Duplex Steel Fittings Manufacturer & Supplier | Duplex Pipe Fittings UNS S31803

Duplex Steel Fittings Manufacturer & Supplier — UNS S31803 / S32205

We are a well-known manufacturer of Duplex Steel Fittings. Duplex Steel Fittings manufactured from material UNS S31803 and S32205 is commonly known as Duplex 2205. Solitaire Overseas is ISO 9001:2015 certified manufacturer, supplier & exporter of Duplex Steel Fittings. We export Duplex Steel Fittings to over 60 countries across the globe, including more than 60 countries. Our offered Duplex Steel Fittings are widely used in various industrial applications, especially in Oil & Gas, Offshore and Marine Industry. Our product range includes elbows, tees, reducers, caps, stub ends, couplings, crosses, pipe bends, etc. These Duplex Steel Fittings are manufactured per ASTM A815, ASME B16.9, B16.11, B16.28 & MSS SP-43 standards. Mill Test Certificates EN 10204 3.1, 3.2 are provided with each and every Duplex Steel Fittings shipment. Extra NDT tests such as PMI, hydrostatic and ultrasonic tests can be performed on request.

Available in standard sizes for immediate dispatch or custom made to exact specifications, under strict quality control and inspected by SGS, TUV, BV, DNV, LLOYDS.

What Are Duplex Steel Fittings?
Duplex Pipe Fittings — Technical Specifications
Chemical Composition of Duplex Stainless Steel UNS S31803 / S32205
Mechanical Properties of ASTM A815 Duplex Steel Fittings (UNS S31803)
Duplex Steel Fittings Equivalent Grades
Complete Range of Duplex Steel Pipe Fittings
Dimensional Tolerances — Duplex Buttweld Fittings (ASME B16.9)
Welding of Duplex Steel Fittings — Key Guidance
Industries & Applications of Duplex Steel Pipe Fittings
Duplex 2205 vs Super Duplex 2507 — When to Upgrade?
Related Products
Frequently Asked Questions — Duplex Steel Fittings

What Are Duplex Steel Fittings?

Duplex steel fittings are piping components manufactured from duplex stainless steel, a dual-phase alloy consisting of approximately equal parts austenite and ferrite. This balanced microstructure provides a unique combination of high mechanical strength and enhanced resistance to chloride-induced corrosion, making duplex materials suitable for demanding industrial environments.

The most widely used grade is Duplex 2205 (UNS S31803 / S32205), which contains optimized levels of chromium, molybdenum and nitrogen. These elements improve resistance to pitting and crevice corrosion while maintaining strong structural performance under pressure.

Due to this combination of properties, duplex pipe fittings are widely specified in applications where standard austenitic stainless steels may not provide sufficient durability or long-term reliability.

Duplex Pipe Fittings — Technical Specifications

We maintain a comprehensive stock of Stainless Steel 316 fittings. Below are the key specifications for our inventory.

Parameter	Specification
Primary Grade	UNS S31803 / S32205 (Duplex 2205)
Also Available	UNS S31500, UNS S32304 (Lean Duplex)
Werkstoff Nr.	1.4462
Standards	ASTM A815 / ASME B16.9 / B16.11 / B16.28 / B16.25 / MSS SP-43 / MSS SP-83 / MSS SP-95 / EN 10253
PREN Value	30–40 (vs 25 for 316L; vs >40 for Super Duplex)
Size Range (BW)	1/2" NB to 48" NB (Seamless: 1/2"–24"; Welded: 24"–48")
Pressure Class (Forged)	3000# / 6000# / 9000# (SW & Threaded per ASME B16.11)
Pressure Rating (Tube)	3,000 PSI – 10,000 PSI (forged SW/threaded; class per ASME B16.11)
Schedule Range	SCH 5S to XXS / SCH 160
Connection Types	Butt Weld, Socket Weld, Threaded (NPT/BSP/BSPT), Beveled, Flanged
Manufacturing Process	Seamless, Welded, Forged, Cast, Fabricated
Temperature Range	-50°C to +300°C
Surface Finish	Pickled & Passivated, Sandblasted, Polished (2B, BA, No.4 optional)
Bending Radius (Bends)	1D (SR), 1.5D (LR), 3D, 4D, 5D, 6D, 8D, 10D
Certifications	EN 10204 3.1/3.2 MTC, NACE MR0175, PED, IBR, ISO 9001:2015
Third Party Inspection	SGS, TUV, BV, DNV, LLOYDS, IRS, PDIL available

