Duplex Stainless Steel Gate Valve DN100: Price & Selection for Seawater Desalination
gate valves In high‑chloride environments like seawater desalination and offshore platforms, duplex stainless steel (2205/2507) offers superior resistance to chloride stress corrosion cracking and pitting, with yield strength roughly double that of 316L. DN100 (4″) is a common size for RO systems and high‑pressure pump discharge lines.The main gate valves product names of China gate Valve Network include:,Electric Wafer Knife-shaped Gate Valve,Electro-hydraulic Wafer Knife-shaped Gate Valve,Electric Slurry ValveElectric Flange Gate Valve,Fire Special Signal Relisient Seat Seal Gate Valve,Fire Special Rising Stem Resilient Seat Seal Gate Valve,Forged Steel Socket Welding Valve,Forged Steel Flange Gate Valve,
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2026 Price Reference (USD, ex‑works)
| Material | Pressure | Price (USD) |
|---|---|---|
| 2205 (S32205) | PN16 | 220–320 |
| 2507 (S32750) | PN16 | 350–480 |
Prices vary by brand and certification. Bulk orders (3+ pcs) save 10–15%.
Why Duplex for Desalination?
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Excellent chloride resistance – 22% Cr, 2.5% Mo, 4.5% Ni; far outperforms 316L.
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High resistance to stress corrosion cracking – superior to austenitic stainless steel.
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Higher strength – allows thinner walls, reducing pipe load by 30–50%.
Key Selection Parameters
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Material grade: 2205 (S32205) for general seawater; 2507 (S32750) for higher pressure or aggressive conditions.
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Design: Rising stem wedge gate (Z41W) for visual indication.
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Connection: Flanged to GB/T 9113 or HG/T 20592, RF facing.
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Seat: Direct machined or hardfaced.
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Packing: Flexible graphite for seawater service.
Installation & Maintenance
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Bidirectional – no flow direction restriction.
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Insulate – use insulating gaskets when connecting to carbon steel to prevent galvanic corrosion.
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Cycle – manually operate fully open/close quarterly to prevent sticking.
Procurement Checklist
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DN100, pressure PN16 or Class 150
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Material 2205 or 2507 (with mill certificate)
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Flange standard & bolt circle (match site piping)
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Seat finish (machined or hardfaced)
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Third‑party or class society certification if required
Bottom Line
A DN100 2205 duplex gate valve costs USD 220–320 in 2026. Choose 2205, flanged rising stem, and flexible graphite packing – reliable for over 10 years in desalination service.
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