Duplex 2205 / UNS S31803 Pipe & Tube
Duplex Stainless Steel 2205 / 31803 Pipes Manufacturer in India | Trusted UNS S32205 / S31803 Tubing Supplier
Stellar Alloys manufactures and stocks a complete range of Duplex 2205 (UNS S32205/S31803) pipes and tubes. Duplex steel combines ferritic and austenitic structures; the 2205 grade has roughly twice the yield strength of standard austenitic stainless steels. This high strength allows thinner‑wall vessels and piping, saving weight without sacrificing durability. Duplex 2205 also resists pitting, crevice corrosion and stress‑corrosion cracking in chloride and chemical environments.
We produce seamless and welded pipes/tubes to ASTM A790 / ASME SA790, ASTM A789 / ASME SA789 and related standards. We maintain full traceability through EN 10204 3.1/3.2 certificates and can arrange third‑party inspections. Competitive pricing and quick turnaround make us a trusted supplier in India and overseas.
What Are Duplex 2205 & Duplex 31803 Pipes?
Duplex 2205 (also sold as UNS S32205/S31803, WNR 1.4462, F51/F60) is a nitrogen‑enhanced duplex stainless steel containing ~22 % chromium, 5–6.5 % nickel and 3 % molybdenum. Its dual microstructure, roughly 50 % austenite and 50 % ferrite, provides high strength and resistance to chloride stress‑corrosion cracking. The alloy’s yield strength (~450 MPa) is almost double that of common austenitic grades like 304/316. However, Duplex 2205 should not be used above ~300 °C (572 °F) because prolonged exposure causes embrittlement; industry guides recommend limiting service temperatures below 600 °F (316 °C).
Types of Duplex 2205 Pipes & Tubes
Duplex 2205 products come in several forms to suit different applications; the table below summarises the key types, their features and typical uses.
| Product Type | Features & Use Cases |
| Seamless Pipe | Manufactured by hot/cold extrusion and drawing; offers superior strength and uniformity for high‑pressure systems; available in sizes 6 mm OD to 24 ″ OD with wall thicknesses up to 60 mm. |
| Welded / ERW Pipe | Produced by strip welding (ERW) or plate welding (EFW); cost‑effective for larger diameters; available up to 36 ″ OD with schedules 5 to XXH. |
| Seamless Tube | Small‑diameter tubes for instrumentation and heat‑exchangers; seamless tubes range from 0.375 ″ to 1 ″ OD with wall 0.035–0.065″ . |
| Welded Tube | Thin‑wall tubing for condenser coils and structural uses; sizes 0.125 ″ to 1 ″ OD with wall 0.035–0.109 ″ |
| Cold‑drawn Tube | Enhanced surface finish and tight tolerances; gauge ranges 25–10 SWG. |
| Rectangular/Square Tubes | Formed by hot‑rolled or cold‑drawn processes; available shapes include square, round, box section and rectangle. |
Titanium Grade 2 Pipe
Titanium Grade 2 Welded Pipe
Titanium Grade 2 Seamless Pipe
Duplex Stainless Steel Pipe Grades & Equivalent Standards
Various standards recognise Duplex 2205 under different names; the following table lists the common equivalents and trade names.
| Standard / Grade | International Equivalent | Notes |
| UNS S31803 / UNS S32205 | W.Nr 1.4462, EN X2CrNiMoN22‑5‑3, F51/F60 forging grade | This dual‑grade composition allows supply in either S31803 or S32205 condition; both are considered Duplex 2205. |
| BS 318S13 / ASTM A790 / A789 | DIN X 2 CrNiMoN 22‑5 | Common specifications for seamless and welded duplex pipe/tube production. |
| Other Trade Names | SAF 2205, URANUS 45N, 22Cr Duplex | Market names used by manufacturers for Duplex 2205. |
Duplex 2205 / UNS S31803 Pipe Specifications (ASTM A789 / A790 / ASME SA789)
General production specifications such as size, thickness and applicable standards are outlined in this table.
