ASTM A790 UNS S31803 Seamless Pipe

ASTM A790 UNS S31803 Seamless Pipe, this alloy features a balanced microstructural composition: approximately 50% ferrite and 50% austenite. This dual-phase matrix provides distinct engineering advantages, particularly for critical pipeline construction projects facing high-chloride stresses or deep-sea environments. HT PIPE is a SS2205 Pipe supplier with 15+ export experience. Contact us for more information and quotes for free!

ASTM A790 UNS S31803 Pipe Specifications

Specifications	ASTM A 789 / ASME SA 789 ASTM A 790 / ASME SA 790
Types	Seamless / Welded / EFW / Fabricated
Pipe Range	1 / 2" NB - 8" NB
Outer Diameter	6.0 - 630mm
Wall Thickness	0.3mm – 50 mm
Schedules	SCH5, SCH20, SCH30, SCH40, STD, SCH60, SCH80, XS, SCH120, SCH140, SCH160, XXS
Length	Single Random, Double Random & Required Length
Form	Round Pipes, Square Pipes, Rectangular Pipe, "U" Shape, Hydraulic Pipes
End	Plain End, Beveled End, Treaded

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Duplex UNS S31803 Material Chemical Composition

Element	Content (%)
Molybdenum, Mo	2.50-3.50
Manganese, Mn	2.0
Silicon, Si	1.0
Nitrogen, N	0.080-0.20
Iron, Fe	63.75-71.92
Chromium, Cr	21.0-23.0
Nickel, Ni	4.50-6.50
Carbon, C	0.030
Phosphorous, P	0.030
Sulfur, S	0.020

 

Seamless vs. Welded Manufacturing

The deployment environment determines whether an engineer should specify a seamless or welded configuration for an installation.

ASTM A790 UNS S31803 Seamless Pipe

Manufactured through hot extrusion or rotary piercing without a longitudinal seam, seamless variants ensure complete geometric uniformity. They are ideal for high-pressure industrial applications, sour gas transport, and deep-well downhole lines where the risk of joint failure must be entirely eliminated.

 

ASME SA789 / SA928 Welded and EFW Pipes

Formed from rolled strip steel and joined using automated autogenous or filler-metal welding practices (typically utilizing over-alloyed 2209 filler material to offset alloy segregation), welded pipes offer a more economical path for larger outer-diameter dimensions. Electric Fusion Welded (EFW) variations undergo rigorous non-destructive volumetric testing-including radiography and ultrasonic sweeps-to guarantee joint performance in lower-pressure distribution networks, wastewater treatment facilities, and desalination headers.

 

Typical Applications

Chemical and Petrochemical: Acetic, sulfuric, and phosphoric acid plants, cracked gas quenching systems in ethylene plants and organic synthesis processes containing chlorides.

Marine Engineering and Seawater Desalination: Seawater cooling piping systems, preheaters, pumps, and piping in seawater desalination plants; and high-pressure seawater systems on ships.

Flue Gas Desulfurization (FGD) Systems: Wet areas most susceptible to corrosion, such as the absorber spray layer, demister, and outlet flue.

Paper Industry: Equipment and piping in the pulp bleaching process (ClO₂ environment).

Pharmaceutical and Food Industries: Demanding process steps requiring extreme cleanliness and corrosion resistance.

Environmental Protection: Wastewater treatment, particularly for industrial wastewater containing high levels of chlorides, sulfides, or acidic components.

 

 

 

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