Chemical Composition of Duplex Stainless Steel UNS S31803 / S32205

Element	UNS S31803 (%)	UNS S32205 (%)
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)	≤ 2.0	≤ 2.0
Carbon (C)	≤ 0.030	≤ 0.030
Silicon (Si)	≤ 1.0	≤ 1.0
Phosphorus (P)	≤ 0.030	≤ 0.030
Sulfur (S)	≤ 0.020	≤ 0.020
Iron (Fe)	Balance	Balance

Mechanical Properties of ASTM A815 Duplex Steel Fittings (UNS S31803)

Property	Value	Test Method
Tensile Strength (min)	620 MPa (90 ksi)	ASTM A370
Yield Strength — 0.2% offset (min)	450 MPa (65 ksi)	ASTM A370
Elongation in 2" (min)	25%	ASTM A370
Hardness (max)	≤ 290 HB / 30 HRC	ASTM E10 / E18
Impact Toughness	Excellent; tested at −46°C	EN 10045-1 / ASTM A370
Density	7.8 g/cm³	—
Modulus of Elasticity	200 GPa	—

Duplex Steel Fittings Equivalent Grades

UNS No.	EN / Werkstoff	Common Name	ASTM Forging	ASTM Pipe/Tube
S31803	1.4462	Duplex 2205	ASTM A182 F51	ASTM A790
S32205	1.4462	Duplex 2205 (revised N)	ASTM A182 F60	ASTM A790
S32304	1.4362	Lean Duplex 2304	ASTM A182 F—	ASTM A789
S31500	1.4424	3RE60	—	ASTM A789

Complete Range of Duplex Steel Pipe Fittings

90° Elbows

Long Radius (1.5D), Short Radius (1D) — seamless & welded

45° Elbows

Gradual direction change with lower pressure drop

180° Return Bends

U-bends for heat exchangers and coil configurations

22.5° / 30° / 60° Elbows

Custom angle elbows for specialized piping layouts

Equal Tees

Three-way equal outlet — straight and swept types

Reducing Tees

Smaller branch outlet; Y-tee and lateral tee also available

Barred / Piggable Tees

Branch reinforced with bars to guide pigs past tee branch

Concentric Reducers

Symmetric size reduction — used on vertical lines

Eccentric Reducers

Off-centre reduction — pump suction, horizontal lines

End Caps / Pipe Caps

Seamless, welded, and hemi-head types

Full & Half Couplings

Threaded and socket weld, small bore piping

Unions

Three-piece threaded or socket weld for easy disconnection

Crosses

Four-way distribution — chemical plant and process skids

Stub Ends — Type A/B

For lap joint flange systems; long and short types

Pipe Bends (3D–10D)

Hot induction, mandrel, roll, and rotary draw bending

Forged Elbows

45°, 90° — socket weld or threaded, 3000# to 9000#

Forged Tees (SW/Threaded)

Equal and reducing — socket weld or threaded

Forged Couplings

Full, half, reducing — SW and threaded

Dimensional Tolerances — Duplex Buttweld Fittings (ASME B16.9)

Dimension	Tolerance
Wall Thickness (T)	±12.5% of nominal wall thickness
Outside Diameter at Ends (≤10" NB)	±1.6 mm
Outside Diameter at Ends (>10" NB)	±2.4 mm
Overall Length (L)	±1% or ±3.2 mm (whichever is greater)
Center-to-End (Elbows & Tees)	Per ASME B16.9 Table 1
Angularity (MSS SP-43)	±1° maximum
Ovality (nominal OD ≤ 2")	±1.5% of nominal OD

Welding of Duplex Steel Fittings — Key Guidance

Duplex 2205 fittings can be welded using GTAW, SMAW, GMAW, and SAW processes with the following key parameters:

Parameter	Requirement
Filler Metal	ER2209 (TIG/MIG) or E2209 (SMAW) — overalloyed to compensate dilution
Preheat	Not required for normal thicknesses (≤25mm); 15°C minimum ambient
Interpass Temperature	Maximum 150°C — critical to maintain phase balance
Heat Input	0.5–2.5 kJ/mm — avoid excessive heat input
Post-Weld Heat Treatment	Solution annealing 1020–1100°C + water quench (if required by spec)
Shielding Gas	Argon or Argon + 2% N2 for root and cover passes
Ferrite Check	Post-weld ferrite content must be 35–65% (ASTM E562 / WRC diagram)