| Parameter | Seamless Pipe | Welded Pipe | Tube |
| Size Range | 6 mm OD – 24 ″ (10.3 mm – 610 mm) | 1/8 ″ – 36 ″ OD (10.3 mm – 914 mm) | Seamless tube 0.375 ″ – 1 ″ OD; welded tube 0.125 ″ – 1 ″ OD |
| Wall Thickness | 1 mm – 60 mm (schedules 10s through XXH) | 1 mm – 60 mm, schedules 5 – XXH | 0.035 ″–0.109 ″ |
| Length | 5.5–6.5 m standard; custom lengths available | Single random (5–7 m), double random (10–12 m) | 6 m; cut lengths available |
| Standards | ASTM A789 / ASME SA789, ASTM A312 / A312M, ASTM A999 etc. for duplex pipes | ASTM A790 / ASME SA790 for welded pipes | ASTM A789/ASME SA789 for tubes |
| Finishes | Annealed & pickled, bright annealed, polished, MF; ends can be beveled, threaded or plain | Pickled & passivated; available in satin/hairline/mirror finishes | Mill finish, bright polished |
Chemical Composition of Duplex Stainless Steel 2205 / 31803 Pipes & Tubes
Duplex 2205’s corrosion resistance and strength stem from its balanced chemistry; typical minimum and maximum element percentages are shown below.
| Element | Minimum (%) | Maximum (%) |
| Carbon (C) | – | 0.030 |
| Phosphorus (P) | – | 0.030 |
| Manganese (Mn) | – | 2.000 |
| Nitrogen (N) | 0.140 | 0.200 |
| Sulfur (S) | – | 0.020 |
| Silicon (Si) | – | 1.000 |
| Chromium (Cr) | 22.000 | 23.000 |
| Nickel (Ni) | 4.500 | 6.500 |
| Molybdenum (Mo) | 3.000 | 3.500 |
| Iron (Fe) | Balance | Balance |
Mechanical Properties & Strength of Duplex 2205 / UNS S32205 Tubes
The mechanical properties of Duplex 2205, including density and yield strength, are summarised in the following table to illustrate its performance compared with standard stainless steels.
| Property | Typical Value |
| Density | 7.8 g/cm³ |
| Yield Strength (0.2 % offset) | ~450 MPa (65,000 psi) |
| Tensile Strength | ~620 MPa (90,000 psi) |
| Elongation | 25–30 % |
| Hardness (Brinell) | ≤ 293 HB |
| Modulus of Elasticity | 200 GPa at 20 °C, decreasing to 180 GPa at 300 °C |
| Melting Range | ~1350 °C to 1440 °C |
The high yield strength and good elongation allow Duplex 2205 pipes to handle high pressures while remaining ductile. Its modulus of elasticity decreases slightly at elevated temperatures but remains higher than standard austenitic steels.
Duplex Stainless Steel Pipe Sizes & Schedule Chart
To assist with design and procurement, the schedule chart below provides typical wall thicknesses for common pipe sizes.
Typical pipe schedules for Duplex 2205 are identical to carbon‑steel pipe schedules. The table below (selected sizes) summarises outside diameters (OD), wall thicknesses and schedules:
| Nominal Pipe Size | Outside Diameter (in) | Schedule 10 (Wall mm) | Schedule 40 (Wall mm) | Schedule 80 (Wall mm) |
| 1/4 ″ | 0.54 | 1.65 | 3.73 | 4.83 |
| 1/2 ″ | 0.84 | 1.65 | 3.73 | 7.47 |
| 1 ″ | 1.315 | 2.77 | 4.55 | 6.35 |
| 2 ″ | 2.375 | 2.77 | 5.54 | 8.74 |
| 4 ″ | 4.50 | 3.05 | 6.02 | 11.07 |
| 8 ″ | 8.625 | 3.76 | 8.18 | 12.70 |
| 12 ″ | 12.75 | 4.78 | 11.13 | 16.66 |
Available Size Range of Duplex 2205 Pipes & Tubes
Duplex 2205 pipes and tubes are stocked in a wide range of sizes; the table below highlights available dimensions for seamless and welded products.
