Duplex 2205 Stainless Steel Flanges

High Strength (≥450 MPa Yield): Approximately twice the yield strength of 316L, allowing for lighter schedules, reduced flange thickness, and significant weight savings in offshore and subsea applications.

Superior Chloride SCC Resistance: Outstanding resistance to chloride-induced stress corrosion cracking, performing reliably in high-chloride environments where .

Excellent Pitting and Crevice Corrosion Resistance: PRE (Pitting Resistance Equivalent) ≥ 34 for S31803 and ≥ 35 for S32205, providing reliable service in seawater, brackish water, and aggressive chemical media.

NACE MR0175 / ISO 15156 Compliant: Fully qualified for sour service (H₂S) applications up to 232°C (450°F), with documented HIC and SSC test reports available.

Good Weldability: Maintains balanced ferrite/austenite ratio (35–65% ferrite) when using proper welding procedures (low heat input, N₂ shielding gas). No post-weld heat treatment required for most applications.

Excellent Erosion and Corrosion Fatigue Resistance: Ideal for high-velocity seawater, slurry, and pump applications where combined mechanical and corrosive attack occurs.

Full Range of Types: Weld neck (WN), slip-on (SO), blind (BL), socket weld (SW), threaded (TH), lap joint (LJ), plate flanges, and orifice flanges.

Pressure Ratings: Available in Class 150, 300, 600, 900, 1500, and 2500 (PN6 to PN400 in metric equivalents).

Low Coefficient of Thermal Expansion: Lower than austenitic grades (13.5 μm/m·K vs 15.9 for 316L), reducing thermal stress in bolted flange connections.

International Certifications: Flanges can be certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK, and comply with NORSOK M-630, NORSOK M-650, NACE MR0175, and ASME standards.

These standards ensure that our Duplex 2205 stainless steel flanges meet global requirements for chemical composition, balanced dual-phase microstructure, mechanical properties, dimensional tolerances, and pressure-temperature ratings.

S32205 is a restricted composition range of S31803, offering tighter control of Cr, Mo, and N to enhance corrosion resistance and ensure optimal phase balance. The addition of nitrogen promotes austenite stability and significantly increases pitting resistance. The PREN for S32205 is ≥35, compared to ≤24 for 316L.

Comparison of PREN (Pitting Resistance Equivalent) Values:

Impact Toughness (Charpy V-Notch, typical at -40°C):

Longitudinal: ≥ 60 J (typical)

NACE MR0175 / ISO 15156 Compliance:
Duplex 2205 is fully qualified for sour service applications up to 232°C (450°F) at H₂S partial pressures and pH levels defined in NACE MR0175/ISO 15156.

Maximum Recommended Service Temperatures:

Critical Note: Duplex 2205 is not recommended for prolonged service above 300°C due to the risk of embrittling intermetallic phase precipitation (sigma phase).

Heat Treatment Condition:
All Duplex 2205 flanges are solution annealed at 1040–1120°C followed by rapid cooling (water quenching) . This heat treatment restores the balanced 40–60% ferrite / 40–60% austenite microstructure, dissolves unwanted intermetallic phases (sigma, chi), relieves internal stresses from forging, and ensures maximum corrosion resistance.

Critical Note: Unlike austenitic grades (304/316), Duplex 2205 requires water quenching after solution annealing. Air cooling is insufficient and will result in intermetallic phase precipitation, severely reducing corrosion resistance and toughness.

Delivery Condition: Flanges normally supplied in solution annealed and pickled condition, providing a clean, smooth surface and excellent corrosion resistance. Bright annealing is not recommended for duplex grades due to the water quenching requirement.

*Reference: Based on ASME B16.5 for duplex stainless steel (Group 2.2). De-rating factors at higher temperatures are more conservative than for austenitic grades due to risk of sigma phase embrittlement.*

Standard Dimensions: ASME B16.5 for sizes up to 24″, and ASME B16.47 Series A/B for large diameters up to 60″. EN 1092-1 dimensions available upon request.

Raw Material Selection: High-quality S31803/S32205 duplex stainless steel bars or billets from certified mills (Outokumpu, Sandvik, POSCO, Baosteel) with certified chemical composition and ferrite/austenite balance. Raw material is NORSOK M-650 qualified and NACE MR0175 compliant.

Cutting & Heating: Material is cut to precise weight using band saws, then induction-heated to forging temperature (lower than austenitic grades, typically 1150–1200°C, to prevent ferrite coarsening).

