Duplex2205 ASTM A790 UNS S31803 Duplex Stainless Steel Seamless Pipe For Seawater System
UNS S31803 is a 22% chromium duplex stainless steel, commonly known as 2205 duplex stainless steel. It has a two-phase microstructure consisting of roughly equal amounts of austenite and ferrite, combining high mechanical strength with excellent resistance to chloride stress corrosion cracking, pitting, and general corrosion. Duplex stainless steel features a balanced dual-phase microstructure, roughly 50% ferrite and 50% austenite after solution annealing. This dual-phase structure combines the benefits of ferritic stainless steel (high strength, chloride stress corrosion cracking resistance) and austenitic stainless steel (toughness, weldability). Seamless pipe means it is produced without longitudinal weld seams, manufactured via hot extrusion, piercing and cold drawing processes, offering superior structural integrity for critical pressure and corrosive environments.
Chemical Composition (ASTM A790, UNS S31803, Weight %):
| C |
Mn |
P |
S |
Si |
Cr |
Ni |
Mo |
N |
| ≤0.030 |
≤2.00 |
≤0.030 |
≤0.020 |
≤1.00 |
21.0–23.0 |
4.5–6.5 |
2.5–3.5 |
0.08–0.20 |
Mechanical Properties:
| Tensile Strength, Rm |
≥620 MPa (≥90 ksi) |
| Yield Strength (0.2% offset), Rp0.2 |
≥450 MPa (≥65 ksi) |
| Elongation (50 mm gauge length) |
≥25% |
| Hardness |
≤290 HB |
Main Features of ASTM A790 UNS S31803 Duplex Stainless Steel Seamless Pipes:
High mechanical strength
Excellent chloride corrosion resistance
Good weldability
Moderate low-temperature toughness
Good general corrosion resistance in many acids and alkalis
Good fatigue resistance
Good toughness at low temperatures
Main Applications:
Oil and gas: offshore platforms, subsea manifolds, flowlines, risers, umbilicals, downhole tubulars.
Chemical and petrochemical: heat exchangers, pressure vessels, reactors, columns, process piping.
Desalination and seawater systems: reverse osmosis plants, brine lines, seawater cooling, intake/outfall piping.
Pulp and paper: digesters, bleach plants, liquor lines.
Flue gas desulfurization, FGD: scrubbers, absorber towers, slurry piping.
Fertilizer and phosphoric acid plants.
Food, pharmaceutical, and high-purity systems when supplied bright annealed, polished, or electropolished.
Storage tanks, pressure vessels, and structural components requiring high strength and corrosion resistance.
Power generation
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