| Product Type | Outside Diameter (OD) Range | Wall Thickness | Typical Lengths |
| Seamless Pipes | 6 mm – 600 mm (1/8 ″ – 24 ″) | 1 mm – 60 mm | 5.5 – 6.5 m standard; custom lengths available |
| Welded Pipes | 1/8 ″ – 36 ″ OD | Similar wall thickness range (1 mm – 60 mm) | Single random lengths 5–7 m; double random lengths 10–12 m |
| Seamless Tubes | 0.375 ″ – 1 ″ OD | 0.035 ″ – 0.065 ″ wall thickness | Standard 6 m; cut lengths on request |
| Welded Tubes | 0.125 ″ – 1 ″ OD | 0.035 ″ – 0.109 ″ wall thickness | 6 m or custom lengths |
Weight Chart of Duplex S31803 / S32205 Pipes, Square Tubes & Capillary Tubes
Duplex 2205 has a density of 7.8 g/cm³. Approximate weight per metre for selected sizes. Using a standard density and weight formula, approximate weights per metre for popular pipe sizes are given in this chart.
| NPS (Pipe Size) | Schedule | Weight (kg/m) |
| 1/2 ″ | SCH 40 | 1.268 |
| 1 ″ | SCH 40 | 2.496 |
| 2 ″ | SCH 40 | 6.804 |
| 3 ″ | SCH 40 | 11.116 |
| 4 ″ | SCH 40 | 15.640 |
| 6 ″ | SCH 40 | 32.285 |
| 8 ″ | SCH 40 | 45.359 |
| 10 ″ | SCH 40 | 61.474 |
Weight formula: Weight (kg/m) ≈ 0.02466 × (OD – WT) × WT, where OD is outside diameter (mm) and WT is wall thickness (mm).
Surface Finish & Roughness of Duplex Stainless Steel Pipes (ASTM A790 DSS Pipe Roughness)
Surface finish affects both aesthetics and corrosion behaviour; the paragraphs below describe common finishes and roughness values available.
| Finish / Roughness Factor | Description & Typical Values |
| Annealed & Pickled | Standard mill finish; pipes are heat‑treated and pickled to remove scale and provide a dull surface (often used for general service). |
| Polished (180–320 grit) | Mechanical polishing produces a bright satin surface; typical roughness (Ra) ≈ 0.3–0.6 µm depending on grit. |
| Hairline / Satin | Fine linear finish created by brushing; aesthetic finish used in architectural or decorative applications. |
| Mirror Finish | Highly reflective surface achieved by fine polishing and buffing; Ra as low as 0.3–0.5 µm and often specified for hygienic systems. |
| Cold‑Drawn Tube | Cold drawing produces a smooth internal surface with Ra ≤ 1.5 µm; suitable for hydraulic and instrumentation tubing. |
| ASTM A790 Roughness | Roughness requirements for A790 duplex pipes typically specify mill or pickled finish; more critical services may request polished or bright‑annealed surfaces. |
Stellar Alloys supplies duplex pipes with any of the above finishes and can polish to 180–400 grit or mirror as required.
