... chemical resistance b.High temperature resistance c. Excellent weather and water resistance Double Flange Butterfly Valve: SizeDN40 - DN1400Design ... can produce butterfly valves, check valves, gate valves and so on with the materials of ductile iron, carbon steel, ... in accordance with the standards of GB, ASME, ANSI, API, BS, DIN, JIS etc. various high quality Double Flange Butterfly valve