A plug-in connection system for fluid-conducting components of fire extinguishing systems that has a first component having an outer peripheral surface and a first recess in the peripheral surface, and a second component having an inner peripheral surface and a second recess in the inner peripheral surface, wherein the first and the second component can be plugged into one another such that the recesses lie opposite one another and define a locking element channel. A locking element which can be inserted into the locking element channel until an interlock position is reached and at least part of which engages in both recesses in the interlock position. A locking element safety device is provided for reversibly releasably securing the locking element on the first and/or second component.