Double Flanged Butterfly Valve

Double Flanged Butterfly Valve – Integral Flanges for Large Diameter & High-Pressure Applications

Double-flanged butterfly valves incorporate integral raised-face or ring-type-joint flanges as part of the valve body casting, providing the highest pressure ratings, most robust construction, and maximum installation flexibility among butterfly valve configurations. This traditional design dominates large-diameter applications (DN 300-3600) common in African municipal water transmission, power plant cooling systems, and HVAC installations where the valve body serves as a spool piece replacing an equivalent length of flanged pipe.

Structural advantages emerge from integral flange design: pressure containment occurs entirely within the valve body rather than relying on compression between pipe flanges (wafer) or threaded lugs (lug style). This enables pressure ratings to PN 63 (ANSI 600) in larger sizes and provides maximum resistance to piping stresses, thermal expansion, and seismic loading critical for African infrastructure projects in seismically active regions and installations subject to thermal cycling from desert temperature extremes.

Installation methodology differs fundamentally from wafer and lug designs: double-flanged valves install identically to flanged pipe spools, with gaskets positioned between valve flanges and mating pipe flanges. This familiar installation approach simplifies training for African contractors, reduces installation errors, and enables valve removal for maintenance or replacement without disturbing adjacent piping—the valve body itself absorbs all loads without transferring stresses to surrounding pipe supports.

Economic considerations favor double-flanged configurations in specific scenarios despite 50-80% higher cost versus wafer designs: applications requiring frequent valve removal for inspection (water treatment filter isolation), high-pressure service exceeding PN 25 (PN 40, 63), and installations where valve serves dual purpose as pipeline spool piece reducing total project costs. Large-diameter African water projects (DN 600-2400) often specify double-flanged butterfly valves for trunk main isolation where the valve cost represents minimal percentage of total pipeline investment while providing maximum reliability and maintenance access.