Industries & Applications of Duplex Steel Pipe Fittings

Oil & Gas (Upstream & Subsea): Duplex Steel Pipe Fittings are specified for subsea pipelines, FPSO topsides, manifolds, wellhead assemblies, and chemical injection lines where H2S partial pressure and chloride concentrations rule out 316L. Compliant with NACE MR0175 / ISO 15156 for sour service environments.
Desalination (SWRO): Used in high-pressure seawater reverse osmosis trains, brine concentrate headers, and intake manifolds operating at 60–80 bar. Duplex 2205 resists chloride-induced SCC at the elevated temperatures and brine concentrations that rapidly degrade austenitic grades.
Petrochemical & Refining: Reactor units, hydrocrackers, condensers, high-pressure loop systems.
Marine & Offshore: Ballast water, riser pipelines, shipbuilding, subsea structures.
Water Treatment: Chlorinated water, filtration skids, chemical dosing systems.
Power Generation: HRSGs, condenser lines, FGD systems, cooling circuits.
Chemical Processing: Acid transport, chlor-alkali, phosphate, urea lines.
Pulp & Paper: Digesters, bleach plants, black liquor pipelines.
Mining: Acid leach systems, slurry transport, chemical pipelines.
Food & Pharma: High-purity CIP systems, moderate chloride process lines.

Duplex 2205 vs Super Duplex 2507 — When to Upgrade?

Property	Duplex 2205 (UNS S31803)	Super Duplex 2507 (UNS S32750)
PREN	30–40	>40
Yield Strength (min)	450 MPa	550 MPa
Chloride Resistance	Good — moderate chloride service	Excellent — high chloride / seawater
SCC Resistance	Good	Superior
Temperature Range	-50°C to +300°C	-50°C to +300°C
Cost vs 316L	~2× 316L	~3–4× 316L
Best For	Oil & gas, desalination, chemical — standard severity	Subsea, deep offshore, hot seawater, sour service

Need to upgrade? View ourSuper Duplex Steel Fittings range.

Frequently Asked Questions — Duplex Steel Fittings

What are duplex steel fittings?

Duplex steel fittings are precision pipe components made from duplex stainless steel — a dual-phase austenitic-ferritic material that delivers approximately 2× the yield strength of 316L and superior resistance to chloride-induced corrosion. The most common grade is UNS S31803 / Duplex 2205, widely used in oil & gas, desalination, marine, and chemical processing. The most common grade for process industry applications is UNS S31803 / Duplex 2205. View our complete range of Duplex Pipe Fittings above, or contact our team for grade selection guidance.

Duplex 2205 vs 316L stainless steel fittings — which should I choose?

Duplex 2205 pipe fittings offer a PREN of 30–40 versus 23–25 for 316L, making them the preferred choice in chloride-rich, high-pressure, and sour service environments where 316L fails prematurely due to pitting or stress corrosion cracking. If budget is the primary concern and the environment is mild, 316L is adequate. For critical offshore, seawater, and chemical applications, duplex is the engineered solution.

What certifications are available?

All Duplex Steel Pipe Fittings from Solitaire Overseas are supplied with EN 10204 3.1 MTCs as standard. EN 10204 3.2 (third-party witnessed), NACE MR0175 / ISO 15156 (sour service), PED, IBR, and NORSOK compliance documentation are available on request. Third-party inspection by SGS, TUV, BV, DNV, and LLOYDS can be arranged.

What is the difference between duplex and super duplex fittings?

Duplex 2205 fittings have a PREN of 30–40 and are ideal for most offshore, marine, and chemical service. Super Duplex fittings (UNS S32750 / S32760, PREN > 40) are used for the most aggressive service conditions — hot seawater, deep subsea, and sour service where Duplex 2205 may be marginal. View our Super Duplex Steel Fittings UNS S32750 / S32760 range for comparison.

What is the lead time and stock availability?

Standard 1/2" to 8" NB duplex steel fittings are typically held in stock for prompt dispatch. Larger or custom orders require 3–5 weeks. Contact our sales team for current availability, pricing, and MTC documentation.

Can I get a price list for duplex steel pipe fittings?

Duplex Steel Fittings pricing varies by grade (UNS S31803 vs S32205), standard (ASTM A815 / MSS SP-43), size, schedule, and quantity. We do not publish a fixed price list due to raw material fluctuations. Contact our sales team with your Piping Material Specification (PMS) and bill of quantities for a rapid quotation — typically within 24–48 hours.

Do you export duplex steel fittings internationally?

Yes. Solitaire Overseas exports Duplex Steel Pipe Fittings to 60+ countries including UAE, Saudi Arabia, USA, UK, Canada, Germany, Australia, Singapore, Malaysia, and South Korea. All export shipments are supplied with EN 10204 3.1 MTCs, packing lists, and country-of-origin certificates. NORSOK-compliant documentation is available for North Sea projects.

Are your duplex tube fittings compatible with Swagelok or Parker A-Lok systems?

Our duplex tube fittings are manufactured to compatible dimensional standards for double-ferrule compression fitting systems. Contact us with your tube OD and pressure rating requirements for a direct cross-reference and dimensional comparison.

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