Duplex Steel S31803 S32205 Welded Seamless Pipe Anti-Corrosion ASME SA790

Duplex Steel S31803 S32205 Welded Seamless Pipe Anti-Corrosion ASME SA790

1. Product Description 

Duplex stainless steel pipe is a manufactured product whose final properties are determined as much by the production route as by the chemical composition. The manufacturing process begins with electric-arc melting (EAF) followed by AOD or VOD refining to achieve tight compositional tolerances, particularly for nitrogen, carbon, and sulfur. The refined molten steel is continuously cast or ingot-cast, then processed via either hot extrusion or piercing (Mannesmann process) to produce hollow shells. These shells undergo multiple cold-drawing or cold-rolling passes with intermediate solution annealing to achieve final dimensions and surface quality. Welded pipes are produced from cold-rolled coils formed into tubular shapes and welded longitudinally (TIG/Laser/SAW) without the addition of filler metal, followed by full-body solution annealing. Every production batch is accompanied by a comprehensive manufacturing process record, including melting, forming, heat treatment, and finishing parameters.

2. Product Applications

In addition to mainstream applications, duplex pipes are increasingly selected as a cost-effective substitute for more expensive or less durable materials in the following contexts:

• Subsea manifolds and jumper spools – replacing CuNi 90/10 alloys, offering comparable seawater corrosion resistance with higher strength and lower weight.

• High-temperature brine reject lines – in desalination plants, replacing titanium grades (e.g., Gr.2) for brine temperatures up to 70°C where titanium is over-specified.

• Offshore platform structure-integrated piping – utilizing the high strength to serve dual structural and fluid-conveying functions, eliminating separate support beams.

• Acid mine drainage (AMD) treatment plants – replacing rubber-lined carbon steel, eliminating lining degradation and maintenance shutdowns.

• FPSO topside modular piping – where weight reduction directly translates to increased payload capacity and fuel savings.

• Green hydrogen production electrolyzer balance-of-plant – for oxygen and hydrogen wet gas streams with trace alkaline or acidic carryover.

​3. Product Advantages 

• Superior to CuNi 70/30 & 90/10 – duplex offers 3–5× higher yield strength, higher allowable flow velocity (30 m/s vs. 3–5 m/s for CuNi), and lower material density, resulting in significantly lighter piping systems for equivalent seawater service.

• Cost-effective alternative to Ti Gr.2 – in non-extreme chloride environments (e.g., seawater < 70°C), duplex provides comparable crevice corrosion resistance at approximately one-third the material cost of titanium.

• Outperforms 6Mo super-austenitic grades (e.g., 254SMO) – in terms of yield strength (450 MPa vs. 300 MPa), while offering similar PREN and lower nickel content, leading to better price stability.

• Superior weld metal toughness compared to carbon steel – no preheating generally required for wall thicknesses ≤ 20mm, reducing welding cycle time and consumable costs.

• Excellent machinability in the solution-annealed condition – despite higher strength, duplex can be machined with standard carbide tools at moderate speeds.

• Easily inspectable with standard NDT methods – magnetic permeability allows magnetic particle inspection (MPI) for surface defects, a clear advantage over fully austenitic grades.

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4.​Key Specifications

FAQ

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2.How long is your delivery time? Generally it is 5-10 days if the goods are in stock. or it is 15-20 days if the goods are not in stock, it is according to quantity.

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