Amardeep Steel Centre is a major manufacturer of duplex steel flanges in India, producing ASTM A182 F51, F60, F53, and F55 in duplex and super duplex forged flanges used in oil and gas, petrochemical, desalination, offshore, and chemical processing sectors across the globe. Our 20 years of experience in the manufacturing of duplex stainless steel flanges gives us the opportunity to export them to 80 or more nations in sizes ranging between 1/2"-60" NPS in the ANSI classes of 150-2500 and DIN/EN classes of PN6-PN250.
Our duplex flanges are made of prime-quality duplex stainless steel billets and meet ASTM A182 solution annealed, water quenched, to attain the best austenite-ferrite phase ratio of about 50:50. All flanges are dimensionally checked, impacted and provided with EN 10204/3.1 mill test certificates that can be located to the original mill heat. All orders can be inspected by TUV, Lloyds Register, SGS, Bureau Veritas and DNV-GL third parties.
Whether you require weld neck duplex flanges for offshore pipeline connections, blind flanges for pressure vessel isolation, or super duplex ASTM A182 F53 flanges for oxygenated seawater service, Amardeep Steel delivers precision-engineered solutions with short lead times, competitive pricing, and full material traceability from mill to delivery.
Current stock: ASTM A182 F51 and F60 duplex 2205 flanges available ex-stock in 1/2" to 12" Class 150 to 600. Super duplex F53 and F55 available in select sizes. Live stock enquiries via WhatsApp or email within 2 business hours.
Why Source Duplex Steel Flanges from Amardeep Steel?
Selecting the right duplex stainless steel flanges manufacturer directly affects project certification compliance, material traceability, and procurement lead time. Here is why engineering procurement teams across 80+ countries consistently choose Amardeep Steel for duplex and super duplex flanges:
- Direct manufacturer with no middlemen, ensuring better pricing and faster dispatch
- Dual-certified duplex 2205 stock in both ASTM A182 F51 (S31803) and F60 (S32205)
- Full grade range: F51, F52, F53, F55, F57, F59, F60, F61 per ASTM A182 and ASME SA182
- Size range: 1/2" to 60" across all ANSI pressure classes 150 to 2500 and DIN PN6 to PN250
- Certifications: EN 10204/3.1, NACE MR0175, ISO 15156, NORSOK MDS D45, PED
- Third-party inspection by TUV, Lloyd's, SGS, Bureau Veritas, DNV-GL on request
- ASTM A923 and ASTM G48 testing for intermetallic phase detection and pitting resistance
- Solution annealing and water quenching performed in-house with documented heat treatment records
- Export-ready packaging with full MTC documentation, EN 10204/3.1 certified
- Approved vendor to major EPC contractors and operators in Saudi Aramco, ADNOC, and ONGC supply chains
Have a live project requiring duplex or super duplex flanges? Send us your line list, pipe schedule, or material requisition. We respond with availability, pricing, and sample MTC within 24 hours.
Types of Flanges Available:
- Forged Flanges
- Slip-on Raised Face Flanges (SORF)
- Blind Raised Face Flanges (BLRF)
- Weld Neck Raised Face Flanges (WNRF)
- Socket Weld Raised Face Flanges (SWRF)
- Screwed/Threaded Flanges
- Orifice Flanges
- Spectacle Blind Flanges
- Reducing Flanges
- Ring Type Joint Flanges
- Tongue & Groove Flanges
- Plate Flanges
- Flat Face Flanges
- ANSI / ASME / ASA B16.5 Flanges
- EN 1092-1 Flanges
- DIN Flanges
- BS 10 Flanges
- BS 4504 Flanges
- JIS STD Flanges
Table of Contents
- Duplex Steel Flanges Specifications
- Forged vs Plate Duplex Steel Flanges
- Duplex Steel Flange Grades
- Duplex Steel Flange Grade Equivalents
- Chemical Composition
- Mechanical Properties
- Size Chart
- Heat Treatment
- Tensile Requirements
- Suitable Environment
- Pressure Rating
- Flange Weight
- Applications
- Surface Finishing and Coating
- Welding Guidelines
- Testing and Quality Control
- Frequently Asked Questions
- Related Products
Duplex Steel Flanges Specifications
Amardeep Steel's duplex stainless steel flanges are manufactured to the most widely specified global standards for industrial piping systems. The table below summarises the full technical parameter range. For project-specific requirements including NORSOK compliance, NACE sour service, or non-standard pressure ratings, contact our technical sales team with your line specification sheet.
