Duplex 2205 Seawater Desalination Concentric Reducer DN250

Seawater desalination trains expose every concentric reducer to chlorides at ambient temperature — precisely the condition where 316L pits and duplex 2205 does not. This concentric reducer is produced from UNS S31803 / S32205 plate with a PREN above 34, solution annealed and water quenched to hold a balanced ferrite and austenite structure.

In a reverse osmosis train, the concentric reducer sits between the high-pressure pump discharge and the membrane rack header, where velocity is high and turbulence at the size change accelerates pitting. Because duplex 2205 has roughly twice the yield strength of 316L, the same DN250 x DN200 concentric reducer can be supplied in a thinner wall without losing pressure capability, which reduces weight on the rack.

• Chloride resistance: the PREN above 34 gives the concentric reducer a critical pitting temperature well above what seawater at ambient temperature demands.
• Strength advantage: duplex 2205 carries about twice the yield of 316L, so wall thickness and support weight on the RO rack can be reduced without changing the rating.
• Balanced microstructure: solution annealing and water quenching keep ferrite between 40 and 60 percent, which is what preserves both toughness and stress corrosion resistance.
• Verified corrosion performance: ASTM G48 Method A testing is available per heat for projects that require documented pitting resistance.
• Application fit: seawater desalination intake headers, RO high-pressure trains, brine discharge lines, cooling water systems and offshore utility piping.