nickel keeps the ferrite-austenite ratio near 50/50. The key strength and corrosion figures that make 2205 a fitting-grade duplex are summarized here, with 316L shown for reference.
| Property | Duplex 2205 | 316 / 316L (reference) |
|---|---|---|
| Yield strength (0.2%, min) | 450 MPa (65 ksi) | 205 MPa (30 ksi) |
| Tensile strength (min) | 620 MPa (90 ksi) | 515 MPa (75 ksi) |
| Elongation (min) | 25% | ~40% |
| Hardness (max) | ≤ 31 HRC (~290 HB) | ~95 HRB |
| Density | 7.80 g/cm³ (0.282 lb/in³) | |
| Magnetic response | Ferromagnetic (ferrite-bearing), unlike austenitic 304/316 | |
| PREN (Cr + 3.3×Mo + 16×N) | ≈ 34–35 | |
| Max continuous service temperature | ≈ 315 °C | ≈ 600 °F |
That ≤ 31 HRC hardness ceiling doubles as the sour-service limit for duplex stainless under NACE MR0175 / ISO 15156. For the head-to-head against the higher-alloy grade, see 2205 vs 2507 and duplex vs super duplex; for the step up in chloride duty, see Super Duplex 2507.
Duplex 2205 Tube Fitting Sizes (1/8-inch to 2-inch OD): Imperial & Metric
Crestflo machines S31803 / S32205 tube fittings in both imperial fractional and metric tube-OD series, with end connections up to 2-inch (50 mm) OD. The chart below covers the standard range. Working pressure for any given fitting depends on size, wall thickness, and temperature; it comes from standard tube-fitting pressure data for the tube OD and wall, following ASTM/ASME practice, and the exact rated pressure for your configuration is confirmed on the quotation. Duplex earns part of its keep here, its high yield strength lets a given wall carry more pressure than a 316 fitting of the same geometry. Values follow the applicable standard and can be customized to requirement.
| Tube OD, imperial | Tube OD, metric | Availability |
|---|---|---|
| 1/8", 1/4", 3/8", 1/2" | 6 mm, 8 mm, 10 mm, 12 mm | Standard range |
| 5/8", 3/4", 1" | 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 25 mm | Standard range |
| up to 2" (50 mm) | up to 50 mm | Made-to-order |
Duplex 2205 Tube Fitting End & Thread Connections: NPT, BSPP, JIC & Weld
Fittings come with tube-OD compression ends, tapered or parallel threads, or weld ends. All are available in national, international, and custom thread types.
| End type | Thread / connection standards |
|---|---|
| Tube-OD (compression) | Fractional inch and metric OD |
| Male / female tapered thread | NPT, NPTF, BSPT |
| Male / female parallel thread | BSPP, ISO parallel, SAE ORB |
| Flare / port | JIC 37°, SAE ORB |
| Weld end | Socket-weld, butt-weld, orbital |
Single vs Double Ferrule & Hardened vs Non-Hardened Options
S31803 / S32205 fittings come in single-ferrule and double (twin) ferrule designs, with hardened or non-hardened ferrules supplied depending on the job. This choice shapes gripping action, vibration resistance, and how many times a fitting can be reassembled. Duplex is already a high-strength base alloy, so ferrule selection and surface treatment are worth getting right, Crestflo applies anti-galling measures such as silver plating on request where repeated make-up or high torque is expected.
| Configuration | Description | When it is used |
|---|---|---|
| Double (twin) ferrule | Front ferrule seals, back ferrule grips | General instrumentation, vibration, gas-tight service |
| Single ferrule | One ferrule seals and grips | Simpler assemblies, certain hydraulic and OEM designs |
| Hardened ferrule | Case-hardened grip surface | Harder tube materials, maximum hold |
| Non-hardened ferrule | Softer grip surface | Thin-wall or softer tubing |
Replacement nuts and ferrules are stocked separately, and so are single-ferrule fittings and double-ferrule fittings.
Available Duplex 2205 Fitting Shapes & Connectors
S31803 / S32205 covers the full geometry range, so you can build a complete instrument run in a single material:
- Union, elbow, tee, cross, and reducer fittings
- Male connectors, female connectors, and adapters for joining mismatched threads
- Bulkhead unions, port connectors, caps, and plugs for sealing off unused lines
- Weld connectors (socket, butt, and orbital)
Duplex 2205 comes in related fitting families too, including 37° JIC flare fittings and DIN 2353 bite-type fittings, all combinable within the same instrument tubing system. For the full geometry range and ferrule design, start at the tube-fittings product hub.