Forging: Hot forged using hydraulic presses (3000–8000 tons) with strict temperature control. Multiple forging steps with careful reduction rates to maintain forgeability and prevent cracking.

Heat Treatment – Solution Annealing: Critical heat treatment at 1040–1120°C followed by immediate water quenching (<30 seconds delay) to restore balanced duplex microstructure and dissolve intermetallic phases.

Machining: CNC lathes and milling machines produce precise dimensions, bolt holes, and facing surfaces. Special tooling and slower cutting speeds are required due to higher strength of duplex.

Surface Finishing: Raised face serration, flat facing, or RTJ groove machining per ASME B16.5 requirements.

Ferrite Content Measurement: Verification of phase balance using magnetic induction or metallographic methods – requirement: 35–65% ferrite.

Marking: Laser engraving or stamping with grade (F51/F60/S31803/S32205), size (NPS), class, heat number, manufacturer identification, and standard.

Inspection & Testing: Dimensional check, PMI, ferrite measurement, hardness test, and NDT as required.

Surface Treatment: Pickling and passivation using specialized pickling acids optimized for duplex grades.

Each Duplex 2205 flange face is inspected for surface roughness, concentricity, and absence of defects.

Chemical Analysis: PMI 100% verification using handheld XRF spectrometer for Cr, Ni, Mo, N.

Ferrite Content Measurement: Magnetic induction (ferritoscope) or metallographic method – requirement 35–65% ferrite.

Microstructure Examination: Verification of balanced dual-phase structure, absence of intermetallic phases (sigma, chi).

Mechanical Testing: Tensile strength (≥620 MPa), yield strength (≥450 MPa), elongation (≥25%), hardness (≤290 HBW).

Charpy Impact Testing: Per NORSOK M-630 at -46°C – ≥60J typical.

Dimensional Inspection: OD, ID, bolt circle, bolt hole alignment, thickness, flatness using calibrated gauges and CMM.

Thread Inspection: NPT thread verification using GO/NO-GO gauges per ANSI B1.20.1.

NDT – Liquid Penetrant Testing (PT): 100% for surface defects including cracks and forging laps.

NDT – Ultrasonic Testing (UT): For internal flaws upon request.

Corrosion Testing (upon request): ASTM G48 Method A pitting test (24 hours in 6% FeCl₃ at 40°C, no pitting required for NORSOK).

Intergranular Corrosion Test (IGC): ASTM A262 Practice E.

Sour Service Qualification (upon request): HIC per NACE TM0284, SSC per NACE TM0177.

NORSOK M-650 Qualification: Complete documentation package available.

Third-Party Inspection: SGS, BV, DNV, TUV, LR, or ABS on customer request.

Offshore Oil & Gas: Topside process piping, subsea manifold connections, riser flange joints, umbilical termination flanges, wellhead equipment (API 6A), Christmas tree flanges, choke and kill line connections (ABS, BV, DNV, LR certified, NACE MR0175 compliant).

Seawater Systems: Seawater cooling pipe flanges, firewater system flanges, ballast water treatment connections, offshore platform seawater lift pump flanges.

Desalination Plants: Brine heater flanges, high-pressure reverse osmosis feed line flanges, brine discharge flanges, multi-stage flash (MSF) evaporator connections.

Chemical Processing: Chloride-containing acid transfer flanges, pulp & paper bleach plant flanges, phosphoric acid and sulfuric acid process flanges.

Flue Gas Desulfurization (FGD): Absorber tower flanges, slurry piping flanges, reheat duct flanges, quench nozzle flanges.

Oil Refining: Sour water stripper flanges, amine regenerator flanges, hydrotreater feed/effluent flanges (NACE MR0175 compliant).

Marine Engineering: Shipboard seawater cooling flanges, ballast system flanges, desulfurization scrubber flanges (classification society certified).

Water Treatment: Brackish water reverse osmosis flanges, chemical injection flanges.

Power Generation: Coastal power plant cooling water flanges, FGD flanges, auxiliary cooling connections.

Small flanges (≤4″): Heavy-duty cartons with moisture barrier paper on pallets.
Medium flanges (6″–12″): Wooden crates with foam padding dividers, VCI paper wrapping.
Large flanges (≥14″): Individual wooden crates or steel-framed pallets with foam padding.

All shipments:

Rust preventive oil coating (optional – may be omitted for pickled finish).