| Parameter | Details |
|---|---|
| Material Standard | ASTM A182 / ASME SA182 |
| Grades | F51 (UNS S31803), F52 (UNS S32205 / Alloy 2205), F53 (UNS S32750), F55 (UNS S32760), F60, F61 |
| Werkstoff No. | 1.4462 (Duplex 2205), 1.4410 (Super Duplex 2507), 1.4501 (Super Duplex S32760) |
| Size Range | 1/2" (15 NB) to 60" (1500 NB) | NB 15 to NB 1500 |
| Standards | ANSI/ASME B16.5, B16.47 Series A & B, B16.48, B16.36, BS 4504, BS 10, EN 1092-1, DIN, GOST, JIS B2220 |
| Pressure Class (ANSI) | Class 150, 300, 400, 600, 900, 1500, 2500 LBS |
| Pressure Class (DIN/EN) | PN6, PN10, PN16, PN25, PN40, PN64, PN100, PN160, PN250 |
| Pressure Class (JIS) | 5K, 10K, 16K, 20K, 30K, 40K, 63K |
| Face Types | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Lap Joint (LJ), Tongue and Groove, Male and Female |
| Production Method | Hot Forging, Solution Annealed, Water Quenched, Machined |
| Heat Treatment | Solution Annealing at 1020°C minimum, followed by immediate water quench |
| Test Certificates | EN 10204 / 3.1 and 3.2, NACE MR0175, ISO 15156, NORSOK MDS D45 Grade F51 |
| Third Party Inspection | TUV, Lloyd's Register, SGS, Bureau Veritas, DNV-GL available |
All duplex flanges supplied by Amardeep Steel are solution annealed and water quenched as per ASTM A182 requirements. Quenching is performed immediately after the flange exits the furnace to prevent detrimental intermetallic phase precipitation, which can severely reduce both corrosion resistance and impact toughness.
Forged Duplex Steel Flanges vs Plate Duplex Steel Flanges
All flanged products supplied by Amardeep Steel with a hub are forged per ASTM A182, not cast or plate-fabricated. Forging produces a refined grain structure with superior tensile strength, fatigue resistance, and impact toughness compared to plate-cut equivalents. Duplex stainless steel plates per ASTM A240 may only be used for the manufacture of blind flanges and plate flanges without hub. For any pressurised, high-cycle, or high-temperature pipeline application, forged duplex steel flanges per ASTM A182 are the engineering-correct specification.
Duplex Steel Flange Grades
Amardeep Steel stocks and supplies the complete range of duplex and super duplex stainless steel flange grades as defined under ASTM A182:
- ASTM A182 F51 (UNS S31803) Duplex Steel Flanges
- ASTM A182 F60 (UNS S32205) Duplex 2205 Flanges
- ASTM A182 F53 (UNS S32750) Super Duplex Steel Flanges
- ASTM A182 F55 (UNS S32760) Zeron 100 Duplex Flanges
- ASTM A182 F61 (UNS S32550) Ferralium 255 Flanges
Duplex Steel Flange Grade Equivalents
The following table shows the ASTM A182 grade designation, UNS number, Werkstoff number, common trade name, and PREN value for each duplex and super duplex grade we supply:
| Grade | UNS Number | Werkstoff Nr. | Common Name | PREN (min) |
|---|---|---|---|---|
| ASTM A182 F51 | S31803 | 1.4462 | Duplex 2205 | 34 |
| ASTM A182 F60 | S32205 | 1.4462 | Duplex 2205 (tighter range) | 35+ |
| ASTM A182 F53 | S32750 | 1.4410 | Super Duplex 2507 | 42 |
| ASTM A182 F55 | S32760 | 1.4501 | Zeron 100 / Super Duplex | 40 |
| ASTM A182 F61 | S32550 | 1.4507 | Ferralium 255 | 38 |
PREN is calculated as: PREN = %Cr + 3.3 x %Mo + 16 x %N. A higher PREN value indicates superior resistance to pitting corrosion in chloride-containing environments. For seawater applications, a minimum PREN of 40 is generally recommended by most offshore standards including NORSOK.
