Duplex and Super Duplex UNS S31803 Weld Neck Flanges

Duplex and Super Duplex UNS S31803 Weld Neck Flanges (WNF) are characterized by a long tapered hub that is butt-welded to the pipe. This design allows for the stress generated by pipe pressure to be transferred to the pipe itself, resulting in a robust, high-integrity connection suitable for demanding conditions. Manufactured from Duplex Stainless Steel (Alloy 2205 / UNS S31803), these flanges are widely used for critical, high-pressure, and high-temperature applications due to their exceptional mechanical strength and superior resistance to corrosion, particularly chloride stress corrosion cracking. Zeron Fastners supplies UNS S31803 Weld Neck Flanges to rigorous industry standards for use in oil and gas pipelines, chemical processing plants, and other major infrastructure projects.

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UNS S31803 Weld Neck Flanges

Duplex and Super Duplex UNS S31803 Weld Neck Flanges Chemical Composition

Element Content (%)
Carbon (C) 0.030 max
Manganese (Mn) 2.00 max
Silicon (Si) 1.00 max
Phosphorus (P) 0.030 max
Sulfur (S) 0.020 max
Chromium (Cr) 21.0 – 23.0
Nickel (Ni) 4.5 – 6.5
Molybdenum (Mo) 2.5 – 3.5
Nitrogen (N) 0.08 – 0.20

Duplex and Super Duplex UNS S31803 Weld Neck Flanges Mechanical Properties

Property Value
Tensile Strength (min) 620 MPa (90 ksi)
Yield Strength (0.2% Offset min) 450 MPa (65 ksi)
Elongation in 4D (min) 25%
Hardness (Brinell max) 290 HB

Duplex and Super Duplex UNS S31803 Weld Neck Flanges Feature Products