Individual tagging: Grade (F51/F60), size, class, heat number, heat treatment condition, standard, PO number.

Waterproof shipping marks for export containers.

Womic Steel’s Delivery Strengths:

Ready stock: Class 150 and 300 Duplex 2205 flanges in sizes 1/2″–12″ – dispatch within 24 hours.

Direct cooperation with global shipowners for the most competitive freight rates.

Professional loading by in-house teams using padded slings to prevent surface damage.

Complete documentation for customs clearance including EN 10204 3.1 MTR, NORSOK M-650 documentation, NACE compliance certificates, ferrite measurement reports, and inspection certificates.

Continuous cargo tracking and after-sales follow-up.

1. What is the difference between S31803 and S32205 Duplex 2205 flanges?
S32205 is a restricted composition range of S31803 with tighter controls on Cr (22.0–23.0%), Mo (3.0–3.5%), and N (0.14–0.20%). S32205 offers higher corrosion resistance (PRE ≥35 vs ≥34) and is generally preferred for new construction, especially in offshore and sour service applications.

2. Are Duplex 2205 flanges suitable for sour service (H₂S environments)?
Yes. Duplex 2205 is fully NACE MR0175 / ISO 15156 compliant for sour service up to 232°C (450°F). We can supply documented HIC and SSC test reports upon request.

3. Can Duplex 2205 flanges be welded to 316L piping?
Yes, but requires careful procedure with appropriate filler metal (typically 2209 or 309LMo). The transition should be designed to avoid galvanic corrosion, and welding procedures must be qualified.

4. What is the maximum service temperature for Duplex 2205 flanges?
250°C (482°F) for chloride service; 300°C (572°F) for non-chloride service. Above 300°C, risk of sigma phase embrittlement increases significantly. For higher temperatures, consider super duplex 2507 or austenitic grades.

5. Do Duplex 2205 flanges require post-weld heat treatment?
Generally, no. However, welding procedures must control heat input and interpass temperature. For maximum corrosion resistance in severe sour service, full solution annealing after welding may be specified.

6. What facing is recommended for high-pressure sour gas flanges?
Ring Type Joint (RTJ) facing with octagonal ring gasket is recommended for high-pressure sour gas service to ensure leak-tight sealing.

7. Can you supply Duplex 2205 flanges with NORSOK M-650 documentation?
Yes. We maintain NORSOK M-650 qualified material and can supply complete documentation packages including manufacturing procedure specification (MPS), procedure qualification record (PQR), and production test reports.

8. Are Duplex 2205 flanges available in EN 1092-1 dimensions?
Yes. We can manufacture Duplex 2205 flanges to EN 1092-1 Type 01, 02, 05, 11, 12 with PN6 to PN400 pressure ratings. Please specify your requirement.

Complete Product Range: Weld neck, slip-on, blind, socket weld, threaded, lap joint, and plate flanges – one-stop purchasing for offshore and marine projects.

Strict Quality Control: ISO 9001:2015, PED 2014/68/EU, and API Q1 certified facilities.

NORSOK M-650 Qualified: Complete documentation packages available for offshore projects.

NACE MR0175 / ISO 15156 Compliant: Sour service certification with HIC/SSC test reports on request.

Advanced Forging & Machining: 3000–8000 ton hydraulic presses and CNC machining centers.

Full Traceability: Heat number stamped on each flange – traceable back to original mill certificate with ferrite measurement records.

Ferrite Content Control: 100% ferrite measurement (35–65% required) documented on test reports.

Flexible Customization: Special facing types (RTJ, T&G, M&F), custom bolt drilling, and non-standard sizes available.

Marine & Offshore Certified: ABS, BV, DNV, LR, GL, RINA certification available.

Global Delivery: Exported to major offshore projects worldwide including North Sea, Gulf of Mexico, Middle East, Southeast Asia, and Australia.

Tel / WhatsApp:
Victor: +86 15575100681
Jack: +86 18390957568

E-mail: info@womicstainless.com

Website: www.womicsteel.com

Contact Womic Steel today for a competitive quote on Duplex 2205 stainless steel flanges. We offer certified quality, NORSOK M-650 documentation, NACE MR0175 compliance, fast production lead times, and reliable global delivery to keep your offshore and marine projects running smoothly.

Stock Examples (Class 150 WN RF – Duplex 2205):

Stock Examples (Class 300 WN RF – Duplex 2205):

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