Temperature Range & Heat Resistance of Duplex 2205 Tubes
Duplex 2205’s heat‑resistance characteristics are summarised below; note the recommended service temperature limits.
| Parameter | Details & Recommended Limits |
| Maximum Service Temperature | Duplex 2205 is not recommended for continuous service above ~300 °C (572 °F) because high temperatures can precipitate brittle intermetallic phases |
| Industrial Guideline Limit | Many producers limit continuous service to ≤ 600 °F (≈316 °C) |
| Low‑Temperature Behaviour | Impact toughness decreases below –50 °C; pipes should be tested for ductile‑to‑brittle transition |
| Oxidation Resistance | Good oxidation resistance at moderate temperatures; suitable for flue‑gas desulphurisation and heat‑exchange applications |
| Alternative Grades for Higher Temperatures | For service > 600 °F (316 °C), Super Duplex (e.g., 2507) or high‑nickel austenitic alloys may be more appropriate. |
Duplex Stainless Steel Tube Gauge & Thickness Chart
Duplex tubes are available in gauges from 25 SWG to 10 SWG; typical thicknesses and tolerances are shown here.
| Gauge (SWG) | Nominal Thickness (in/mm) | Typical Use & Notes | Tolerance on Outside Diameter |
| 25 SWG | 0.020 ″ / 0.51 mm | Extra‑thin wall for instrumentation and capillary tubing. | ±0.25 mm (OD ≤ 25 mm) |
| 22 SWG | 0.028 ″ / 0.71 mm | Light‑wall tubing used in heat exchangers. | ±0.25 mm (OD ≤ 25 mm) |
| 20 SWG | 0.036 ″ / 0.91 mm | General‑purpose welded tube. | ±0.25 mm (OD ≤ 25 mm) |
| 18 SWG | 0.048 ″ / 1.22 mm | Typical gauge for exhaust/structural tubing | ±0.25 mm (OD ≤ 25 mm); ±0.50 mm (OD > 25 mm) |
| 16 SWG | 0.064 ″ / 1.63 mm | Thicker wall for high‑pressure tubes. | ±0.50 mm (OD > 25 mm) |
| 14 SWG | 0.080 ″ / 2.03 mm | Heavy‑wall instrumentation tubing. | ±0.50 mm (OD > 25 mm) |
| 12 SWG | 0.104 ″ / 2.64 mm | Structural and column tubing. | ±0.50 mm (OD > 25 mm) |
| 10 SWG | 0.128 ″ / 3.25 mm | Used where high mechanical strength is required. | ±0.50 mm (OD > 25 mm) |
Stellar Alloys adheres to these tolerances and supplies custom gauge thicknesses on request.
Applications and Uses of Duplex Stainless Steel 2205 / 31803 Pipes
Duplex 2205 pipes are chosen for environments where austenitic steels struggle. Competitors note common applications:
- Chemical & Petrochemical
- Marine & Offshore
- Pulp & Paper
- Power Generation & Heat Exchangers
- Food & Pharmaceutical and many more.
The combination of high strength and corrosion resistance also makes Duplex 2205 suitable for structural applications where weight reduction is beneficial.
Manufacturing Process of Duplex 2205 / S31803 Pipes
Manufacturing Duplex 2205 pipes requires controlled forming and heat treatment to achieve the alloy’s characteristic 50 % ferrite / 50 % austenite microstructure; the key steps are outlined below.
Cold working for most sizes: Duplex 2205 pipes are typically manufactured by cold rolling or cold drawing. Because the alloy has roughly twice the yield strength of austenitic stainless steels, forming forces are significantly higher.
Higher forming forces & larger bending radii: The high strength requires powerful equipment, larger bending radii and careful tooling to avoid cracking. Intermediate annealing may be necessary during complex forming operations to relieve work‑hardening stresses.
Hot forming for larger diameters: For heavy‑wall or large‑diameter pipes, producers switch to hot forming methods such as hot extrusion or rotary piercing. Hot forming reduces forming loads and prevents cracking but must be followed by controlled cooling.
Solution annealing after cold work: After cold working, pipes are solution‑annealed at 1020–1100 °C, then rapidly quenched in water to restore corrosion resistance and toughness. This heat treatment dissolves any intermetallic phases and ensures a balanced microstructure.
Rapid quenching: Quenching is critical; slow cooling can allow harmful sigma phase precipitation, which reduces corrosion resistance. Water quenching or forced air cooling is typically used to avoid this
Testing & Quality Standards for Duplex 2205 Tubes (Hydro, PMI, NDT)
Reputable suppliers subject Duplex 2205 pipes and tubes to a comprehensive suite of tests:
- Hydrostatic Test & Eddy Current Test: ensures leak‑proof integrity.
