Duplex Steel UNS S31803 Flanges Manufacturer
Midland Alloys Inc. is a trusted duplex steel UNS S31803 industrial flanges manufacturer and supplier in India. These flanges are made from a nitrogen-enhanced, low-carbon duplex stainless steel that combines both austenitic and ferritic structures. It composes of 22% chromium, 5–6% nickel, 3% molybdenum, and nitrogen. This s31803 duplex stainless steel grade offers strong resistance to corrosion, pitting and stress cracking in harsh environments. It is reliable for use in acidic and chloride-rich systems. Available in seamless and welded forms like WNRF, SORF, BLRF, threaded, and lap joint, they suit many industrial needs. These UNS S31803 Duplex Steel Flanges are widely used across oil, gas, chemical, and marine industries. We ensure high-quality products at competitive pricing.
Product Overview
B16.48 Duplex UNS S31803 Flanges are made from strong and reliable duplex stainless steel, known for lasting performance in tough settings like marine zones and chemical units. Offered in various types such as weld neck, slip-on, socket weld, threaded, and blind flanges. B16.48 Duplex UNS S31803 Flanges handle heat, pressure and demanding environments without losing strength. Designed to connect smoothly with pipes, valves, and pumps, these flanges work across industries. ASTM A182 s31803 flanges come in standard and custom sizes.
Key Benefits of Duplex Steel UNS S31803 Flanges
Duplex UNS S31803 Flange offer strong and steady performance across demanding industrial setups.
- Resists corrosion in saltwater and chemical zones
- Stays strong under heavy loads over time
- UNS S31803 duplex stainless steel flange welds easily with standard techniques
- Handles high heat without losing strength
- Maintains size accuracy for tight fittings
- Smooth surface finish for better sealing
- Matches ASME 16.5 and global norms
- Needs low maintenance which reduces service time and meet ASME 16.5 standards
Duplex Steel UNS S31803 Flanges Specification
The key specifications such as standard, pressure class, type, face type, and finish are given below. It helps you confirm if the flanges match your technical needs before purchase.
1/2" (15 NB) to 48" (1200NB)
ASTM A182 / A240 & ASME SA182 / SA240
ANSI/ASME B16.5, B 16.47 Series A & B, B16.48, BS4504, BS 10, EN-1092, DIN, etc.
Threaded / Screwed / Forged / Plate
150#, 300#, 600#, 900#, 1500#, 2500#, PN6, PN10, PN16, PN25, PN40, PN64 etc.
Flate Face (FF), Raised Face (RF), Ring Type Joint (RTJ)
Forging, Rolling, Casting
FNPT, NPT, BSPT, MNPT, BSPP
Types of Duplex Steel UNS S31803 Flanges
Manufacturing Types
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SORF (Slip-On Raised Face)Slides over the pipe and gets welded for easy installation in low-pressure systems.
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BLRF (Blind Raised Face)Closes off pipe ends; used for testing or sealing flow in a system.
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SWRF (Socket Weld Raised Face)Pipe fits into a recessed area and is welded around the edge. Ideal for small-bore, high-pressure lines.
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WNRF (Weld Neck Raised Face)Has a long, tapered hub and welds to the pipe for strong, leak-proof joints under high pressure.
Face Forms
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Raised Face (RF)The most common type has a raised surface that improves gasket sealing in medium to high pressure.
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Ring Type Joint (RTJ)Uses a metal ring for sealing and works well in high-pressure, high-temperature services.
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Flat Face (FF)Flat surface flange used with cast iron or low-pressure piping where full face gasket is needed.
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Lap-Joint Face (LJF)Used with stub ends and are easy to align and install. Good for systems that need frequent dismantling.
Contact us today to discuss how Duplex Steel UNS S31803 Flanges can benefit your application. Whether you need guidance in selecting the right pipes or have specific requirements, our team of experts is here to help you find the optimal solution.
Technical Details & Delivery Condition
The DIN 1.4462 s31803 flanges equivalent international standards like EN, DIN, and Werkstoff numbers are mentioned below. This is useful when comparing global material compatibility across different countries or suppliers.
| STANDARD | WERKSTOFF NR. | UNS |
| Duplex S31803/ F51 | 1.4462 | S31803 |
This table lists the chemical makeup of S31803 flanges, including chromium, nickel, molybdenum, nitrogen, and more. It gives you clarity on what elements offer the corrosion and strength benefits.