Chemical Composition of Duplex Steel Flanges
The chemical composition of ASTM A182 duplex steel flanges must comply with the heat analysis limits defined in the standard. All heats supplied by Amardeep Steel are verified against mill test certificates traceable to the originating steel mill. The following table shows composition requirements for the two primary duplex grades:
| Grade | C (max) | Mn (max) | Si (max) | Cr (%) | Mo (%) | Ni (%) | N (%) | Fe |
|---|---|---|---|---|---|---|---|---|
| S31803 | 0.030 | 2.00 | 1.00 | 21.0 – 23.0 | 2.50 – 3.50 | 4.50 – 6.50 | 0.08 – 0.20 | Bal. |
| S32205 | 0.030 | 2.00 | 1.00 | 22.0 – 23.0 | 3.0 – 3.5 | 4.50 – 6.50 | 0.14 – 0.20 | Bal. |
Mechanical Properties of Duplex Steel Flanges (ASTM A182)
Minimum mechanical property requirements for duplex stainless steel forgings per ASTM A182. Duplex flanges achieve approximately twice the yield strength of standard austenitic grades (304 and 316) in the annealed condition:
| Property | S31803 / F51 | S32205 / F60 | Unit |
|---|---|---|---|
| Tensile Strength (min) | 620 | 620 | MPa |
| Yield Strength (min) | 450 | 450 | MPa |
| Elongation (min) | 25 | 25 | % |
| Hardness (max) | 293 | 293 | HBW |
| Impact Energy (min) | 45 | 45 | J at 0°C |
| Density | 7.805 | 7.805 | g/cm³ |
| Melting Range | 1420 – 1465 | 1420 – 1465 | °C |
The superior yield strength of duplex stainless steel flanges allows reduction in wall thickness and flange size in many applications, resulting in lower material weight and installation cost compared to equivalent austenitic stainless steel flange designs.
Duplex Stainless Flanges Size Chart
| Pressure | Size |
|---|---|
| Class 150 | Up to 24" |
| Class 300 | Up to 20" |
| Class 600 | Up to 20" |
| Class 900 | Up to 16" |
| Class 1500 | Up to 10" |
| Class 2500 | Up to 8" |
Heat Treatment Of Duplex Forged Flanges
| Process | Temperature |
|---|---|
| Annealing | 1040 – 1080°C / 1900 – 1975°F |
Tensile Requirements of 2205 Flanges
| Temperature | Tensile Strength |
|---|---|
| 122°F | 96 KSI |
| 212°F | 90 KSI |
| 392°F | 83 KSI |
| 572°F | 81 KSI |
Suitable Environment of Alloy 2205 Flanges
| Suitable Environment | Grades |
|---|---|
| Organic acids | 2205, RDN 903 |
| Chlorine acid, hydrogen chlorine and hydrochloric acid | 2205, 2304, Zeron 100 |
| Sulphuric acid | 2205 |
| Corrosion-resistant service | 2205 |
Duplex Stainless Steel Flange Pressure Rating
Working Pressure = 75 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 145 | 130 | 115 | 100 | 85 |
| 600°F | 650°F | 700°F | 750°F | - |
| 70 | 60 | - | - | - |
Working Pressure = 150 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 290 | 260 | 230 | 200 | 170 |
| 600°F | 650°F | 700°F | 750°F | - |
| 140 | 125 | 110 | 95 | - |
Working Pressure = 300 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 750 | 745 | 665 | 615 | 580 |
| 600°F | 650°F | 700°F | 750°F | - |
| 555 | 545 | 540 | 530 | - |
Working Pressure = 600 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 1500 | 1490 | 1335 | 1230 | 1160 |
| 600°F | 650°F | 700°F | 750°F | - |
| 1115 | 1095 | 1085 | 1065 | - |
Working Pressure = 900 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 2250 | 2230 | 2000 | 1845 | 1740 |
| 600°F | 650°F | 700°F | 750°F | - |
| 1670 | 1640 | 1625 | 1595 | - |
Working Pressure = 1500 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 3750 | 3720 | 3335 | 3070 | 2905 |
| 600°F | 650°F | 700°F | 750°F | - |
| 2785 | 2735 | 2710 | 2660 | - |
Working Pressure = 2500 PSI