Corrosion & Service: Chlorides, Chloride SCC, Sour (H₂S) & Seawater Duty
What a fitting actually sees in service is the whole reason to specify Duplex 2205 over 316. The table below sums up how S31803 / S32205 behaves against the media that drive fitting selection. These are the grade's published, standard-referenced characteristics, not a per-fitting rating; the corrosion allowance and suitability for a specific stream stay the specifier's call.
| Media / service | Duplex 2205 behavior | Note |
|---|---|---|
| Warm chlorides / brackish water | Excellent | Higher critical pitting & crevice temperatures than 316L |
| Chloride stress-corrosion cracking | Highly resistant | Duplex structure vs austenitic 304/316, the key advantage |
| Seawater (ambient) | Good | For hot seawater, step up to 2507 or 254 SMO |
| Sour service (wet H₂S) | Suitable | To NACE MR0175 / ISO 15156, hardness controlled ≤ 31 HRC |
| Dilute sulfuric / organic acids | Good | Often better than 316L; verify concentration and temperature |
| Hot seawater / aggressive subsea | Limited | Step up to Super Duplex 2507, PREN >42 |
| Above ≈ 600 °F (315 °C) | Not recommended | Sigma-phase / 475 °C embrittlement, 2205 is not a high-temp grade |
Where the driver is hotter chloride, seawater, or more aggressive subsea and sour duty, the super-duplex route is the better fit, compare 2205 vs 2507 and move to Super Duplex 2507 tube fittings. Where the service is strongly reducing or oxidizing acid, a nickel alloy is usually the call.
Standards, Testing & NACE MR0175 Sour-Service Compliance
Crestflo qualifies its compression tube fittings to ASTM F1387, the performance standard for mechanically attached fittings. That's the basis for the dimensional interchange and mechanical-integrity claims below. For sour service, S31803 / S32205 fittings are offered to NACE MR0175 / ISO 15156, supplied solution-annealed with hardness controlled to the ≤ 31 HRC ceiling the standard sets for duplex stainless. The grade's product-form specifications cover ASTM A789 (seamless/welded tube), A815 (wrought fittings), A182 F51/F60 (forgings), and A479 (bar); we hold the standard approvals that apply to instrumentation tube fittings.
| Standard / certification | Scope | Applies here |
|---|---|---|
| ASTM F1387 | Mechanically attached fitting performance | Yes |
| NACE MR0175 / ISO 15156 | Sour-service materials (≤ 31 HRC, solution-annealed) | Yes |
| EN 10204 MTC 3.1 / 3.2 | Material test certification | Yes |
| ASTM A789 / A815 / A182 F51-F60 | Duplex tube, wrought-fitting & forging feedstock | As applicable |
| ISO 9001 / 14001 / 45001 & PED | Quality, environmental, safety, pressure | Certified |
These fittings go through a wide battery of tests. Hydraulic proof, burst, and impulse come first. Then pneumatic, flexure-fatigue, rotary-flex, vibration, and thermal-cycling work, plus pull-out and vacuum checks. Positive material identification (PMI) confirms the alloy on every piece, important on a duplex, where chemistry controls the ferrite-austenite phase balance and the corrosion performance. NDT is standard and done in-house. Destructive testing goes out to labs accredited under ISO/IEC 17025. Third-party inspection is available on request.
Material Traceability & Certification
Every S31803 / S32205 part is marked with its own heat/lot number. Each shipment comes standard with an EN 10204 MTC 3.1 certificate, and 3.2 is available on request. PMI confirms grade at the part level, every time. That documentation backs solid audit trails for offshore, chemical, seawater, and sour-service work, the jobs where a mis-specified or under-alloyed fitting is not a small problem. Datasheets and CAD models are available to customers on request.
