The Intercem changeover flaps or Intercem double tipping flaps are used for continuous metering, blocking and discharging of bulk materials. Furthermore, Intercem butterfly valves are manufactured for cement preheaters, which prevent counter gas flow through material pipes between two stages of the preheater. The flexible design of the flaps enables reliable guiding and separation of free-flowing bulk materials from and into pressure difference chambers (e.g. filter systems). Double flaps are operated pneumatically, electrically or mechanically. The welded construction makes the valves lighter than cast iron and less expensive. The design is adapted to the conditions and can be designed to be highly resistant to wear.