| -20~100°F | 200°F | 300°F | 400°F | 500°F |
|---|---|---|---|---|
| 6250 | 6200 | 5560 | 5120 | 4840 |
| 600°F | 650°F | 700°F | 750°F | - |
| 4640 | 4560 | 4520 | 4430 | - |
Duplex Flange Weight
| NPS | Class 150 | Class 300 | Class 400 | Class 600 | Class 900 | Class 1500 |
|---|---|---|---|---|---|---|
| 1/2 | 0.5 | 0.9 | 0.9 | 0.9 | 2.7 | 2.7 |
| 3/4 | 0.9 | 1.4 | 1.4 | 1.4 | 2.7 | 2.7 |
| 1 | 0.9 | 1.4 | 1.6 | 1.8 | 3.4 | 3.6 |
| 1¼ | 1.4 | 2 | 2 | 2.3 | 4.5 | 4.5 |
| 1½ | 1.4 | 2.9 | 2.9 | 3.2 | 6.3 | 6.3 |
| 2 | 2.3 | 3.2 | 3.6 | 4.1 | 9.9 | 11.3 |
| 2½ | 3.6 | 4.5 | 5.4 | 5.9 | 13.9 | 16.2 |
| 3 | 4.1 | 5.9 | 6.8 | 7.2 | 16.2 | 21.6 |
| 3½ | 4 | 7.7 | 9.5 | 9.5 | - | - |
| 4 | 5.9 | 10.6 | 11.7 | 16.7 | 23.9 | 32.9 |
| 5 | 6.8 | 13.0 | 13.9 | 28.4 | 37.4 | 59.4 |
| 6 | 8.6 | 17.6 | 19.8 | 36 | 49.5 | 74.3 |
| 8 | 13.5 | 26.1 | 30.2 | 51.8 | 77.4 | 117 |
| 10 | 19.4 | 36.5 | 40 | 79.7 | 110.3 | 196.2 |
| 12 | 28.8 | 51.8 | 58.5 | 96.8 | 146.7 | 300.2 |
| 14 | 40.5 | 74.3 | 85 | 116.6 | 180 | 423 |
| 16 | 47.7 | 94.5 | 113.9 | 164.7 | 206.6 | 562.5 |
| 18 | 58.5 | 113.9 | 139.5 | 214.2 | 291.2 | 731.3 |
| 20 | 74.3 | 141.8 | 170.1 | 275.4 | 356.4 | 922.5 |
| 22 | 83.3 | 166.5 | 182.3 | 265.5 | - | - |
| 24 | 99 | 220.5 | 242.6 | 394.2 | 666 | 1271 |
Applications for Duplex Stainless Steel Pipe Flanges
The unique combination of high strength, outstanding chloride corrosion resistance, and resistance to stress corrosion cracking makes duplex steel flanges the material of choice across the following industries and service environments:
- Oil and Gas Production and Transmission
- Desalination and Water Treatment
- Petrochemical and Chemical Processing
- Pulp and Paper
- Marine and Shipbuilding
- Power Generation
- Food, Beverage, and Pharmaceutical
Surface Finishing and Coating Options for Duplex Steel Flanges
Duplex stainless steel is inherently corrosion resistant and does not require additional coating for most service environments. However, the following finishing and protective treatment options are available on request:
- Passivation
- Pickle and Passivate
- Electrolytic Polishing
- Anti-corrosion Oil Coating
- Custom Protective Coatings
Welding Guidelines for Duplex Steel Flanges
Duplex stainless steel flanges require specific welding procedures to maintain the correct austenite to ferrite phase balance (50:50 target) in the heat-affected zone. Incorrect welding can result in a predominantly ferritic or austenitic microstructure, reducing corrosion resistance and toughness. The following guidelines apply to butt welding of ASTM A182 F51/F60 duplex flanges to duplex pipe:
- Use duplex filler metals with slightly higher nickel content than the base material to promote austenite formation in the weld deposit. AWS ER2209 wire is standard for MIG/TIG welding of Alloy 2205.
- Maintain interpass temperature below 150°C (300°F) to prevent excessive ferrite formation in the heat-affected zone.
- Do not preheat. Duplex stainless steel does not require preheating and preheating can promote sigma phase precipitation.
- Post-weld heat treatment (PWHT) is generally not required or recommended for duplex grades. If solution annealing is performed post-weld, the entire assembly must be heated to 1020°C minimum and water quenched immediately.
- Ferrite content of completed welds should be verified by ferritoscope measurement per ANSI/AWS A4.2 or equivalent. Target ferrite number (FN) in the weld deposit is typically 30 to 60 FN.