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | Fe |
| Duplex S31803/ F51 | 0.030 max | 2 max | 1 max | 0.030 max | 0.020 max | 22 – 23 | 3 – 3.50 | 4.50 – 6.50 | 0.14 – 0.20 | Bal |
The table covers tensile strength, yield strength, elongation, and hardness. This helps you assess how the material performs under mechanical stress and ensures it fits your pressure and load needs.
| Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| 7.8 g/cm3 | 1350 °C (2460 °F) | Psi – 116000 , MPa – 800 | Psi – 80000 , MPa – 550 | 15 % |
This section provide dimension details like flange thickness, bolt circle, and bore diameter. It ensure that the flange fit perfectly with your piping and valve system.
| Outside Diameter ≤ 24 = 1.6 mm | > 24 = ± 3.2 mm | Inside Diameter not applicable |
| Diameter of Contact Face 1.6 mm Raised Face = ± 0.8 mm 6.35 mm Raised Face, Tongue & Groove / Male-Female = ± 0.4 mm | Outside Diameter of Hub ≤ 12 = + 2.4 mm / – 1.6 mm | ≥ 14 = ± 3.2 mm |
| Diameter of Counterbore not applicable | Drilling Bolt Circle = 1.6 mm | Bolt Hole Spacing = ± 0.8 mm Eccentricity of Bolt Circle with Respect to Facing ≤ 2½ = 0.8 mm max. | ≥ 3 = 1.6 mm max. |
| Thickness ≤ 18 = + 3.2 mm / – 0 | ≥ 20 = + 4.8 mm / – 0 | Length thru Hub ≤ 18 = + 3.2 mm / – 0.8 mm | ≥ 20 = + 4.8 mm / – 1.6 mm |
The chart provides details of pressure ratings of flanges to withstand different temperature ranges. This help in picking the right flange for high-pressure or heat-based systems.
| Temp. ℃ | Pressure-temperature rating for ASME B16.47 by class, bar | |||||
| 75 | 150 | 300 | 400 | 600 | 900 | |
| -29 to 38 | 10.0 | 20.0 | 51.7 | 68.9 | 103.4 | 155.1 |
| 50 | 9.8 | 19.5 | 51.7 | 68.9 | 103.4 | 155.1 |
| 100 | 8.8 | 17.7 | 50.7 | 67.5 | 101.3 | 152.0 |
| 150 | 7.9 | 15.8 | 45.9 | 61.2 | 91.9 | 137.8 |
| 200 | 6.9 | 13.8 | 42.7 | 56.9 | 85.3 | 128.0 |
| 250 | 6.0 | 12.1 | 40.5 | 53.9 | 80.9 | 121.4 |
| 300 | 5.1 | 10.2 | 38.9 | 51.8 | 77.7 | 116.6 |
| Temp, ℃ | Pressure-temperature rating for ASME B16.5 by class, bar | ||||||
| 150 | 300 | 400 | 600 | 900 | 1500 | 2500 | |
| -29 to 38 | 20.0 | 51.7 | 68.9 | 103.4 | 155.1 | 258.6 | 430.9 |
| 50 | 19.5 | 51.7 | 68.9 | 103.4 | 155.1 | 258.6 | 430.9 |
| 100 | 17.7 | 50.7 | 67.5 | 101.3 | 152.0 | 253.3 | 422.2 |
| 150 | 15.8 | 45.9 | 61.2 | 91.9 | 137.8 | 229.6 | 382.7 |
| 200 | 13.8 | 42.7 | 56.9 | 85.3 | 128.0 | 213.3 | 355.4 |
| 250 | 12.1 | 40.5 | 53.9 | 80.9 | 121.4 | 202.3 | 337.2 |
| 300 | 10.2 | 38.9 | 51.8 | 77.7 | 116.6 | 194.3 | 323.8 |
| Nominal Pipe Size (NPS) | Outside Diameter (OD) mm | Pressure Class (LB) | Typical Thickness (mm) |
|---|---|---|---|
| ½″ (DN15) | 90 | 150 / 300 / 600 | 11.2 – 14 |
| 1″ (DN25) | 115 | 150 / 300 / 600 | 12.7 – 16 |
| 2″ (DN50) | 150 | 150 / 300 / 600 | 15.9 – 20 |
| 3″ (DN80) | 190 | 150 / 300 / 600 | 19.1 – 22 |
| 4″ (DN100) | 229 | 150 / 300 / 600 | 22.2 – 24 |
| 6″ (DN150) | 279 | 150 / 300 / 600 | 25.4 – 28 |
| 8″ (DN200) | 343 | 150 / 300 / 600 / 900 | 28.6 – 32 |
| 10″ (DN250) | 406 | 150 / 300 / 600 / 900 | 30.2 – 36 |
| 12″ (DN300) | 483 | 150 / 300 / 600 / 900 | 31.8 – 38 |
| 14″ (DN350) | 533 | 150 / 300 / 600 / 900 | 34.9 – 42 |
| 16″ (DN400) | 597 | 150 / 300 / 600 / 900 | 36.5 – 45 |
| 18″ (DN450) | 635 | 150 / 300 / 600 / 900 | 39.7 – 48 |
| 20″ (DN500) | 698 | 150 / 300 / 600 / 900 | 42.9 – 52 |
| 24″ (DN600) | 813 | 150 / 300 / 600 / 900 | 47.7 – 58 |
| 26″ – 48″ (DN650–DN1200) | 850 – 1600 | 150 / 300 / 600 / 900 (B16.47 A/B) | 50 – 75+ |
Duplex Steel UNS S31803 Flanges Grades We Offer
Duplex Steel UNS S31803 vs UNS S32205 Flanges – Grade Difference Explained