Drop-In Interchange with Swagelok, Parker & Hy-Lok
Crestflo S31803 / S32205 fittings are built as dimensional interchange / equivalent fittings for the major instrumentation brands, and that claim rests on ASTM F1387 performance qualification, not on marketing language. These aren't "compatible" or "intermix" parts. Brand names such as Swagelok®, Parker®, and Hy-Lok® remain trademarks of their respective owners, and Crestflo is not affiliated with them; the interchange is strictly dimensional. We don't publish a part-number table. Instead, we prepare interchange references per project: request your cross-reference, and our engineering team will map your existing part numbers to Crestflo Duplex 2205 equivalents.
Origin & US-Serving Positioning
Crestflo manufactures for the US market. Standard product comes from India; US or European melt is available on request, with full material traceability. Parts are engineered as US drop-in replacements and ship in 6-8 weeks. TAA/DFARS and domestic-melt requirements are handled straight, no hedging, on our US-origin compliance page. If a project calls for a specific melt origin, just specify it on the RFQ.
Applications & Industries for Duplex 2205 Tube Fittings
Duplex 2205 fittings show up wherever chloride attack, chloride SCC, and higher pressure outrun what a 316 austenitic can handle, but the duty doesn't yet justify a super duplex:
- Offshore and upstream oil & gas, topside instrument and hydraulic lines, produced-water and sour systems, where chloride SCC resistance and high strength both count.
- Chemical and petrochemical, chloride-bearing process and sampling lines, dilute-acid service, and flue-gas desulphurisation.
- Seawater and brine handling, cooling and process lines in ambient chloride service, with the step up to 2507 reserved for hot seawater.
- Pulp & paper, bleach-plant and chloride-laden process instrumentation.
- Marine and shipboard systems, high-chloride instrument and sample lines.
Crestflo supplies S31803 / S32205 instrumentation components into oil and gas and chemical processing applications, among others.
Why Crestflo for Duplex 2205 Tube Fittings
Crestflo operates as the instrumentation division of an export house with four decades behind it and formal recognition from the Government of India. That parent company has a proven delivery record across the Middle East. Its backing grounds a new, focused instrumentation brand built on a handful of clear advantages:
- Lead time of 6-8 weeks versus 20+ weeks typical of the majors.
- ASTM F1387 drop-in interchange proof that mill and trading suppliers rarely publish.
- Small MOQ and private label for distributors and OEMs.
- Both imperial and metric on every fitting, single or double ferrule, hardened or non-hardened.
- Heat-number marking plus MTC 3.1/3.2 on every order, PMI-confirmed.
- Cost-competitive after US duties and tariffs, ISO 9001 / 14001 / 45001 & PED certified.
We Engineer Confidence.
Request a Quote for Duplex 2205 Fittings
Give us the details: size, shape, ferrule, thread, and quantity. We'll price it out and get your order scheduled:
- Request a quote, the fastest path to pricing and lead time.
- Request a sample for qualification.
- Become a distributor for line-card and stocking programs.
Datasheets and CAD models are available to customers on request. Reach Crestflo's US sales desk at sales@crestflousa.com or +1 346 594 9005 (Houston, TX). Round out your system with the related Duplex 2205 instrumentation valves and Duplex 2205 tubing, and serve the corrosion-critical lines in oil and gas and chemical processing.
Frequently Asked Questions
Are 2205, S31803, and S32205 the same thing?
Yes. "Duplex 2205," "2205 duplex," "grade 2205," and "22Cr duplex" all point to the same material: a 22Cr-5Ni-3Mo-N ferritic-austenitic duplex stainless steel designated UNS S31803 (the original) and UNS S32205 (the modern, nitrogen-enhanced version), also listed as EN / Werkstoff 1.4462 (X2CrNiMoN22-5-3). In forged and fitting form it maps to ASTM A182 F51 (S31803) and F60 (S32205). A fitting labeled "2205" today is almost always certified to both UNS numbers at once.
Why use Duplex 2205 tube fittings instead of 316, and when should I step up to 2507?
Duplex 2205 is the better choice where the stream carries chlorides, is prone to chloride stress-corrosion cracking, or needs more strength than 316 can give. With a PREN near 35 it resists pitting and crevice corrosion well beyond 316L (≈24), its duplex structure resists chloride SCC, and its yield strength is roughly double that of 316, so thinner walls hold the same pressure, all at a moderate cost. Step up to Super Duplex 2507 (PREN >42) when the duty is hot seawater, aggressive subsea, or the harshest sour service; 2205 is under-alloyed for those, and over 316's grade for ordinary instrument service.
