A duplex steel butterfly valve (seawater-grade butterfly valve) is a high-performance quarter-turn rotary valve featuring pressure-retaining bodies and discs fabricated from duplex or super duplex stainless steel. Its balanced austenitic-ferritic microstructure combines the superior corrosion resistance of austenitic steel with the high tensile strength and stress corrosion cracking resistance of ferritic steel. Conforming to standards like API 609 and ASME B16.34, these compact valves utilize concentric, double-offset, or triple-offset disc configurations to provide reliable isolation and throttling in aggressive, chloride-rich environments. The two primary material specifications are standard duplex 2205 (ASTM A182 F51) with a Pitting Resistance Equivalent Number (PREN) of 35 for brackish cooling loops, and super duplex 2507 (ASTM A182 F53) with a PREN of 43 to handle continuous high-salinity seawater without pitting. Desalination plant contractors and offshore procurement networks can maximize system lifecycle and eliminate chloride pitting by importing certified duplex steel butterfly valves directly from leading manufacturers in China via our advanced B2B commercial platform.
