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ASTM A790 UNS S31803
ASTM A790 UNS S31803 is a specification for duplex steel material. The material is an alloy of steel with chromium and molybdenum. The addition of these materials makes the pipes stronger and much more corrosion resistant. The SA 790 UNS S31803 is one of the super duplex grades which is stronger and more corrosion resistant. The duplex grades are divided into three groups as duplex, lean and super duplex. The super duplex is used for special applications operating at elevated temperatures. Duplex UNS S31803 pipe also has increased strength due to the way it is manufactured. The material can be hot rolled and welded or cold drawn. The cold-drawn tubes are seamless and have less absolute roughness, making them dimensionally accurate. The hot rolled and welded A928 UNS S31803 material, on the other hand, is much stronger and could be used in welding applications. The ease of welding in ASTM A790 UNS S31803 pipe makes it a choice for high pressure applications where extensive welding is required at installation.
SA 790 UNS S31803 tubing is also highly corrosion resistant in seawater and other chloride ion rich environments. This resistance to chloride ion corrosion stress cracking makes it one of the most cost effective solutions over the long term. Duplex 31803 seamless tubing is used in highly sensitive applications where measurements must be accurate. However, the seamless nature reduces the strength compared to Duplex UNS S31803 Welded Tubes.
Applications for A790 gr S31803 DSS ERW tubing can be found in seawater and marine environments, chemical industries, food processing plants, heat generators, automotive components, boiler parts and other high temperature applications. For less specific application requirements, the electrofusion welded Duplex S31803 UNS EFW pipes can also be used interchangeably.
About ASTM A789 and ASTM A790 Duplex Steel S31803
| Chemical Composition % | ||||
| Cr | Ni | Mo | C | N |
| 22.0-23.0 | 4.50-6.50 | 3.00-3.50 | .030 Max | 0.14-0.20 |
| Mn | Si | P | S | Fe |
| 2.00 Max | 1.00 Max | .030 Max | .020 Max | Balance |
ASME SA790 UNS S31803 Pipe Mechanical Characteristics
| Melting Point | Density | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| (2460 °F) 1350 °C | 7.8 g/cm3 | MPa – 800, Psi – 116000 | MPa – 550, Psi – 80000 | 15 % |
ASTM A790 Equivalent UNS S31803 Welded Tube
| PIPE STANDARD | UNS | WERKSTOFF NR. |
| UNS S31803 Pipe | S31803 | 1.4462 |