Both UNS S31803 and UNS S32205 are duplex stainless steels, but S32205 is an improved version with slightly better chemical balance. Duplex Steel UNS S31803 Flanges are suitable for broad applications in the oil and gas, water treatment, refinery, and construction sectors. They offer strength, corrosion resistance, and cost. S32205 flanges are used in systems that experience more harsh conditions or stress corrosion. While 2205 duplex (S32205) is more durable in harsh situations, S31803 flanges provide consistent performance in stable environments. For the majority of industrial applications, S31803 remains a low-cost and dependable alternative.
Manufacturing Process of Duplex Steel UNS S31803 Flanges
Our Duplex Steel UNS S31803 Flanges are manufactured utilizing cutting-edge technology to ensure the highest quality. We begin by carefully selecting duplex-grade raw materials. The technique entails cutting, heating and creating the desired shapes. Welding is done using approved processes. The flanges are then heat treated to boost their strength and corrosion resistance. The surface is polished to guarantee a smooth seal. We conduct quality tests and inspections to maintain consistency. Prior to shipment, final testing confirm that the flanges meet ASTM A182 and ASME SA182 requirements.
Plate
Shear
Press
Inspection
Lathe
Drilling
Cleaning
Flange
Inspection
Analytic
Marking
Packing & Shipping
Our Packaging Process
Duplex steel UNS S31803 Flanges are packed with export-grade materials to prevent damage during handling and shipping. Common methods include HDPE wrapping, shrink wrapping, hardwood containers and end protection caps. Labeling contains product grade, size, standards, and heat numbers for simple identification. We arrange local deliveries by road and rail, and exports by sea or air. We ensure fast shipment of bulk orders and urgent requests. In-stock goods ship the same day, however custom flanges have a set schedule. Documents such as test certificates, invoices and export paperwork are included. We also adhere to specific customer or international packaging standards as needed.
Duplex Steel UNS S31803 Flanges Application
Duplex Steel UNS S31803 Flanges are used in industries that demand reliable connections in harsh environments. In the petrochemical sector, these flanges are used in high-pressure lines and process equipment. Oil and gas industries utilize them for offshore rigs and pipelines. In power generation, they connect heat exchangers and boilers. The chemical and petrochemical industry uses these flanges for reactors and processing units. Offshore platforms and marine environments benefit from their strength against seawater and salt exposure.
Why Choose Us
Midland Alloys is a leading manufacturer and supplier of Duplex Steel UNS S31803 Flanges with a trusted global presence. We offer custom sizes, meet global quality norms, and deliver on time—every time. With advanced manufacturing units, certified materials, and strict inspection checks, our products meet international standards. We serve a wide range of industries with consistent quality and quick turnaround. Our export-grade packaging, competitive pricing, and full traceability make us a reliable choice. Certification like ISO and test reports ensure every flange is high-quality, and ready for use.
FAQ
S32205 is a refined version of S31803 with better chemical balance for tougher environments. S31803 is ideal for general use.
UNS stands for Unified Numbering System. It assigns a unique code to metals, like S31803 for duplex stainless steel.
Yes. Duplex S31803 flanges can be welded using standard procedures suited for duplex stainless steel.