How much do Duplex 2205 tube fittings cost?
2205 fittings cost more than 316 but less than super duplex 2507 or a nickel alloy, and the price shifts with size, shape, ferrule type, and quantity ordered. Crestflo stays cost-competitive against the majors after US duties and tariffs, but it quotes per configuration. There's no live pricing posted anywhere. Request a quote to get a firm number.
What are Duplex 2205 tube fittings used for?
They handle chloride- and pressure-driven instrumentation lines wherever 316 is under-alloyed but a super duplex is over-specified: offshore and upstream oil-and-gas systems, chemical and petrochemical process and sampling lines, seawater and brine handling in ambient chloride service, pulp-and-paper bleach plants, and marine and shipboard lines. In instrumentation terms, that's the fittings on chloride-bearing analyzer, sampling, and process runs.
Are Crestflo Duplex 2205 fittings NACE-compliant?
Yes. Crestflo offers S31803 / S32205 fittings to NACE MR0175 / ISO 15156 for sour H₂S service, supplied solution-annealed with hardness controlled to the ≤ 31 HRC ceiling and material traceability backing project qualification. Confirm the exact service envelope, H₂S partial pressure, chloride level, and temperature, against the standard for your application.
Do they interchange with Swagelok, Parker, or Hy-Lok fittings?
They're built as dimensional interchange and equivalent fittings, with performance backed by ASTM F1387 qualification. We don't call them "compatible" or "intermix," and every brand name mentioned belongs to its respective owner; Crestflo is not affiliated. Send us your cross-reference request and we'll map your part numbers.
What sizes are available?
Tube-OD sizes run from 1/8-inch up to 2-inch (50 mm), covering both imperial fractional and metric series, in single or double ferrule. Standard sizes span 1/8" to 1" and 6 mm to 25 mm; anything larger is made to order.
Is Duplex 2205 magnetic?
Yes. Roughly half the structure is ferrite, and that's what makes 2205 ferromagnetic, unlike the austenitic 304 and 316 grades, which are essentially non-magnetic in the annealed condition. It's a handy way to tell a duplex fitting from a standard austenitic one in the field.
What is the maximum service temperature for a Duplex 2205 fitting?
Continuous service is generally limited to about 600 °F (315 °C). Prolonged exposure above that range risks sigma-phase formation and 475 °C embrittlement, which degrade toughness and corrosion resistance, so 2205 is not intended for high-temperature service, and its ferrite content rules it out of cryogenic duty as well.
Are single and double ferrule versions both offered?
Yes. Both single-ferrule and double (twin) ferrule designs are available, with hardened or non-hardened ferrules supplied depending on what's required. Because duplex is a high-strength base alloy, anti-galling measures such as silver plating are offered on request where repeated make-up or high torque is expected.
What material certification comes with the fittings?
Standard practice is an EN 10204 MTC 3.1 certificate, though 3.2 is available on request. Every part gets a heat/lot number stamped on it, and PMI confirms the alloy is genuinely S31803 / S32205, which matters on a duplex, where chemistry controls the phase balance and corrosion performance.
Are these made in the USA?
Crestflo manufactures for the US market. Standard product comes from India, though US or European melt is available on request, complete with full material traceability. It's engineered for a US drop-in fit and ships in 6-8 weeks. For TAA and origin specifics, see the US-origin compliance page.
What thread and end connections are available?
Tube-OD compression ends come standard, alongside NPT, NPTF, BSPT, BSPP, and ISO parallel threads. JIC 37° and SAE ORB fittings round out the lineup, and weld ends are available in socket, butt, and orbital styles. National, international, or custom thread, they're all supported.
What is the minimum order and lead time?
Small minimum order quantities apply, and lead time for US orders runs 6 to 8 weeks. Standard items ship from ready stock; specials are made to order. Private-label and custom or made-to-print options are also available.
Related Pages
- Duplex 2205 alloy grade & corrosion data
- Duplex 2205 instrumentation valves
- Duplex 2205 tubing
- 2205 vs 2507 · duplex vs super duplex · Super Duplex 2507 · Super Duplex 2507 tube fittings
- Tube-fittings product hub · single-ferrule fittings · double-ferrule fittings · ASTM F1387 standard
- Oil and gas · chemical processing