TTV Ductile Iron Wafer Aluminium Bronze Disc TTV Butterfly ValvesNow Fully WRAS Approved Valve & EPDM Seat TTV Ductile Iron Wafer Butterfly Valves with Aluminium Bronze Disc & EPDM Seat The TTV Ductile Iron Wafer Butterfly Valve with Aluminium Bronze Disc is now fully WRAS approved, including both the EPDM seat and the complete valve assembly. This makes it a certified solution for use in potable water systems, while still offering the strength and corrosion resistance needed for tougher industrial environments.