ASTM A790 UNS 31803 Duplex Steel Seamless Pipe For Marine Environments
Jan 15, 2026
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GNEE is a professional exporter of high-quality duplex stainless steel pipes. We have been specializing in exporting S31803/S32205 (2205, EN 1.4462) series stainless steel pipes for 19 years and have consistently received praise from our customers!
We supply high-quality ASTM A790 UNS 31803 seamless pipes, which perform exceptionally well in seawater environments, with a PREN of 32-35. The corrosion rate in a 3.5% NaCl solution (simulated seawater) is ≤0.08 mm/year, and its pitting corrosion resistance is 2-3 times higher than 316L, and its resistance to marine atmospheric corrosion is more than 5 times better than 304; it complies with NACE MR 0175/ISO 15156 standards and is resistant to crevice corrosion and chloride stress corrosion cracking in tidal zones.
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Is S31803 the same as 2205?
UNS numbers S31803 and S32205 represent alloys with more characteristics in common than distinct differences. Firstly, they are both stainless steels with similar elemental compositions. Both S31803 and S32205 belong to the duplex 2205 family, which means they comprise almost equal parts austenite and ferrite.
ASTM A790 UNS S3180 Compositions
| UNS No | AISI | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| S32205 | 2205 | 0.030 | 1.00 | 2.00 | 0.030 | 0.020 | 22.0/23.0 | 3.0/3.5 | 4.5/6.5 | N 0.14/0.20 |
Heat Treatment
The solution temperature is around 1100°C, and rapid cooling.
| UNS Designation | Temperature | Quench |
|---|---|---|
| S31803 | 1870-2010 °F [1020-1100°C] | Rapid Cooling In Air Or Water |
| S32205 | 1870-2010 °F [1020-1100°C] | Rapid Cooling In Air Or Water |
Tensile And Hardness Requirements
| Grade | Tensile Strength, Min., Ksi [MPa] | Yield Strength, Min., Ksi [MPa] | Elongation In 2 In., Or 50mm, Min, % | Hardness, Max Brinell |
|---|---|---|---|---|
| S31803 | 90 [620] | 65 [450] | 25 | 290 |
| S32205 | 95 [655] | 70 [485] | 25 | 290 |
ASTM A790 UNS 31803 Duplex Steel Seamless Pipe Applications
Offshore Oil & Gas: Platforms, pipelines, and processing equipment exposed to seawater.
Desalination Plants: Handling corrosive saltwater.
Water Treatment: Seawater cooling systems and pumps.
Marine Vessels: Components requiring high corrosion resistance and strength.
Pulp & Paper: Digesters and liquor tanks.
We supply UNS 31803 stainless steel cold-rolled tubes that conform to ASTM A790 and ANSI B36.19 standards, with outside diameters ranging from NPS 1/8 to NPS 30, and wall thickness schedules including Sch 5S, SCH10S, SCH40S, and SCH80S. Other sizes are available upon request. The dimensional tolerances of the ASTM A790 pipes shall conform to the requirements for outside diameter and wall thickness specified in ASTM A999. The pipes shall be pickled to remove scale. If bright annealing is used, pickling is not required.
Duplex steel S31803 type
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