Harry Fittings, based in Houston, USA, stands out as a top-notch manufacturer and supplier of Duplex Steel S31803 Pipe Fittings, designed to excel in high-stress and corrosive settings. This nitrogen-enhanced duplex stainless steel merges the best traits of ferritic and austenitic structures, providing impressive strength, outstanding corrosion resistance, and good weldability. Harry Fittings offers a diverse selection of buttweld pipe fittings—including elbows, tees, reducers, and caps—that meet ASME B16.9, ASTM A815, and various international standards. These fittings are perfect for critical applications across industries like oil & gas, marine, chemical processing, and power generation.
Specifications ASTM A815 / ASME SA815
Dimensions ASME/ANSI B16.9, ASME B16.28, MSS-SP-43
Size 1/2″ NB to 24″NB in
Type Seamless / Welded / Fabricated
Bending Radius R=1D, 2D, 3D, 5D, 6D, 8D, 10D or Custom
Thickness Sch 5s, Sch 10s, Sch 40s, Sch 80s, Sch 160s, Sch XXS
Duplex Steel S31803 Pipe Fittings from Harry Fittings are made up of about 21–23% chromium, 4.5–6.5% nickel, 2.5–3.5% molybdenum, along with nitrogen and manganese. This well-balanced composition boosts their resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking. They deliver exceptional mechanical strength, featuring a yield strength of around 450 MPa and a tensile strength of about 620 MPa—nearly double that of standard stainless steels. These fittings maintain toughness across a broad temperature range and undergo rigorous testing for mechanical integrity, corrosion resistance, and dimensional accuracy, ensuring they are dependable for high-demand systems.
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | Fe |
| S31803 | 0.030 max | 2.00 max | 1.00 max | 0.030 max | 0.020 max | 22.0 – 23.0 | 3.0 – 3.5 | 4.50 – 6.50 | 0.14 – 0.20 | 63.72 min |
| Grade | Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| S31803 | 7.8 g/cm3 | 1350 °C (2460 °F) | Psi – 116000 , MPa – 800 | Psi – 80000 , MPa – 550 | 15 % |
Harry Fittings is a leading supplier of Duplex Steel S31803 Pipe Fittings in Houston, USA. We offer an extensive range of Monel K500 fittings, renowned for their excellent corrosion resistance and high strength, which makes them perfect for demanding industrial applications like chemical processing, marine environments, and high-temperature systems. With a commitment to quality and reliable delivery, we ensure our clients receive top-tier products tailored to meet the specific needs of various industries.
We provide products that come with both mill test certificates and third-party test certificates, ensuring the highest standards of quality and compliance.
| STANDARD | UNS | WERKSTOFF NR. |
| Duplex 2205 | S31803 | 1.4462 |
Duplex Steel S31803 Pipe Fittings from Harry Fittings offer exceptional corrosion resistance, especially in seawater and harsh environments. They are known for their high strength, durability, and resistance to pitting and crevice corrosion, ensuring long-lasting performance. We provide precise manufacturing, quality control, and reliable service for diverse industrial applications.
Duplex Steel S31803 pipe fittings offer exceptional corrosion resistance, particularly against pitting, crevice corrosion, and stress corrosion cracking, making them ideal for harsh environments. They provide high strength and excellent resistance to fatigue, making them durable under pressure. The alloy’s good weldability and formability enhance the ease of fabrication. Duplex Steel S31803 pipe fittings also offer superior toughness and stress resistance, ensuring reliability in demanding applications such as chemical processing, marine, and oil & gas industries. Their cost-effectiveness and long-lasting performance make them a preferred choice for critical piping systems.
| Outer Diameter And Inside Diameter | Equivalent | Diameter Of Pipe Nominal | Typical Threads In Inches |
| 5/16 | 0.313 | 1/16 | 27 |
| 13/32 | 0.405 | 1/8 | 27 |
| 35/64 | 0.540 | 1/4 | 18 |
| 43/64 | 0.675 | 3/8 | 18 |
| 27/32 | 0.840 | 1/2 | 14 |
| 1-3/64 | 1.050 | 3/4 | 14 |
| 1-5/16 | 1.315 | 1 | 11-1/2 |
| 1-21/32 | 1.660 | 1-1/4 | 11-1/2 |
| 1-29/32 | 1.900 | 1-1/2 | 11-1/2 |
| 2-3/8 | 2.375 | 2 | 11-1/2 |
| 2-7/8 | 2.875 | 2-1/2 | 8 |
| 3-1/2 | 3.500 | 3 | 8 |
| 4 | 4.000 | 3-1/2 | 8 |
Yes, custom sizes for Duplex Steel S31803 Pipe Fittings are available at Harry Fittings. We offer tailored solutions to meet your specific requirements, ensuring optimal performance for your projects. For more information, please contact us at sales@harryfittings.us.
Duplex Steel S31803 Pipe Fittings from Harry Fittings find extensive use in chemical processing, offshore oil rigs, marine systems, desalination plants, and the pulp and paper industry. Renowned for their remarkable resistance to chloride stress corrosion and robust mechanical performance, these fittings are ideal for seawater piping, pressure vessels, heat exchangers, process piping, and storage tanks. Their impressive strength-to-weight ratio and corrosion resistance minimize maintenance requirements and extend service life in challenging environments.
Get in touch with one of our Technical Sales Representatives to request a quote or get answers to any questions you may have.








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