- Mechanical Tests: tensile, hardness, and flattening/flaring tests.
- Chemical Analysis / Positive Material Identification (PMI): verifies composition.
- Micro & Macro Examination: checks grain structure and absence of defects.
- Pitting Resistance & Intergranular Corrosion Tests.
- Non‑Destructive Tests (NDT): ultrasonic or radiographic testing upon request.
Test certificates (MTCs) per EN 10204 3.1/3.2 are provided. Third‑party inspections by SGS, TUV, DNV or other agencies can be arranged.
Price List of Duplex 2205 / Duplex 31803 Seamless & Welded Tubes in India
Pricing varies with size, thickness and market conditions. Competitor price lists indicate approximate ranges:
| Product | Price Range (INR/kg) | Price Range (US$/kg) |
| Duplex 2205 Seamless Pipe | ₹520 – ₹800/kg | $6–$8/kg (approx) |
| Duplex 2205 Welded Pipe | ₹450 – ₹550/kg | $4–$6/kg |
| Duplex 2205 Tube (Small OD) | ₹450/kg | $5.31/kg |
| Super Duplex & Special Sizes | Price on request; premium due to higher alloy content | – |
Note: Prices fluctuate with global nickel and molybdenum markets; please contact Stellar Alloys for current quotations.
Other Services We Offer for Duplex 2205 / Duplex 31803 Tubes
Stellar Alloys provides a full range of value‑added services to meet project‑specific requirements:
- Cut‑to‑length & Saw Cutting.
- Beveling & Threading to prepare ends for welding or threaded connections.
- Polishing & Surface Finishing to 180–400 grit or mirror.
- Heat Treatment & Annealing including solution annealing and stress relieving.
- Bending, Punching & Forming operations using powerful equipment to accommodate duplex’s high strength.
- Non‑Destructive Testing (UT, ET, RT) and PMI services.
- Packaging in plywood cases with protective film or wooden boxes to prevent damage during transit.
Why Choose Stellar Alloys for Duplex Stainless Steel Pipes & Tubes?
Choose Stellar Alloys for Duplex 2205 / UNS S31803 stainless steel pipes & tubes, our specialist duplex expertise, ready stock, certified quality, competitive pricing, and end-to-end processing ensure faster, defect-free deliveries.
Expertise: We specialise in duplex materials and understand the unique forming, welding and heat-treatment requirements, ensuring defect‑free pipes with balanced microstructure.
Comprehensive Inventory: Stock of seamless and welded pipes/tubes in sizes up to 36 ″ allows us to fulfil urgent requirements without delays.
Quality Assurance: Every product is supplied with EN 10204 3.1/3.2 certificates. Third‑party inspections can be arranged to verify compliance.
Competitive Pricing: Our bulk procurement and efficient production enable us to offer pricing on par with or better than major competitors.
Value‑Added Services: Cutting, beveling, polishing, heat treatment and logistics support are available under one roof, reducing lead times.
FAQ for Duplex Stainless Steel Pipe
Duplex stainless steel pipe is a type of stainless steel pipe characterized by a dual-phase microstructure consisting of roughly equal parts austenite and ferrite, resulting in a high-strength, corrosion-resistant material.
No, 304 is not a Duplex Stainless Steel. It is an austenitic stainless steel known for good corrosion resistance and formability but lacks the mixed microstructure and higher strength of duplex stainless steels.
Yes. Duplex stainless steels have greater resistance to chloride stress-corrosion cracking than 316 and are more robust, with higher strength than austenitic 316 stainless steel.
Grade 2205 duplex stainless steel offers roughly twice the yield strength of 316L and far better resistance to chloride-induced corrosion (pitting and stress corrosion cracking) than 316.
