ASTM A790 / ASME SA790 UNS S31803 Duplex Steel Seamless And Welded Pipe For Boiler
ASTM A790 S31803 Duplex Steel Pipe
Overview
ASTM A790 is the designation for the standard specification for seamless and welded ferritic/austenitic stainless steel pipe. It covers pipes intended for general corrosive service and high-temperature service.
S31803 is the grade designation for the duplex stainless steel alloy specified in ASTM A790. It is also known as UNS S31803 or duplex 2205. The "S" prefix indicates a stainless steel material, and "31803" is the Unified Numbering System (UNS) designation for this particular alloy.
ASTM A790 S31803 is a specification that covers seamless and welded ferritic/austenitic stainless steel pipes for general corrosive service and high-temperature service. S31803 is the grade designation for a duplex stainless steel alloy specified in ASTM A790.Duplex stainless steels like S31803 offer a combination of properties from both austenitic and ferritic stainless steels, including high strength, excellent corrosion resistance, and good weldability. This makes them suitable for a wide range of applications, particularly in corrosive environments found in industries such as oil and gas, chemical processing, and marine engineering.
Chemical Composition of ASTM A790 S31803
| Grade | C | Mn | S | P | Si | Ni | Cr | Mo | N | |
| S31803 | Min | 4.5 | 21.0 | 2.5 | 0.08 | |||||
| Max | 0.03 | 2.0 | 0.02 | 0.03 | 1.0 | 6.5 | 23.0 | 3.5 | 0.20 |
Mechanical Properies of ASTM A790 S31803
| Grade | Tensile Str Ksi(Mpa) | Yield Str Ksi(Mpa) | Elongation(%) | Brinell(HBW) | Rockwell C(HRC) |
| S31803 | ≥90(620) | ≥65(450) | ≥25 | ≥290 | ≥30 |
Wall Thickness Tolerance os ASTM A790
| OD Range | t/D Ratios | Wall Thickness Tolerance | |
| Under(-) | Over(+) | ||
| 1/8"~2 1/2" (Incl.) | All | 12.5% | 20% |
| 3"~18" (Incl.) | t/D up to 5% Incl. | 12.5% | 22.5% |
| >18" (Incl.) | t/D up > 5% Incl. | 12.5% | 15% |
| >18" Welded | All | 12.5% | 17.5% |
| >18" Seamless | t/D up to 5% Incl. | 12.5% | 22.5% |
| t/D up > 5% Incl. | 12.5% | 15% | |
Applications of ASTM A790 S31803 Pipe
Oil and Gas Industry: S31803 pipes are extensively used in the oil and gas industry for transporting hydrocarbons, both onshore and offshore. They are suitable for applications such as flowlines, pipelines, risers, and subsea structures due to their excellent corrosion resistance, high strength, and resistance to stress corrosion cracking in chloride-rich environments.
Chemical Processing: In chemical processing plants, where corrosive chemicals and solutions are handled, S31803 pipes are employed for conveying fluids and gases. They offer resistance to corrosion by various acids, alkalis, and organic compounds, making them suitable for applications such as chemical reactors, storage tanks, and process piping.
Desalination Plants: S31803 pipes are used in desalination plants for seawater intake and brine discharge pipelines. These pipes withstand the corrosive nature of seawater and offer high strength and durability, making them essential for the production of fresh water through reverse osmosis and other desalination processes.
Pulp and Paper Industry: In the pulp and paper industry, where corrosive chemicals and high temperatures are common, S31803 pipes are utilized for conveying pulp, bleaching agents, and process fluids. They offer resistance to corrosion by bleach liquor, chlorine dioxide, and other aggressive chemicals, making them suitable for applications such as pulp digesters, bleach towers, and paper machine piping.
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