An actuator system is provided for operating a flow regulating element, e. g. a flap or a valve shutter for regulating a fluid flow in a fluid transportation pipe. The actuator system may include an actuator having an actuating motor coupled to a pivotable shaft of the flow regulating element which projects from the wall of the pipe. The actuator system has at least one attachment component for attachment of the attachment component to the wall of the fluid transportation pipe. The actuator and the attachment component(s) are configured as a modular system.