- Avoid using carbon steel tooling, wire brushes, or grinding discs that have previously been used on carbon steel. Cross-contamination with carbon steel particles causes surface corrosion on duplex stainless steel.
Testing and Quality Control for Duplex Steel Flanges
Each duplex steel flange manufactured at Amardeep Steel undergoes the following quality control and testing procedures before dispatch. All test records are included in the material documentation package:
- Chemical Analysis (Heat Analysis)
- Mechanical Testing
- Hardness Testing
- Dimensional Inspection
- Intermetallic Phase Detection
- Pitting Corrosion Resistance Test
- Positive Material Identification (PMI)
- Dye Penetrant Inspection (DPI)
- Ultrasonic Testing (UT)
- Radiographic Testing (RT)
Frequently Asked Questions about Duplex Steel Flanges
What is the most common grade for duplex steel flanges?
ASTM A182 F51 (UNS S31803) and F60 (UNS S32205) are the most widely used duplex stainless steel flange grades, both collectively known as Alloy 2205 or Duplex 2205. S32205 has a tighter composition range producing a minimum PREN of 35, and can be dual-certified as S31803. For the most aggressive environments including subsea and seawater service, super duplex F53 (S32750) or F55 (S32760) are specified.
What is the difference between duplex and super duplex steel flanges?
Duplex grades such as F51 and F60 have a PREN of 34 to 36 and are suitable for general corrosive service including oil and gas pipelines, chemical plants, and desalination. Super duplex grades (F53, F55) have a PREN of 40 to 43 and are engineered for highly aggressive environments including oxygenated seawater, subsea systems, and chlorinated process streams where standard duplex 2205 would suffer pitting corrosion.
What sizes and pressure classes do you supply?
Amardeep Steel supplies duplex steel flanges from 1/2" to 60" NPS in all ANSI pressure classes from 150 to 2500 and DIN/EN classes from PN6 to PN250. Custom sizes, special borings, and non-standard pressure classes are available on request.
What is PREN and why does it matter when specifying duplex flanges?
PREN stands for Pitting Resistance Equivalent Number. It is calculated using the formula: PREN = %Cr + 3.3 x %Mo + 16 x %N. A higher PREN value means better resistance to chloride pitting. Duplex 2205 achieves a PREN of approximately 34 to 36. Super duplex S32750 achieves 40 to 43. For seawater applications, most offshore standards recommend a minimum PREN of 40, which is why super duplex grades are mandatory in those environments.
Can duplex steel flanges be used in sour gas service?
Yes. ASTM A182 F51 and F60 duplex flanges are NACE MR0175 and ISO 15156 compliant for use in sour service environments containing hydrogen sulphide, subject to Brinell hardness limits (310 HBW maximum), operating temperature restrictions (not above 315°C), and H2S partial pressure limits. Amardeep Steel can supply NACE-compliant material test certificates confirming hardness compliance.
What is the maximum operating temperature for duplex stainless steel flanges?
Duplex stainless steel flanges must not be used in sustained service above 315°C (600°F). Extended exposure above this temperature promotes the precipitation of the brittle sigma phase and chi phase intermetallic compounds, which can cause severe embrittlement and loss of corrosion resistance. For service temperatures above 315°C, austenitic stainless steel or alloy steel grades must be specified instead.
Do you provide EN 10204/3.1 material test certificates?
Yes. All duplex steel flanges supplied by Amardeep Steel are accompanied by EN 10204/3.1 mill test certificates as standard, including heat analysis, mechanical test results, heat treatment records, and dimensional inspection reports. For critical applications requiring third-party witnessed certification to EN 10204/3.2, we coordinate with TUV, SGS, Lloyd's Register, Bureau Veritas, and DNV-GL.
What is your lead time for duplex steel flanges?
Standard duplex 2205 flanges (F51/F60) in common sizes from 1/2" to 12" in Class 150 to 600 are available ex-stock and can be dispatched within 3 to 5 business days. Non-standard sizes, super duplex grades (F53/F55), and large project quantities typically carry a lead time of 2 to 4 weeks depending on size, class, and order volume. Contact our sales team for a live stock check.
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Source duplex steel pipe flanges direct from a manufacturer with full in-house forging, heat treatment, and testing capability. Amardeep Steel ships to 80+ countries with EN 10204/3.1 certification, export-ready packaging, and technical support from our engineering team. Contact us today for a competitive quote, live stock check, or sample MTC.
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